Interior permanent magnet motor with a novel tangentially magnetized rotor for refrigerant compressors

This paper presents the design and analysis of an interior permanent magnet synchronous motor (IPMSM) with a novel tangentially magnetized rotor for refrigerant compressors in inverter air-conditioners. To reduce cogging torque, torque ripple, and the weight of magnet usage, a new salient pole rotor design is proposed using permanent magnets arranged for tangential magnetization. The results of magnetic circuit analysis show that the rotor structure proposed in this study considerably reduces the total harmonic distortion (THD) of the air gap flux wave, cogging torque, torque ripple, and the amount of magnet usage. The electromagnetic analysis software JMAG was used to design the new IPMSM to further improve the THD of the air-gap flux waveform and to reduce cogging torque and torque ripple in the motor. The geometry of the rotor structure was optimized using design of experiments (DOE). The results show that the design developed in this study is effective in reducing cogging torque, torque ripple, and the material costs of motors. The motor proposed in this work is thus suitable for application in refrigerant compressors in inverter air-conditioners.