An Inverter Nonlinearity Compensation Method for PMSM Drives Based on Dead-Time Elimination

High switching frequency is suitable for high fundamental frequency and can significantly improve current dynamic response. However, the nonlinear effect of inverter is more prominent at high frequency operation, causing distortion of phase voltage and current. To mitigate the adverse effects of inverter nonlinearity, we propose a hybrid PWM modulation strategy that combines dead-time elimination and inverter nonlinear compensation. Dead-time is eliminated by generating underlap periods based on the stator current direction of the motor. Furthermore, the error voltage characteristics caused by inverter nonlinear effects, including turn-on and turn-off delay, parasitic capacitance and voltage drop on the power devices, were obtained by injecting a ramp current signal into the direct axis during self-commissioning process. Based on this relation, we realize the nonlinear compensation of the inverter. The proposed method is simple, and it is more suitable for dead-time nonlinear compensation of inverters under the condition of high switching frequency. Simulation results demonstrate that the proposed method can effectively reduce the current harmonic content, and the compensation effect is better than conventional compensation methods.