Modulation-Enabled Single-Stage Current-Fed Dual Active Bridge AC-AC Converter with ZCS Turn-Off of Primary-Side Switches

This paper proposes a single-stage, high-frequency, bidirectional current-fed converter topology for single-phase AC-AC applications, employing a novel modulation technique that achieves zero-current switching at turn-off for the primary-side switches over the entire operating range. Soft turn-off minimizes overvoltage stress on the primary-side switches, potentially eliminating the need for snubbers. This topology shares characteristics with the classical current-fed full-bridge converter used in DC-DC applications, including rapid input current control, low input current ripple and voltage boosting. However, there are unique challenges for AC-AC applications, particularly in managing zero-voltage crossing regions, which this work addresses. This paper presents the circuit topology, operating principles, and a state machine-based implementation of the modulation technique. Simulation results for a 4.16 kV to 240 V, 75 kW converter are provided.