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Home , Linear induction motor, Permanent magnet motor

SPECIAL PURPOSE MACHINES

D.VENKATESH G.MADAN

L6EE924 Y5EE840 EMAIL: [email protected] EMAIL:[email protected]

Phone: 9963510494 Phone: 9963510494

R.V.R & J.C.COLLEGE OF ENGINEERING

Chandramoulipuram Chowdavram GUNTUR - 19

ABSTRACT:

Day by day the interest on Nano generator special machines increases. Because Researchers have these machines serves for several demonstrated a prototype nanometer- applications.For instance,the nano scale generator that produces continuous generator could drive biological sensors direct-current electricity by harvesting by making use of wind energy or water mechanical energy from such flow,eliminating the need for external environmental sources as ultrasonic batteries.This not only reduces the waves, mechanical vibration or blood device cost but also at the same time flow. The nanogenerators take advantage reduces the entire equipment size. of the unique coupled piezoelectric and Integrated generator semiconducting properties of zinc oxide which is used in electric vehicles acts as nanostructures, which produce small a bidirectional energy converter as a electrical charges. motor when powered by the battery or a generator when driven by the engine.Linear motors are used to propel high speed trains.Micro motors plays an important role in computer hard drives,optics,sensors and actuators.A special type of outer motors used to drive the polygonal rotating mirrors which are mounted directly on the rotor in laser printers. Our paper tries to introduce some of these machines and their applications in various fields.The recent developed technology of nano Fabrication begins with growing an generators is included and its working is array of vertically-aligned nanowires also explained. approximately a half-micron apart on

2 gallium arsenide, sapphire or a flexible Nano motor polymer substrate. A layer of zinc oxide is grown on top of substrate to collect Even smaller motors the current. The researchers also have been made using nanotechnology. fabricate silicon “zig-zag” electrodes, An example is shown below. It consists which contain thousands of nanometer- of a tiny gold slab rotor, about 100 nm scale tips made conductive by a platinum square, mounted on concentric carbon coating. nanotubes.The outer tube carries the rotor, driven by electrostatic electrodes, The electrode is then lowered rotating around an inner tube which acts on top of the nanowire array, leaving just as a supporting shaft. By applying enough space so that a significant voltage pulses of up to 5 Volts between number of the nanowires are free to flex the rotor plate and , the position, within the gaps created by the tips. speed and direction of rotation of the Moved by mechanical energy such as rotor can be controlled. It measures waves or vibration, the nanowires about 500 nanometers across, 300 times periodically contact the tips, transferring smaller than the diameter of a human their electrical charges. By capturing the hair. tiny amounts of current produced by hundreds of nanowires kept in motion, the generators produce a output in the nano-Ampererange. If we had a device like this in our shoes when we walked, we would be able to generate our own small current to power small electronics.Anything that makes the nanowires move within the generator The motor was built from can be used for generating power. Very multiwalled nanotubes created in an little force is required to move them. electric arc and deposited on the flat silicon oxide surface of a silicon wafer. A rotor, nanotube anchors and opposing

3 stators were then simultaneously shaped glass fibre circuit board which patterned in gold around the selected rotates in the air gap between pairs of nanotubes using electron beam permanent arranged around the lithography. A third was already periphery of the disk. The windings fan buried under the silicon oxide surface. out in a series of radial loops around the The silicon was then etched to create a surface of the disk. The magnets are trough beneath the rotor with sufficient arranged alternatively north and south so clearance for the rotor to rotate.Possible that the magnetic fields in the air gaps of applications are moveable mirrors for adjacent pairs are in opposite optical switches or paddles for moving directions. The magnets are held in place fluids. by two iron end caps in a compact "pancake" shaped block to complete the Axial Field Motors magnetic circuit. Current is fed to the rotor windings via brushes through Axial field motors precious metal segments have been developed for applications printed on the disc. which require short, flat, "pancake" construction.

Printed Circuit (PCB) or "Pancake" Motor:

The printed circuit motor is an example of an ironless or coreless motor with several unique features. The pancake construction uses an axial to achieve the short flat construction. Radial field PCB Operating Principle: motors are also possible. Traditional electric motors Construction: have a radial magnetic field or flux with The rotor windings are printed, the rotor current flowing axially along stamped or welded onto a thin, disc the length of the rotor. In typical printed

4 circuit motors the construction is Since the rotor does not have drag a reversed. The magnetic field is axial lump of iron around, it has very low (oriented along the axis of the machine) inertia and can run up to speed very and the current flows radially from the quickly. Because of the many axis to the edge of the disc and back commutator segments and the low again. A tangential force on the disk is current capability of the windings, the created by the current passing through PCB motor is only suitable for low the magnetic fields in the air gaps power applications and is not suitable for between the pole pairs of the permanent continuous operation. It is however ideal magnets. So that the return current does for servo systems and industrial controls not cancel out the effect of the outgoing and automotive applications such as current, the return wire is physically electric window winders. separated or displaced to one side from the outgoing wire by the width of the Outer Rotor Motors magnet. In this way it interacts with the magnetic field of the adjacent magnet There are many designs using which is in the opposite direction and this construction, mostly for small sizes. thus reinforces the tangential force on Two examples of low power motors are the disk. shown below. High power versions are used for "in wheel" automotive In many ways it is similar applications. to Faraday's 1831disk or which used a single magnet and Inside Out Motor was driven by a unidirectional current These are permanent fed by brushes at the centre and on the magnet motors with the moving magnets periphery of the disk. arranged around the periphery of a multi pole fixed stator carrying the field Applications : windings. The printed circuit motor is a very compact and light weight design making it useful in confined spaces.

5 Because of the low inertia and friction free rotor, the toroidal motor is capable of speeds up to 25,000 RPM. Suitable for low power applications it is used for example to drive the polygonal rotating mirrors which are mounted directly on the rotor in laser printers.

Integrated starter Used for automotive generator(ISG): drive systems including in-wheel motors. Low power versions used in small cooling fans and direct drive The electronically controlled record. integrated starter generator used in mild hybrid electric vehicles (HEVs) Toroidal Coil Motor combines the automotive starter and into a single machine. This is an "inside out" brushless with a toroidal wound stator covered by a cup shaped permanent magnet outer rotor.

"Design of a Switched Reluctance Machine for Extended Speed Operation"

6 The conventional starter is a low speed, The system voltage in a mild HEV is 42 high current DC machine, while the Volts which means that, for the same alternator is a variable speed 3 phase ac cranking power as a 12 Volt machine, machine. the starter current can be reduced. The ISG has four important functions in Typical power throughput is between a hybrid vehicle application 5kW and 15 kW with a possible peak power of 70 kW for cold cranking. • It enables the "start-stop" The brushless function, turning off the engine when the ISG design eliminates one rotating vehicle is stationary saving fuel. machine completely as well as the • It generates the electrical energy associated commutator and brushes from to power all the electrical ancillaries. the DC machine and the sliprings and • It provides a power boost to brushes from the AC machine. The assist the engine when required, starter solenoid, the Bendix ring (starter permitting smaller engines for gear) and the pulley or gear drive to the similar performance. alternator are also no longer needed and • In some configurations it because of the higher system voltage, the recuperates energy from regenerative diameter and weight of the copper braking. cabling is also reduced substantially. The savings however come at a cost. The In a typical system must be integrated with several implementation (below), the ISG is a subsystems as follows short axis, large diameter "pancake" shaped switched reluctance machine • An AC/DC converter to rectify mounted directly on the end of the the generator output voltage. engine crankshaft between the engine • A DC/DC converter to supply the and the clutch in the gearbox bell vehicle's electrical power system housing.The ISG is a bi-directional voltages. energy converter acting as a motor when • Power electronics and software powered by the battery or a generator to control the ISG current, voltage, when driven by the engine.

7 speed, torque and temperature as appropriate.

• An overall energy management system integrated with the vehicle's engine, battery and brakes.Larger versions of this construction are also used in full hybrid electric vehicles. The switched reluctance machine with its simple rotor of inert iron is very robust,

able to operate at high speed and to In the diagram withstand the harsh operating conditions above, when the magnet is directly in the engine compartment. above the current carrying conductor as shown, the magnetic forces (north and MagLevTraction south poles) from the two adjacent current loops cancel out and there is no Motors: lift. If however the magnet is moving The principle of very quickly over the coils, it will reach the linear is used to a position over like, repulsive, poles propel high speed Maglev (Magnetic (north poles in the diagram) which are Levitation) trains which float on a displaced from the attractive south poles magnetic field created by electromagnets so that the net effect is a force repelling in the trackbed under the train . A the magnet away from the track. This is separate set of trackside guidance only possible because the current in the magnets is used to control the lateral trackbed magnets lags the voltage due to position of the train relative to the track. the inductance of the windings, creating Thus the maglev train uses a delay in the build up of the balanced electromagnetic forces for three different field by which time the magnet has tasks, to suspend, to guide and to propel moved into the adjacent region where the train. there is a net repulsive force. This effect only happens when the magnet on the train is moving at high speed across the

8 trackbed magnets. Thus the train needs to be in motion for this system to work and the train needs wheels for support as it accelerates from rest and when it is slowing to a halt.

Micro-motors

The motor shown below is an example of semiconductor The motor is not assembled from manufacturing technology used to individual components. Instead the fabricate very small mechanical components are built up on a components. It measures 100 microns semiconductor substrate by masking and across, or about the width of a human etching and a mask-less post-processing hair. Similar in principle to a reluctance release step is performed to etch away motor, it depends on electrostatic sacrificial layers, allowing the structural attraction, rather than magnetic layers to move and rotate. attraction, between the stator and rotor Micromachined poles. Because the dimensions are so micromotors can be monolithically tiny, very high electric fields can be built integrated together with the necessary up with only a few volts between the CMOS drive circuits, containing motor poles. oscillators, frequency dividers and counters, and transistors for the drive circuit all on one silicon chip.Common uses include defense/munitions applications, computer hard drives, optics, sensors and actuators .

9 Conclusion: Reference:

All these special machines 1)http://en.wikipedia.org plays a key role in their respective fields.These machines reduces the time 2)http://www.nanoscience.gatech.edu/zl wang/ of operation of the system and at the same time provides smooth 3)www.mpoweruk.com operation.The researchers of nano generator said, “You could envision 4)The world’s first having these nanogenerators in your wind turbines unveiled in China shoes to produce electricity as you walk. This could be beneficial to soldiers in the field, who now depend on batteries to power their electrical equipment. As long as the soldiers were moving, they could generate electricity.”This statement indicates the importance of the special machines.

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