Common-mode voltage mitigation with a predictive control method considering dead time effects of three-phase voltage source inverters

This study proposes a technique to mitigate common-mode voltages with dead time effects taken into account in three-phase voltage source inverters (VSIs), on the basis of finite-set model predictive control methods. The effects of dead time on common-mode voltage in three-phase VSIs controlled by the model predictive control method are investigated. On the basis of the investigation, a common-mode voltage reduction method is proposed, which is not affected by the inevitable dead time of the VSIs. The proposed method pre-excludes, from the candidates for future vectors, those voltage vectors which can increase the common-mode voltage during the dead time. In addition, when zero vectors are chosen as an optimal vector from the standpoints of current errors, each zero vector is replaced with two non-zero vectors in opposite directions, so as not to deteriorate current performance by simply excluding the zero vectors. On the basis of the proposed pre-selective technique, the proposed method can restrict the common-mode voltage within ±V_dc/6 of the three-phase VSIs, whereas the common-mode voltages of the conventional method vary within ±V_dc/2. Simulation and experimental results are presented to verify the effectiveness of the proposed method.