PWM and phase-shifted control method for isolated asymmetric half- bridge bi-directional converter

In this paper, a novel improved control method for Isolated asymmetric half bridge (IAHB) bi-directional converter (BDC) is proposed. Usually traditional phase-shift(PS) control method is applied in the topology. Theory analysis and simulation results show there are a big current press more than ration current and the loss will be greater under the case that the voltage of low voltage battery side and high voltage bus side are not matched. The larger the voltage error is ,the larger the current peak is .In order to solve the problem, usually a multi-wirings transformer is needed. In order to solve above problems, a improved control method i.e PWM plus phase-shift (PS) control applied for IAHB is presented. In this control method, PWM control and phase-shift control are combined. Voltage balance between the two sides of energy transport inductor can be realized automatically and the transformer can be saved. The current press and the loss are reduced and ZVS range is expanded .The operation principle of the method is analyzed, a state space average model is set up and ZVS condition is derived. The feature of converter with improved PS control and realization method are introduced. The comparison of current press under the same power and comparison of ZVS range are given. A prototype using this control method is built to verify analysis. Experimental results show the novel control method is reliable.