Abstract
A simple Stop-Start Concept based on a standard 12V board-net has been designed to cope for the increasing demand to reduce fuel consumption and polluting emissions. A reversible 2,5 kW Voltage Source Inverter is placed between the battery and the optimized claw-pole synchronous machine to allow for both, starter and generator operation.
Application of standard parts and realization of the Power Electronics in a separated box yields a cost competitive and reliable system that can be easily integrated to whatsoever motor platforms.
Starter operation is realized by full-wave operation controlling the firing angle between stator voltage and rotor flux. The strategy yields an important per volume starting torque allowing for cold-cranking of small combustion engines. As the torque is transmitted to the crankshaft by a belt, the result is a noiseless and quick start, highly acceptable for the driver.
Generator operation is realized by a synchronous rectifier that actively fires the power semiconductors depending on the phase current, the latter being detected without using current sensors. The method allows to significantly increase the alternator efficiency.
The resulting benefits of both Stop-Start operation and increased alternator efficiency have been validated by simulation and measurements on a 1,4L gasoline engine powered vehicle, yielding a fuel reduction of 5% in normalized MVEG and 10% in city drive-cycles.
Evolution towards 42V is easy and can be realized with additional features such as motor boost.