Electric drives for pump, fan, and compressor loads in automotive applications

Optimization of automotive power plants is moving in the direction of increased utilization of electrically driven auxiliary loads. Such subsystems include cooling and power assist functions. The power levels required by these loads range from hundreds to tens of hundreds of watts. At these power levels, the current ratings of switching devices and motor phase leads, assuming tradition drive and motor designs, can exceed 100 amps at the standard 13.5 VDC bus level. This paper discusses alternative drive and motor configurations which will mitigate the current rating requirements of the drive and motor components. The authors present the case for usage of H-bridge and bipolar bus drives and usage of five-phase machines.