基于磁场调制原理的齿槽转矩研究

The cogging torque of permanent-magnet machines will cause the torque ripple and reduce the accuracy of motor control. How to reduce the cogging torque has been one of the research hotspots in the field of permanent-magnet machines. The deduction process of traditional analytical method of cogging torque is commonly based on energy method. In this paper, a new cogging torque analysis method for permanent magnet machine is proposed by combining energy method with magnetic field modulation theory. The mechanism of cogging torque is explained, and the expression of cogging torque is deduced. It is proved that cogging torque is the result of the interaction of several modulated magnetic fields. Based on the analysis of the expression of the cogging torque component, the period constraints of the harmonic permanent magnetic field and the harmonic air-gap permeance are obtained to generate each cogging torque component. The integer-slot winding machine and the fractional-slot winding machine are simulated by finite element method. The cogging torques of machines with different pole/slot combinations are studied. The variations of the amplitudes of the harmonic magnetic fields in the air gap with the rotation of the rotor are studied, verifying the theoretical derivation. Finally, based on the analysis method of cogging torque in this paper, the design method of the machine is provided to suppress the cogging torque.