A PWM Strategy for Suppressing Common Mode Voltage of Robot Joint Drive Motor

The common mode voltage (CMV) generated by the drive motor end of the electric driven robot joint under the PWM modulation strategies, brings certain hidden dangers and effects the safety of the system. At present, most modulation strategies are based on SVPWM strategy, which suppress the high frequency CMV of the drive motor end. However, it is not obvious for the low frequency component. In this paper, a SPWM modulation strategy with third harmonic injection based on carrier phase shift 120° method (PSC-THISPWM) is proposed to reduce the low frequency component of V while suppressing its high frequency component. The simulation results show that the proposed CMV suppression strategy is effective compared with four existing suppression strategies. Finally, the hardware platform of the robot joint drive motor system is built to further verify the suppression ability of the proposed strategy on the CMV of the drive motor end.