Voltage balancing control of a four-level hybrid-clamped inverter using modified phase-shifted PWM

This paper presents a voltage balancing method for a four-level hybrid-clamped inverter. The relationship between the capacitor currents and switching functions is studied. A modified phase-shifted PWM method is used to regulate the capacitor currents by adjusting the start and end time of the PWM signals slightly according to the capacitor voltages and the polarity of the output current. Experimental results are presented to verify this method.