Voltage balancing method using phase-shifted PWM for stacked multicell converters

Abstract

This paper proposes an active voltage balancing method for stacked multicell converters (SMC) using phase-shifted pulse-width modulation, which is easy to implement and extend to high number of levels. The proposed method balances the voltages of the capacitors by modifying the duty cycle of each switch of the SMC using a proportional controller. The crossed effect between capacitor currents and duty cycles is considered and is used for optimal capacitor voltage balance. The performance of the proposed voltage balancing method is verified by simulation for different operating conditions, such as unbalanced linear loads, non-linear loads and load transients.