Modulation Strategy for Bidirectional Power Flow on a High-Frequency Link AC-DC Converter Topology That Mitigates the Device Voltage Overshoot

A modulation strategy for bidirectional power flow on a high-frequency link step voltage switched (SVS) AC-DC converter topology is presented in this paper. This strategy mitigates the voltage overshoot across the AC/grid side devices. Also, it includes secondary side phase shift modulation to ensure zero circulating current on the DC side bridge and soft switching in most devices. The proposed modulation strategy is symmetric and does not need any additional auxiliary circuit during AC to DC power conversion or to restrict the voltage overshoot. It has been tested on a 1kW, 72V DC, 220V AC hardware prototype operating at 100kHz, and a peak efficiency of 94.5% is observed. The feasibility of the proposed modulation scheme with a non-unity power factor (non-UPF) load is also verified experimentally, ensuring reactive power compensation. A closed-loop control strategy for grid interfacing is also presented in this paper.