Improved boundary operation for voltage-fed semi-DAB With ZVS achievement and nonactive power reduction

An improved boundary operation is proposed for the voltage-fed semi dual active bridge converter for applications needing only unidirectional power flow capability. The leakage inductor current works in boundary mode under most operating conditions. The operating principle and comparison with conventional single-phase-shifted control are presented in detail. The nonactive power can be suppressed under most working conditions and the conduction loss for output MOSFETs can be reduced significantly. All the power switches can achieve zero-voltage switching (ZVS) while the output side rectifying diodes can obtain zero-current switching in most operating conditions. The parameter design including the compensated value and the dead-time selection is given. The ZVS achievement can be obtained with reduced nonactive power and the closed loop implementation can be simplified. The effectiveness of the control strategy has been validated by the experimental results of 1-KW hardware prototype.