Research On The Modified Asymmetrical Half-Bridge DC-DC Converter

In this paper, asymmetrical half-bridge dc/dc converter, which is applied in middle power and high input voltage occasion, is invested. The research focuses on the control method and the problem of integration.Compared with conventional topology, the novel asymmetrical half bridge has a branch comprising an auxiliary switch and a diode , realizes zvs of main switches, and eliminates the shortcoming of the nonlinear relation between input and output voltage and the dc bias of magnetizing current exist in transformer which occurs in conventional half bridge converter.System with current control has faster response than that with voltage control., in addition, it has the ability of character of current limitation and automatic parallel current sharing. In this paper, the modified asymmetrical half-bridge dc/dc converter with current control is discussed including the problem of stability. Small signal model is built of the converter. Analysis and compare of between the current control and voltage control are made. Design process is given on the compensation network.Based on the theory analysis, the design about power circuit, control circuit, driving circuit and protect circuit is given in this paper. Following the design, simulation and experimental results are obtained, and the following conclusion is made: converter with peak current control has problem of stability, and solution can be made through slop compensation technology; Compared with voltage control, converter with peak current control has ability of current limitation and has faster response.Finally, primary research on integrated problem of the modified asymmetrical half-bridge dc/dc converter is made. Basic problem of the power module design, the power loss of the switch, and the power loss of rectifier diode are discussed in this paper. The thermal filed of the power module is analyzed and find the highest junction temperature of the power component and the highest temperature of the magnetic core, which is very important to thermal analysis of the converter.