不对称半桥单相单级式车载充电系统改进控制策略研究

对称半桥可以有效吸收单相变换系统直流侧二次纹波、减小系统体积、提高功率密度，但当半桥上下桥臂电容容值不等时，会在直流侧产生一次纹波。针对这一问题，分析研究了不对称半桥单相单级式车载充电系统，提出电感电流加电容偏置补偿的改进控制策略。基于该控制策略，从满足二次纹波功率补偿、电池最低电压及避免过调制三方面研究了半桥电路电感及电容参数设计方法。仿真和实验结果验证了不对称半桥通过采用改进的控制策略不仅能够有效滤除二次纹波，且不产生一次纹波，还可降低电池端电压与电流纹波；仿真验证了参数设计方法的有效性。

Research on Improved Control Strategy for Single-phase Single-stage On-board Charger System with Asymmetrical Half-bridge Circuit

A symmetrical half-bridge circuit can effectively absorb secondary ripple of a single-phase converter system on the DC side, reduce the system volume, and improve power density; however, it will induce first ripple on the DC side when the capacitances of upper and lower bridge arms are unequal. To solve this problem, a single-phase single-stage on-board charger system with an asymmetrical half-bridge circuit is studied in this paper, and an improved control strategy of inductor current and capacitor offset compensation is also proposed. Based on this strategy, the parameter design method for the inductor and capacitor of the half-bridge circuit is studied by satisfying three aspects, i.e., compensation for secondary ripple power, lowest voltage of battery, and avoiding over-modulation. Finally, simulation and experimental results verified that under the improved control strategy, the asymmetrical half-bridge circuit can not only filter secondary ripple effectively, but also avoid inducing first ripple, thus reducing the battery''s terminal voltage and current ripples; in addition, simulations verified the effectiveness of the parameter design method.