Variable Magnet Based Performance Improvement of PM-Assisted Synchronous Reluctance Motor

Permanent magnet synchronous reluctance motors (PMsynRM) have been attracting a growing interest because they can provide high torque and efficiency in a wide speed range by using less amount of magnets compared to classical permanent magnet synchronous motors (PMSMs). As in PMSMs, field weakening is required for the PMsynRM when it runs over the rated speeds. Therefore, the motor also suffers from limited efficiency since the increase in phase current is needed to realize the field weakening. This paper presents a design to improve performance as well as the speed range of a PMsynRM based on variable magnets (VMs). The provided analysis results show that replacing a partial amount of NdFeB magnets with Alnico magnets and making a proper design can lead to almost the same efficiency up to rated speed and higher efficiency over the rated speed.