# Analysis of the Charging Characteristics of High Voltage Capacitor Chargers Considering the Transformer Stray Capacitance

• Lee, Byungha (Defense Advanced R&D Institute, Agency for Defense Development) ;
• Cha, Hanju (Dept. of Electrical Engineering, Chungnam National University)
• Published : 2013.05.20

#### Abstract

In this paper, the charging characteristics of series resonant type high voltage capacitor chargers considering the transformer stray capacitance have been studied. The principles of operation for the four operational modes and the mode changes for the four different switching frequency sections are explained and analyzed in the range of switching frequency below the resonant frequency. It is confirmed that the average charging currents derived from the above analysis results have non-linear characteristics in each of the four modes. The resonant current, resonant voltage, charging current, and charging time of this capacitor charger as variations of the switching frequency, series parallel capacitance ratio ($k=C_p/C_s$), and output voltage are calculated. From the calculation results, the advantages and disadvantages arising from the parallel connection of this stray capacitance are described. Some methods to minimize charging time of this capacitor charger are suggested. In addition, the results of a comparative test using two transformers whose stray capacitances are different are described. A 1.8 kJ/s prototype capacitor charger is assembled with a TI28335 DSP controller and a 40 kJ, 7 kV capacitor. The analysis results are verified by the experiment.

#### Acknowledgement

Supported by : Korea Institute of Energy Technology Evaluation and Planning (KETEP)

#### References

1. I. W. Jung, J. S. Kim, G. I. Gusev, and G. H. Rim, "Design of 35 kJ/s 25 kV capacitor charging power supply for pulsed power system," in Proc. IEEE-IECON, pp. 2860-2863, 2004.
2. A. C. Lippincott and R. M. Nelms, "A capacitor-charging power supply using a series-resonant topology, constant on-time/variable frequency control, and zero-current switching," IEEE Trans. Ind. Electr. Vol. 38, No. 6, pp. 438-447, Dec. 1991. https://doi.org/10.1109/41.107099
3. B. Lee and H. Cha, "Comparative analysis of charging mode of series resonant converter for a energy storage capacitor," in Proc. IEEE-APEC, pp. 2200-2205, Feb. 2012.
4. Colonel Wm. T. McLyman, Transformer and Inductor Design Handbook, 2nd ed., Marcel Dekker, Inc. New York, chap. 6, 1988.
5. I. R. McNab, F. Stefani, M. Crawford, M. Eregnil, C. Persad, S. Satapathy, H. Vanicek, T. Watt, and C. Dampier, "Development of a naval railgun," IEEE Trans. Magn., Vol. 41, No. 1, pp. 206-210, Jan. 2005. https://doi.org/10.1109/TMAG.2004.839285
6. M. Del Guercio, "A 4.5-MJ pulsed power supply for railgun experiments," IEEE Trans. Magn., Vol. 39, No. 1, pp. 280-284, Jan. 2003. https://doi.org/10.1109/TMAG.2002.805926
7. T. Wolfe, P. Riedy, J. Drake, F. MacDougall, and J. Bernardes, "Preliminary design of a 200 MJ pulsed power system for a naval railgun proof of concept facility," in Proc. 15th International Pulsed Power Conf., pp. 70-74, 2005.
8. J. M. Neri and B. M. Human, "Operation of a 5-MJ capacitor bank for EML materials testing," in Proc. 16th International Pulsed Power Conf., pp. 1736-1739, 2007.
9. G. Ortiz, D. Bortis, J. Biela, and J. W. Kolar, "Optimal design of a 3.5 kV/11 kW DC-DC converter for charging capacitor banks of power modulators," IEEE Trans. Plasma Sci., Vol. 38, No. 10, pp. 2565-2573, Oct. 2010. https://doi.org/10.1109/TPS.2009.2038162
10. S.-H. Kim, B.-S. Kim, Y.-D. Lee, B.-K. Kwon, J.-S. Kim, C.-H. Choi, and S.-G. Choi, "A new capacitor charging power supply using phase-shifted PWM full-bridge converter," in Proc. IEEE-ECCE, pp. 490-494, 2009.
11. H. Sheng, W Shen, H. Wang, D. Fu, Y. Pei, X. Yang, F. Wang, D. Boroyevich, F. C. Lee, and C. W. Tipton, "Design and implementation of a high power density three-level parallel resonant converter for capacitor charging pulsed-power supply," IEEE Trans. Plasma Sci., Vol. 39, No. 4, pp. 1131-1140, Apr. 2011. https://doi.org/10.1109/TPS.2011.2108319
12. M. Borage, S. Tiwari, and S. Kotaiah, "Constant-current, constant- voltage half-bridge resonant power supply for capacitor charging," IEE Electr. Power. Appl., Vol. 153, No. 3, pp. 343-347, May 2006. https://doi.org/10.1049/ip-epa:20050338
13. Q. Tan, F. Lin, S. Wang, H. Zhong, G. Liu, and Y. Deng, "Improved capacitor charging power supply for a power conditioning system," IEEE Trans. Dielectr. Electr. Insul., Vol. 18, No. 4, pp.1214- 1220, Aug. 2011. https://doi.org/10.1109/TDEI.2011.5976118
14. Z. Zhang, Q. Liu, Z. Wu, Q. Wang and H. Yang, "Design and implementation of HF AC-link capacitor charging power supply," in Proc. AIMSEC, pp. 3856-3859, 2011.
15. Y. Gao, Y. Sun, P. Yan, and Y. Shi, "High power capacitor charging power supply for EML applications," in Proc. 14th Electromagnetic Launch Technology Sympos., pp. 10-18, 2008.
16. A. K. Jain, C. P. Henze, C. B. Henze and K. Conroy, "Development of a 350kW,10kV pulse power converter for capacitor charging," in Proc. IEEE-APEC., pp. 1164-1170, 2007.

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