Four-Space-Vector Pulse Width Modulation for Neutral-Point-Clamped Three-Level Inverter

In this paper, a four-space-vector pulse width modulation strategy is proposed and designed for a three-phase three-level neutral-point-clamped (NPC) inverter. It is implemented based on vector space decomposition (VSD), which could be applied for high-power and high-reliability applications. As four vectors are used to synthesize every target vector, the control speed of the neutral-point potential balance within full modulation ratio can be improved and the shortcoming of the traditional vector control that the medium vector affects the neutral-point potential can be avoided. To verify the effect of this strategy, virtual space vector pulse width modulation (VSVPWM) strategy is also simulated as comparative experiments.