Abstract：Wide input voltage range is a critical feature for LLC converter to guarantee enough hold-up time. A small magnetizing inductor can bring wide input voltage range for conventional LLC converter for hold-up operation. However, this inevitably increases reactive power and reduces efficiency for normal operation. In this paper, an improved LLC converter with auxiliary bidirectional switch is proposed to obtain enough voltage gain in hold-up mode with larger magnetizing inductor to reduce normal losses. The working principle, voltage gain and design rules in normal operation mode and hold-up mode are analyzed in detail. Finally, a prototype with 200~390V input voltage range and 48V/21A output is built and tested, which demonstrates the proposed converter has high efficiency and wide input voltage range.
[1] Yang Bo, Lee F C, Zhang A J, et al.LLC resonant converter for front end DC/DC conversion[C]//7th Applied Power Electronics Conference and Expo- sition, Dallas, 2002: 1108-1112. [2] Xing Yan, Huang Lipei, Cai Xuansan, et al.A combined front end DC/DC converter[C]//8th Applied Power Electronics Conference and Exposition, Miami Beach, 2003: 1095-1099. [3] Kathiresan R, Das P, Reindl T, et al.A novel ZVS DC-DC full-bridge converter with hold-up time operation[J]. IEEE Transactions on Industrial Elec- tronics, 2017, 64(6): 4491-4500. [4] Lai Y S, Su Z J, Chen W S.New hybrid control technique to improve light load efficiency while meeting the hold-up time requirement for two-stage server power[J]. IEEE Transactions on Power Electronics, 2014, 29(9): 4763-4775. [5] 怀全, 候小虎, 何良策, 等. 一种含分布式电源的中低压配电网状态估计方法研究[J]. 电力系统保护与控制, 2018, 46(21): 69-85. Huai Quan, Hou Xiaohu, He Liangce, et al.A method of state estimation for middle voltage and low voltage distribution network with distributed generations[J]. Power System Protection and Control, 2018, 46(21): 69-85. [6] 李菊, 阮新波. 全桥LLC谐振变换器的混合式控制策略[J]. 电工技术学报, 2013, 28(4): 72-79. Li Ju, Ruan Xinbo.Hybrid control strategy of full bridge LLC converters[J]. Transactions of China Electrotechnical Society, 2013, 28(4): 72-79. [7] 张涛. LLC全桥变换器电动汽车充电机设计[J]. 电气技术, 2018, 19(8): 164-167. Zhang Tao.The design of full bridge EV charger based on LLC[J]. Electrical Engineering, 2018, 19(8): 164-167. [8] 陈启超, 王建赜, 纪延超. 双向LLC谐振型直流变压器的软启动及功率换向控制[J]. 电工技术学报, 2014, 29(8): 180-186. Chen Qichao, Wang Jianze, Ji Yanchao.Control scheme of bidirectional LLC resonant DC-DC trans- former for soft start and power conversion[J]. Transactions of China Electrotechnical Society, 2014, 29(8): 180-186. [9] Beiranvand R, Rashidian B, Zolghadri M R, et al.Using LLC resonant converter for designing wide- range voltage source[J]. IEEE Transactions on Industrial Electronics, 2011, 58(5): 1746-1756. [10] Hu Zhiyuan, Qiu Yajie, Liu Yanfei, et al.A control strategy and design method for interleaved LLC con- verters operating at variable switching frequency[J]. IEEE Transactions on Power Electronics, 2014, 29(8): 4426-4437. [11] 孙孝峰, 申彦峰, 朱云娥, 等. 一种Boost型宽电压范围输入LLC谐振变换器[J]. 中国电机工程学报, 2015, 35(15): 3895-3903. Sun Xiaofeng, Shen Yanfeng, Zhu Yune, et al.A boost-integrated LLC resonant converter for wide input voltage range[J]. Proceedings of the CSEE, 2015, 35(15): 3895-3903. [12] Lee J B, Kim J K, Baek J I, et al.Resonant capacitor on/off control of half-bridge LLC converter for high-efficiency server power supply[J]. IEEE Transa- ctions on Industrial Electronics, 2016, 63(9): 5410-5415. [13] 王镇道, 赵亚魁, 章兢, 等. LLC半桥式谐振变换器参数模型与设计[J]. 电工技术学报, 2012, 27(12): 51-55. Wang Zhendao, Zhao Yakui, Zhang Jing, et al.Parameter model and design for LLC resonant half- bridge converter[J]. Transactions of China Electro- technical Society, 2012, 27(12): 51-55. [14] Lee I O, Moon G W.Analysis and design of a three-level LLC series resonant converter for high- and wide-input-voltage applications[J]. IEEE Transa- ctions on Power Electronics, 2012, 27(6): 2966-2979. [15] 吕正, 颜湘武, 孙磊. 基于变频-移相混合控制的L-LLC 谐振双向DC-DC变换器[J]. 电工技术学报, 2017, 32(4): 12-24. Lü Zheng, Yan Xiangwu, Sun Lei.A L-LLC resonant bidirectional DC-DC converter based on hybrid control of variable frequency and phase shift[J]. Transactions of China Electrotechnical Society, 2017, 32(4): 12-24. [16] 李浩昱, 李振伟, 赵雷, 等. 宽输入LLC谐振变换器多电平控制策略[J]. 电工技术学报, 2017, 32(4): 48-57. Li Haoyu, Li Zhenwei, Zhao Lei, et al.Multi-level control strategy of wide input LLC resonant converter[J]. Transactions of China Electrotechnical Society, 2017, 32(4): 48-57. [17] Kim M Y, Kim B C, Park K B, et al.LLC series resonant converter with auxiliary hold-up time compensation circuit[C]//8th International Conference on Power Electronics, Jeju, 2011: 628-633. [18] Wu Hongfei, Mu Tiantian, Gao Xun, et al.A secondary-side phase-shift-controlled LLC resonant converter with reduced conduction loss at normal operation for hold-up time compensation appli- cation[J]. IEEE Transactions on Power Electronics, 2015, 30(10): 5352-5357. [19] Wang Haoyu, Li Ziqiang.A PWM LLC type resonant converter adapted to wide output range in PEV charging applications[J]. IEEE Transactions on Power Electronics, 2017, 33(5): 3791-3801. [20] Cho I H, Kim Y D, Moon G W.A half-bridge LLC resonant converter adopting boost PWM control scheme for hold-up state operation[J]. IEEE Transa- ctions on Power Electronics, 2013, 29(2): 841-850. [21] Wang Hongliang, Chen Yang, Fang Peng, et al.An LLC converter family with auxiliary switch for hold- up mode operation[J]. IEEE Transactions on Power Electronics, 2017, 32(6): 4291-4306.
2020, Vol. 35 
