Extension of Zero-Voltage Switching Region of Wide Volage Ratio Range Dual-Active-Bridge Converter by LC Antiresonant Network

Zero-voltage switching (ZVS) for dual active bridge (DAB) with wide voltage conversion ratio has a contradiction with low conduction loss, especially under light power transmission. Root mean square (rms) increase of inductor current is unavoidable just by optimizing modulation schemes. Inspired by the various frequencies (VFs) and inductors (VIs), this article proposes a DAB converter with the capability of regulating the impedance of the resonant tank to extend the ZVS region. With an LC antiresonant circuit in series with original inductor, the equivalent inductance of the resonant network of the proposed converter increases along with the switching frequency within the designed frequency range. Thereby, when the voltage mismatches and the transferred power decreases, a large impedance is obtained by slightly increasing frequency to help to achieve ZVS. Moreover, the proposed DAB is found that single phase shift (SPS) has nearly identical characteristics of ZVS and conduction loss compared with multiple phase shift (PS) modulation. The benefit of this is that the complexity of close-loop control is significantly reduced just considering the switching frequency and external shift phase. In addition, ZVS characteristics and optimal control method are analyzed in detail. Finally, a 2-kW 360-400-V/40-60-V prototype is built, and the main experimental results are provided to verify the feasibility of the proposed converter and soft switching range of all switches.