International Journal of Automobile Engineering Research & Development (IJAuERD) ISSN 2277-4785 Vol. 3, Issue 2, Jun 2013, 1-14 © TJPRC Pvt. Ltd.
POWER MANAGEMENT SOLUTION BY NETWORK MANAGEMENT STRATEGY AND ANALYSIS OF A DC-DC AUTOMOTIVE BUCK CONVERTER
ANILA T Research Scholar, Department of EEE, BSAU, Chennai, Tamilnadu, India
ABSTRACT
This paper will focus on the Power Management solution of Automotive Infotainment Systems especially inluxury vehicles, considering the Network Management Strategies involved in ECUs via ECU Node Simulation and analyzing parameters related to Clock Synchronisation.
This paper also considers a Buck Converter with a 42V/14V dc/dc converter based topology. 42V/14V dual voltage system will become a replacement to the separate 14V system which is currently available in the industry.
KEYWORDS: Automotive, Infotainment System, Powertrain, CANoe, Capl Debugger, Clock Synchronisation, DC-to- DC Converter
INTRODUCTION
AUTOMOTIVE INFOTAINMENT SYSTEMS
Integrated infotainment systems in automobiles that deliver entertainment and information content. In-Vehicle Infotainment, or IVI, development has been spurred largely by Intel and its Atom processor, Microsoft and its Windows Embedded Automotive platform, and a number of automobile manufacturers.
As system complexity increases in cars, so too does the volume of data to be processed and distributed.Automakers therefore need to ensure that information is processed securely and protected againstexternal access and manipulation (e.g. car tuning, counterfeit spare parts).
Furthermore, new payment methods, such as parking fees or road tolls, require a secure flow of transaction data. Infineon can drawon years of expertise in chip card and identification systems to take automotive data security to the nextlevel.
With our components delivering cost-effectiveness, high efficiency and power density, Infineon is drivingthe future of automotive electronics and paving the way for market-viable and affordable electromobility. 2 Anila T
Figure 1: Automotive Infotainment System HMI
In-Vehicle Infotainment systems are currently available in select automobiles from manufacturers like Ford (SYNC and MyFord Touch), Toyota (Entune), Kia Motors (UVO), Cadillac (CUE) and Fiat (Blue&Me). IVI systems frequently utilize Bluetooth technology and/or smartphones to help drivers control the system with voice commands, touchscreen input, or physical controls.
While each IVI system is different, typical tasks that can be performed with an in-vehicle infotainment system include managing and playing audio content, utilizing navigation for driving, delivering rear-seat entertainment such as movies, games, social networking, etc., listening to incoming and sending outgoing SMS text messages, making phone calls, and accessing Internet-enabled or smartphone-enabled content such as traffic conditions, sports scores and weather forecasts.
BUILDING BLOCKS
The Main Building blocks include the below:
Figure 2a: High Level Building Blocks of Automotive Infotainment System Power Management Solution by Network Management Strategy and Analysis of a Dc-Dc Automotive Buck Converter 3
Figure 2b: Detailed Building Blocks of Automotive Infotainment System
Figure 2c: Feature Connectivity
POWERTRAIN MODULE
The standard powertrain is a 182-horsepower, 2.5-liter four-cylinder mated to a continuously variable transmission (CVT).
Tuned here for higher mileage than ever, OEMs aiming for an EPA highway rating of 27 miles per gallon city, 38 miles per gallon highway, putting it on par with some hybrids and above leaders like today's standard Hyundai Sonata, rated at 35 mpg highway.
It's plenty of power for the point-A-to-point-B school of driving, though the drivetrain can be loud at the higher reaches of its range. 4 Anila T
Figure 2D: Engine Powertrain
NETWORK MANAGEMENTSTRATEGY DATA ACQUISITION
Figure 3: Data Acquisition and Network Management Power Management Solution by Network Management Strategy and Analysis of a Dc-Dc Automotive Buck Converter 5
This is a System which acquires data, generally by digitizing analog channels and storing the data in digital form.
These systems can be standalone or married to a computer and can acquire multiple channels of data.
CANoe TOOL
CANoe is the comprehensive software tool for development, test and analysis of entire ECU networks and individual ECUs.
It supports you throughout the entire development process. Its versatile functions and configuration options are used worldwide by OEMs and suppliers
ANALYSIS WINDOWS IN CANoe
Measurement Setup for graphic display and parameterization of function blocks and evaluation functions
Scope window for offline display of measurements of bus levels recorded using the SCOPE option
Interactive Generator for stimulating the buses and for easy sending of modified signals
UTILITY OF CANoe IN ECU NM
Figure 4: CANoe Use in Network Management
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CAPL DEBUGGER
Figure 5: CAPL Debugger
SIMULATION TOOL FEATURES
Diagnosis/engine/transmission/ABS/air-conditin/ Immo etc. for ECU repairing, auto teaching aid model driver, auotmobilesR&D.It fit for multi-brands Cars.
Item Function
Users can set the engine control system, independent of different types of crank signal output
Engine speed signal output
Speed output (Hall signal, magnetic signal)
Automatic transmission input and output shaft signal simulation
Set the waveform data is written directly
Three, four-channel ABS wheel speed signal output
PC board working current test
Injector simulation
Idle stepper motor simulation (four-lane, six-lane)
A\C relay simulation, Pump relay simulation, Radiator fan relay simulation
Audio signal outputs, power amplifier driver
Automatic Shift Valve, shift quality valves, hydraulic control valve simulation
EGR solenoid valve drive Power Management Solution by Network Management Strategy and Analysis of a Dc-Dc Automotive Buck Converter 7
Carbon can clear the solenoid valve drive or valve simulation
Tachometer drive
Blower Control Module Driver
Idle valve driver
Stepper motor drive (4, 6 lines)
Injector Driver
Ignition coil driver,module drive
Parking sensor (ultrasound) probe drive
Automatic Shift Valve Drive, Shift quality valve drive, hydraulic valve drive
Water temperature, intake air temperature, outdoor temperature, evaporation temperature sensor signal simulation box
Oxygen sensor signal simulation (manual/ auto signal), Throttle signal simulation, EGR solenoid valve simulation
Air flow sensor, intake air pressure sensor (analog, digital) signal simulation
Ignition coil simulation
Fuel injection pulse width measurement
Central lock server simulation
Burglar resistance simulation
Output signal: magnetic signals, Hall signals, optical signals
Special Features
Sensor Simulation Experts
It can be set arbitrary waveform output, can produce all the models of today's engine crankshaft, camshaft signals (Hall, magnetic, optical signals), waveform memory card from the long-term preservation, waveform data for free online updates.
Crank simulation experts:
ABS wheel speed signal, speed signal (Hall, magnetic, optical signals), the oxygen sensor signal, throttle signal, air flow, inlet pressure sensor (analog, digital) and other signal simulation
CLOCK SYNCHRONISATION
Cristian’s algorithm
The simplest algorithm for setting the time would be to simply issue a remote procedure callto a time server and obtain the time. That does not account for the network and processing delay.We can attempt to compensate for this by measuring the time (in local system time) at which the request is sent (T0) and the time at which the response is received (T1). 8 Anila T
Our best guess at the network delay in each direction is to assume that the delays to and from are symmetric (we have no reason to believe otherwise). The estimated overhead due to the network delay is then (T1- T0)/2.
The new time can be set to the time returned by the server plus the time that elapsed since the server generated the timestamp.
Suppose that we know the smallest time interval that it could take for a message to be sent between a client and server (either direction). Let's call this time Tmin. This is the time when the network and CPUs are completely unloaded. Knowing this value allows us to place bounds on the accuracy of the result obtained from the server.
If we sent a request to the server at time T0, then the earliest time stamp that the server could generate the timestamp is T0 + Tmin. The latest time that the server could generate the timestamp is T1 - Tmin, where we assume it took only the minimum time, Tmin, to get the response.
The range of these times is: T1 - T0 - 2Tmin. Several time requests may be issued consecutively in the hope that one of the requests may be delivered faster than the others (e.g., it may be submitted during a time window when network activity is minimal). This can achieve improved accuracy.
Cristian's algorithm suffers from the problem that afflicts all single-server algorithms: the server might fail and clock synchronization will be unavailable. It is also subject to malicious interference.
Berkeley algorithm
The Berkeley algorithm, developed by Gusella and Zatti in 1989, does not assume that any machine has an accurate time source with which to synchronize. Instead, it opts for obtaining an average time from the participating computers and synchronizing all machines to that average. The machines involved each run a time daemon process that is responsible for implementing the protocol.
One of the machines is elected (or designated) to be the master. The others are slaves. The server polls each machine periodically, asking it for the time. The time at each machine may be estimated by using Cristian's method to account for network delays.
When all the results are in, the master computes the average time (including its own). The hope is that the average cancels out the individual clock's tendencies to run fast or slow. Instead of sending the updated time back to the slaves, which would introduce further uncertainty due to network delays, it sends each machine the offset by which its clock needsadjustment.
BLOCK DIAGRAM OF 42V/14V BUCK CONVERTER
The 42V/14V System used in luxury cars is referred below: Power Management Solution by Network Management Strategy and Analysis of a Dc-Dc Automotive Buck Converter 9
Figure 6: 42V/14V System
MODE OF OPERATION
A buck converter operates in continuous mode if the current through the inductor (IL) never falls to zero during the commutation cycle. In this mode, the operating principle is described by the plots in figure 4:
When the switch pictured above is closed (On-state, top of figure 2), the voltage across the inductor is
. The current through the inductor rises linearly. As the diode is reverse-biased by the voltage source V, no current flows through it;
When the switch is opened (off state, bottom of figure 2), the diode is forward biased. The voltage across the inductor is (neglecting diode drop). Current IL decreases.
The energy stored in inductor L is
Therefore, it can be seen that the energy stored in L increases during On-time (as IL increases) and then decreases during the Off-state. L is used to transfer energy from the input to the output of the converter.
The rate of change of IL can be calculated from:
With VL equal to during the On-state and to during the Off-state. Therefore, the increase in current during the On-state is given by: 10 Anila T
Conversely, the decrease in current during the Off-state is given by:
If we assume that the converter operates in steady state, the energy stored in each component at the end of a commutation cycle T is equal to that at the beginning of the cycle. That means that the current IL is the same at t=0 and at t=T (see figure 4).
So we can write from the above equations:
It is worth noting that the above integrations can be done graphically: In figure 4, is proportional to the area of the yellow surface, and to the area of the orange surface, as these surfaces are defined by the inductor voltage (red) curve. As these surfaces are simple rectangles, their areas can be found easily: for the yellow rectangle and for the orange one. For steady state operation, these areas must be equal.
As can be seen on figure 4, and . Where D is a scalar called the duty cycle with a value between 0 and 1. This yields:
From this equation, it can be seen that the output voltage of the converter varies linearly with the duty cycle for a given input voltage. As the duty cycle D is equal to the ratio between tOn and the period T, it cannot be more than 1.
Therefore, . This is why this converter is referred to as step-down converter.
So, for example, stepping 12 V down to 3 V (output voltage equal to a fourth of the input voltage) would require a duty cycle of 25%, in our theoretically ideal circuit.
OUTPUT VOLTAGE RIPPLE
Output voltage rippleOutput voltage ripple is the name given to the phenomenon where the output voltage rises during the On-state and falls during the Off-state.
Several factors contribute to this including, but not limited to, switching frequency, output capacitance, inductor, load and any current limiting features of the control circuitry. At the most basic level the output voltage will rise and fall as a result of the output capacitor charging and discharging. Power Management Solution by Network Management Strategy and Analysis of a Dc-Dc Automotive Buck Converter 11
SELECTION OF DC-TO-DC CONVERTERS, SOME REFERENCES FOR BETTER EFFICIENCY
The DC/DC Converters are most viable in market. A Market Analysis of the available DC/DC Converters is done and the suitable ones for Automotive Industry is listed below:
LT8584 DC/DC converter offers active balancing for high-voltage battery stacks
Linear Technology
The LT8584 monolithic flyback DC/DC converter from Linear Technology is designed to actively balance high- voltage stacks of batteries commonly found in electric and hybrid vehicles as well as failsafe power supplies and energy storage systems.
LT3905 DC/DC converter from Linear Technology is designed to bias APDs
Linear Technology
The LT3905 is a fixed-frequency, current-mode step-up DC/DC converter designed to bias avalanche photodiodes (APDs) in optical receivers.
150W LLC DC/DC resonant converter using the LCS702HG
Power Integrations
This design example report from Power Integrations describes a 24V, 150W LLC DC/DC converter utilising a LCS702HG integrated LLC power stage IC.
Linear Technology releases LT8302 flyback regulator for simplifying DC/DC converters
Linear Technology
Linear Technology has introduced the LT8302, a monolithic flyback regulator designed to simplify the design of isolated DC/DC converters. By sampling the isolated output voltage directly from the primary-side flyback waveform, the part requires no opto-isolator or third winding for regulation.
Linear Technology offers LT3795 DC/DC converter for driving high-brightness LEDS
Linear Technology
Linear Technology has announced the the LT3795: a 110V, high-side current-sense DC/DC converter designed to regulate a current or voltage to a constant value, that is suitable for driving high-brightness (HB) LEDs.
Linear Technology offers high-temperature version of its LTC3122 DC/DC converter
Linear Technology
Linear Technology has announced the release of the LTC3122HMSE — its high-temperature H-grade version of the LTC3122 DC/DC converter in a12-lead thermally enhanced MSOP package. This version is suitable for automotive, industrial and military applications that are subject to high ambient temperatures.
Application note: applications of the LT1300 and LT1301 micropower DC/DC converters
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Linear Technology
This application note from Linear Technology describes the applications of the LT1300 and LT1301 micropower DC/DC converters, which provide improvements in both electrical and physical efficiency.
Data sheet: LT3955 DC/DC converter from Linear Technology
Linear Technology
Linear Technology is offering the LT3955, a DC/DC converter that is designed to operate as a constant-current source and a constant-voltage regulator with an internal 3.5A switch.
CONCLUSIONS
The Network Management principles incorporation followed by the design of Buck Converter will pave the way to efficient Power Management and Battery Management in Cars. This is simulated in CANoeand the efficient usage can be triggered by testing the developing the modules in Embedded C and testing the ECUs and measuring the output ripple.
ACKNOWLEDGEMENTS
The author would like to thank B.S. AbdurRahman University for providing the work environment and theneeded support.
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