An efficient neutral point voltage control algorithm with reduced switching losses for three level inverters

This paper proposes an efficient neutral point control algorithm for three level T-type inverters. The proposed algorithm helps to get balanced neutral point voltage with high efficiency steady state operation. The proposed controller relies on using the hysteresis control for DC link capacitors´ voltage balancing. The proposed algorithm is implemented by adjusting the type of redundant small vectors and its duration times in the nearest three vectors (N3V) space vector modulation (SVPWM). Lower switching losses have been achieved by using reduced transitions in the output voltages. The proposed neutral point voltage controller achieves multiple objectives as it increases significantly the ability of the T-type three level inverter to balance the voltage of neutral point with reduced switching events. The proposed method is simple to implement without need for complex calculation or additional hardware. The results of simulation and experimental work are shown in order to verify the feasibility and effectiveness of the proposed controller.