Sensorless Drive of Six-phase PMSM Based on Signal Injection with Torque Ripple Cancellation Algorithm

Sensorless control of PMSM based on signal injection is widely used in low-speed operation range because it can estimate the rotor speed and position at low speeds as well as at standstill. But the signal injection method causes the torque ripples due to the injected harmonic voltages. In this paper, the torque ripple cancellation algorithm for the sensorless control of six-phase PMSM based on signal injection method is proposed. Two complementary harmonic voltages for estimating rotor position are applied to each three-phase PWM inverters. The torque ripples generated by each three-phase PWM inverters have complementary phases so that the torque ripples due to harmonic voltages can be canceled. MATLAB/Simulink simulation and 1kW six-phase PMSM verifies the effectiveness of the proposed method.