Model Predictive Control Methods to Reduce Common-Mode Voltage for Three-Phase Voltage Source Inverters

In this paper, we propose model predictive control methods to reduce the common-mode voltage of three-phase voltage source inverters (VSIs). In the reduced common-mode voltage-model predictive control (RCMV-MPC) methods proposed in this paper, only nonzero voltage vectors are utilized to reduce the common-mode voltage as well as to control the load currents. In addition, two nonzero voltage vectors are selected from the cost function at every sampling period, instead of using only one optimal vector during one sampling period. The two selected nonzero vectors are distributed in one sampling period in such a way as to minimize the error between the measured load current and the reference. Without utilizing the zero vectors, the common-mode voltage controlled by the proposed RCMV-MPC algorithms can be restricted within ±Vdc/6. Furthermore, application of the two nonzero vectors with optimal time sharing between them can yield satisfactory load current ripple performance without using the zero vectors. Thus, the proposed RCMV-MPC methods can reduce the common-mode voltage as well as control the load currents with fast transient response and satisfactory load current ripple performance compared with the conventional model predictive control method. Simulation and experimental results are included to verify the effectiveness of the proposed RCMV-MPC methods.