电动汽车车载充电DC/DC变换器研究

DC/DC converter for on-board charger of electric vehicles

针对电动汽车车载充电电源的DC/DC变换器存在滞后臂零电压开关(ZVS)丢失、输出整流管电压振荡和导通损耗较大等问题,将箝位二极管引入传统移相全桥(PSFB)DC/DC变换器,同时在变压器副边采用同步整流(SR)技术。分析加入箝位二极管后,对变压器副边整流管电压振荡的抑制过程。同步整流管采用或驱动逻辑,降低整流管的导通损耗。对主电路进行损耗计算,结果表明,采用软开关同步整流技术比硬开关二极管整流技术效率高8%。仿真和实验结果表明,该DC/DC变换器抑制了变压器副边整流管的电压振荡,实现了宽负载范围的软开关,且具有很好的动态性能和抗干扰能力;当负载高于10%额定负载时,系统效率高于95%。

Clamping diodes are introduced to a traditional phase-shifted full-bridge(PSFB)DC/DC converter,and synchronous rectification(SR)technology is adopted on the secondary side of a transformer for the problems of the DC/DC converter of on-board charger for electric vehicles such as the loss of the zero voltage switching(ZVS)range of the lagging bridge,the voltage oscillation and the large conduction loss of the output rectifier. The suppression process of the voltage oscillation of the secondary rectifier of the transformer after adding the clamp diode is analyzed. OR drive logic is used for a synchronous rectifier to reduce the conduction losses of the rectifier. The results of loss calculation for the main circuit show the efficiency of using the soft switching and SR technology is higher than using the hard switching and diode rectification technology by 8%. The simulation and experimental results show that the DC/DC converter suppresses the voltage oscillation of the rectifier on the secondary side of the transformer,realizes soft switching in a wide load range,and has good dynamic performance and anti-interference ability;the efficiency is above 95% for loads above 10% of the rated load.