Space vector modulation method to balance the neutral voltage for a three level inverter

This paper investigates the capacitor voltage balance scheme for a neutral point clamped inverter. A symmetrical space vector modulation is used to analyze the imbalance in neutral point voltage. This method overcomes the drawbacks of Nearest Three Vector modulation method. The redundancies of different switch configurations for the generation of the same output voltage are used to limit the voltage drift when modulation index is less than half. The deviation in the neutral voltage is further reduced by adjusting the duty cycle distribution variable. The voltage balance scheme is analyzed for linear and non linear loads. The performance of control strategy is also examined for a grid connected inverter.