一种高效率的宽输出电压范围LLSC谐振变换器及其控制方法

A High Efficiency and Wide Gain Range LLSC Resonant Converter and Its Control Method

针对LLC谐振变换器高效率优势难以适应宽输出电压范围应用的问题,该文给出一种调节等效电容值的调压方式,提出一种LLSC谐振变换器拓扑及协同控制方法。该拓扑在LLC谐振变换器的电容旁加入由反向串联功率器件组成的旁路。调节旁路功率器件与逆变桥功率器件间滞后时间,连续调节等效电容值、改变输出电压。在这种调压方式基础上,调节开关频率,降低励磁电流、谐振电流有效值,从而降低损耗。分析了所提出变换器的工作原理、换流过程、电压增益模型及协同控制方法。最后,设计了一台400W的LLSC谐振变换器样机,实验结果验证了所提拓扑及协同控制方法的可行性。

Considering that the high efficiency advantage of LLC resonant converters is difficult to adapt to the application of wide output voltage range,this paper proposes a voltage regulation method to adjust the equivalent capacitance value,and proposes a topology and cooperative control method for LLSC resonant converters.In this topology,a bypass composed of reverse series power devices is added beside the capacitor of the LLC resonant converter.The delay time between bypass power device and inverter power device is adjusted,the equivalent capacitance is continuously adjusted and the output voltage is changed.On the basis of this voltage regulation mode,the switching frequency is adjusted to reduce the effective value of excitation current and resonance current,so as to reduce the loss.The operation principle,commutation process,voltage gain model and cooperative control method of the proposed converter are analyzed.Finally,a 400W LLSC resonant converter prototype is designed,and the experimental results verify the proposed topology and cooperative control method.