Single-Phase Single-Stage Bidirectional DAB AC-DC Converter With Extended ZVS Range and High Efficiency

Conventional analyzations on the dual active bridge-based single-phase single-stage ac-dc converter relies on the line-piecewise model with which power switches are viewed as ideal and the commutation process between the top and bottom switch in each bridge leg are ignored. Although many soft-switching have been proposed, the effects of the commutation process make them inaccurate because of the difference between the line-piecewise model-based theoretical waveforms and the real ones. In this article, the commutation process is described in view of the nonlinearity of the switch junction capacitance, the commutation delay time and the dead time of each bridge leg. Furthermore, the control variables are compensated with the commutation delay time so that the zero voltage switching (ZVS) range can be extended widely. The variable dead time control helps to achieve critical turn-on, reducing the body diode conduction loss. Finally, a 1-kW prototype is built to evaluate the proposed method can achieve extend ZVS and achieve high conversion efficiency.