三相准单级充电系统中LLC变换器的最优效率追踪与纹波抑制策略

doi:10.19595/j.cnki.1000-6753.tces.250302

Abstract
Figure/Table
References
Related Citation (14)

Download: PDF (10421 KB) HTML (1 KB)
Export: BibTeX | EndNote (RIS)

Abstract In modern three-phase quasi-single-stage charging systems for electric vehicles (EVs), the replacement of large electrolytic capacitors with compact film capacitors and the adoption of two-phase clamped discontinuous pulse-width modulation (2/3DPWM) in the front-stage AC/DC converter have significantly improved power density and reliability. However, this architecture introduces a 300 Hz six-pulse voltage ripple on the DC link, challenging the subsequent LLC resonant converter to maintain stable operation across a wide range of output voltages (200 V to 800 V) and powers. The time-varying output voltage accelerates equipment aging and degrades efficiency due to suboptimal operating points. This paper addresses these challenges through an innovative strategy combining comprehensive time-domain analysis, hybrid frequency-phase modulation, and dynamic feedforward compensation.
Time-domain characteristics of the LLC converter under operational conditions are analyzed, including pulse frequency modulation (PFM) and phase-shift modulation (PSM) modes. A novel analytical framework is developed to model seven resonant states, enabling precise characterization of voltage gain, resonant currents, and switching losses. The model identifies critical operational boundaries, such as zero-voltage switching (ZVS) conditions and mode transitions. The model integrates detailed loss calculations for MOSFETs, diodes, and magnetic components, thereby quantifying energy dissipation under real-world conditions and guiding the design of efficient control algorithms.
To address the conflicting demands of wide voltage regulation and high efficiency, a dual-mode hybrid control strategy is proposed. For mid-to-high voltage ranges, PFM maintains ZVS and efficiency by operating above the resonant frequency. In instances where the gain falls below a certain threshold, the utilization of PSM becomes imperative. This approach entails dynamically adjusting the optimal frequency to achieve balanced management of switching and conduction losses. A hysteresis-based algorithm ensures seamless mode transitions without transient oscillations.
A time-domain feedforward control is implemented to suppress output voltage ripple. Real-time estimation of voltage gain (M) and quality factor (Q) from input/output measurements enables the derivation of pre- computed frequency/phase shift commands using look-up tables (LUTs) generated from time-domain analysis. These commands are combined with PI controllers to compensate for voltage variations, resulting in a 64% reduction in transient response time for PFM and a 93% reduction for PSM compared to conventional methods. The effectiveness and reliability of the control are demonstrated at different operating points, as well as in arbitrary operating modes. Efficiency optimization is achieved through a loss-minimization algorithm that uses a 3D efficiency map integrating voltage gain, quality factor, and switching frequency. This map enables real-time selection of the most efficient mode and frequency, ensuring transitions occur where PSM efficiency exceeds PFM. In PSM mode, an optimized switching frequency is adjusted to minimize losses by reducing the RMS conducting current, resulting in a 0.72% efficiency improvement at 200 V compared to fixed-frequency PSM.
A 20 kW Vienna+LLC prototype has been constructed. The system achieves >80% ripple rejection under a range of operating conditions, thereby reducing the output voltage ripple from 42 V (in conventional PI) to 7 V. Furthermore, dynamic performance is improved by more than 60% under different load conditions (constant resistance and constant current). Overshoots are kept within ±1% of the reference value. A peak efficiency of 96.2% is achieved for 400 V/5 kW, and a 0.72% improvement is observed for 200 V/5 kW compared to state-of-the-art hybrid control. The prototype exhibits seamless functionality in both parallel (200 V to 400 V) and series (400 V to 800 V) configurations.
In this paper, an optimized control strategy for LLC converters is proposed to provide a compact, reliable, and efficient solution for three-phase quasi-single-stage charging systems. This solution integrates full-modal time-domain analysis, hybrid modulation, and dynamic feedforward compensation, combining wide-ranging voltage regulation, fast transient response, and real-time efficiency optimization.

Key words： Three phase quasi-stage AC-DC converter frequency-phase hybrid control loss analysis ripple suppression

Received: 26 February 2025

PACS:

TM464

	Service

	E-mail this article
	Add to my bookshelf
	Add to citation manager
	E-mail Alert
	RSS
	Articles by authors
	Shi Xiyuan
	Cao Kaihong
	Qie Weidong
	Wang Yong
	Xu Junzhong

Cite this article:

Shi Xiyuan,Cao Kaihong,Qie Weidong等. Optimal Efficiency Tracking and Ripple Suppression Strategy for LLC Converter in Three-Phase Quasi-Stage Charging System[J]. Transactions of China Electrotechnical Society, 2026, 41(4): 1397-1413.

URL:

https://dgjsxb.ces-transaction.com/EN/10.19595/j.cnki.1000-6753.tces.250302 OR https://dgjsxb.ces-transaction.com/EN/Y2026/V41/I4/1397

[1] 高辉, 彭成薇, 李炜卓, 等. 电动汽车与充电设备充电安全预警研究综述[J]. 电力系统自动化, 2024, 48(7): 47-61.
Gao Hui, Peng Chengwei, Li Weizhuo, et al.Review on early warning of charging safety for electric vehicles and charging equipment[J]. Automation of Electric Power Systems, 2024, 48(7): 47-61.
[2] 黄学良, 刘永东, 沈斐, 等. 电动汽车与电网互动:综述与展望[J]. 电力系统自动化, 2024, 48(7): 3-23.
Huang Xueliang, Liu Yongdong, Shen Fei, et al.Vehicle to grid: review and prospect[J]. Automation of Electric Power Systems, 2024, 48(7): 3-23.
[3] Wang Huai, Liserre M, Blaabjerg F.Toward reliable power electronics: challenges, design tools, and opportu- nities[J]. IEEE Industrial Electronics Magazine, 2013, 7(2): 17-26.
[4] Kacetl J, Fang Jingyang, Kacetl T, et al.Design and analysis of modular multilevel reconfigurable battery converters for variable bus voltage powertrains[J]. IEEE Transactions on Power Electronics, 2023, 38(1): 130-142.
[5] Monteiro V, Ferreira J C, Nogueiras Meléndez A A, et al. Experimental validation of a novel architecture based on a dual-stage converter for off-board fast battery chargers of electric vehicles[J]. IEEE Transactions on Vehicular Technology, 2018, 67(2): 1000-1011.
[6] Menzi D, Bortis D, Kolar J W.Three-phase two- phase-clamped Boost-Buck unity power factor rectifier employing novel variable DC link voltage input current control[C]//2018 IEEE International Power Electronics and Application Conference and Expo- sition (PEAC), Shenzhen, China, 2018: 1-8.
[7] Xu Junzhong, Soeiro T B, Wang Yong, et al.A hybrid modulation featuring two-phase clamped discon- tinuous PWM and zero voltage switching for 99% efficient DC-type EV charger[J]. IEEE Transactions on Vehicular Technology, 2022, 71(2): 1454-1465.
[8] Soeiro T B, Bauer P.Fast DC-type electric vehicle charger based on a quasi-direct Boost-Buck recti- fier[C]//2019 AEIT International Conference of Electrical and Electronic Technologies for Auto- motive (AEIT AUTOMOTIVE), Turin, Italy, 2019: 1-6.
[9] Qamar H, Qamar H, Korada N, et al.Control and performance of 240-clamped space vector PWM in three-phase grid-connected photovoltaic converters under adverse grid conditions[J]. IEEE Transactions on Industry Applications, 2022, 58(6): 7408-7420.
[10] Xu Junzhong, Soeiro T B, Yang Wu, et al.A carrier- based two-phase-clamped DPWM strategy with zero- sequence voltage injection for three-phase quasi- two-stage Buck-type rectifiers[J]. IEEE Transactions on Vehicular Technology, 2022, 37(5): 5196-5211.
[11] Zhang D, Leontaris C, Huber J, et al.optimal synergetic control of three-phase/level Boost-Buck voltage DC-link AC/DC converter for very-wide output voltage range high-efficiency EV charger[J]. IEEE Journal of Emerging and Selected Topics in Power Electronics, 2024, 12(1): 28-42.
[12] Li Yunni, Anderson J A, Haider M, et al.Optimal synergetic operation and experimental evaluation of an ultracompact GaN-based three-phase 10-kW EV charger[J]. IEEE Transactions on Transportation Electrification, 2024, 10(2): 2377-2396.
[13] 姜昊宇, 张晨, 巫彤宁. 电动汽车低频磁场人体暴露安全性研究[J]. 电气技术, 2022, 23(7): 1-6.
Jiang Haoyu, Zhang Chen, Wu Tongning.Study on the human exposure safety of low-frequency magnetic field in electric vehicles[J]. Electrical Engineering, 2022, 23(7): 1-6.
[14] 谷彦洁, 于人杰, 张岩. 基于LLC谐振变换器的开关电源优化方法综述[J/OL]. 电源学报, 1-16 [2025- 04-16]. http://kns.cnki.net/kcms/detail/12.1420.tm.20240118.1519.002.html.
Gu Yanjie, Yu Renjie, Zhang Yan. Optimization strategy of switch mode power supply based on LLC resonant converter[J/OL]. Journal of Power Supply, 1-16 [2025-04-16]. http://kns.cnki.net/kcms/detail/12.1420.tm.20240118.1519.002.html.
[15] 赵永秀, 刘泽伟, 王崇杰, 等. 变模态倍压型LLC谐振变换器多目标参数优化[J]. 电工技术学报, 2024, 39(22): 7139-7153.
Zhao Yongxiu, Liu Zewei, Wang Chongjie, et al.Multi objective parameter optimization of variable mode voltage doubling LLC resonant converter[J]. Transactions of China Electrotechnical Society, 2024, 39(22): 7139-7153.
[16] 张俊涛, 林国庆. 多模态超宽输出双LLC谐振变换器拓扑及控制策略[J]. 电工技术学报, 2025, 40(24): 8052-8065, 8079.
Zhang Juntao, Lin Guoqing.A variable-mode ultra- wide output voltage gain dual LLC resonant converter and control method[J]. Transactions of China Electrotechnical Society, 2025, 40(24): 8052-8065, 8079.
[17] 周国华, 邱森林, 张小兵. 宽增益高效率级联式四开关Buck-Boost LLC变换器[J]. 电工技术学报, 2024, 39(4): 1103-1115.
Zhou Guohua, Qiu Senlin, Zhang Xiaobing.Cascaded four-switch Buck-Boost LLC converter with wide gain range and high efficiency[J]. Transactions of China Electrotechnical Society, 2024, 39(4): 1103-1115.
[18] 陈杰, 刘昌咏, 邓文明, 等. 四开关三电平半桥 LLC 变换器的控制策略与效率优化[J]. 电工技术学报, 2024, 39(24): 7833-7845.
Chen Jie Zhao, Liu Changyong, Deng Wenming, et al.Control improvement and efficiency optimization of four switch three-level half-bridge LLC converter[J]. Transactions of China Electrotechnical Society, 2024, 39(24): 7833-7845.
[19] 荣振帅, 迟迎超, 孙战, 等. 基于氮化镓的高频LLC变换器研究[J]. 电气传动, 2023, 53(2): 3-9.
Rong Zhenshuai, Chi Yingchao, Sun Zhang, et al.Research on high frequency LLC converter based on GaN[J]. Electric Drive, 2023, 53(2): 3-9.
[20] Shakib S M S I, Mekhilef S. A frequency adaptive phase shift modulation control based LLC series resonant converter for wide input voltage appli- cations[J]. IEEE Transactions on Power Electronics, 2017, 32(11): 8360-8370.
[21] Lin Jingyuan, Yueh H Y, Lin Yifeng, et al.Variable- frequency and phase-shift with synchronous recti- fication advance on-time hybrid control of LLC resonant converter for electric vehicles charger[J]. IEEE Journal of Emerging and Selected Topics in Industrial Electronics, 2023, 4(1): 348-356.
[22] 刘宝泉, 周歧浩, 韩猛. LLC谐振变换器混合调制自适应控制策略[J/OL]. 电源学报, 1-12 [2025-04- 16]. http://kns.cnki.net/kcms/detail/12.1420.tm.20240702.1740.002.html.
Liu Baoquan, Zhou Qihao, Han Meng. LLC converter hybrid modulation adaptive control strategy[J/OL]. Journal of Power Supply, 1-12 [2025-04-16]. http://kns.cnki.net/kcms/detail/12.1420.tm.20240702.1740.002.html.
[23] 巫春玲, 张旭鑫, 张震, 等. 基于混合控制的全桥LLC谐振变换器[J]. 电气工程学报, 2024, 19(4): 186-193.
Wu Chunling, Zhang Xuxin, Zhang Zhen, et al.Research on high frequency LLC converter based on GaN[J]. Journal of Electrical Engineering, 2024, 19(4): 186-193.
[24] Ishraq N, Dey S, Mallik A.Hybrid phase-frequency control-enabled global loss minimization of a full- bridge LLC converter under wide gain and load-range operation[C]//2022 IEEE Energy Conversion Congress and Exposition (ECCE), Detroit, MI, USA, 2022: 1-7.
[25] Xu Qingyuan, Zou Rongyan, Wen Tingting, et al.A nonlinear load current feedforward strategy for the charge-controlled LLC converter and its digital implementation to improve the dynamic response[J]. IEEE Transactions on Industrial Electronics, 2023, 70(10): 10195-10203.
[26] Choi H.Charge current control for LLC resonant converter[C]//2015 IEEE Applied Power Electronics Conference and Exposition (APEC), 2015: 1448-1452.
[27] Hu Zhiyuan, Wang Laili, Liu Yanfei, et al.Bang- Bang charge control for LLC resonant converters[C]// 2013 IEEE Energy Conversion Congress and Expo- sition, Denver, CO, USA, 2013: 140-146.
[28] 李佳昊, 陈捷, 邵志冲, 等. LLC谐振变换器简化时域算法及其频率前馈控制[J]. 中国电机工程学报, 2025, 45(8): 3147-3160.
Li Jiahao, Chen Jie, Shao Zhichong, et al.Simplified time-domain algorithm and frequency feedforward control of LLC resonant converter[J]. Proceedings of the CSEE, 2025, 45(8): 3147-3160.
[29] 张宇鑫, 陈捷, 王简, 等. 基于简化时域模型的LLC谐振变换器同步整流在线驱动策略[J]. 电工技术学报, 2025, 40(8): 2615-2629.
Zhang Yuxin, Chen Jie, Wang Jian, et al.Syn- chronous rectifier on-line driving strategy for LLC resonant converter based on a simplified time domain model[J]. Transactions of China Electrotechnical Society, 2025, 40(8): 2615-2629.
[30] Chen Jie, Jiang Lingfeng, Gong Linxiao, et al.State plane feedforward control for LLC converter with geometric simplification[J]. IEEE Transactions on Power Electronics, 2023, 38(10): 12469-12481.
[31] Chen Jie, Xu Junzhong, Wang Yong.Seamless con- trol of full-bridge and half-bridge topology morphing LLC converter based on state plane analysis[J]. IEEE Transactions on Power Electronics, 2024, 39(1): 198-211.
[32] Chen Jie, Xu Junzhong, Zhang Yuxin, et al.Geo- metrical state-plane-based synchronous rectification scheme for LLC converter in EVs[J]. IEEE Transa- ctions on Transportation Electrification, 2024, 10(4): 10239-10252.
[33] Fang Xiang, Hu Haibing, Shen Z J, et al.Operation mode analysis and peak gain approximation of the LLC resonant converter[J]. IEEE Transactions on Power Electronics, 2012, 27(4): 1985-1995.
[34] Liu Wei, Wang Binbin, Yao Wenxi, et al.Steady-state analysis of the phase shift modulated LLC resonant converter[C]//2016 IEEE Energy Conversion Congress and Exposition (ECCE), Milwaukee, WI, USA, 2016: 1-5.