Generalized PWM Approach for DC Capacitors Voltage Balancing in Diode-Clamped Multilevel Converters

This paper develops a generalized Pulse Width Modulation approach to eliminate both the low frequency oscillations and imbalances in the dc-link capacitor voltages, which are the main drawbacks of diode clamped converters. The algorithm has been developed within the Carrier-Based PWM framework to facilitate its implementation in diode clamped converters with four or more levels. In addition, a generalized control strategy for the dc voltages control is proposed and its stability is demonstrated. The good performance of the proposed modulation technique is demonstrated from simulation results of a four level diode clamped inverter.