Low Cost and High Power Density PM-Assisted Synchronous Reluctance Machine Drive System for Automotive Engine Torque Management

The demand for increased power and improved fuel economy are driving changes in alternator technology for automotive applications. To meet these demands requires a drive system with capabilities of torque assist, regenerative braking, and power generation to supply vehicle loads while keeping the battery charged. Furthermore, to minimize add-on cost, the system must be air-cooled and operate at 12V with the same or smaller packaging footprint of the current alternator. In this paper, a low cost 12V 4kW air-cooled IPM drive system for automotive electric power management is presented. The design and analysis in terms of machine, inverter, controller and control algorithm are discussed in detail. Thermal performance of system under different operating conditions are studied. Finally a prototype drive system was built and tested and found to meet the cost, performance and packaging requirements.