Automotive Claw-Pole- Rotor Generator Systems

Enhancing comfort & safety in cars, trucks, & buses driven by combustion engines require more installed electric power on board. As of now, the claw-pole-rotor generator is the only category of automotive generator used in industry, with whole powers per unit up to 5 kW and speeds up to 18,000 rpm

 A solid rotor claw-pole structure possessing ring-shaped single direct current (DC) excitation coil, though supplied via slip-rings & brushes from the battery on board, has proven to be simple & reliable, with low cost, low volume and low excitation power loss. In common, the claw-pole-rotor generator is a 3-phase generator with 3 or 6 slots per pole & with 12, 14, 16, 18 poles, & a diode full power rectifier.

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Permanent Magnet Synchronous Generator Systems

By the term permanent magnet (PM) synchronous generators (SGs), we imply here radial or axial air gap PM brushless generators with distributed (q greater than 1) or concentrated (q ≤ 1) windings & rectangular or sinusoidal current control having surface PM or interior PM (IPM) rotors.

A PMSG’s output voltage amplitude & frequency both are proportional to speed. In case of constant speed prime mover applications, PMSGs might carry out voltage self-regulation by appropriate design; i.e., inset or interior PM pole rotors. Small speed variation (from ±10 to 15%) may be suitable for diode rectified loads with series capacitors & voltage self-regulation. However, the majority applications require operation at variable speed, and, in this case, constant output voltage vs. load, be it direct current (DC) or alternating current (AC), requires full static power conversion & close-loop control.

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Wound Rotor Induction Generators WRIGS

WRIGs have been constructed for powers per unit up to 4 hundred megawatt (MW) in pump-storage power plants & down to 4.0 MW per unit when used in wind power plants. Diesel engine or gas–turbine-driven WRIGs for stand-by or autonomous operation up to twenty to forty MW may also be useful to reduce fuel consumption & pollution for variable load. Under1.5 to 2 MW/unit, WRIGs are not straightforward to justify in terms of cost per performance and benefits against full the power rating converter synchronous or cage-rotor induction generator systems.

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Switched Reluctance Generators

This tutorial is on Switched reluctance generators (SRGs). The SRGs are double-saliency electric generators that have non- over-lapping stator multi-phase windings & containing passive rotors. They could also be assimilated with stepper motors with position-controlled pulsed currents. Multiphase configurations are necessary for smooth power delivery & eventual self-starting & for motoring process, if the application requires it. SRGs were studied mainly for the following:

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Variable Speed Generators

The design specifications are made to tie to the application. For a generator-only application (this includes wind generator, auxiliary power generator on aircraft, etc.), the motoring mode is not included from start, at the same time the DC output voltage power bus may be as follows:

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