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İňđųčțįǿň Věřșųș ĐČ Břųșħŀěșș Mǿțǿřș Wally Rippel, Principal Power Electronics Engineer January 9, 2007

Wally Rippel is a long­time proponent of electric vehicles. Prior to joining Tesla Motors, he was an engineer at AeroVironment, where he helped develop the EV1 for General Motors and was featured in the documentary movie, Who Killed the Electric Car? Wally has also worked for the Jet Propulsion Laboratory on electric vehicle battery research, among other projects. In 1968, as a Caltech undergraduate student, he built an electric car (a converted 1958 Volkswagen microbus) and won the Great Transcontinental Electric Car Race against MIT.

One Size Does Not Fit All In that odious world of gas powered vehicles, engines are not all alike. There are flat­heads, Hemis, straight, opposed, and V configurations. And on and on. One would have thought that, years ago, someone would have figured out which was best. That would have ended all the choices and thereafter only the one best engine type would be in production. Not so. There is no one best engine type, rather there are different types of engines to suit personal requirements, such as price and performance. This is also true for electric vehicle drives.

Back when I had hair on my head and carried a slide rule, there were lead acid batteries, DC brush motors, and contactor controllers. Today, none of these remain (including my hair). Lead has been replaced by lithium and DC by either DC brushless or induction. Contactors, meanwhile, have given way to modulating inverters. So, will each of these elements also become obsolete in the near future or is it possible that some “stability” may be at hand? Without a good crystal ball, it is hard to predict the future. My guess, however, is that we will see both induction and brushless machines “duke it out” for many years to come. Each will have its loyal proponents and religious detractors.

A Closer Look So what are these two technologies? How do they work? What differentiates them? And what do they have in common? Let’s start with DC brushless drives.

With brushless machines, the rotor includes two or more permanent magnets that generate a DC magnetic field (as seen from the vantage point of the rotor). In turn, this magnetic field enters the stator core (a core made up of thin, stacked laminations) and interacts with currents flowing within the windings to produce a torque interaction between the rotor and stator. As the rotor rotates, it is necessary that the magnitude and polarity of the stator currents be continuously varied – and in just the right way ­ such that the torque remains constant and the conversion of electrical to mechanical energy is optimally efficient. The device that provides this current control is called an inverter. Without it, brushless motors are useless motors.

Let’s move on to induction motor drives. A forerunner of the 3­phase induction motor was invented by Nikola Tesla sometime before 1889. Curiously, the stators for the 3­phase induction motor and the DC brushless motor are virtually identical. Both have three sets of “distributed windings” that are inserted within the stator core. The essential difference between the two machines is with the rotor.

Unlike the DC brushless rotor, the induction rotor has no magnets – just stacked steel laminations with buried peripheral conductors that form a “shorted structure.” Currents flowing in the stator windings produce a rotating magnetic field that enters the rotor. In turn, the frequency of this magnetic field as “seen” by the rotor is equal to the difference between the applied electrical frequency and the rotational “frequency” of the rotor itself. Accordingly, an induced voltage exists across the shorted structure that is proportionate to this speed difference between the rotor and electrical frequency. In response to this voltage, currents are produced within the rotor conductors that are approximately proportionate to the voltage, hence the speed difference. Finally, these currents interact with the original magnetic field to produce forces – a component of which is the desired rotor torque.

When a 3­phase induction motor is connected to utility type 3­phase power, torque is produced at the outset; the motor has the ability to start under load. No inverter is needed. (Were an inverter needed, Tesla’s invention would have been useless until sometime in the 1960s.) The fact that induction motors are directly compatible with conventional utility power is the main reason for their success. In contrast, a brushless DC motor produces no starting torque when directly connected to fixed frequency utility power. They really need the aid of an inverter whose “phase” is maintained in step with the angular position of the rotor.

While 3­phase induction motors have great utility, they also have some severe limitations. They cannot operate from DC; AC is a must. Shaft speed is proportionate to line frequency. Hence, when used with utility power, they are constant speed machines. Finally, when operated from utility power, they have limited starting torque and somewhat limited running peak torque capabilities, when compared to DC type machines.

Add an inverter (without any feedback control) and it becomes possible to power an induction machine from a battery or other DC source; variable speed also becomes possible simply by adjusting the inverter frequency. Still, torque performance is low compared with DC machines. Add some feedback loops such that the inverter produces the exact frequency that the motor “desires,” and the induction motor is now capable of competing with DC and DC brushless for vehicle applications.

Brushless or Induction? Back in the 1990s all of the electric vehicles except one were powered by DC brushless drives. Today, all the hybrids are powered by DC brushless drives, with no exceptions. The only notable uses of induction drives have been the General Motors EV­1; the AC Propulsion vehicles, including the tzero; and the Tesla Roadster.

Both DC brushless and induction drives use motors having similar stators. Both drives use 3­ phase modulating inverters. The only differences are the rotors and the inverter controls. And with digital controllers, the only control differences are with control code. (DC brushless drives require an absolute position sensor, while induction drives require only a speed sensor; these differences are relatively small.)

One of the main differences is that much less rotor heat is generated with the DC brushless drive. Rotor cooling is easier and peak point efficiency is generally higher for this drive. The DC brushless drive can also operate at unity power factor, whereas the best power factor for the induction drive is about 85 percent. This means that the peak point energy efficiency for a DC brushless drive will typically be a few percentage points higher than for an induction drive.

In an ideal brushless drive, the strength of the magnetic field produced by the permanent magnets would be adjustable. When maximum torque is required, especially at low speeds, the magnetic field strength (B) should be maximum – so that inverter and motor currents are maintained at their lowest possible values. This minimizes the I² R (current² resistance) losses and thereby optimizes efficiency. Likewise, when torque levels are low, the B field should be reduced such that eddy and hysteresis losses due to B are also reduced. Ideally, B should be adjusted such that the sum of the eddy, hysteresis, and I² losses is minimized. Unfortunately, there is no easy way of changing B with permanent magnets.

In contrast, induction machines have no magnets and B fields are “adjustable,” since B is proportionate to V/f (voltage to frequency). This means that at light loads the inverter can reduce voltage such that magnetic losses are reduced and efficiency is maximized. Thus, the induction machine when operated with a smart inverter has an advantage over a DC brushless machine – magnetic and conduction losses can be traded such that efficiency is optimized. This advantage becomes increasingly important as performance is increased. With DC brushless, as machine size grows, the magnetic losses increase proportionately and part load efficiency drops. With induction, as machine size grows, losses do not necessarily grow. Thus, induction drives may be the favored approach where high­performance is desired; peak efficiency will be a little less than with DC brushless, but average efficiency may actually be better.

Permanent magnets are expensive – something like $50 per kilogram. Permanent magnet (PM) rotors are also difficult to handle due to very large forces that come into play when anything ferromagnetic gets close to them. This means that induction motors will likely retain a cost advantage over PM machines. Also, due to the field weakening capabilities of induction machines, inverter ratings and costs appear to be lower, especially for high performance drives. Since spinning induction machines produce little or no voltage when de­excited, they are easier to protect. I almost forgot: Induction machines are more difficult to control. The control laws are more complex and difficult to understand. Achieving stability over the entire torque­speed range and over temperature is more difficult with induction than with DC brushless. This means added development costs, but likely little or no recurring costs. Still No Winner My conclusion is that DC brushless drives will likely continue to dominate in the hybrid and coming plug­in hybrid markets, and that induction drives will likely maintain dominance for the high­ performance pure electrics. The question is what will happen as hybrids become more electrically intensive and as their performance levels increase? The fact that so much of the hardware is common for both drives could mean that we will see induction and DC brushless live and work side by side during the coming golden era of hybrid and electric vehicles.

Tags: Roadster and Electric Next: The Perfect Car, Enemy of the Good Car

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leboismark2014@... 1 year 1 week

This article piqued my interest in the latest products available on the market, and I found a great resource here: http://www.directindustry.com/industrial­manufacturer/dc­motor­60997.html. Hope this is a useful resource for you other readers.

michaelb1 3 years 4 months

Thank you for this post. It is extremely informative, although I still dont know which motor is best to put in my electric motorcycle prototype. ~MB William Robertson 4 years 3 months

Excellent summary. I'm currently (ha!) converting a car to EV. Ultimately it, or another, will be all wheel drive, but in the interim it will be a single motor, directly driving the diff. (FWD) I'm going to use a 220VAC BRUSHED ALTERNATOR (from a generator set) for the simple reason that the amount of control will be huge: driving the rotor with a PWM circuit means that I can vary the performance and regen/braking completely. They're also relatively cheap, robust and readily available. While brushes are a bit of a 'no­no' the brushes/slip rings last a very long time. Quite easy to add water­cooling if necessary.

SAMU 5 years 2 months thank you for the very wonderful information that you have supplied....we have learned alot from it...

Jackson 5 years 3 months

EEstor is developing the supercap which could replace the battery for the pure electric car very soon. Supercap is the future in the development of pure electric car. China has already developed pure electric bus powered by supercap and has already run for two years in Shanghai. The bus route is No.11.

EEstor has annouced that their supercap can power a vehicle to run 800km per one charge. The charging is less then one hour.

Sam Whobuddy 5 years 4 months

Yes, Tesla is the car of the future, and the future is here now! We need to get off our duffs, roll up our sleeves, and get this technology available to the masses. The big oil barrons, need to take their greed and stick their heads in the sand. They have bilked us for all we are worth, go away, you already have more than you will ever need. Spread the wealth of knowledge, of electric transportation. Keep it in a uniform and universal manner, so the transformation can be smooth and understandable. Thank you for your time, and, wecome to the 21st century.

William Henry Otto

Aditya 5 years 6 months

Sir, a very good and interesting article. I am an engineering student doing a seminar on whether multi­phase(5­phase or 6­phase) induction motors have prospects in the field of hybrid vehicles.....i hoped that you could shed some light on the topic...

Richard W 5 years 6 months

All this information is wonderful, but, what about recuperative/regenerative breaking? How do the different motor types lend themselves to that?

Nawab Ahmed 5 years 8 months we required above3000 rpm 2 hp 3 phase or single phase ac or dc electric motor (compact & light weight). Thanks.

gulkhan 5 years 11 months i need inforrmation about induction motor starting strategy as there is no basic description of starts per hour of 3 phase induction motor. although there is some restriction on starts per hour for different hp as 12 starts per hour for 10 hp and 4 starts for 150 hp. but there is no detail that why its starts are limited and what happens when increase the starts perhour. explain please. 1)i am working on soft starter for 10 hp and face the problem of crawling that starts with reduced voltage from 25­30 very slowly i.e 3­4 revolution per second and at once i.e within a secon takes full speed when the current reaches 42 amp. this occurs some times irregularly. although it is normal in the first 5­7 starts. explain

Chis Marrie 5 years 12 months

I am interested in , investing in Youre company and wish You would send me the stock symbol . Thank You very much

Chris Marrie

john edwards 6 years 1 month how much power does the motor actualy use per hour , so if for example if the motor use 1 watt p/h and the baterry hold 5watt p/h then the car sould go for 5 hour right?

BRIAN BARWELL 6 years 1 month

CAN I POWER WITH WIND TUBINE GEN?

Brendan McHenry 6 years 1 month

Tesla motors is know worldwide for its innovative cars, so is there a possibility of Tesla Motors being floated on the stock exchange? I'd love to purchase shares in this privately held company and I think a lot of others would be like minded. goowSteatinge 6 years 1 month

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dinesh d dhawale 6 years 3 months

I m very much impressed by touch tecniques and wish to be a part of it

Frederick W. Pe... 6 years 3 months

In my estimation, hybrid electric drive is the best approach to solving the automotive power problem. Pure electric cars at this time only pass the problem on to the source. And, the only good solution for eliminating fossil fuels is to use nuclear power for electric generation. This also gives us the option of producing cheap hydrogen, which in turn can be used to power the combustion engine in the hybric vehicle. You will notice that I said combustion and not internal combustion. External combustion as used to power steam or any other fluid to drive a turbine results in a higher overall efficiency of operation than does the internal combustion engine.

G. Dixon 6 years 4 months

WOW! WOW! WOW! I've patiently read all these blogs about which motor to use in order to increase the efficiency of an electric vehicle a few percent and how amazing the Tesla electric vehicle would be if it weren't a $100,000 technically over engineered marvel that uses a power supply that will have to be replaced within approximately 5 years to the cost of $20,000+. I really want to buy stock in a company that produces a product that will be technically obsolete by the time it hits the street [just like a computer ­ todays' high tech is tomorrows' junk]. Anybody can build a simple electric vehicle with extended distant capabilities if they pack it with enough battery power. The idea is to produce a practical low cost, low maintenance vehicle with extended distance properties. The problem is NOT the motor. Any capable motor will suffice. THE PROBLEM IS THE BATTERY. More than a few companies have touted the development of new battery technology based on nano technology. The idea is basically simple. The only difference seems to be the basic material used to create more energy output at a lower temperature in a smaller and lighter package. However, these companies are not looking at the auto industry as a market for their product. Why build a battery for an industry that has a limited market, no viable product and is in total disarray and confusion. The big money is in small consumer electronic devices such as cell phones, pda units, toys, laptops, etc. These companies feel that the accumulation of money is more important than weather we and our children can breathe clean air in the near future. Get these companies to apply this technology to creating a practical auto power supply and you would see a low cost, extended mileage vehicle in a very short time. The battery is the key. Stop nit­picking about motors, controllers, braking systems. It all doesn't matter until we get the right power supply ­ then it's GAME ON and may the best man win!

Joesph Banks 6 years 5 months

The battery technology is pretty much keeping the EV car at bay at this time. The cost associated with this part of the equation is astronomical. The company that owns the Lion tech patent is A123 systems which all the car companies want or wanted to use. This is exactly the company that Tesla uses for its parts. The funny thing is that Tesla patented the "technology" of honeycombing the cells together which I find kinda funny because almost any three year old with building block experience can do. Alter this just a little bit and you have gotten past the patent.

The sad thing is the government is always wagging the dog. Meaning they are distracting folks with "hydrogen" fuel knowing they are very far off from delivering anything whilst you can actually deliver a car which 95% of the public now can use everyday!!! The cost of A123 cells would drop as production rises so the ability to stymie the EV car leads to the cost structure we have today.

Thats it!

Major Weber 6 years 5 months

The problem doesn't really hinge on the type of motor/engine; the problem is a viable, efficient and readily available fuel source. If electric motors are to be used , hauling around heavy rechargeable batteries adds to the vehicle inefficiency. Recharging batteries is an inefficient process that consumes more energy than what is temporarily stored in a battery. The use of batteries requires long term recharging that either renders the vehicle unusable for an extended period of time and greatly reduces the efficacy of the vehicle as a functional means of transportation. To overcome the recharging downtime, we'll end up buying two or more vehicles to perform the function of one. Instead of better motors/engines and instead of trying to build better batteries with less and less improvement for the investment involved, we need to figure out how to transmit electrical energy to the vehicle while it is in use. Subways do this through a "hot" rail just like many early electric train sets we used to play with as kids. Streetcars did it with an overhead "hot" cable that a spring loaded arm ran against to pick up the electric current needed to run motors. Now is the time to explore high/low radio frequency energy transmission like microwaves or radio transmissions that can be located in the roadbed. As development in this area progressed, the energy received by a vehicle could be metered and charged to the operator/owner. The system infrastructure could start with the Interstate Highway network then branch out to major feeder highways, etc. As the network moved down to local roads vehicles could be equipped with traditional fueled engines or a smaller battery set to get to the "electrical fueled" highway. The transmission of power through land lines (literally) could ultimately be replaced by some sort of radiated energy transmissions through the air that would still drive the same type of motors (and or charge batteries) and eventually replace petroleum powered vehicles altogether.

Jordan Barr 6 years 5 months

I was wondering if shares were available for you wonderful company.

Donna Young 6 years 6 months

Can anyone tell me of the history of the electric battery and Thomas Edison. Did he improve the battery. Was his Patent purchased and held to not deveop the EV in USA and Canada, to support gasoline cars, stone walling EV's development? EV's even for commercial use, ought to have evolved along side the gasoline cars. If we had thought ahead, we would not have destroyed our one island, Planet Earth. It is though too late to undo the damage by our beloved cars and to our health, by pollution. Who purchased the patent on Edison's vehicle electric battery? Was it improved to what was being used, then, in the early 1900's? Shame on us, for not caring more for cleaner air. We were all responsible, but mostly the car manufacturers and the oil and gas corporations. Shame on them. John Kennedy 6 years 6 months

Mr. Rippel, Hopefully you would take a moment and answer this, you are obviously extremely qualified. It is my project to build a wind powered home heating system. I have designed a tower with louvered vanes to allow prevailing wind to enter from any direction (better looking than those stupid three blades), follow a venturi path to drive a rotor design. This spins a wheel covered with an equal number of magnets at it's circumference. The coils will be equal in number, distributed to a fixed radius. The question becomes one of, can the coils be of a small guage wire because there are so many of them? Can the cores be some simple soild material? The object here is to achieve current with minimal spin from light winds, and have the current supply a common electric hot water heater with a circulator supply to baseboards. If the wind blows lightly, you get some hot water and if it storms, you get more heat. My hair is disappearing too, hopefully I can finish this before it is gone all together. Best, John

Marla Sweeney 6 years 7 months

Will public stock ever be available? I just saw the 60 Minutes Story regarding your company and competition from Fisker Automotive and GM. You make GM look like the greedy idiots they are. Even if stock will never be available I truly believe you are the best hope the United States to end its oil dependence and save our world from greenhouse emissions and global warming. Good luck to you and your truly amazing technological breakthrough in the next generation of automotive technology. I am from suburban Cleveland Ohio and this type of vehicle would be so welcomed here for sale as well as trying to get you to consider opening a manufacuring facility here in terribly economically depressed Ohio!

Ryan M. 6 years 9 months

I've been debating about whether to go brushless or ac for my next ebike. You haven't made my decision any easier but I am more informed. Thank you. John 6 years 9 months

You've probably been asked but 1 more time ­ Why aren't you or Volt using ram air generators for re­charging or whatever? I know patents exist for same but you must have other reasons?

Jeremy 6 years 10 months

Hi wally, I know that you are an Engineer & you probably dont have a lot to do with the sales end of your company. I just wanted to say I am a HUGE fan of electric motor technology BUT did you guys ever think that a 100K price tag is a totally STUPID price to put on a car that has huge selling potential? I mean I would TOTALLY buy a car right NOW that was built in a simlar way to the current Roadster with a reasonable price tag of 25­35 K dollars. I understand that battery production is an expensive process & things like that but mass production has always been a solution to high production cost. If I could, I would like to recommend that Tesla has some sort of online registration & expression of interest (which can be seen by everyone visiting your site) in an economical version of the Roadster that potentially has some sort of slightly cramped but available back seat (call it a Tesla Sedan), do some basic marketing & request for expression of interest and then get going with your production! I for one know that I have about 25 people that I know who would buy a $25000 electric car, here in Australia & Im sure that there are at least 20k other people that would as well. Maybe its worth thinking about the mass production of your item so that its within the reach of everyone that would actually use it & not just a select few buisness men ! :)

Great explaination BTW ­ very informing. & props to the whole Tesla team on the car ­ its great all around ­ except for the price! ;)

James Elger 6 years 11 months

Here's a schematic and a explaination you should read. http://elgersmad.homestead.com/files/Motor.gif James Elger 6 years 11 months

You know how you can hook up one transformer to the output of another and loose very little energy. Well, squirrel cage motors don't allow you to do that. Imagine having the same effeciency as a power transformer, and being able to pass that power on down the line to another motor, then another, and another just like the transformers. For the second motor you only 20% of the power lost in windings and magnetic core materials by the first motor. That means that with 4 to 6 motors, you can power 2 generators, and all 6 motors once the battery has started the two with generators to fully spinning. The theory is perfectly sound, or squirrel cage motors just don't work.

Patrick Crachiolo 7 years 3 weeks

Back when I had hair, typewriters did not have a "1". You had to use the lower case "L". Enough of telling of ages and war stories.

I believe that Tesla is on the right track. I am myself designing a rudimentary electric car as I see this as the absolute wave of the future in transportation. Direct drive induction motors have been used since the 50's starting with the diesel locomotive, then street trolleys and now most mass transit systems operate electrically with direct drive induction motors.

I have followed the Tesla story for some time and have never had an outlet to speak out until I found this blog today. Tesla has a responsibility to humanity with this technologically advance vehicle. When I first read of the an induction motor capable of 250 HP weighing in at 125 lbs, I am sure my eyes bugged out. Tesla should consider downsizing to a vehicle with a 50 hp motor for commuter use. I could be mistaken, but I am sure the time is now for this type of vehicle considering $4/gallon for regular in California and there is no end in sight.

I do not have a bevy of engineers at my disposal nor are my resources as nearly unlimited as Tesla's. I do, however, plan to continue my quest for an electrically operated vehicle. If Tesla does come out with a 25 ­ 50 HP induction motor, I want to buy it.

Sincerely,

Patrick Crachiolo Salisbury, NC Carlo Savarese 7 years 1 month

Esteemed Engeneer, I'm an italian student in Automatic Engeneering. I have read with attention this article because I'm doing a thesis on "cruise control for an electronic vehicle" for the exam of "Tecnlogies of Automatic systems" . To write the mathematical model of the motor I need to consider a real case. Could I have the data of the Tesla motor to write the model? Exactly I need of these data : Electrical voltage V, amperage I, resistivities R, inductances L, Moment of inertia Jm, coefficient of friction Bm, electric constant Ke and torque constant Kt.

Thank you very much. Best regards, Carlo

Tommey Reed 7 years 2 months

I am working on a permanent magnet hub motor, this is 18" hub with 16 fields on stator. This is a 200v 1000 amp hub motor, I will put this on you tube soon.

Clint Judd 7 years 2 months

Very informative But riddle me this batman. If the DC brushless motor has limitations because of the permanent magnet rotor(flux control) then why not make a slip ring rotor and have more control over the rotor for higher starting torque. Slip rings would have a better lifespan than a commutator. The rotor could be a series motor rotor with the com removed and slip rings installed and the rotor coils wired either in series or parallel to the slip rings...... Food for thought maybe?

Cedric Lynch 7 years 2 months

Would it be possible to contact Rolly Concepcion of Manila, Philippines, who is looking for better motors for tricycles (in posting at 9.00pm on 19 Sep 2007)? Bill Howland 7 years 2 months

To Sean Healy. You didn't give either the frequency nor the speed of the motor, so I'm going to guess that since you stated 250kw instead of 350 horsepower, also you mentioned 400 volts, so I'm assuming this is a metric 50 hz motor with a synchronous speed of 3000 rpm. Is there a 'pf' or Cosine theta stamped on the motor? American motors have a CODE LETTER, and a NEMA CLASS which tell much about the rotor resistance / reactance. New motors also have an efficiency stamp. I assume SCIM means self­cooled induction motor? What brand is it?

Hope this helps.

­ Bill.

Sean Healy 7 years 3 months

Hey, I am a final year electrical eng. student i was wondering if anyone would know where to get information on a 250kW 2 pole 400V cast iron SCIM motor. In relation to the resistance and inductive reactance of the rotor and stator. I would be very greatful for a data sheet or something like that or if someone could point me in the right direction thanks sean

gdattn 7 years 4 months

May by you've allready thought about it? But I'd like to have a car with a motor inside each wheel of it. Not central one with parasit mechanical links. Dennis Reece 7 years 5 months

I am sorry, but the author of this article made a mistake with this statement: "Back when I had hair on my head and carried a slide rule, there were lead acid batteries, DC brush motors, and contactor controllers. Today, none of these remain (including my hair)"

He is wrong about lead acid batteries and brushed DC motors in saying they do not exist, lead acid batteries are still made, just pop your hood on your car and see. Brushed DC motors are STILL MADE by various motor manufacturers.. Like for example: series­wound, shunt­wound, compound­wound, and permanent magnet. All those I listed use a commutator and carbon brushes and yes they are still used in industry.

Now if he said that a series­wound motor use in cars and trains is starting to be replaced by poly­ phase induction motors thanks in part to flux­vector control to give the induction motor DC like performance then he would be correct...I just don't want people to go thinking that brushed motors have disappeared. We need to educate, not trick people.....

jovencio 7 years 5 months i want to learn the widing and the wiring of motors example wye to delta, delta to wye, wye to wye, delta to delta and etc..... can you give the web that can get infomatiom in this learning?

shumin 7 years 6 months

Does anybody know who is the best in making electric motors for EVs? Are they optimized for EV applications?

Bruce Scher 7 years 7 months

How about a wheelmotor (ring in ring or disk on disk) motor of inductive type designed as a retrofit to fit over existing brake assemblies in a variety of sizes­ 13", 14", 15" etc. These motors would be transferable from one vehicle to another, and allow for the creation of instant hybrids from almost every vehicle, allowing for rapid transformation of the worldwide fleet to electric. (Thanks, I'll take my answer off the air.) Bruce Scher, Tucson AZ USA Earth

Stanley Sufficool 7 years 7 months

Series wound DC mototrs have the disadvantage of low efficiencies (

rudy 7 years 7 months

Using series D. C. motors ( brushes required ) would eliminate the need for a converter. You would only need a dc controller. You could either pulse it or use scr's to control voltage. Very high starting torque and as the load is decreased so is the rotor's magnetic field. You will need an rpm limit device as these machines have no rpm limit when mechanical load is lost. Regen. braking is also possible. I don't know if this is an advantage. I don't have any experiance with pm motors.

Linda 7 years 8 months

Does Tesla Motors have plans to go public in the near future?

Probyn Gayle 7 years 8 months

Very good explanation of the motor types. I will point people to this to save me some explaining. Roy Harvie should add Power Technologies Inc. www.pwtcbattery.com to his list. Similar to Firefly Energy. rolly concepcion 7 years 8 months

I am from Manila, Philippines, inviting suggestions on design, motor (brushless traction motor 36 or 48 volts w/ corresponding Controller), etc. for application on our prototype "tricycle" for public transporation, replacing the AIR AND NOISE polluting 125 cc motorcycles with sidecars extensively used in urban and suburban, remote areas of the Philippines as a means of cheap transporation that penetrate small country roads to transport people as well as farm goods, fish, construction materials, etc., thereby abused in overloading. we have built several prototypes using 2.3 4.2 4.0 H.P with corresponding Controllers. some burned, others overheat, controllers burned. Some direct drive, others with the original 2stroke transmission wich we converted and modified and driven by the Electric Motor.some achieve 25­ 30 km/h speed with a rang of 60 km before the 82 ampere batteries die. we have experimented different size sprachkets and pulleys. we need more technical inputs. The Market is tremendously huge. The country is so hep in the conversion program, due to the global conciousness of warming, pollution, etc, etc. It'll also mean tremendous savings in Fuel and parts that that need foreign exchange conservation. There are close to 4 million "tricycles" in a country of 87 million people. I need someones help out there to reraliza a great contribution to my Countyry. THANX

Dave G 7 years 8 months

OK. I think I've got the basic idea. In simplistic terms, a brushless DC motor has magnets in the rotor, while AC induction motors have wire coiled up in the rotor. Both have wire coiled up in the stator. When using a battery for power, both use pulses of DC current to the stator coils in order to get the rotor to turn. Software controls these pulses precisely to get the best power and efficiency. The only difference is in the software algorithms for induction or brushless. So the term AC and DC are really deceptive in this instance, since both are controlled relatively similarly. I probably have some of this wrong, so please correct me.

My question is: Why not use a combination of magnets and coiled wire in the rotor? Does this have a name? Would this be more efficient?

Probably dumb questions, but that’s how I learn.

sanjay 7 years 8 months how do BLDC & Induction fare against each other in regenrative breaking? Bernard Stollman 7 years 9 months

Have you considered designing a vehicle utilizing an induction motor that is powered by a subsurface power line, eliminating the need for batteries ? High speed trains with induction motors are the inspiration. Can they not be miniaturized?. A lightweight pod can travel in a dedicated lane, programmed as to speed, with collision avoidance capability , while the occupants move about, free to engage in a wide variety of activities . Installation of the power line can proceed rapidly at relatively modest cost. Do you see any drawback to this approach?

jim hendershot 7 years 9 months

Mr Ripple,

I sincerely congratulate you on your concise and very accurate discussion of the electric traction motor comparisons between PM self­synchronous and AC induction. (You omitted Switched Reluctance of course because it is not as yet a serious alternative). I believe all engieers who are currently working in this technical arena should read your article first so they have a chance of understanding the issues and making the right choices.

Jim Hendershot

Chandika Das 7 years 10 months

Hi, What's difference between DC Motor Frequency and Induction motor frequency parameters,how we will measure its whole strength

TEG 7 years 12 months # Wally wrote in this blog: “” Today, all the hybrids are powered by DC brushless drives, with no exceptions. “”

# I responded: "Why then am I seeing reports that the Prius uses an AC motor?!" # www.toyota.com/prius/specs.html “” Motor type = Permanent magnet AC synchronous motor “”

Thanks, KiwiME for responding with some details as to this "gray area" of semantics.

Sorry, Wally, that I made a fuss over your use of terminology.

In hindsight, going back to Martin's old "Motor City" blog, there was a warning about this already: http://www.teslamotors.com/blog2/?p=30 ""JB warns me: “Be a bit careful here. The brushless DC motor is actually an AC motor. You need an inverter to drive it! A better name for this type of motor would be: “synchronous permanent­magnet AC motor.” Most people ask why we don’t use a brushless DC permanent magnet motor, like all hybrids today use. We chose not to use one of these mainly because of the wide efficiency plateau that we get from an AC induction motor (which means high efficiency over a wide RPM and power range), not because it is really a DC motor.” (Some of you have asked about the use of niobium or other advanced magnets in our car. If we used a brushless DC motor, we’d have such magnets. But we don’t)""

KiwiME 8 years 2 days

When brushless PM motors first appeared on the servomotor scene two decades ago I recall they where refered to as "DC" by some ­ typically the American brands, and "AC" by others ­ typically the Japanese. It seemed to be more of a marketing choice by the former as they were trying to replace conventional brushed DC designs and presumably didn't want to confuse us poor engineers as we made the transition. In addition, there were designs of both servos and other motors that had the electronics built­in to the housing so actually did run on DC. Clearly, however, all 3­phase motors (and SR) are powered by "AC" in some form or another in the context of this discussion.

KiwiME 8 years 2 days

In the context of an pure electric car (or serial hybrid) the 3­ph induction motor seems like a fairly clear choice simply based on the lower losses at low power levels. For the two motors in the Toyota Prius I would imagine a "DC" brushless motor was a prefered choice as they may be easier to control position­wise at very low speeds, a critical feature for starting the internal combustion engine without any perceptable roughness to the driver. You can imagine how complex the balance of torque is across the planetary gearset between the road wheels and two motors while fighting start­up engine compression.

Marko Senjanin 8 years 5 days

I understand that Tesla is privately held, but is there any indication or future plans of having telsa stocks available to the public in the near future? Even over the counter stocks such as "Tesla.ob"?

Tommy Andersen 8 years 6 days

Even though you don't have hair left, you certainly have a lot of youth left: a boyish entuiasme for what you are doing.

The inverters are essential. Interesting that renewabels support green cars. Wind power would have been nothing with out power electronics. Wind turbines have to run on variable speed, hence the generators. That has develloped inverters etc dramaticlly in the recent years + plus they have become much cheaper and more efficient.

Perhaps we can look forward to, that the expanding market for EV' will contribute to further devellopment of power electronics, which can be benificial for WP too.

Keep up steam.

Tommy Andersen Denmark.

Bill Ricker 8 years 2 weeks

Aren't there efficiency losses converting DC to AC and back(during braking)? Your analysis was great in your white paper...... but at no time have you anywhere explained the efficiency of the AC motor setup choosen. As a mechanical engineer I'm so curious as to this choice. Could you explain it to just me atleast?

Alvin 8 years 2 weeks

I too am interrested in knowing if the stock is available for people to purchase? Please email me the contact for investment options for Tesla motors. I would like to consider having Tesla motors as part of my portfolio. Thanks.

Sincerely,

Alvin

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Editor's Answer: Tesla Motors is privately held.

Adrian Snyder 8 years 1 month

Mr. Rippel,

I am participating in a project at my university which involves building a fuel cell powered racing kart, and we've decided to use either DC brushless or induction motors. We have had a lot of trouble finding potential suppliers, and I was wondering if the induction motors used by Tesla were developed in house or if you went to a supplier? I know it's somewhat of a long shot, and there might be confidentiality issues, but if you could provide some help in where to source a motor it would be appreciated. Thank you.

­Adrian Snyder

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Editor's Answer: You can find out all about the motor in the Motor City blog.

Rupert Pilkington 8 years 1 month

Where are all the answers to these questions? I've been looking everywhere for informationon how to buy shares in Tesla Motors, and can't find anything.

Are shares available? Please let me know. Thank­you. R. Pilkington.

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Editor's Answer: Tesla Motors is a privately held company.

Randy Grainger 8 years 2 months

I agree with the ac induction choice. The new supercapacitor technology will provide ultra­fast charge times ­­ like a couple of minutes ­­ less then it takes to fuel with gas. Any plans to incorporate the supercapacitor into your mix of energy sources? It would be fun to see the aerodynamics and super structure laminated with carbon aerogel to provide the needed energy. What do you think?

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Editor's response: I think you'd be interested in the recent blog, Balance, written by Tesla Motors CEO Martin Eberhard.

goukl 8 years 2 months

thank you ,give some more informatoins of induction motor

Robert Melodia 8 years 3 months

Wally, I have read your explanation with interest. You explained the difference but state there are no winners. I beg to differ. Soon there will be an announcement of an engine that is brushless and has no permenant magnets. It is expandanble to meet power needs and easily fixable with low maintainence costs. It comes apart like an accordian and goes back together again the same way. It fits into any vehicle on the planet with the adapter for that model.

Most things today are made too complicated and the basics are not maintained that give the best performance, reliabilty and maintainence. All things everyone is lookiing for in an electric vehicle.

Stanley Sufficool 8 years 3 months

SR machines have great potential for regenerative braking as well as high efficiency points. However from my limited research on this technology, they also have a high torque ripple and massive vibrational characteristics when scaled to high output.

They are currently used on IC power steering and aux systems.

Patrick Chi­kwo... 8 years 4 months

The 'DC' used in 'Brushless DC motors' was due to the fact that these motors, with its trapesoidal back­emf, have a DC (brushed) motor characteristic. The 'AC' used in 'Brushless AC motors' was due to the fact that these motors, with its sinusoidal back­emf, have characteristics similar to an AC synchronous machine. They are very different machines for the motor designers, with very different positional sensor requirements ­ DC type using simple 3­hall sensors, and AC type an expensive resolver. However, this community appears to have omitted an important alternative ­ the switched reluctance motor (SRM) technologies, which can potentially combine the benefits of the AC induction and brushless PM. I concede, however, SRM has some way to prove its credibility in the vastly risk­averse automotive industry. I do hope that the EV community will be less risk­averse and more open­minded, like our great mentors Tesla and Eddison, who showed us to think 'out of the box'. Then, the future will be more exciting for the benefits of all.

Milan Tatalovic 8 years 4 months Very nice explenation and very enhanced project! I hope it will be wide spread car.

Comment: Induction motor with an encoder, fed by vector control inverter (i.e. SIMOVERT VC) require magnetization current (Isd) about 30­40 % of motor's rated current and inverter maintains it constantly within constant torque area. Certainly it will cause looses. Brushless motor has not need for such a current due to permanent magnets. Eddy exist in induction motors too. From my modest personal experience (drive specialist in steel industry), I can say that brushless motor has much better performance than induction motor. Respond to step torque is delayed about 10 ms for induction and less then 1 ms for brushless motor. This is the reason that all our (DANIELI) high­dynamic servo motors (for positioning machines) are brushles. I base this statments according to my experience in work with Siemens SIMOVERT VC and MC drives.

Best regards and good luck in your mission!

With deepest regards,

Milan Tatalovic

John Wolf 8 years 4 months

I've been fascinated with electric motors since childhood; in addition to being a musician I also repair commercial and domestic appliances, and encounter both induction and brushless D.C. machines. Someone posted a question regarding regenerative braking in induction motors. I believe that this is accomplished by progressively reducing the supply current frequency, as induction motor speed is a direct function of the number of poles in the stator and the frequency of the supply current. For example, the drive motors of Whirlpool Duet front­load washers are of the 3­phase inverter controlled induction type; when they come out of the spin cycle the frequency is dropped drastically, causing a rapid braking action (to the accompanying magnetic whine, dropping in pitch, as the machine slows down). Am I on the right track with this?

Kevin Pacansky 8 years 4 months

How would u compare the Tesla Roadster to other fully electric cars made this year. flabby 8 years 4 months

Exciting news from EESTOR. http://www.greencarcongress.com/2007/01/eestor_announce.html#more

TEG 8 years 4 months

By the way, the # of Ford Ranger EVs on the road is more than EV­1, AC Propulsion, tzero and Tesla combined right now... http://media.ford.com/newsroom/release_display.cfm?release=8005

"Ranger EV is the national leader in electric vehicle sales, with 561 vehicles sold in North America during the 2000 model year. There are now over 1,250 Ranger EVs in use by customers throughout the U.S. and Canada." (That doesn't even include postal vehicles)

So, at the moment it is the king of induction AC motors on the road in the US even if it is a rather wimpy motor...

TEG 8 years 4 months

Well if nothing else, I learned to think in terms of "induction versus permanent magnet" rather than "AC vs DC" when it comes to comparing motor technologies...

Wally did say: "The only notable uses of induction drives have been the General Motors EV­1; the AC Propulsion vehicles, including the tzero; and the Tesla Roadster."

So, I am still wondering why no one seems to want to talk about the Induction motor in the Ford Ranger EVs...

Is there nothing notable about them? www.mavin.com/index.php?crn=200&rn=362&action=show_detail www.greencarcongress.com/2006/12/ballard_selling.html Malcolm Wilson 8 years 4 months

The DC in DC Brushless starts out as a DC supply (from the battery) but is converted into AC by the drive electronics. These AC signals are fed to the motor to make the permanent magnets/rotor spin which is why, confusingly, it has these conflicting labels.

Have a look round: http://www.st.com/stonline/products/support/motor/tutorial/motor.swf

(BLDC = Brushless DC motor)

Roy Harvie 8 years 4 months

Van Humphries ­ Wow! I think Flynn Research really has something. This motor design would be particularly efficient at low speed, and for those applications it is a winner. Wally Rippel chose the induction motor over a permanent magnet motor largely because of cost and I don't imagine that the Flyn Research motors are cheap for this reason. Let's assume that Tesla's motor is 93% efficient and Flynn Research's is 97%. Is the 4% gain worth the cost? Also Flynn Research says their motor is very compact, so is Tesla's, and I suspect Tesla delivers more power per pound. I am going to watch Flynn's site to see when they publish figures, then we can compare.

Hydrogen production on Isracast article produces CO, since when was carbon monoxide not considered a pollutant?

TEG 8 years 4 months

CM wrote: ## To clarify ­ the “permenent magnet synchrnous AC motor” actually is another name for “DC Brushless motor”. Both use a sophisticated inverter control, both use a permenent magnet rotor.

Really? Toyota says their motor uses 3­phase A/C http://www.hybridsynergydrive.com/en/electric_motor.html

According to the electric motor definitions here, "Synchronous AC motors" are in the AC motor category: http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=02nQXG3MYxC...

Wikipedia also puts them in the "AC motor" category: http://en.wikipedia.org/wiki/Electric_motor

Maybe they are a gray area in between? Should we refer to them as AC/DC "Hyrbid" electric motors for the Hybrids?

I guess the question is: Is the motor defined as an AC motor because it runs off of AC current? Or does the fact that it has permanent magnets automatically make it a DC motor?

CM 8 years 4 months

To clarify ­ the "permenent magnet synchrnous AC motor" actually is another name for "DC Brushless motor". Both use a sophisticated inverter control, both use a permenent magnet rotor.

As for the "Engineuity" technology, no real breakthrough there. It is the revival of an old method of making hydrogen by reacting an alkaline metal with steam to create a metal oxide and hydrogen. The hydrogen is then burned it in a internal combustion engine. The process requires a lot of metal, and refining the metal (and recycling the metal oxide) takes a lot of energy. It is both very inefficient and very expensive. Do you have any idea what a "fillup" of 220 lbs of magnesium wire would cost?

Van Humphries 8 years 4 months

Just wondering what you think of the electric motor in development at Flynn Research: http://www.flynnresearch.net/

Is their "Parallel Path Magnetic Technology" any good?

David 8 years 4 months Len ­ I think FreeHydrogen effectively trashed Engineuity's concept ­ http://freehydrogen.blogspot.com/2006/01/engineuity­recycled.html ­ Sorry, I wish it made sense too...

James Anderson ... 8 years 4 months

# Len Cozzolino wrote on January 15th, 2007 at 7:42 pm

1 zink matrix battery. 2­Engineuity.the Isreli technology…. www.isracast.com. Go to technology.Scroll down to .The car that makes its own fuel. I hope you injoy this article.Len Cozzolino

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Editor’s comment: The article Len is referring to can be found here: www.isracast.com/Articles/Article.aspx?ID=43 ======

Interesting idea. I wonder if the hydrogen flow is sufficient to power the Mazda Renesis engine that switchably runs on gasoline or hydrogen?

T.J. 8 years 4 months

The place to build the Whitestar car is Caleefornia­if Arnie knows what's good for both.

Alfred 8 years 4 months

Just would like to make a comment about the Chevolet Volt. Based on what I could find on the internet and other sources, I doubt Teslamotors have any real competition coming their way from GM. It is obvious that GM is not really serious about selling this car to the public. Even from the Gm official website, they state that they do not know when the car will be officially sold and that this is just a concept car. I guess they wanted to flex their engineering muscle to a degree but are not ready to make an actual commitment. Meanwhile, when is a picture of the Whitestar going to appear on this site?

Len Cozzolino 8 years 4 months

1 zink matrix battery. 2­Engineuity.the Isreli technology.... www.isracast.com. Go to technology.Scroll down to .The car that makes its own fuel. I hope you injoy this article.Len Cozzolino

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Editor's comment: The article Len is referring to can be found here: www.isracast.com/Articles/Article.aspx?ID=43

TEG 8 years 4 months

Wally wrote in this blog: "" Today, all the hybrids are powered by DC brushless drives, with no exceptions. ""

Why then am I seeing reports that the Prius uses an AC motor?!

http://www.toyota.com/prius/specs.html "" Motor type = Permanent magnet AC synchronous motor ""

http://en.wikipedia.org/wiki/Image:PriusBatteryModule.jpg "" utilizes an inverter to "step­up" the power to 500 Volts, and convert the DC battery power to the AC required for the electric motors.""

I can see you missing a detail here or there in your descriptions but you go out of your way to say "with no exceptions" yet you overlook the most popular hybrid model sold today! Did you write your article in 1996 or something (before the Prius and Ford Ranger EV came out) ?!?!?

Donna Kaphan 8 years 4 months To whom it may concern: Iam very interrested in your Roadster and your company, will Stock in your company ever be available?

Bart Hibbs 8 years 4 months

Titania: For a permanent magnet machine you are right: you do want the electrical frequency to by synchronous to the rotor. And you do control torque with the phase. But for an induction machine operating synchronously results in zero torque. You have to have the electrical frequency a little faster (up to 3% or so) than the rotor to get positive torque for motor operation, and have the electrical frequency a little slower than the rotor to get negative torque for generator operation.

Example: A normal plug in the wall induction motor spins at 1800 RPM with no load. If you load it up it slows to 1725 RPM, producing tourque and consuming power. If you spun the shaft with, say, a windmill it would speed up to 1875 RPM and it would generate power.

Jon Norris 8 years 4 months

The article in brushless vs. induction was interesting reading. I would suspect that the victor will be the design that is the most economical to produce and operate.

Regarding the diesel motor (mentioned above), that motor was designed 100 years ago to run on vegetabvle oil. This new fad of using non­fossilfuels to power vehicles is nothing new.

The real problem that must be addressed is the battery. A decent/economical battery could quickly obsolete gasoline driven commuter automobiles. Until that time, I will be forced to fill­up my Corolla with gasoline (and donate to our 21st century robber barons).

Jon

Joseph E Thomas 8 years 4 months

I was favorably impressed by the high temperature, diesil "burning", fuel cells that were being used some years ago. I suspect development has been on going, I don't know, but it sure looked like a way to keep the people with all their eggs in the oil basket from mounting an attack and reducing fuel consumption.

Best wishes

JoeT

ian 8 years 4 months

Ronald Greene ­ "I believe that GM has over come a major barrier"

Uhm, GM has yet to produce anything. And the series hybrid concept pre­dates the GM Volt design by 50+ years. As far as Hydrogen goes, it's just an inefficient energy storage system. Read the Telsa white papers on well to wheel effiency or Popular Mechanics article on alternative fuels so see how it compares with today's battery technology.

Tesla isn't interested in a series hybrid EV, but make no mistake, Tesla is much closer to producing one than GM...since GM would first need an electric car in order to make a series hybrid electric car.

Doug @ Stanford 8 years 4 months

More news on the possible location of the new plant: http://www.freep.com/apps/pbcs.dll/article?AID=/20070114/COL06/701140657 Apparently Michigan's governor is trying to woo Martin to put the plant in her state. Personally, I really hope the plant goes up in California, then Arizona as a distant second. Putting the new plant for the car that will change the world in a western state makes it feel fresh and exciting. Putting it in Michigan, like all the other car manufacturers, makes it feel a little tired from the get go. Also for my own personal interest, I'll finish my Ph.D. in Applied Physics around this time next year and maybe I can try to get a job from you guys. But after growing up on the east coast, I certainly don't want to live in Michigan.

Ed van der Pol 8 years 4 months

I would like to see you design a 'sport coupe' along the lines of the Mercedes CLS 500! I will be in line to put in my order, as I need a four door car but want the performance and styling.

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Editor's response: We have plans for a four­door sports sedan. See The Secret Tesla Motors Master Plan.

Roger 8 years 4 months

Hi All,

Just some idle speculation . I wonder if Chevy considered a gas turbine for their battery charger instead of the small 3 cylinder reciprocating thingy thats mentioned in the press releases ? Turbines have replaced reciprocating engines in many major applications from power plant, ~1890­ish (???), ships, 1904 HMS Dreadnought, and aircraft, ME 262/Meteor/etc 1944 onwards, and even some recent military vehicles M1 Abrams/M2 Bradley. I realize that gas turbines lose efficiency as you scale them down in size and for direct drive applications the gearbox design is horrendously difficult and startup up times can be a pain so an extremely refined 3 cylinder reciprocating engine may have the edge when it comes to design/analysis/manufacture/test but I think that for a task that requires constant RPM, such as turning a generator, an equivalently powerful turbine might be lighter, more compact, have lower emissions issues and fewer moving parts.

Anthony Kelman 8 years 4 months

Wally, I remember seeing you speak at an early showing of "Who Killed the Electric Car" last June in Pasadena, great to find out you're at Tesla now. Motor technology has always been at an interesting confluence of mechanical and electrical engineering. It is such a useful subject to understand for practical applications, but academic instruction is a bit lacking since it is between disciplines. At least control theory applies whether you've got a mechanical system, an electrical system, or a combination of the two. You say "Ideally, B should be adjusted such that the sum of the eddy, hysteresis, and I² losses is minimized," and I hear "cost function" and "linear­quadratic regulator." Keep up the good work, I hope pricing and availability work their way into a timeframe that lets me make the jump to pure­electric soon. Oh yeah, when do the Customer Care Centers open so I can at least take a test drive in the meantime? T.J. 8 years 4 months

You know, I wonder why the economies of all the countries ahead of U.S. in Yale/Columbia Pilot report aren't wrecked­because that's what "some of our esteemed govt. officials" say would happen to our economy if we ever really got with it environmentally. You would think that if the report rankings were played up in the major media, the country would be clamoring for Gore/'08. But noooo­that wouldn't happen­that would make too much sense (for this country at least).

T.J. 8 years 4 months

According to "Pilot 2006 Environmental Performance Index " study (by Yale & Columbia U.), U.S. ranks 28 in world­behind every european country except Russia, Hungary, Poland, Belgium & Romania­and Russia is close at #32. The report covers policy catagories of : health, bio­diversity, energy,water,air & natural resources. Among "peer group" countries of U.S. ("nations at a similar level of development") U.S. ranks 23 out of 29. Looks like there's "some room for improvement" ­ Perhaps!? I think whatever money silicon valley venture capitalists are investing in this problem they should triple it: big problem=big opportunity.

Dixie King 8 years 4 months

OK ­­ so I'm like your typical suburban soccer mom (yes, I actually coached soccer for 6 years); environmentally engaged, willing to look at a hybrid or electric car for my next purchase. I sort of see myself as Tesla's future client base (wishing for some point in time when millions of us buy electrics or hybrids for our second car etc.l). So let's talk AFFORDABILITY: when is there going to be a car for the middle classes???? What's realistic for an idealist like myself? A Toyota hybrid in the near term and a Tesla if I win the lottery? (p.s. love the look of the roadster ­­ very cute)

T.J. 8 years 4 months

"Certain groups" in this country have never wanted an energy efficient country­the more we spend on oil every year, the better­and the longer the better. Just as "certain groups " also like long, drawn out halibut­like fishy wars­the longer they run, the better for "business" (and other purposes). Anyone who knows the Real history of the world knows that "things are made to happen", which wouldn't otherwise happen , just to enable this game plan (as in: "con") to succeed ­again and again.

T.J. 8 years 4 months

U.S. consumes 20 million barrels of oil per day (25% of world's total). The next 5 top consumers, in millions of barrels per day, are: China: 6.4,Japan 5.6, Russia 2.8, Germany, 2.6 and India 2.3. The total for these countries: 19.7. Germany is closest to U.S. in industrialization. U.S. population is 3.6 that of Germany, if we consumed oil at their rate, our consumption would be 9.4. Using 10.6 million barrels of oil less per day would put a lot of wasted oil money back into our economy. Time for Tesla to raise enough money to come out with both the sports and family sedans within 5 yrs. Tesla would have the high ground while the other car companies still putz around with improved hybrids.

Doug @ Stanford 8 years 4 months http://www.autobloggreen.com/2007/01/14/next­tesla­will­definitely­be­a­...

Ronald Greene 8 years 4 months

Jay Purser wrote on January 11th at 4:34 The Chevrolet Volt concept of a small gasoline engine to charge the batteries when needed does gives the driver the confidence that he (or she) won't be left on the side of the road if the batteries discharge completely. We have all had dead batteries and we all hate it when that happens and our cars will not start. Thus, I believe that GM has over come a major barrier in getting people to buy electric cars. Electric cars need to have their own source of electricity to charge the batteries or run the car in case of a complete discharge which may not be the fault of the driver such as road detours and etc. For examples, there are fuel cells that look just like another battery but it will act as a source of electricy that will power the car to get you home or to a place where the car can be recharged. Electric cars must provide such a back up sytem in order to succeed.

Ben Farmer 8 years 4 months

Has Tesla ever thought to offer Renewable Power Plants to make the car completely renewable by charging with Solar/Wind? I work for one of the USA's fasted growing Renewable Energy Retail companies. Its great the car is so efficient and non polluting, in fact its awesome to see the Electric Car making a comeback, since the first cars started this way. But if the electric "fuel" is made from Coal plants, still makes it not the most optimal situation. For those that can afford this car, they can probably also afford their own Solar Car Port. [Contact info removed.]

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Editor's comment: See our FAQ: Can the Tesla Roadster use Solar Power?

james howell 8 years 4 months

why batteries why not a generator powered by small diesel engine ? they have been doing in trains for 50 years I trully think your on the way keep up the idea machine and sorry when you can get the price to around 20 grand ill be ready to buy one

Paul Hollowaty 8 years 4 months

When will Tesla be moving into their new engineering center in Rochester Hills, Michigan?

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Editor's comment: We expect to add the location of the new office to our Contact Us page soon. BRIAN NIGHTINGALE 8 years 4 months

HAVE YOU GUYS AT TESLA MOTORS CONSIDERED USEING THE DELOREAN PLATFORM TO START YOUR ELECTRIC REVOLUTION / REBELLION. IF YOU DO THIS TYPE OF DELOREAN REFURBISH WITH YOUR POWER TRAIN YOU WILL NOT FAIL. TO BEGIN WITH TESLA MOTORS WOULD HAVE THE ENTIRE DMC VEHICLE OWNERS AT YOUR BECKONING, SECONDLY TESLA MOTORS WOULD HAVE THE ENTIRE DMC REMANUFACTURERS TO CALL UPON FOR YOUR EVERY NEED. I AM AN AUTHORITY IN VISIONARY INSIGHT AND STRESS THAT THIS ADVICE IS A SEVEN MOVE CHECKMATE STRADEGY THAT WILL TOPPLE ALL OF YOUR OPPONENTS. DO THE NECESSARY LEGAL MANEUVERS AND DONT CHEAP OUT ON A BIG PRICE TAG ON THE FINISHED PRODUCT, TAKE IT EASY, LONG & SLOW, (YOU WILL WIN BIG).

Roger 8 years 4 months

It would be interesting to know how the efficiency of the tesla design compares to the truly dc Cedric Lynch motor.I have experimented with these motors using an invalid carriage for a test bed, very exciting but dont recomend it.

Malcolm Wilson 8 years 4 months

It could be that the "Electric Elise" label is a hangover from 1998. http://fixedreference.org/en/20040424/wikipedia/Zytec_Lotus_Elise

(links from the above page no longer work)

Apparently this one is now in the Motor Museum in Gaydon, West Midlands. I must try to get to see it. Not that it will look wildly different from a normal Elise. No exhaust and....that's it.

T.J. 8 years 4 months

There's an interview with Ted Turner in "emagazine.com" (don't know how old). Says he has fund called "Turner Endangered Species Fund" and he "actively crusades for cleaner transport (that would be Tesla), sustainable population growth, wilderness conservation & greener business (ditto, Tesla)". Talking about the environment and those that don't believe there's a crisis he says: "If this were a baseball game, it's the 7th inning and we're down by 3 runs...I put my money on the smart minority ,not the dumb majority, wouldn't you?". Time for Ted to put his money into Tesla­ definitely the smart minority of the auto world.

Titania 8 years 4 months

Ross, Those are some great points and I think your suggestion for a proper forum (maybe vBulletin) rather than a blog is a great suggestion. vBulletin has a great search function and a simple sticky post asking people to search before posting usually does the trick. I have installed and administer a number of vBulletin forums, including my own on my website, and it really is a great resource. It is also a great way to achieve higher listings on search engines too. Essentially, every word and post anyone posts on a forum is crawled by search engine bots. Quote by Ross ­ "And hey, if nothing else, as soon as we both get our roadsters we can have a race to settle it :) Disclaimer: it may take me longer to get mine." Sounds great to me. :)

T.J. 8 years 4 months

Tesla will have to call Ted later­he's down in rural Argentina, out of cell phone range (by press reports)­Patagonia, no doubt­visiting the old lair of Butch & Sundance. He's a renegade, alrigh: a mogul environmentalist­the perfect Tesla investor.

T.J. 8 years 4 months

Yesterday Ted Turner announced he's getting into solar power in Calif. by investing in company called DT Solar. Next Tesla should get him on the horn­he would be a good investor,being a long­ time environmentalist ( biggest private landowner in U.S.­with big wilderness tracts in Montana,Dakotas, New Mexico & Florida). He could scrape together the kind of money to accelerate the Whitestar Sedan & Offwhitestar Family Sedan after that. That way he could help on the two main CO2 fronts: buildings & cars. What more could he ask for­why attack just one?­He should go for both. If I were him I'd invest in Tesla.

monty sandoe 8 years 4 months

does the car have a heater to keep people warm in cold Canada. And also do you have any trucks planed? or reguler sized cars for familys. I am a farmer and i would like to purchase a truck with a 8 ft long box to use for short runs about 250 miles maximum but mainly for short runs about 20 miles at aa time. ty for producing electric cars

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Editor's response: The Tesla Roadster comes standard with a heater and heated seats. See the blog, Blowing Hot and Cold. A bit of information about plans for additional models at The Secret Tesla Motors Master Plan.

Dan 8 years 4 months

I have been attempting to aquire information on the stock and if it is available. I have sent an e­ mail to Tesla Hdqtrs via the standard option offered on the Tesla website and have received no response. So the question is ­ "Is stock in Tesla Motors available and if so how do I go about aquiring the stock?

­­­ Editor's response: Tesla Motors is a privately held company and so its stock is not traded in the public markets.

Wade 8 years 4 months

In a cold climate such as the Michigan winter, how much range diminution might occur due to a.) cold batteries, and/or b.) energy required to heat the vehicle interior? Is there a practical low­ temperature limit for the present Tesla Motors technology? Could some of the regenerative braking recovered energy be budgeted to the heater, or conversely in hot climates, to provide air conditioning? (I always wished, with internal­combustion cars, that absorption refrigeration were practical in a moving platform to relieve engine heat load while cooling the occupants, win­win, rather than pile more heat onto the powerplant with the conventional air conditioning condenser physically co­located with the engine radiator. Congratulations, Tesla Team, and best regards. Please drive one by here (Brighton, MI) sometime. Coming to North Am. Auto Show Jan. 20 2007.

Malcolm Wilson 8 years 4 months

Oops. My bad.

Still it's happened before.....

http://www.cs.uwaterloo.ca/~alopez­o/math­faq/mathtext/node18.html

ross 8 years 4 months

So, I was reading around about your car (something I've probably spent too much time at work doing) and the article I was reading, along with a number of others that I've seen, referred to your car as "the Electric Elise." Does that make you angry, annoyed, or roll your eyes? It's definitely a myth you've been trying to bust ever since the car was unveiled, but unfortunately you haven't converted everyone.

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Editor's response: We would never roll our eyes ;) But, seriously, the Tesla Roadster is a new car and it may take awhile to correct some fallacies out there. As you know, Tesla Motors designed and developed the Tesla Roadster. Background on our relationship with Lotus and some of our technology decisions can be found across our site. These two blogs are particularly helpful: Lotus Position and Balance. Feel free to pass the word.

Iz 8 years 4 months # Jay Purser wrote on January 11th, 2007 at 4:37 pm # Have you thought of producing a similiar system and mounting it on a trailer, with extra luggage space included, for road trips beyond the normal 250 mile range?

Jay, refer to Martin's blog entry of 9/27/2006 "Hybrids, Plug­in or Otherwise". Check out the links for amazing contraption and second version. The version 2 photo is quite interesting.

ross 8 years 4 months

Titania: I agree. It is a good question and deserves to be answered. It's so good a question, in fact, that many people have asked it on previous blogs. But, at the same time, it's also so good of a question that it's been answered more than once on this website. Looking back I see that my comment makes me sound like a fish (some would specify halibut), but the point was that it is asked so often here that there should be a "required reading" section of some sort easily noticable from any blog post to answer it.

Another possibility is to have a real forum on this site, or at least a link to the unofficial one at http://teslamotorsclub.com/forum/ to give readers a way to still directly respond to the blog, but also for general discussion questions such as yours and many others (including a few of mine).

And hey, if nothing else, as soon as we both get our roadsters we can have a race to settle it :) Disclaimer: it may take me longer to get mine.

Titania 8 years 4 months

Ross ­ no offense but I think my question was quite appropriate and most certainly doesn't make me look naive. I am fully qualified in electronics and have a keen interest in alternative energy supplies. I was very keen to hear the opinions and points of view of the Tesla engineers on matters relating to fuel cells. The information was graciously provided by the editor. Asking those who work with such considerations on major projects such as this is a great way to further ones knowledge and appreciation of the effort that has gone into creating this vehicle. I am seriously considering investing in my own Roadster and, as such, have a vested interest in finding out as much as possible about it. The good folks here on this blog are a wonderful and open source of such valuable information.

Bart Hibbs ­ I am curious. I was under the impression that it was more efficient to have the frequencies of the electronics and the motor operating at the same reducing or increasing frequency but adjust the phase and impedance to control the rate of change of speed. I am no expert in this field (pun intended) but I also believe that some of more complex controllers use harmonics to increase performance under different conditions.

ross 8 years 4 months

Jay Purser: see editor's response to Titania's first post.

Editor: 2...

Doug @ Stanford 8 years 4 months

Lots of nice high res photos of the Roadster on AutoBlogGreen: autobloggreen.com

Tommey Reed 8 years 4 months

Have anyone started to redesign the dc motor? I have seen most electric motors have small armature, would it be much better with a bigger one? This would allow high torque with less amps to run, Even if it does lose rpms its really the torque that moves the car. Let say a 16 in. armature this would have high torque output, and it could be all made of magnets. Now would this not use less power to run and also have torque? A am working on this design, this is a brushless dc motor, could this be more efficient then any dc motor today? What do you think Tesla Motors?

AdvanceEnergySystems.com Tom TEG 8 years 4 months

# Malcolm Wilson wrote on January 11th, 2007 at 2:49 am # Radians are based on pi (3.14285).

# ross wrote on January 11th, 2007 at 3:19 pm # I don’t know where you got your value of pi from, because its close but wrong.

Apparently they used the common 22/7 shortcut rather than remembering real digits. http://mathforum.org/library/drmath/view/55842.html

Jay Purser 8 years 4 months

The Chevrolet VOLT concept of a small gasoline engine to charge the batteries when needed does give the driver the confidence that he (or she) won't be left on the side of the road if the batteries discharge completely. Have you thought of producing a similiar system and mounting it on a trailer, with extra luggage space included, for road trips beyond the normal 250 mile range?

Roy Baudoin 8 years 4 months

I watched Wired Science the other evening and am interested very much in Telsa Motor products. When will information be forthcoming on new models? The 5 passenger Sedan and smaller local commuter.

Bart Hibbs 8 years 4 months

Hey, Wally, you forget about my car? There are still a hundred or so of us USelectricar owners with induction motors under the hood. The cars have been going for 15 years, certainly that counts as "notable".

Note on induction machines and regen braking: when an induction machine is operating as a motor the rotor is spinning slightly slower than the electrical frequency. When it is operating as a generator the rotor is spinning slightly faster then the electrical frequency. The induced currents then try to slow the rotor, causing braking.

ross 8 years 4 months

Malcolm Wilson wrote on January 11th, 2007 at 2:49 am #However, you will need to know that engineers measure angles in units called Radians, #not Degrees. Radians are based on pi (3.14285).

Just a little nitpicking here: I don't know where you got your value of pi from, because its close but wrong. The real value is 3.14159265... (goes on forever), so your first 3 digits were right. I wouldn't have said anything if you stuck to them :) Also, 3.142 is correctly rounded, but then you have two rogue digits.

Also a note to the editor re: re: Titania: Why are you still surprised? There is at least 3 comments per blog that could be answered with those two links, including the blog that you link to. Maybe put a statement somehwere obvious (like at the top above the blogger's pic and credentials) that says "BEFORE POSTING GENERAL QUESTIONS ABOUT LI­ION vs OTHER TECHNOLOGIES, PLEASE FOLLOW AND READ THESE TWO LINKS: The 21st Century Car and The Future of Cars Is Electric."

No offense to those who ask these questions, but it's always best to at least try to find the answer on your own before asking it rather than just asking and sounding naive.

Alvar Hanso 8 years 4 months

"Since spinning induction machines produce little or no voltage when de­excited, they are easier to protect."

I guess I don't really understand the context of that little sentence. I'm not even sure that this situation would be encountered in an AC drive system that utilizes regenerative braking unless the controller disconnects completely from the motor in some safety initiated situation. Don't you require free­wheeling protection diodes on an unloaded spinning induction motor to achieve little or no generated voltage?

(Jim:) Normally in an AC drive the regenerative braking condition is induced by altering the phase of the applied inverter frequency such that the motor itself becomes the generator. The battery system becomes the load as currents are driven back into the batteries and to some extent they are "recharged" although not all of this energy is recovered ­ but something is better than nothing! The voltages/currents generated by the AC motor (now a generator) are dependent on the load impedances caused by the inverter circuit and the batteries.

The question was brought up as to what you do with energy created from regenerative breaking if your batteries are fully charged. Fortunately for a pure electric vehicle such as the Tesla roadster this is not a large problem since the energy state of the batteries will generally always be less than when you left your garage immediately after charging. There is at least one scenario that could cause this, however. If your morning commute carries you downhill for several thousand feet of vertical height you could indeed over­charge your battery with regenerative currents unless your vehicle's controller system has the smarts to prevent this from happening. In this case regenerated currents must be redirected away from the battery pack and into something that dissipates the energy like a bank of well cooled power resistors. Have you ever seen the several large cooling fan exhausts on the top of a diesel­electric locomotive? Those fans are there to dissipate the energy of the train in the form of heat generated in resistive loads as the train slows down during regenerative braking. A diesel­electric locomotive is a lot like a Tesla roadster except that it has a diesel motor/electric generator to generate electricity instead of batteries. Q: Why is it so great to use AC drive systems in a locomotive? A: You would need a ridiculously large number of gears in a mechanical locomotive transmission to get a train to pull a large load from a dead stop. The AC drive system IS the transmission due to the large amount of torque available in the AC induction motor at low speeds.

Roy Harvie 8 years 4 months

To Albert Covemaeker ­ I know that it would be great to see the Tesla Roadster in person, but the fact is that a booth in a major auto show is very expensive. Why should Tesla pay for a booth to promote sales of their cars when they already have more orders than they can fill? Latest I have seen is 270 cars sold, congratulations Tesla! And these with hefty down payments.

I am glad to see the Chevy Volt from GM. This car is not competition for Tesla as Tesla is committed to the best environmental solution wheras the Volt is more pratical for the masses. GM says that this car is slated for production not vaporware. They are looking for low cost batteries, not exotic but currently available technology at significantly lower price.

Titania 8 years 4 months

Dear editor, Thank you very much for the information, in particular the PDF document. That answers many of my questions on current fuel cell technology and efficiency. Certainly food for thought and, although it is pretty clear that Tesla Motors have done their homework, this makes it even more obvious. From the first moment I saw one, I had my heart set on purchasing a Tesla Roadster and this blog and all the information on it just strengthen my passion for this car. :­)

Andre Brisebois 8 years 4 months

I live in Canada, in the province of Quebec.

Have­you ever tested the induction motor in northen climates ?

Since we have plenty of hydro­electric facilities here, electricity is extremely available and cheap.

I would like to develop the market for Tesla cars up here north. Any plan for distribution in Canada ? Any interest in doing so ?

Titania 8 years 4 months

The Tesla Roadster is a very exciting development to me and it is great to be able to read about the reasons and developments behind the technology involved. I would expect that Tesla have looked into the myriad of developing fuel cell technologies as potential power sources. I believe that this kind of technology will, at some point very soon, become a preferred and more cost effective solution to Lithium Ion batteries. At this point there are certain fuel cell types that can generate significant power with greater pollution efficiency than typical internal combustion engine combinations. Also, the fuel cells would be far more cost effective in the mid to long term over Li­Ion batteries. Obviously there is something I have mised here or Tesla would be using this technology. Perhaps it is the lack of widespread availability in a suitable form of fuel sources such as hydrogen that are the major contributor to choosing Li­Ion.

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Editor's surprise: Check out the following links: The 21st Century Car and The Future of Cars Is Electric. kert 8 years 4 months

Everybody would very much like to hear an official opinion by specialists whether the technology is there for 40­mile electric car battery pack or not. GM essentially said "the batteries arent ready" by what they meant that the basic chemistries are there ( A123, valence, etc, there are several inherently safe lithium chemistries around ) but currently only small­format cells are shipping in volume, and they are not going to put these in a car. Also, that the safety and cost at the pack level have to be verified. I.e. just straight engineering challenges. Tesla has gone ( and is still going ) through these engineering and validation challenges, using the previous generation of "unsafe" cells making it a safe pack. Now what was said by GM is taken by media and spun as "Volt requires some miracle technological breakthroughs to become viable and nobody knows when or if this will happen". This is in stark contrast of what is actually the situation. Also, nobody mentions that NiMH is viable today, and that there are thousands of EVs zipping around with good old lead­acid ( 800 g­ Wiz/Reva city cars in london, for example ) Someone should go out and set the record straight. A high­profile Interview with mr. Lutz, maybe. Both mr. Eberhard and Lutz on Larry King live ?

Malcolm Wilson 8 years 4 months

James Anderson Merritt wrote:­

#Give this presentation some pictures or animations, and it would make #an excellent orientation to modern electric motors for the curious #consumer (or the schoolkid starting an engineer’s journey!).

Lots of animations here:­ http://www.st.com/stonline/products/support/motor/tutorial/motor.swf

Under Motor Type, select Asynchronous Motor (Induction). As you read through, words in blue can be clicked on to reveal close­up photos etc. Some paragraphs are a little too free with engineering terminology, but pages 4 to 9 are BRILLIANT!

However, you will need to know that engineers measure angles in units called Radians, not Degrees. Radians are based on pi (3.14285). pi/2 rads = 90 degrees, pi rads = 180 degrees etc. So the 2/3 pi and 4/3 pi rads mentioned on page 7 are equal to 120 and 240 degrees respectively.

On page 9, notice how the black arrow which represents the total magnetic field provided by the three stators is rotating faster than the squirrel cage. This is the idea behind Slip. If you could see the arrow representing the total magnetic field induced in the rotating squirrel cage, you would see that it lags behind the black arrow by a particular angle ­ the Angle of Slip.

Hope all this helps.

Dick Pong 8 years 4 months

January 10, 2007 may or may not be remembered as a seminal day in racing history, but if a proposed 500 mile race runs in May 2009—perhaps at Indianapolis Motor Speedway— featuring hydrogen fuel cell­powered electric vehicles, it will mark the beginning of a new era as the sport fights to remain relevant and responsible in evolving environmental and automotive market climates.

That is the vision of the Hydrogen Electric Racing Federation, the brainchild of Peter DeLorenzo, an automotive advertising and marketing veteran and publisher of Autoextremist.com.

HERF held its coming­out party at a Birmingham, Michigan hotel, and it drew curious senior executives from Audi, General Motors, Honda, Hyundai, Nissan, Toyota, Bridgestone­Firestone and Michelin, as well as IMS boss Tony George.

The proposal: Racing should serve as the ultimate proving ground for the “electrification of the automobile,” through a proposed race car formula that specifies closed­wheel race cars weighing no less than 900 kg and featuring 300 kw (minimum), 400 hp hydrogen fuel cell powerplants. HERF wants to run its inaugural race, The Hydrogen 500, at IMS or perhaps California Speedway, as part of a two oval event first season. Three races would run in 2010, including two ovals and one road course, followed by five rounds in 2011 that HERF hopes include an oval in Japan and a road course in Shanghai, China.

A pipedream? Not necessarily, said automotive executives who attended the meeting. “We’re excited [by the idea],” said Steven Wesoloski, road racing group manager for GM. GM Racing boss Mark Kent backed that view, though noted—as did others in attendance—that the proposed time frame is “very aggressive.” However, GM’s Doug Fehan, program manager for American Le Mans Series racing, said the two­year target is achievable.

The picture should become clearer in 90 days, when a signed letter of intent to compete is due. Judged by the reaction and discussions that took place at the meeting’s conclusion, the auto manufacturers are taking HERF very seriously. http://www.autoextremist.com/page3.shtml#fumes TEG 8 years 4 months

Mention of Malcolm Bricklin's new venture here:

autobloggreen.com

T.J. 8 years 4 months

The europositron battery on Harvie's post has a really big energy density per wt. & volume­ according to graph on site's "techniques compared" section. A lot more than lith.­ion.Supposed to have 3000 charge cycles.

Albert Covemaeker 8 years 4 months

If I attend the Detroit Auto show, where will I be able to see your car ? Is it there ? If not , WHY NOT ? I have seen nothing in the news media bout your car. We have only heard about the GM Hybrid product that goes 40 miles on a charge, then switches to gas..NO THANKS for what they want for it..

Can you please reply, as I plan to go to the car show, and would be looking for your vehicl, and display..

Thanks Albert Covemaeker

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Editor's response: We brought the Tesla Roadster to the San Francisco and Los Angeles auto shows, but we don't have a booth at the Detroit Auto Show this year.

Mike Harrigan 8 years 4 months

I've seen the question regarding replacing the battery pack at a "service station" asked in several Tesla blogs over the past few weeks and I'd like to comment. The Tesla Roadster battery pack (ESS) weighs around 900 lbs. It's not like pulling the Li­ion battery out of your laptop or cell phone. Special equipment and training is required to remove and replace an ESS. In the roadster it's about a 2­3 hour job for two people. Remember that the ESS is liquid cooled so you must disconnect/reconnect the cooling system hoses as well as the electrical connections. In short, it's a labor intensive job that requires special equipment to remove/replace as well as special equipment to maintain an inventory of ESS units. The savings in time over the 3.5 hour charge time are not enough to justify the process.

Mike Harrigan is Vice President of Customer Service & Support at Tesla Motors.

Nick 8 years 4 months

Thanks much, as a member of the general public, all of this has been quite informative, I will now wait until my pocketbook level reaches your technology level.....I am not complaining about the automakers....they are after all tied to making decisions based on stockholder needs....I like what you did.....beat them at their game.....I want to be a stock holder of yours....in the mean time I will not buy another car unless it is driven by lithium Ion and an induction motor.....Thank you once again !!

Peter G 8 years 4 months

I am shocked! First GM goes and announces that they are going to produce a PHEV, then I find out that Wally has put aside his slide rule and is now blogging on top of everything ;). Did I wake up in a parallel universe?

Michael Littlewood 8 years 4 months

Although the article is well written it was too technical and very condensed, why tease a neophyte?. A few isimple llustrations would have made more sense, yes a picture is worth a thousand words. Neil 8 years 4 months

Good explanation Wally! Don't suppose you could do a blog on regenerative breaking? (What do you do if the battery is already full, efficiencies, backup etc.. ). One more question: will supplies of rare earth metals have an impact on DC brushless?

Roy Harvie 8 years 4 months

Thank you flabby for the information and link to EEStor patent (previous blog). I had almost forgotten EEStor as when I first heard about it I could not find any figures, only hype. I have now added it to my chart comparing battery types at http://www.plasticlabels.ca/index_files/compareEVbatteries.htm . EEStor is working hard to deliver samples to their first customers and I assume that they are also working on a controller that can handle the 3500 peak voltage. Current IGBTs are rated about 1500 volts max so this will not be easy.

ian 8 years 4 months

The Volt is a pipe dream. I love the concept and have been in favor of a series hybrid for a while, but GM is all talk no walk. Their battery system has yet to be built and is based on some fictional system they hope to see available in the future.

I hope GM's marketing campaign isn't successful. They should realize that they have little credibility and need to produce an actual product before touting it.

Apple is a good example (and Tesla). Steve jobs recently unveiled the iPhone, which looked almost ready to go out the door. They're saying June. Anyway, they could have said they were coming out with an iPhone a year ago, but they didn't...why? Probably because they knew they were actually going to build it, so why hype it a year and a half early?

So GM, if you're actually going to build the Volt, then why hype it now? Bruce Wallace 8 years 4 months

Excellent account of the motor type selection. I noticed that you only discussed Induction and BLDC types. Was Switched Reluctance ever evaluated? I know that an SR motor requires very high air gap precision, and tends to produce a fair amount of acoustic noise, but can it also better the efficiency and power density of an induction unit?

Mark 8 years 4 months

After seeing the new iPhone demonstration, it would almost be a sin if the new Tesla couldn't talk with it in a meaningful way :)

That thing has the most incredible user interface I have ever seen.

Raj Iyer 8 years 4 months

How feasible is simply replacing spent battery packs at service stations with fully charged packs ? (Service stations charging a fee for the charging / cleaning service.)

Strada Auto Store 8 years 4 months

Very informative....Thank You! Are these motors for the Tesla manufactured in China?

James Anderson ... 8 years 4 months

Give this presentation some pictures or animations, and it would make an excellent orientation to modern electric motors for the curious consumer (or the schoolkid starting an engineer's journey!). Thank you, Mr. Rippel! Malcolm Wilson 8 years 4 months

Thank you. That was a very helpful comparison of brushless and induction motors.

The US's very own Texas Instruments have an extensive on­line library of support documents for a wide range of electronic components ­ including AC motor control devices. If anyone wishes to find out more, the following web address provides a link to a pdf document from 1996, dealing with various motor control strategies. Since the document is so old, the focus is on general industrial applications rather than electric vehicles. http://focus.ti.com/general/docs/techdocsabstract.tsp?abstractName=bpra043

Alternatively, typing a keyword like "induction" into the search facility at the top of the same page above, provides access to far more information than is probably healthy :)

CM 8 years 4 months

Wonderful information. I was unaware of the reason Tesla Motors chose AC induction for their motor, but now it makes sense.

I checked out your "other" blog, found the commentary there interesting as well http://sirycars.blogspot.com/2007/01/why­electric­vehicles­make­good­sen...

The big hulabaloo this weekend was the announcement by GM of their "pluggable hybrid" effort, the Chevy "Volt". They are pushing the electric drive aspect and they're not calling it a serial hybrid, even though the concept car has a generator driven by a gas engine. More interesting is what GM calls the "E­flex" platform ­ the basic design can be modified by replacing the gas engine generator with a diesel generator or fuel cell, or removing the generator and adding more batteries to make an all electric version! No mention on a production date, GM claims that the batteries are not quite ready. (yeah, right...)

Tesla Motors, "Who Killed the Electric Car", rising fuel prices, and Toyota have hit GM with a quadruple whammy. GM has no clear sense of direction and is anxiously covering all bases, supporting research programs on assorted type of hybrids, electrics, diesel, gas, ethanol, biodiesel, and hydrogen fuel cells. GM doesn't have a clue as to which technology is best, so it is trying "all of the above".

2009 and 2010 should be interesting years ­ GM plans to market a fuel cell car, Mr. Bricklin wants to start importing luxury Chinese hybrid cars, Toyota will introduce a new version of the Prius, and of course, Tesla will be introducing new models as well.

T.J. 8 years 4 months

On Wally's post on "Horseless Age" site he talks about amazing deception pulled off by car & oil companies & White House re. hydrogen cars. What's amazing is how often the public is conned in this country­by both govt. & industry­it's a regular tag­team effort. Another example being the fact that Denmark banned all trans fats something like 45 years ago. They "knew something" a long time ago­ which means our govt./food industry knew "the same thing" . But just like case of big tobacco, after a lot of people have suffered ill effects or died over decades, they finally say "sorry !" (suckers). My question is "who raised these 'people' ?". They're basically point­blank unrepentant conniving "catch us if you can" liars­and for what: more (& yet more­and then more) money/power/staus quo.If I had accumulated their kind of cash I'd have been living off the interest and going straight long ago. But noooo! The lobbyist /govt. job/lobbyist revolving door in this country is pathetic. I think the tech. world people in silicon valley & elsewhere need a big full­time press corps so word can get out more to the proverbial man in the street and the abovementioned weasels can be slammed at every turn .Really.I also hope they make more halibutin' money than "cod" , hand over foot­and put it into the right things­such as companies like Tesla­in a big way.Then we could just bypass the rodents in question.

Jim 8 years 4 months

Great explanation and comparison. But I'm still wondering how does an induction motor generate regenerative power under braking?

Anatoly Moskalev 8 years 4 months

Some people keeps wandering in comments to previous article on this blog why GM and other car makers appear technologically way behind with electricity in cars. Part of the answer discussed is oil addiction of business structures ­ likely true.

But it exist apparent other reason discussed earlier on this blog ­ high battery cost. It is not a random fact that Tesla Roadster price is close to $100000. Today battery upfront and depreciation cost makes it happen. Tesla Roadster battery cost was guessed ~$20000 or may be higher. Mass market car manufacturing cost overall should be $10000 ­ $15000 I guess. Out of that gasoline saving and parts reduction would count probably for less than $5000 total of affordable cost of battery pack in a vehicle. Big unknown is maintenance cost in cars support infrastructure and affiliated businesses because all the technicians have to learn new tricks with electrical cars ­ would not come fast and cheap.

Battery cost did not come down 4 times yet from today value per the same energy density and charge cycle count. Nobody knows would battery cost come down that much soon or never. Depending on this factor whole business with electric cars could make big sense or no sense at all. I guess risk level associated with this factor is still too high for big car companies so they are searching smooth evolution and are extremely reluctant to go electrical.

It remains to be demonstrated that anybody could make electric car matching not only today cars performance but also doing it exactly for the same or even lower initial car price and having same or lower maintenance cost. Taking into account today's technology it is flat out not possible.

TEG 8 years 4 months

# Wally wrote: # "Back in the 1990s all of the electric vehicles except one were powered by DC brushless drives. "... # "The only notable uses of induction drives have been the General Motors EV­1; the AC Propulsion vehicles, including the tzero; and the Tesla Roadster."

Why not mention the Ford Ranger Electric?

It uses a water cooled 3 phase AC induction motor... They were offered for sale in 1997/1998/1999/2000 http://www.mavin.com/index.php?crn=200&rn=362&action=show_detail http://www.greencarcongress.com/2006/12/ballard_selling.html

The rest of your article was very informative for the "lay­person" who has some interest in this technology. Thanks for sharing!

Roy Harvie 8 years 4 months Thank you for this explanation. I have not had a clear understanding of the differences between induction and dc brushless, only that there were more similarities than differences. Despite your declaration that they are equivalent, the advantages with a fancy control does make induction a clear winner for electric cars. I guess GM thinks so too as the Chevy Volt has the same motor as the EV1.

David Nelson 8 years 4 months

Very interesting and informative. Thank you. How does a brushless DC motor compare to a SEM DC motor? Is a SEM a motor without permenant magnets but still has brushes?

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