Abstract：A parallel switching transformer-based LLC (ST-LLC) multi-resonant converter was proposed in this paper. The transformer indirect parallel method and switching control strategy were used to construct a novel variable topology LLC based on the idea of variable inductance ratio k. The efficiency of the converter was effectively improved and the decentralized design of the transformer hot-spot was achieved, while maintaining soft switching characteristics. Detailed analysis for characteristics of voltage gain and the main operating modes was given. Besides, an optimal load partition control strategy was proposed based on the logic of transformer switching control, and wide range of high efficiency was achieved. Furthermore, the analytical formula of the maximum power of the transformer switching point was derived, and the design process of the main component parameters of the circuit was also given. A 1kW prototype was designed and manufactured, and the feasibility of the proposed scheme was verified by simulation and experiment. The working efficiency of the prototype could maintain more than 90% in the 82% load range.
刘晓东, 董保成, 吴慧辉, 方炜, 刘宿城. 基于并联变压器切换的LLC谐振变换器宽范围效率优化控制策略[J]. 电工技术学报, 2020, 35(14): 3018-3029.
Liu Xiaodong, Dong Baocheng, Wu Huihui, Fang Wei, Liu Sucheng. Wide Range Efficiency Optimization Control Strategy for LLC Resonant Converter Based on Parallel Transformer Switching. Transactions of China Electrotechnical Society, 2020, 35(14): 3018-3029.
[1] Lo Y K, Lin C Y, Hsieh M T, et al.Phase-shifted full-bridge series-resonant DC-DC converters for wide load variations[J]. IEEE Transactions on Industrial Electronics, 2010, 58(6): 2572-2575. [2] Lo Y K, Pai K J.Feedback design of a piezoelectric transformer-based half-bridge resonant CCFL inver- ter[C]//IEEE 2007 International Aegean Conference on Electrical Machines and Power Electronics, Bodrum, Turkey, 2007: 162-167. [3] 胡杨良, 王议锋, 陈博, 等. 一种双CLT谐振软开关直流变换器设计与实现[J]. 电工技术学报, 2018, 33(7): 1461-1471. Hu Yangliang, Wang Yifeng, Chen Bo, et al.The design and implementation of a dual-CLT resonant soft-switching DC-DC converter[J]. Transactions of China Electrotechnical Society, 2018, 33(7): 1461-1471. [4] 林雪凤, 许建平, 周翔. 谐振软开关耦合电感高增益DC-DC变换器[J]. 电工技术学报, 2019, 34(4): 747-755. Lin Xuefeng, Xu Jianping, Zhou Xiang.Soft- switched high step-up DC-DC converter with coupled inductor of resonance[J]. Transactions of China Electrotechnical Society, 2019, 34(4): 747-755. [5] 钱城晖, 钱挺. 辅助半桥调节的定频LLC谐振功率变换器[J]. 电工技术学报, 2019, 34(7): 1459-1467. Qian Chenghui, Qian Ting.A fixed-frequency LLC resonant converter adjusted by auxiliary half- bridge[J]. Transactions of China Electrotechnical Society, 2019, 34(7): 1459-1467. [6] Wang Haoyu, Dusmez S, Khaligh A.Design and analysis of a full-bridge LLC-based PEV charger optimized for wide battery voltage range[J]. IEEE Transactions on Vehicular technology, 2013, 63(4): 1603-1613. [7] Huang Daocheng, Kong Pengju, Lee F C, et al.A novel integrated multi-elements resonant converter[C]// IEEE Energy Conversion Congress and Exposition, Phoenix, AZ, USA, 2011: 3808-3815. [8] 徐恒山, 尹忠东, 黄永章. 考虑最大输出电压和效率的LLC谐振变流器的设计方法[J]. 电工技术学报, 2018, 33(2): 331-341. Xu Hengshan, Yin Zhongdong, Huang Yongzhang.Design method of LLC resonant converter considering maximum output voltage and efficiency[J]. Transa- ctions of China Electrotechnical Society, 2018, 33(2): 331-341. [9] 冯雪. LLC谐振变换器损耗分析与效率优化[D]. 北京: 北京交通大学, 2017. [10] 胡海兵, 王万宝, 孙文进, 等. LLC谐振变换器效率优化设计[J]. 中国电机工程学报, 2013, 33(18): 48-56, 16. Hu Haibing, Wang Wanbao, Sun Wenjin, et al.Optimal efficiency design of LLC resonant con- verters[J]. Proceedings of the CSEE, 2013, 33(18): 48-56, 16. [11] 任仁, 张方华, 刘硕. 基于LLC直流变压器(LLC- DCT)效率优化的死区时间与励磁电感设计[J]. 电工技术学报, 2014, 29(10): 141-146. Ren Ren, Zhang Fanghua, Liu Shuo.Optimal design for efficiency based on the dead time and magnetizing inductance of LLC DC transformer[J]. Transactions of China Electrotechnical Society, 2014, 29(10): 141-146. [12] Feng Weiyi, Lee F C, Mattavelli P.Optimal trajectory control of Burst mode for LLC resonant converter[J]. IEEE Transactions on Power Electro- nics, 2013, 28(1): 457-466. [13] Yang C H, Liang T J, Chen K H, et al.LLC resonant converter controller with novel light load control[C]// International Power Electronics and Application Conference and Exposition, Shanghai, China, 2014: 131-135. [14] Chen Jian, Sato T, Yano K, et al.An average input current sensing method of LLC resonant converters for automatic burst mode control[J]. IEEE Transa- ctions on Power Electronics, 2016, 32(4): 3263-3272. [15] Fei Chao, Li Qiang, Lee F C.Digital implementation of light-load efficiency improvement for high- frequency LLC converters with simplified optimal trajectory control[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2018, 6(4): 1850-1859. [16] Wang Bin, Xin Xiaoni, Wu S, et al.Analysis and implementation of LLC burst mode for light load efficiency improvement[C]//Twenty-Fourth Annual IEEE Applied Power Electronics Conference and Exposition, Washington DC, USA, 2009: 58-64. [17] Jeong Y, Moon G W, Kim J K.Analysis on half- bridge LLC resonant converter by using variable inductance for high efficiency and power density server power supply[C]//IEEE Applied Power Elec- tronics Conference and Exposition (APEC), Tampa, FL, 2017: 170-177. [18] Hua C C, Fang Y H, Chen Weilin.LLC resonant converter for electric vehicle battery chargers[J]. IET Power Electronics, 2016, 9(12): 2369-2376. [19] Liang Zhigang, Guo Rong, Li Jun, et al.A high- efficiency PV module-integrated DC/DC converter for PV energy harvest in FREEDM systems[J]. IEEE Transactions on Power Electronics, 2011, 26(3): 897-909. [20] Yang Bo, Lee F C, Zhang A J, et al.LLC resonant converter for front end DC/DC conversion[C]// Seventeenth Annual IEEE Applied Power Electronics Conference and Exposition, Dallas, TX, USA, 2002: 1108-1112.
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