Study on the permanent magnet reduction design in single-phase line-start permanent magnet motor for household appliance

In this paper, a study focus on cost reduction of magnet material by utilizing the structure advantage of rotor design in a single-phase line-start permanent magnet motor (LSPM) is presented. Base on a prototype LSPM having single-barrier rotor structure, a double-barrier IPM rotor design is adopted for saving the permanent magnet material and maintaining the main machine performances. The advantage of double-barrier rotor structure to create higher rotor saliency that benefits to reluctance torque production is utilized to compensate the decreasing of magnet torque production since the less permanent magnet use. Therefore, the hybrid torque is generated at a new balance ratio of reluctance torque and magnet torque. The improvements of the machine performances by adopting double-barrier rotor structure are emphasized in this study. Validation of this proposed approach is proved by finite element method and experiment method.