两级结构模块化ISOP组合的DC-DC变换器均压控制策略

Research on Voltage Sharing Control Strategy of a Combined TwoStage Modular Input-Series Output-Parallel DC-DC Converter

针对高电压/宽范围输入、低压大电流输出的应用需求,提出了一种基于两级结构的模块化输入串联输出并联组合DC-DC变换器及其均压控制策略。模块单元采用开环定频LLC+闭环Buck级联的两级结构拓扑,兼具高性能的同时也便于进行串并联的组合。通过构造均压母线并间接采样模块的输入电压,将信号分别叠加到反馈电压与参考电压上,使得模块单元实现输入均压自调节的同时还能维持良好的输出电压精度。模块的采样、控制与通信均在后级完成,各自独立工作,简化了电路结构,使系统具有良好的模块化特性。结合系统的小信号模型,对其稳定性进行了理论分析和仿真验证。最后,通过搭建由三个模块构成的ISOP组合变换器实验平台,验证了此均压控制策略的可行性。

Aiming at the applications of high voltage and wide voltage input,low voltage and high current output,a combined two-stage modular input-series output-parallel DC-DC converter and its voltage sharing control strategy are proposed.The module unit adopts a two-stage topology combining the LLC working in fixed-frequency and open-loop mode and the Buck working in closed-loop mode,which is both efficient and convenient for serial-parallel connection.By constructing the voltage-sharing bus and sampling the input voltage of the module indirectly,the signals are respectively superimposed on the feedback voltage and the reference voltage so that the module unit can achieve input voltage sharing by self-regulation while maintaining a good output voltage accuracy.The sampling,control and communication of the module are completed on post-stage.They work independently and simplify the circuit structure with a good modular features.Combined with the small signal model,the stability of the system is theoretically analyzed and verified by simulation.Finally,a combined ISOP converter consisting of three modular units is built in the lab to verify the strategy.