基于多线圈变压器的DC-DC变换器闭环控制策略

摘要

级联式DC-DC变换器因具备高耐压能力的优势,被广泛应用于高压直流输电.在级联式变换器中,将多个模块中的独立变压器整合为一个共享磁芯回路的多线圈变压器,可自动均衡模块电容电压,降低系统复杂程度.针对基于多线圈的级联式DC-DC变换器提出了一种闭环控制策略,为设计移相闭环控制器,采用周期平均法及小信号动态分析法对系统进行建模,引入校正环节改善了系统的稳态和暂态性能,实现了级联式DC-DC变换器输出电压的稳定控制.最后,在Matlab/Simulink环境中搭建了系统仿真模型,验证了所提级联式DC-DC变换器闭环控制方法的可行性.%Cascaded DC-DC converters are widely applied in HVDC power transmission because of their strong voltage endurance capability.In the cascaded converter, independent transformers in several modules are integrated into a multi-coil transformer sharing the loop of the magnetic core, so that the capacitor voltages of the modules can be equalized automatically and the system is made less complex.With respect to multi-coil-based cascaded DC-DC converters, this paper presents a closed-loop control strategy.In order to design a phase shift closed loop controller, we use the periodic average method and small-signal dynamic analysis method to establish a model for the system.Furthermore, a correction link is introduced to improve steady-state and transient performance of the system, and steady control of the output voltage of the cascaded DC-DC converter is achieved.Finally, a system simulation model is built in Matlab / Simulink environment, and the feasibility of the proposed closed-loop control method for the cascaded DC-DC converter is verified.