The Multiple Degree of Freedom based Neutral Point Potential Control of Three Level Neutral Point Clamped Converters

摘要

Although the virtual space PWM and the dual wave modulation (DWM) method can eliminate the low frequency neutral point potential (NPP) fluctuation, which appears in some NPP control based on the nearest three vector PWM essentially, they will increase the switching frequency and fade the control ability of the NPP drift problem. In this paper, a novel multiple degree of freedom based NPP control with the strong control ability of low frequency NPP fluctuation and NPP drift problem is proposed for three level converter. The traditional DWM method sacrifices many control domains of neutral point current (i