A Five-Level Discontinuous SVPWM for Parallel Three-Level Inverters to Reduce Common Mode Voltage and Output Current Ripples

Conventional reduced common mode voltage (RCMV) discontinuous modulation (DPWM) method for three-level inverter can reduce the common mode voltage by selection of certain vectors which generates the smallest common mode voltage. However, it cannot provide additional performance enhancements when applied directly on parallel three-level inverters. Based on the interactions between the parallel inverters, this paper reveals that dual parallel three-level inverters could be analyzed and controlled as a single five-level inverter. A novel five-level discontinuous modulation method is therefore proposed to further reduce the common mode voltage of the system, in addition to improve the output current quality compared with synchronous parallel application of conventional discontinuous modulation. The effectiveness and advantages of the proposed method are verified by experimental results.