Analysis of High-Frequency Harmonics of the Common Mode Voltage Under AZSPWM1

In the motor drive system, the high-frequency harmonic components of the common mode voltage (CMV) acting on the stray capacitance of the motor to ground can cause common mode leakage current and conducted electromagnetic interference (EMI). For traditional three-phase permanent magnet synchronous motors (PMSMs), existing strategies can effectively suppress the amplitude of the CMV, but the high-frequency harmonic components of the CMV are not yet clear, and the conducted EMI may not be suppressed. This article demonstrates the principle of harmonic analysis of the CMV and analyzes the sideband harmonic components of the CMV generated by active zero-state pulse width modulation1 (AZSPWM1), filling the theoretical analysis gap of the sideband harmonic components of the CMV. The correctness of the theoretical analysis is verified through experiments. And by measuring the conducted EMI, it is verified that when the high-frequency harmonic components of the CMV are not considered, only the suppression of the CMV amplitude cannot significantly suppress the conducted EMI.