Design and analysis of a low cost and high power density PM-assisted synchronous reluctance machine for automotive electric power 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 machine 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, two low cost 12V 4kW air-cooled PM-assisted synchronous reluctance machine designs for automotive electric power management are presented. The design and analysis in terms of electromagnetic, mechanical and thermal behaviors are discussed in detail. One of the machines was built and tested and found to meet the cost, performance and packaging requirements.