基于交错Boost变流器和LLC谐振变流器的高效率车载充电机

2019-01-10 01:48:14 现代电子技术2019年1期

李静宇 周明 李庚银

关键词: 车载充电机; 交错Boost变流器; 零电流开关; 电动汽车; LLC谐振变流器; 效率分析

中图分类号: TN99?34; TM721                       文献标识码: A                   文章编号: 1004?373X(2019)01?0119?05

Abstract: On?board charger (OBC) is a key component of electric vehicle (EV), and supplies the charging access for EV. The fore?stage AC/DC circuit of OBC uses the interleaved Boost converter for power factor correction and DC bus voltage regulation. The post?stage DC/DC converter utilizes the full?bridge LLC resonant converter to control the charging voltage and charging power. The efficiency of the interleaved Boost converter is calculated, and efficiency of the LLC resonant converter is optimized. A 3.3 kW OBC prototype was developed, whose overall efficiency and power factor can reach up to 94.9% and 99.5% respectively. The efficiency of interleaved Boost converter and LLC resonant converter can reach up to 97.7% and 97.6% respectively. The power density of OBC can reach up to 1.05 kW/L.

Keywords: on?board charger; interleaved Boost converter; zero current switching; electric vehicle; LLC resonant converter; efficiency analysis

0  引  言

限于车载空间和体积,载充电机(On?Board Charger,OBC)须以高功率密度[1]、高效率为设计目标,同时还须有电气隔离、良好的PF和THD性能。OBC典型电路结构如图1所示。

前级AC/DC承担功率因数矫正和稳定直流母线电压的功能,后级DC/DC提供电气隔离,控制输出电压和功率。传统BoostPFC的电流应力大[2],电感体积大,电流纹波大,影响直流母线电容寿命。交错BoostPFC(Interleaved Boost Power Factor Correction,IBPFC)具有电流纹波小、电感体积小[3]、效率高、功率密度高、PF和THD高的优点。

LLC具有无噪音、软开关、效率高、输出电压范围宽、无反向恢复[4]等优点。但OBC的负载对象为DC 230~430 V的蓄电池,输出高压时,易失去ZCS特性;输出低压时,原边关断损耗增加。因此,实现宽输出电压范围内LLC的高效率是必须要解决的难题[5]。

4  結  论

本文将两级电路拓扑应用于3.3 kW OBC,交错BoostPFC进行功率因数校正、稳定直流母线电压。对PFC的效率进行了详细的计算和优化,其峰值效率高于97.7%,THD<4%,PF>0.99。从时域分析角度对LLC的效率进行了优化,LLC的峰值效率超过97.6%。

研制一台高功率密度、高效率3.3 kW OBC样机,其体积仅有3.1 L,功率密度超过1.05 kW/L,输出电压范围为230~430 V,整机峰值效率超过94.9%。

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