输入串联输出并联的双全桥变换器输入电容均压问题的研究

Study on Input-series-output-parallel Converter With Voltage Sharing Between Input-capacitor

高输入电压的变换器可以采用一种输入串联输出并联的拓扑。ISOP拓扑的关键问题是输入电容的动态均压。该文提出对两个输入电容的压差进行检测,通过输出电压反馈和压差前馈方式实现均压的新控制方式。为提高动态响应特性,高频变压器采用了两原边两副边四绕组共铁芯的磁集成结构,分析了这种结构的工作原理。同步信号保证双全桥中的开关器件能够实现ZVS。控制策略上采用了电压环、压差环和限流环的三环控制方式。这种结构与控制方式可以保证将低压IGBT安全可靠地用于高输入电压的工况下,而且保证有良好的动态均压效果。给出了小信号模型和PID控制的仿真结果。制作了一台样机以验证理论分析。实验结果表明所采用的方法使变换器具有良好的动态均压与负载均分特性。

For a high input voltage converter, a topology of input-series-output-parallel （ISOP） can be adopted. A key problem of ISOP topology is the input voltage balancing. In this paper ,a new control method with output voltage feedback and feedforward of voltage error between two input capacitor is presented. In order to increase the dynamic characteristic,an integrated-magnetic transformer is applied. In order to realize ZVS , synchronous drive is proposed. Three closed loops of output voltage, limited load current and input capacitor error are proposed. This configuration enables the usages of low rating voltage IGBT for a high input voltage system and the cost is lower. A small signal model and the simulation results of PID Controller are presented. A prototype is made to verify the theory analysis. The experimental results shows the converter has a good performance of input capacitor voltage balancing and load sharing..