A generalized discontinuous PWM based neutral point voltage balancing method for three-level NPC voltage source inverter with switching losses reduction

In order to control the neutral point voltage of inverter with discontinuous PWM (DPWM), this paper proposed a generalized discontinuous PWM (GDPWM) based neutral point voltage balancing method for three level neutral point clamped (NPC) voltage source inverter (VSI). Firstly, a triangle carrier based (TCB-GDPWM) is proposed. Secondly, the affection on neutral point voltage for the modulation wave are analyzed. Base on the analysis, a bang-bang control is adept to control the neutral point voltage via changing the polarity of the certain part of the common mode voltage (CMV). Finally, the proposed method is verified by simulation and experiment. The results show that the propose method has good performance at neutral point voltage control and switching losses reduction.