Pulse width modulation for reduction of power losses in three-phase neutral point clamped inverters

This paper investigates the digital implementation of a modulation strategy that can completely remove the low-frequency voltage oscillation, which appears in the neutral point, for all the operating points and for any kind of loads. The implementation is based on a hybrid modulation technique that produces low switching losses and is simple to implement. Losses, average switching frequency, and performance in terms of voltage balance and low frequency neutral point oscillation, THD, and WTHD are investigated. Simulation and experimental results confirm the feasibility of the approach.