三电平电流型推挽双向DC/DC变换器及工作特性分析

Three-level current-fed push-pull bidirectional DC/DC converter and operation characteristics analysis

储能DC/DC变换器需要解决电池侧电流纹波和宽电压范围问题。本文研究了一种可用于电能路由器储能环节的三电平电流型推挽式双向DC/DC变换器,具有高增益、电流纹波小和宽输入电压范围的特征。以传输电感两端电压匹配为原则研究了采用脉冲宽度调制(PWM)加移相控制下的工作机理,深入分析了正向和反向工作模式。研究了占空比、桥间移相比和桥内移相比对功率传输的影响以及不同模式下的系统性能,以实现变换器的高效率功率传输。通过建立各功率管开通时刻的瞬态等效电路深入研究了功率管寄生电容、变压器励磁电感对实现软开关的影响。推导出开通时刻的准谐振方程,从而得到功率管实现软开关的条件,为参数优化设计奠定了基础。在3 kW实验平台上进行了实验研究,实验结果验证了理论分析的正确性。

It is necessary for the energy storage DC/DC converter to solve the problems of battery side current ripple and wide voltage range. In this paper, a three-level current type push-pull bidirectional DC/DC converter is studied for energy storage in power routers, which has high gain, low current ripple and wide input voltage range. The operating principle under PWM plus phase shift control is studied based on the principle of voltage matching at both ends of the transfer inductor. The forward and reverse modes of operation are analyzed in depth. The effects of duty cycle, inter-bridge shift ratio and intra-bridge shift ratio on power transfer and the system performance in different modes are investigated to achieve high efficiency power transfer of the converter. The effect of power tube parasitic capacitance and transformer excitation inductance on the realization of soft switching is studied by establishing the transient equivalent circuit at the turn-on time of the power tube. The quasi-resonant equations at the turn-on time are derived to obtain the conditions for soft switching of the power tubes, laying the foundation for parameter optimization design. The experimental study was carried out on a 3 kW experimental platform, and the experimental results verified the correctness of the theoretical analysis.