This paper proposes a cascaded multilevel converter to reduce the number of IGBT switches for the purpose of improving system stability and decreasing switching losses. This converter can eliminate second-order ripple caused by energy exchange between grid and batteries, and thus extend battery life. This cascaded connection between the equivalent buck/boost circuit and the half-bridge inverter is also able to reduce the number of switch tubes. A control strategy based on state of charge (SOC) closed-loop tracking is designed to implement the errorless follow-up control of average SOC values for electric vehicle batteries. The equivalent circuit under different working modes of the topology is analyzed, and the effectiveness of the control strategy is verified. Simulated and experimental results show that this converter can effectively achieve grid connection requirements and balance the battery units to meet practical needs.
"A Cascaded Multilevel Converter Based on SOC Closed Loop Tracking," Progress In Electromagnetics Research C,
Vol. 88, 103-115, 2018. doi:10.2528/PIERC18090501
1. Liu, S., X. Wang, and P X. Liu, "A stochastic stability enhancement method of grid-connected distributed energy storage systems," IEEE Transactions on Smart Grid, Vol. PP, No. 99, 1-9, 2017.
2. Shili, S., A. Hijazi, A. Sari, et al. "Balancing circuit new control for supercapacitor storage system lifetime maximization," IEEE Transactions on Power Electronics, Vol. 32, No. 6, 4939-4948, 2017. doi:10.1109/TPEL.2016.2602393
3. Jousse, J., N. Ginot, C. Batard, et al. "Power line communication management of battery energy storage in a small-scale autonomous photovoltaic system," IEEE Transactions on Smart Grid, Vol. 8, No. 5, 2129-2137, 2017. doi:10.1109/TSG.2016.2517129
4. Dong, J., F. Gao, X. Guan, et al. "Storage sizing with peak-shaving policy for wind farm based on cyclic Markov chain model," IEEE Transactions on Sustainable Energy, Vol. 8, No. 3, 978-989, 2017. doi:10.1109/TSTE.2016.2637916
5. Yang, Z., J. Sun, X. Zha, et al. "Power decoupling control for capacitance reduction in cascaded H-bridge converter-based regenerative motor drive systems," IEEE Transactions on Power Electronics, Vol. PP, No. 99, 1-1, 2018.
6. Moeini, A. and S. Wang, "The state of charge balancing techniques for electrical vehicle charging stations with cascaded H-bridge multilevel converters," 2018 IEEE Applied Power Electronics Conference and Exposition (APEC), 637-644, IEEE, 2018. doi:10.1109/APEC.2018.8341079
7. Chen, F., H. Wang, W. Qiao, et al. "A grid-tied reconfigurable battery storage system," 2018 IEEE Applied Power Electronics Conference and Exposition (APEC), 645-652, IEEE, 2018. doi:10.1109/APEC.2018.8341080
8. Bahr Eldin, S. M., K. S. Rama Rao, R. Ibrahim, and N. Perumal, "Cascade multi-level converter based generalized unified power quality conditioner," 2012 4th International Conference on Intelligent and Advanced Systems (ICIAS2012), Vol. 1, 479-484, 2012. doi:10.1109/ICIAS.2012.6306241
9. Jin, Y., Q. Song, and W. Liu, "High capacity chain battery energy storage system and its charge and discharge equilibrium control," Electric Power Automation Equipment, Vol. 31, No. 3, 6-11, 2011.
10. Lee, J. S., K. B. Lee, and Y. Ko, "An improved phase-shifted PWM method for a three-phase cascaded H-bridge multi-level inverter," 2017 IEEE Energy Conversion Congress and Exposition (ECCE), 2100-2105, IEEE, 2017. doi:10.1109/ECCE.2017.8096417
11. Nakanishi, T. and J. Itoh, "High power density design for a modular multilevel converter with an H-bridge cell based on a volume evaluation of each component," IEEE Transactions on Power Electronics, Vol. 33, No. 3, 1967-1984, 2017. doi:10.1109/TPEL.2017.2690454
12. Kim, I. H. and Y. I. Son, "Regulation of a DC/DC boost converter under parametric uncertainty and input voltage variation using nested reduced-order PI observers," IEEE Transactions on Industrial Electronics, Vol. 64, No. 1, 552-562, 2017. doi:10.1109/TIE.2016.2606586
13. Chincholkar, S. H., W. Jiang, and C. Y. Chan, "An improved PWM-based sliding-mode controller for a Dc-Dc cascade boost converter," IEEE Transactions on Circuits and Systems II: Express Briefs, 1-1, 2017. doi:10.1109/TCSII.2016.2546902
14. Alishah, R. S., S. H. Hosseini, E. Babaei, et al. "New high step-up multilevel converter topology with self-voltage balancing ability and its optimization analysis," IEEE Transactions on Industrial Electronics, Vol. 64, No. 9, 7060-7070, 2017. doi:10.1109/TIE.2017.2688968
15. Jin, Y., Q. Song, and W. Liu, "Chain extended battery energy storage system based on common DC bus and its control," Automation of Electric Power Systems, Vol. 15, 66-70, 2010.
16. Lu, D. and H. Xu, "High-frequency resonance suppression of grid-connected medium voltage converter," Automation of Electric Power Systems, Vol. 23, 018, 2017.
17. Zheng, G., W. Xiaojie, and D. Peng, "Rapid voltage model predictive control strategy for modular multilevel converter," Automation of Electric Power Systems, Vol. 41, No. 1, 122-127, 2017.
18. Mukundan, C. M. N. and P. Jayaprakash, "A new binary hybrid cascaded H-bridge multi level converter for power quality applications," 2016 IEEE 7th Power India International Conference (PIICON), 1-6, IEEE, 2016.
19. Wei, W., X. Shaojun, Z. Zhao, et al. "Control strategy analysis and design of supercapacitor energy storage system based on MMC bidirectional DC-DC converter," Chinese Journal of Electrical Engineering, Vol. 34, No. 27, 4568-4575, 2014.
20. Qiang, C., L. Rui, and C. Xu, "Suppression method of second-order ripple power on battery side of chain energy storage system," Transactions of China Electrotechnical Society, Vol. 30, No. 8, 231-237, 2015.
21. Liu, X., Z. Wan, Y. He, et al. "A unified control strategy for inductor-based active battery equalisation schemes," Energies, Vol. 11, No. 2, 405, 2018. doi:10.3390/en11020405
22. Liu, X., H. Li, Y. He, et al. "SOC estimation method based on IUPF algorithm and variable parameter battery model," Journal of Southeast University, Vol. 48, No. 1, 54-62, 2018.
23. He, Y., C. Cao, X. Liu, et al. "SOC estimation method for lithium batteries based on variable temperature model," Journal of Electrical Machines and Control, Vol. 22, No. 1, 43-52, 2018.
24. Chen, D., Y. Xu, and A. Q. Huang, "Integration of dc microgrids as virtual synchronous machines into the ac grid," IEEE Transactions on Industrial Electronics, Vol. 64, No. 9, 7455-7466, 2017. doi:10.1109/TIE.2017.2674621
25. Amin, M. R., "Virtual synchronous converter based motor drives for future electric vehicles," Newsletter, 2017.
26. Liu, J., M. J. Hossain, J. Lu, et al. "A hybrid AC/DC microgrid control system based on a virtual synchronous generator for smooth transient performances," Electric Power Systems Research, Vol. 162, 169-182, 2018. doi:10.1016/j.epsr.2018.05.014