Permanent magnet synchronous motors using primarily reluctance torque

Abstract

Permanent magnet synchronous motors (PMSMs) are widely used in many applications as high-performance variable-speed drives. In traction drives, such as those used for electric vehicles or for the compressor drives of air conditioners, a wide constant-power speed range and high-efficiency operation are desired. The aim of this paper is to develop a high-performance PMSM that offers high-efficiency performance in the high-speed region, including light-load conditions, as well as a wide constant-power speed range. Simulations show that the proposed interior PMSM, which produces chiefly reluctance torque and in which the permanent magnet flux assists torque production, is capable of meeting the above performance requirements. A prototype PMSM is designed in accordance with this new design concept and several drive tests are carried out. The saliency ratio of the prototype IPMSM is about 5, and, as a result, reluctance torque is the principal torque component, representing more than 70% of total torque. The prototype IPMSM can attain a constant-power speed range of up to 5:1 with high-efficiency drive in the high-speed, constant-power region. The proposed IPMSM is suitable for variable-speed drives requiring high-speed, constant-power operation. © 2000 Scripta Technica, Electr Eng Jpn, 134(3): 60–68, 2001