An Active Voltage Balancing Strategy for Stacked-Inverter ICN Converters

This paper presents an active voltage balancing strategy for the impedance control network (ICN) resonant converters with stacked inverters. The stacked mode of operation of this converter is analyzed in detail and the reason for the voltage imbalance is discussed. An active voltage balancing strategy leveraging the phase-shift between the converter’s inverter and rectifier is proposed to mitigate this voltage imbalance. The impact of this voltage balancing strategy on the converter’s soft-switching capability is examined and an enhancement to this balancing strategy is also proposed to ensure soft-switching by introducing slight voltage imbalance. The proposed voltage balancing strategy and its enhanced version are experimentally validated using a 20-V, 330-W ICN ac-dc converter prototype operating at high line input (230 Vrms). This prototype achieves a peak efficiency of 93.8% at high line.