Prediction and evaluation of PWM-induced current ripple in IPM machines incorporating slotting, saturation, and cross-coupling effects

This paper presents an improved analytical model for estimating the high-frequency current ripple of interior permanent magnet (IPM) synchronous machines due to PWM switching. The proposed model accounts for the impact of slotting effects, magnetic saturation, and cross-coupling between the d- and q-axes. The model is subsequently used to investigate several factors that influence the PWM-induced current ripple. These include the PWM switching frequency, fundamental frequency (i.e., machine speed), dc-bus voltage, current control angle (i.e., γ angle), and the excitation current amplitude (i.e., saturation level). Experiments have been conducted to verify the analytical prediction results. These results show that the analytical model can predict the PWM-induced current ripple waveshape very well for many operating conditions and accurately estimate its rms value over a fundamental period.