Analytical Modeling and Calculation of Electromagnetic Torque of Interior Permanent Magnet Synchronous Motor Considering Ripple Characteristics

Abstract

<div class="section abstract"><div class="htmlview paragraph">Based on the classical <i>dq</i> theory, this paper proposes a new electromagnetic torque analytical model (AM) for interior permanent magnet synchronous motor (IPMSM) considering ripple characteristics, including permanent magnet (PM) torque ripple and reluctance torque ripple. The analytical expression of PM torque considering the effect of PM flux linkage harmonics is first derived according to <i>dq</i> transformation and energy method. Then, an improved inductance calculation method considering the non-sinusoidal magnetic field distribution and cross-coupling effect is proposed, and the reluctance torque model is established by taking the influence of inductance harmonics into consideration. Subsequently, the total electromagnetic torque can be obtained by the superposition of PM torque and reluctance torque. Finally, the proposed AM was verified by finite-element method (FEM). The results show that the proposed AM is accurate enough to predict the instantaneous electromagnetic torque waveforms and the average electromagnetic torque. In addition, according to the proposed AM, the sources and order features of torque ripples can be directly determined, and the intrinsic relationship between key electromagnetic parameters and torque harmonics can be revealed.</div></div>