Application of SVPWM in single phase three-level neutral point clamped rectifiers

Aiming at the problem of multiple switches simultaneous turning on or off in single-phase three-level neutral point clamped (NPC) rectifiers, we put forward a space vector pulse width modulation (SVPWM) method. This method can reasonably design the modulation sequences inside each sector, and add transition modulation sequences in sector switch, so as to ensure the continuity of switching states. On the basis of analyzing the influence of each switching state on the neutral point voltage, this method selects appropriate redundant small vector according to the neutral point voltage and grid current, so as to achieve the neutral point voltage control. In addition, by using redundant zero vectors, this method can achieve the effect of frequency doubling. For this SVPWM method, a prototype was built to carry out experimental research. The experimental results showed that the proposed SVPWM method can guarantee only one switch turning on or off at one time, and the change of the output voltage is always half the DC side voltage, and that the phase of the grid voltage is the same as that of the grid current, with good dynamic performance. This method can realize the neutral point voltage control with fast dynamic response speed and accurate steady control.