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To solve the problems of permanent magnet vernier motor（PMVM） with high torque density and high power density, the performance of PMVM was compared with that of traditional permanent magnet synchronous motor（PMSM）. The structure and working principle of 6-slot/32-pole split-tooth PMVM were introduced. The air-gap flux density of PM field and armature reaction magnetic field（ARMF）, the no-load EMF, the torque and the loss of 6-slot/32-pole split-tooth PMVM were analyzed by finite element simulation software of JMAG and quantitatively compared with those of two traditional PMSMs with the same diameter, stack length and number of stator teeth. The results show that compared with 6-slot/32-pole and 6-slot/4-pole PMSMs, the average torque of 6-slot/32-pole split-tooth PMVM is increased by about 45.0% and 76.2%, and the torque ripple is decreased about 90.5% and 95.0%, respectively. The results reveal that the split-tooth PMVM has merits of high torque density and low cogging torque. However, the air-gap flux density of the split-tooth PMVM contains large number of harmonics with different pole-pairs and rotation speeds, which leads to higher iron loss and PM eddy current loss. [ABSTRACT FROM AUTHOR]

In order to reduce the cost of the universal motor, a new four pole double brush universal motor is designed based on a pick motor. The motor has the advantages of short end of armature winding, reduced brush number, and no need of excitation winding for stator auxiliary magnetic pole, which can effectively reduce the material cost of the series motor. By improving the structure of the traditional two-poles series motor, the structural parameters of the new four-poles series motor are preliminarily determined, and the two-dimensional finite element model of the motor is established using Maxwell software. The mathematical model and air gap flux density of the new series motor are analyzed, and the operating characteristics and load performance of the motor are compared and analyzed. The results show that the four-poles series motor is superior to the original two-pole motor in terms of operating characteristics and load performance. The above findings provide a research basis for further optimization of the motor. [ABSTRACT FROM AUTHOR]