Minimum resonant capacitor design of high-power LLC resonant converter for comprehensive efficiency improvement in battery charging application

作者：Zhao, Zhenxing; Xu, Qianming^*; Dai, Yuxing; Luo, An

来源：IET Power Electronics, 2018, 11(11): 1866-1874.

DOI：10.1049/iet-pel.2017.0649

• resonant power convertors
• insulated gate bipolar transistors
• bipolar transistor circuits
• power capacitors
• electric vehicle charging
• battery powered vehicles
• secondary cells
• approximation theory
• switching convertors
• comprehensive efficiency improvement
• minimum resonant capacitor design approach
• electric vehicle battery charging application
• power device IGBT
• LLC resonant converter prototype
• insulated-gate bipolar transistor-based high-power LLC resonant converter

Here, a minimum resonant capacitor design approach is proposed for the insulated-gate bipolar transistor (IGBT)-based high-power LLC resonant converter to improve its comprehensive efficiency in the electric vehicle (EV) battery charging application. The mathematical model of LLC resonant converter is established by using the first harmonic approximation (FHA) method. Then, the switching losses of IGBT-based high-power LLC resonant converter are analysed. Also, the relationship between predominant turn-off losses and turn-off current of power device IGBT is derived. To improve the comprehensive efficiency, the minimum resonant capacitor is proposed to reduce the turn-off losses, avoiding complex control or auxiliary circuit. Finally, the proposed approach is verified by a 2kW LLC resonant converter prototype with 690V DC input voltage and 75-150V DC output voltage. Experimental results show the comprehensive efficiency of the prototype is up to 93.7%.

• 出版日期2018-9-18
• 单位湖南大学