Improved Duty Compensation Control-Based Bidirectional Resonant DC−DC Converter With Reduced Input-Current Ripple for Battery Energy Storage Systems

This article proposes an improved duty control-based resonant bidirectional dc–dc converter (BDC) to remarkably minimize input-current ripple for battery energy storage systems. The proposed converter offers a resonant-boost operation using a pulsewidth-modulation (PWM) full-bridge circuit with a push-pull transformer under the forward mode. Whereas, in the backward mode, a resonant-buck operation is implemented with a PWM neutral-point-clamped (NPC)-type. Unlike conventional current-fed BDCs, the most appealing characteristic of the proposed converter is the NPC-type structure with a push-pull transformer, which can significantly mitigate the input-current ripple without using extra input-inductors. Moreover, the proposed BDC minimizes the conduction loss of the low-voltage side bottom switches by alleviating unbalanced dc offset-currents via proposed duty-compensation control under mismatched magnetizing inductances of the transformer's primary windings. The designed circuit operation is analyzed in detail and its practicability has been fully confirmed with the proportional-integral and spider-monkey-optimization control techniques-based experimental verifications using a prototype 1-kW test bed.