考虑寄生电容的半桥LLC谐振变换器参数优化设计

Optimal Design of Half-bridge LLC Resonant Converter Considering Parasitic Capacitance

含变压器的隔离型变换器易受到寄生电容的影响,降低系统运行的稳定性。针对LLC谐振变换器,建立含变压器寄生参数的等效电路模型,推导电压增益公式。对比无寄生参数和含寄生参数的电压增益曲线,分析寄生电容对选取电感比及其品质因数所产生的影响。在设计参数时考虑寄生电容的影响,分析开关管实现ZVS的条件,推导电感比的计算方法以及品质因数的取值范围。优化设计电感比、品质因数,进而优化各谐振参数。搭建实验样机,验证该优化方法的正确性和可行性。

An isolation-type converter with a transformer is prone to be affected by parasitic capacitance, thus reducing the stability of system operation. In this paper, an equivalent circuit model containing transformer parasitic parameters is set up for an LLC resonant converter, and the formula for voltage gain is derived. From the comparison of voltage gain curve with and without parasitic parameters, the influence of parasitic inductance on the selection of inductance ratio and quality factor is analyzed. The effect of parasitic capacitance is considered in the design of parameters, the condition of realizing ZVS for a switching tube is analyzed, and the calculation method for inductance ratio and the range of quality factor are derived. The inductance ratio and quality factor are optimized, thus optimizing various resonance parameters. An experimental prototype was set up, which verified the correctness and feasibility of the optimization method.