Bidirectional Isolated Hybrid Ripple-Cancel Dual Active Bridge Converter with Automatic Voltage Sharing for High Voltage Application

Abstract

A high voltage bidirectional DC/DC converter is necessary for interconnecting a medium voltage (MV) DC network to a low voltage DC network in future DC power distribution networks. Several multilevel converter topologies have been investigated to handle the high voltage stress on the MV network, including a diode/capacitor clamped converter, a modular multilevel converter, and a cascaded H-bridge converter. However, these converters face the problem of voltage imbalance. In this study, a novel bidirectional isolated hybrid ripple-cancel dual active bridge (HRCDAB) converter for high voltage applications is developed. The proposed converter inherits the cancellation of the high-frequency ripple of DC-link capacitors, zero-voltage switching (ZVS), elimination of the DC bias current of the transformer, and automatic voltage and current sharing between stacked semiconductors. The circuit operation and certain features of the proposed circuit are comprehensively analyzed in this paper. Moreover, the design methodology of the proposed converter is presented. A scaled-down 900-V/600-V/1.2-kW prototype of the proposed converter is fabricated to experimentally demonstrate the validity of the comprehensive operation analysis and design theory.