Common‐mode voltage reduction algorithm for photovoltaic grid‐connected inverters with virtual‐vector model predictive control

Model predictive control (MPC) has been proven to offer excellent model‐based, highly dynamic control performance in grid converters. The increasingly higher power capacity of a PV inverter has led to the industrial preference of adopting higher DC voltage design at the PV array (e.g., 750–1500 V). With high array voltage, a single stage inverter offers advantages of low component count, simpler topology, and requiring less control tuning effort. However, it is typically entailed with the issue of high common‐mode voltage (CMV). This work proposes a virtual‐vector model predictive control method equipped with an improved common‐mode reduction (CMR) space vector pulse width modulation (SVPWM). The modulation technique essentially subdivides the hexagonal voltage vector space into 18 sub‐sectors, that can be split into two groups with different CMV properties. The proposal indirectly increases the DC‐bus utilization and extends the overall modulation region with improved CMV. The comparison with the virtual‐vector MPC scheme equipped with the conventional SVPWM suggests that the proposed technique can effectively suppress 33.33% of the CMV, and reduce the CMV toggling frequency per fundamental cycle from 6 to either 0 or 2 (depending on which sub‐sector group). It is believed that the proposed control technique can help to improve the performance of photovoltaic single‐stage inverters.