Carrier multi-modulation used for the common-mode voltage suppression in a three-phase inverter

The output common-mode (CM) voltage will bring many negative effects in a three-phase inverter, which is controlled by the sinusoidal pulse width modulation (SPWM) method. The carrier multi-modulation (CMM) scheme, which is composed of the carrier peak position modulation (CPPM) technology and the carrier 2-frequency-modulation (C2FM) technology, is presented to suppress the CM voltage (CMV) in this paper. By using the CPPM strategy of CMM, the CM peak voltage is reduced in the time domain. By using the C2FM strategy of CMM, in which the carrier-frequency is modulated twice, the peak harmonics of the CMV are lowered optimally in the frequency domain. The feasibility and validity of the CMM scheme are proved by experiment results in a three-phase inverter.