A neutral-point potential balancing control method with third harmonic injected pulse width modulation for three-level converters

The unbalance of neutral-point potential (NPP) is an important problem in three-level converter. This paper proposes a neutral-point potential balancing control method with the third harmonic injected pulse width modulation (PWM) for three-level converters, which can a) realize better steady and dynamic performance of restraining the NPP unbalance; b) realize the similar performance with the space vector pulse width modulation (SVPWM) but with less amount of calculation; c) be applied in multiple operating modes such as grid-tied/off-grid mode, voltage-source/current-source mode. Finally, simulation results are presented, which validate the performance of the proposed method