Resonant Tank Design Considerations and Implementation of a LLC Resonant Converter with a Wide Battery Voltage Range

  • Sun, Wenjin ;
  • Wu, Hongfei ;
  • Hu, Haibing ;
  • Xing, Yan
  • Received : 2014.09.13
  • Accepted : 2015.05.21
  • Published : 2015.11.20


This paper illustrates resonant tank design considerations and the implementation of a LLC resonant converter with a wide battery voltage range based on the fundamental harmonic approximation (FHA) analysis. Unlike the conventional design at zero load, the parameter K (the ratio of the transformer magnetizing inductor Lm to the resonant inductor Lr) of the LLC converter in this paper is designed with two charging points, (Vo_min, Io_max1) and (Vo_max, Io_max2), according to the battery charging strategy. A 2.9kW prototype with an output voltage range of 36V to 72V dc is built to verify the design. It achieves a peak efficiency of 96%.


Charger;FHA;LLC;Resonant converter


  1. N. H. Kutkut, C. Q. Lee, and I. Batarseh, “A generalized program for extracting the control characteristics of resonant converters via the state-plane diagram,” IEEE Trans. Power Electron., Vol. 13, No. 1, pp. 58-66, Jan. 1998.
  2. A. J. Forsyth, G. A. Ward, and S. V. Mollov, “Extended fundamental frequency analysis of the LCC resonant converter,” IEEE Trans. Power Electron., Vol. 18, No. 6, pp. 1286-1292, Nov. 2003.
  3. A. K. S. Bhat, “A generalized steady-state analysis of resonant converters using two-port model and Fourier-series approach,” IEEE Trans. Power Electron., Vol. 13, No. 1, pp. 142-151, Jan. 1998.
  4. Haoyu Wang, Serkan Dusmez, and Alireza Khaligh. “A novel approach to design EV battery chargers using SEPIC PFC stage and optimal operating point tracking technique for LLC converter,” in Proc. IEEE Appl. Power Electron. Conf. Expo., pp. 1683-1689, 2014.
  5. F. Musavi, M. Craciun, D.S. Gautam, W. Eberle, W. G. Dunford, “An LLC resonant DC-DC converter for wide output voltage range battery charging applications,” IEEE Trans. Power Electron., Vol. 28, No. 12, pp. 5437-5445, Dec. 2013.
  6. A. Khaligh and S. Dusmez, “Comprehensive topological analysis of conductive and inductive charging solutions for plug-in electric vehicles,” IEEE Trans. Veh. Technol., Vol. 61, No. 8, pp.3475-3489, Oct. 2012.
  7. S. Chudjuarjeen, A. Sangswang, and C. Koompai, “An improved LLC resonant inverter for induction-heating applications with asymmetrical control,” IEEE Trans. Ind. Electron., Vol. 58, No. 7, pp. 2915-2925, Jul. 2011.
  8. B. Yang, "Topology investigation for frontend DC/DC power conversion for distributed power systems," Ph. D. dissertation, Virginia Polytechnic Institute and State University, Blacksburg, VA, 2003.
  9. J. Yamamoto, T. Zaitsu, S. Abe, and T. Ninomiya, “PFM and PWM hybrid controlled LLC converter,” IEEE International Power Electron. Conf., pp. 177-182, May 2014.
  10. H. Pan, C. He, F. Ajmal, H. Chen, and G. Chen, “Pulse-width modulation control strategy for high efficiency LLC resonant converter with light load applications,” IET Power Electron., Vol. 7, No. 11, pp. 2887-2894, Aug. 2013.
  11. X. Fang, H. Hu, F. Chen, U. Somani, E. Auadisian, J. Shen, and I. Bataresh, “Efficiency-oriented optimal design of the LLC resonant converter based on peak gain placement,” IEEE Trans. Power Electron., Vol. 28, No.5, pp. 2285-2296, May 2013.
  12. S. De Simone, C. Adragna, C. Spini, and G. Gattavari. “Design-oriented steady state analysis of LLC resonant converters based on FHA,” in Proc. IEEE Symp. on Power Electron., Elect. Drives, Automation and Motion, pp. 200-207, 2006.
  13. B. Lu, W. Liu, Y. Liang, F. C. Lee, and J. D. van Wyk, “Optimal design methodology for LLC resonant converter,” in Proc. IEEE Appl. Power Electron. Conf. Expo., pp. 533-538, 2006.
  14. S. S. Hong, S. H. Cho, C. W. Roh, and S. K. Han, “Precise analytical solution for the peak gain of LLC resonant converters,” Journal of Power Electronics, Vol. 10, No. 6, pp. 680-685, Nov. 2010.
  15. C. H. Park, S. H. Cho, J. Jang, S. K. Pidaparthy, T. Ahn, and B. Choi, “Average current mode control for LLC series resonant DC-to-DC converters,” Journal of Power Electronics, Vol. 14, No. 1, pp. 40-47, Jan. 2014.
  16. B.-C. Kim, K.-B. Park, and G.-W. Moon, “Asymmetric PWM control scheme during hold-up time for LLC resonant converter,” IEEE Trans. Power Electron., Vol. 59, No. 7, pp. 2992-2997, Jul. 2012.
  17. B.-H. Lee, M.-Y. Kim, C.-E. Kim, K.-B. Park, and G.-W. Moon, “Analysis of LLC resonant converter considering effects of parasitic components,” in Proc. IEEE Telecommun. Energy Conf., pp. 1–6, 2009.
  18. J. K. Jeong, B. M. Han, J. Y. Lee, and N. S. Choi, “High-efficiency grid-tied power conditioning system for fuel cell power generation,” Journal of Power Electronics, Vol. 11, No. 4, pp. 551-560, Jul. 2011.