Design and analysis of PMSMs for HEVs based upon average driving cycle efficiency

Permanent magnet synchronous machines (PMSMs) are widely used as traction machines in the hybrid and electrical vehicles (HEVs) due to their high power density, wide field weakening range and high efficiency. An optimized and efficient design of PMSMs depends upon the driving cycle requirements and consideration of losses of every subsystem in the traction drive. Efficiency of a traction drive over a driving cycle is more important than the efficiency of the traction machine at one operating point. This paper presents an approach for the design of PMSMs based upon the average driving cycle efficiency (ADCE) of traction drive for an urban series hybrid bus for a specific driving cycle. It includes the efficiency of machine, inverter as well as the energy utilized by their cooling systems. The proposed approach was applied to two different machines to demonstrate its validity.