Reduction of Electrical Losses of Flying-Capacitor Modular Multilevel Converter (FC-MMC) in Electric Drive Application
Subject Areas : electrical and computer engineeringAhmad Bagheri 1 , H. Iman-Eini 2
1 - University of Tehran
2 - University of Tehran
Keywords: Flying-capacitor modular multilevel converter (FC-MMC), modular multilevel converter, voltage ripple, medium-voltage electric drive,
Abstract :
The flying-capacitor modular multilevel converter (FC-MMC) has been introduced as a hardware development of the conventional MMC with the aim of reducing the cell capacitor ripple voltage in the application of electrical drive at low speeds. The capacitor ripple voltage of the cells in this converter is reduced only by injecting high frequency circulating current between the arms. In the conventional control method of this converter, the circulating current component is injected with the aim of complete elimination of the voltage ripple at low frequencies, which leads to an unnecessary increase of the current amplitude in the converter arms. In this paper, the converter control system is modified by finding the relationship between the cell capacitor voltage ripple and the high frequency circulating current amplitude. Then, by injecting the appropriate amplitude of the circulating current, the voltage ripple is controlled in an acceptable range. It is shown that by partial compensation (instead of full elimination of the voltage ripple), in addition to reducing the amplitude of the arm currents, the losses of the electrical system are significantly reduced. The results of simulations and experiments confirm the successful performance of the proposed method.
[1] S. Debnath, J. Qin, B. Bahrani, M. Saeedifard, and P. Barbosa, "Operation, control, and applications of the modular multilevel converter: a review," IEEE Trans. Power Electron., vol. 30, no. 1, pp. 37-53, Jan. 2015.
[2] A. Dekka, B. Wu, R. L. Fuentes, M. Perez, and N. R. Zargari, "Evolution of topologies, modeling, control schemes, and applications of modular multilevel converters," IEEE J. Emerg. Sel. Top. Power Electron., vol. 5, no. 4, pp. 1631-1656, Dec. 2017.
[3] F. Deng, Y. Lu, C. Liu, Q. Heng, Q. Yu, and J. Zhao, "Overview on submodule topologies, modeling, modulation, control schemes, fault diagnosis, and tolerant control strategies of modular multilevel converters," Chin. J. Elect. Eng., vol. 6, no. 1, pp. 1-21, Mar. 2020.
[4] B. Li, S. Zhou, D. Xu, S. J. Finney, and B. W. Williams, "A hybrid modular multilevel converter for medium-voltage variable-speed motor drives," IEEE Trans. Power Electron., vol. 32, no. 6, pp. 4619-4630, Jun. 2016.
[5] Y. S. Kumar and G. Poddar, "Control of medium-voltage AC motor drive for wide speed range using modular multilevel converter," IEEE Trans. Ind. Electron., vol. 64, no. 4, pp. 2742-2749, Apr. 2016.
[6] M. S. Diab, A. Massoud, S. Ahmed, and B. Williams, "A modular multilevel converter with ripple-power decoupling channels for three-phase MV adjustable-speed drives," IEEE Trans. on Power Electronics, vol. 34, no. 5, pp. 4048-4063, May 2019.ُ [7] A. Marzoughi, R. Burgos, D. Boroyevich, and Y. Xue, "Design and comparison of cascaded h-bridge modular multilevel converter and 5-l active neutral point clamped topologies for motor drive application," IEEE Trans. Ind. Appl., vol. 54, no. 2, pp. 1404-1413, Mar./ Apr. 2018.
[8] A. Antonopoulos, L. Angquist, S. Norrga, K. Ilves, L. Harnefors, and H. P. Nee, "Modular multilevel converter ac motor drives with constant torque from zero to nominal speed," IEEE Trans. Ind. Appl., vol. 50, no. 3, pp. 1982-1993, May/Jun. 20140
[9] S. Debnath, J. Qin, and M. Saeedifard, "Control and stability analysis of modular multilevel converter under low-frequency operation," IEEE Trans. Ind. Electron., vol. 62, no. 9, pp. 5329-5339, Sept. 2015.
[10] B. Li, et al., "An improved circulating current injection method for modular multilevel converters in variable-speed drives," IEEE Trans. Ind. Electron., vol. 63, no. 11, pp. 7215-7225, Nov. 2016.
[11] S. Sau and B. G. Fernandes, "Modular multilevel converter based variable speed drive with reduced capacitor ripple voltage," IEEE Trans. Ind. Electron., vol. 66, no. 5, pp. 3412-3421, May 2019.
[12] J. Kolb, F. Kammerer, M. Gommeringer, and M. Braun, "Cascaded control system of the modular multilevel converter for feeding variable-speed drives," IEEE Trans. Power Electron., vol. 30, no. 1, pp. 349-357, Jan. 2015.
[13] B. Wu and M. Narimani, High-Power Converters and AC Drives, John Wiley & Sons, 2017.
[14] S. Du, B. Wu, and N. R. Zargari, "Common-mode voltage elimination for variable-speed motor drive based on flying-capacitor modular multilevel converter," IEEE Trans. Power Electron., vol. 33, no. 7, pp. 5621-5628, Jul. 2018.
[15] S. Du, B. Wu, and N. Zargari, "Common-mode voltage minimization for grid-tied modular multilevel converter," IEEE Trans. on Ind. Electron, vol. 66, no. 10, pp. 7480-7487, Jul. 2018.
[16] M. Huang, J. Zou, X. Ma, Y. Li, and M. Han, "Modified modular multilevel converter to reduce submodule capacitor voltage ripples without common-mode voltage injected," IEEE Trans. Ind. Electron., vol. 66, no. 3, pp. 2236-2246, Mar. 2019.
[17] S. Du, B. Wu, K. Tian, N. R. Zargari, and Z. Cheng, "An active cross-connected modular multilevel converter (AC-MMC) for a medium-voltage motor drive," IEEE Trans. Ind. Electron., vol. 63, no. 8, pp. 4707-4717, Aug. 2016.
[18] S. Du, B. Wu, and N. R. Zargari, "A star-channel modular multilevel converter for zero/low-fundamental-frequency operation without injecting common-mode voltage," IEEE Trans. Power Electron., vol. 33, no. 4, pp. 2857-2865, Apr. 2018.
[19] S. Du, B. Wu, and N. R. Zargari, "A delta-channel modular multilevel converter for zero/low-fundamental-frequency operation," IEEE Trans. Ind. Electron., vol. 66, no. 3, pp. 2227-2235, Mar. 2019.
[20] S. Du, B. Wu, and N. Zargari, "Delta-channel modular multilevel converter for a variable-speed motor drive application," IEEE Trans. Ind. Electron., vol. 65, no. 8, pp. 6131-6139, Aug. 2018.
[21] S. Du, B. Wu, N. R. Zargari, and Z. Cheng, "A flying-capacitor modular multilevel converter for medium-voltage motor drive," IEEE Trans. Power Electron., vol. 32, no. 3, pp. 2081-2089, Mar. 2016.
[22] S. Du, A. Dekka, B. Wu, and N. Zargari, Modular Multilevel Converters: Analysis, Control, and Applications, John Wiley & Sons, 2017.
[23] S. Du, B. Wu, and N. R. Zargari, "Current stress reduction for flying-capacitor modular multilevel converter," IEEE Trans. Power Electron., vol. 34, no. 1, pp. 184-191, Jan. 2019.
[24] D. Dung Le and D. C. Lee, "Reduction of half-arm current stresses and flying-capacitor voltage ripples of flying-capacitor MMCs," Access IEEE, vol. 8, pp. 180076-180086, 2020.
