Journal of Power Electronics

The Korean Institute of Power Electronics (전력전자학회)
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Phase current control to reduce unbalanced outputs in paralleled inverters

  • Bong-Ki Lee (Department of Electrical and Computer Engineering, Ajou University) ;
  • Heon-Su Lee (LS ELECTRIC R&D Campus) ;
  • Kyo-Beum Lee (Department of Electrical and Computer Engineering, Ajou University)
  • Received : 2024.01.26
  • Accepted : 2024.07.21
  • Published : 2024.10.20
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Abstract

When paralleled inverters operate an electric motor, a circulating current is typically generated due to a device-switching timing error. To mitigate this error, an AC reactor is installed at the output of the inverters to reduce the circulating current. However, unbalanced output currents (UOCs) are produced due to the difference between the resistance and inductance in the AC reactor. When there is a difference in the output currents of the inverters, a single inverter outputs excessive current. As a result, the motor cannot be controlled to its maximum power. In this study, mathematical modeling is performed and the causes for the generation of UOCs in parallel connected electric motor drive systems are analyzed. Furthermore, the unbalanced load is minimized by controlling the current output based on the output status of the inverters in the control algorithms of a motor. The proposed control method is experimentally verified by implementing a system that connects three inverters in parallel.

Keywords

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT), the Korea Institute of Energy Technology Evaluation and Planning (KETEP), and the Ministry of Trade, Industry & Energy (MOTIE) of the Republic of Korea (No. RS-2024-00333208, No. 20225500000110).

References

  1. A.J. Marques Cardoso, E. Popkov, E. Koptjaev, Evolution and development prospects of electric propulsion systems of large sea ships. In: 2020 International Ural Conference on Electrical Power Engineering (UralCon), pp. 296-303 (2020) 
  2. Hansen, J.F., Wendt, F.: History and state of the art in commercial electric ship propulsion integrated power systems and future trends. Proc. IEEE 103(12), 2229-2242 (2015) 
  3. Hua, M., Hu, H., Xing, Y., He, Z.: Distributed control for AC motor drive inverters in parallel operation. IEEE Trans. Ind. Electron. 58(12), 5361-5370 (2011) 
  4. Takongmo, M., Zhang, C., Wdaan, S., Telmesani, W.A.M., Yapa, D., Salmon, J.: Parallel-connected voltage source converters with a DC common mode and an AC diferential mode PWM filter. IEEE Trans. Power Electron. 38(3), 3664-3675 (2023) 
  5. M. Takongmo, C. Zhang, J. Salmon, Parallel inverters using a DC common mode PWM filter with an AC differential mode PWM flter. In: Proceedings of IEEE Applied Power Electronics Conference and Exposition, pp. 1189-1196 (2021) 
  6. Ohn, S., Zhang, X., Burgos, R., Boroyevich, D.: Differential-mode and common-mode coupled inductors for parallel three-phase AC DC-converters. IEEE Trans. Power Electron. 34(3), 2666-2679 (2019) 
  7. Chen, T.P.: Circulating zero-sequence current control of parallel three-phase inverters. Proc. Inst. Electr. Eng. Electr. Power Appl. 153(2), 282-288 (2006) 
  8. Ye, Z.H., Boroyevich, D., Choi, J.Y., Lee, F.C.: Control of circulating current in two parallel three-phase boost rectifiers. IEEE Trans. Power Electron. 17(5), 609-615 (2002) 
  9. Choi, H.W., Lee, K.B.: Circulating current reduction for parallel-connected modular inverters based on suppression of common-mode voltage. IEEE Trans. Power Electron. 38(9), 11091-11101 (2023) 
  10. N. Hofstotter, J. Lamp, IGBT Modules in parallel operation with central and individual driver board. SEMIKRON Application Note AN 17-001 (2017) 
  11. Guerrero, J.M., Garcia De Vicuna, L., Matas, J., Castilla, M., Miret, J.: Output impedance design of parallel connected UPS inverters with wireless load-sharing control. IEEE Trans. Ind. Electron. 52, 1126-1135 (2005) 
  12. Xiao, S., Lee, Y.S., Dehong, X.: Modeling, analysis, and implementation of parallel multi-inverter systems with instantaneous average-current-sharing scheme. IEEE Trans. Power Electron. 18, 844-856 (2003) 
  13. Tsai-Fu, W., Yu-Kai, C., Yong-Heh, H.: 3C strategy for inverters in parallel operation achieving an equal current distribution. IEEE Trans. Ind. Electron. 47, 273-281 (2000) 
  14. Jung, H.S., Sul, S.K.: Decomposed current controller for a paralleled inverter with a small interfaced inductor. IEEE Trans. Power Electron. 34(9), 9316-9328 (2019)