Reducing the Common-Mode Currents at the Input and Output Sides in DC-AC Inverter Systems

In photovoltaic (PV) inverter systems and motor drive systems, the inverters generate common-mode (CM) voltages, which can lead to the CM electromagnetic interference (EMI) and leakage current at the input and output sides. In this chapter, a generalized CM noise model for the inverter system is derived. Then, building upon the CM voltage cancellation (CMVC) method for DC-DC converters presented in Chap.  9 , the CMVC method for DC-AC inverters is proposed for reducing the CM currents at both the input and output sides in inverter systems. The comparison between the CMVC method and the existing solutions are discussed. Finally, a single-phase inverter prototype with silicon-carbide (SiC) devices is built in the lab. The CM currents at both the input and output sides are measured and compared, verifying the effectiveness of the proposed CMVC method.