计及DCM的电动汽车充电机LLC谐振变换器参数设计与优化

Parameter design and optimization of LLC resonant converter in electric car charger based on DCM analysis

电动汽车充电技术是促进电动汽车发展与规模化应用的关键。LLC谐振变换器具有效率高、输出电压范围宽、功率大等特点,在电动汽车充电机中得到广泛应用。由于谐振过程十分复杂,通常采用基波等效分析(First Harmonic Approximation,FHA)方法设计LLC谐振变换器。该方法由于没有考虑不连续导通(Discontinuous Conduction Mode,DCM),从而存在较大的误差,并且需要多次反复迭代寻找合适的电路参数。提出了一种计及DCM分析的电动汽车充电机参数设计与优化方法,可以更精确地求解变换器电压增益,并且设计过程不需要迭代。针对某容量3.3 kW、输入400 V、输出250~430 V的LLC谐振变换器进行仿真分析,结果表明,采用所提方法对LLC谐振变换器参数进行优化设计,变换器的效率更高,且电压增益误差比传统方法减小了74.9%。

Electric vehicle charging technology is one of the important technologies of electric vehicle application.The LLC resonant converter is characterized by high efficiency,wide output voltage range,high power,etc.,and is widely used in electric vehicle chargers.Due to the complexity of the resonant process analysis,the LLC resonant converter is usually designed using the First Harmonic Method(FHA)method.This method does not take into account Discontinuous Conduction Mode(DCM),thereby resulting in a large error,and needs repeated iteration to find the appropriate circuit parameters.This paper presents a parameter optimization design method based on DCM analysis,the gain of the converter circuit can be solved more precisely,and the design process does not require iteration.A 3300 W LLC converter simulation model with 250~430 V outputs and 400 V inputs is built,results show that the LLC resonant converter parameters based on DCM analysis possesses high operation efficiency,meets the converter’s voltage gain requirements,and reduces the voltage gain error by 74.9%than the traditional method.