双输出端口LLC电路及其控制技术研究

新能源汽车的车载充电机和DC/DC大多都是独立运行。基于一个变压器控制双输出端口的思想,设计了一种带LLC谐振电路双输出端口的充电机,其包括原边侧转换电路、副边侧第一转换电路、副边侧第二转换电路、以及连接这3个电路的变压器。原边转换电路连接外部电源,副边第一转换电路连接高压电池,副边第二转换电路连接低压负载。通过采样,获得副边第二转换电路的输出电压和输出电流,并与基准值比较和补偿,最终实现控制原边转换电路中开关管的通断时间;采样原边转换电路输出电流,经过零检测计算出过零延时,控制副边第二转换电路中整流开关管的通断时间。基于对该技术的研究,研制了一台6.6kW LLC谐振变换器的样机,并采用双闭环控制策略,仿真与实验结果验证了理论分析的正确性。

LLC circuit with dual output port and control technique

Most of the on-board charger of new energy vehicles and DC/DC operate independently.By using a transformer that controls double output port,a dual output port charger with LLC resonant circuit was designed,including a primary side conversion circuit,a secondary side first conversion circuit,a secondary side second conversion circuit and a transformer connecting the three parts.The primary side conversion circuit was connected to the external power supply,the secondary side first conversion circuit was connected to the high-voltage battery and the secondary side second conversion circuit was connected to the low-voltage load.By sampling the output voltage and output current of the second conversion circuit and comparing with the reference value and compensating,the on-off time of the switch in the original conversion circuit was finally controlled.The output current of the original side conversion circuit was sampled,and the zero-time delay was calculated after zero-cross detection,the on-off time of the rectifier switch in the second side conversion circuit was controlled.The experimental prototype of a 6.6 kW LLC resonant converter was designed by using a dualoutput port circuit,which adopts the dual closed-loop control strategy.Simulation and experimental results verify correctness of the theoretical analysis.