Simplified Model Predictive for Controlling Circulating and Output Currents of a Modular Multilevel Converter

Document Type : Research Article


Department of Electrical and Computer Engineering, University of Sistan and Baluchestan, Zahedan, Iran


Model Predictive Control (MPC) has attracted wide attention recently, especially in electrical power converters. MPC advantages include straightforward implementation, fast dynamic response, simple system design, and easy handling of multiple objectives. In conventional MPC, the optimal value of the cost function is obtained after calculating all switching states, which makes this method impossible to implement. In this paper, a Simplified Model Predictive Control (S-MPC) is presented to control the circulating and output currents in a Modular Multilevel Converter (MMC). Using a discrete mathematical model of MMC and the neighboring index values with respect to their previously applied values, the calculation burden can be reduced rapidly, and even the number of Sub-Modules (SMs) increases. The conventional MPC is expressed for comparison with the proposed method. In addition, a bilinear mathematical model of the MMC is derived and discretized to predict the states of the MMC for one step ahead. A sorting algorithm is used to retain the balancing capacitor voltage in each SM, while the cost function guarantees the regulation of the output current, and MMC circulating current. In the simulation section, the proposed method is implemented in a three-phase MMC with four SMs in each arm. The accuracy and performance of the proposed method are evaluated with simulation and experimental results.


Main Subjects

[1]   A. Pirhadi and M. T. Bina, “Design of DC-side fault current limiter for MMC-HVDC systems: Safety of the MMC along with frequency stability,” vol. 14, pp. 2419–2429, 2020.
[2]    Pan, Xicai, et al. "Circulating Current Analysis and Power Mismatch Elimination Strategy for an MMC-Based Photovoltaic System." 2020 IEEE Energy Conversion Congress and Exposition (ECCE). IEEE, 2020.
[3] Yu, Zixiang, et al. "Power Converter Topologies and Control Strategies for DC-Biased Vernier Reluctance Machines." IEEE Transactions on Industrial Electronics 67.6 (2019): 4350-4359.
[4]   Harikumaran, Jayakrishnan, et al. "Failure modes and reliability-oriented system design for aerospace power electronic converters." IEEE Open Journal of the Industrial Electronics Society 2 (2020): 53-64.
[5]   Kurochkin, Denis A., et al. "Multiport DC-DC Converter with Additional Inductance for Spacecraft Power Systems." 2020 21st International Conference of Young Specialists on Micro/Nanotechnologies and Electron Devices (EDM). IEEE, 2020.
[6]    Deng, Fujin, et al. "Overview on submodule topologies, modeling, modulation, control schemes, fault diagnosis, and tolerant control strategies of modular multilevel converters." Chinese Journal of Electrical Engineering 6.1 (2020): 1-21.
[7]    Bakbak, Ali, and Erkan Me┼če. "An Approach for Space Vector PWM to Reduce Harmonics in Low Switching Frequency Applications." 2019 International Aegean Conference on Electrical Machines and Power Electronics (ACEMP) & 2019 International Conference on Optimization of Electrical and Electronic Equipment (OPTIM). IEEE, 2019.
[8]     Mittal, Arvind, Kavali Janardhan, and Amit Ojha. "Multilevel inverter-based Grid Connected Solar Photovoltaic System with Power Flow Control." 2021 International Conference on Sustainable Energy and Future Electric Transportation (SEFET). IEEE, 2021.
[9]    Hariri, Raghda, Fadia Sebaaly, and Hadi Y. Kanaan. "A Review on Modular Multilevel Converters in Electric Vehicles." IECON 2020 The 46th Annual Conference of the IEEE Industrial Electronics Society. IEEE, 2020.
[10] Song, Shuguang, and Jinjun Liu. "Interpreting the individual capacitor voltage regulation control of PSC-PWM MMC via consensus theory." IEEE Access 7 (2019): 66807-66820.
[11]  J. Qin and M. Saeedifard, “Predictive control of a modular multilevel converter for a back-to-back HVDC    system,” IEEE Trans. Power Deliv., vol. 27, no. 3, pp. 1538–1547, 2012.
[12]  M. H. Mohsen Vatani, Behrooz Bahrani, Maryam Saeedifard, “Indirect Finite Control Set Model Predictive     Control of Modular Multilevel Converters,” IEEE Trans. Smart Grid, vol. 6, no. 3, pp. 1520 – 1529, 2015.
[13]  B. Gutierrez and S. S. Kwak, “Modular Multilevel Converters (MMCs) Controlled by Model Predictive Control with Reduced Calculation Burden,” IEEE Trans. Power Electron., vol. 33, no. 11, pp. 9176–9187, 2018.
[14] Zhou, Dehong, Shunfeng Yang, and Yi Tang. "Model-predictive current control of modular multilevel converters with phase-shifted pulse width modulation." IEEE Transactions on Industrial Electronics 66.6 (2018): 4368-4378.
[15]   M. Zhu and G. Li, “Modular Multilevel Converter with Improved Indirect Predictive Controller,” IEEE J. Emerg. Sel. Top. Power Electron., vol. 7, no. 2, pp. 976–989, 2019.
[16] P. Münch, D. Görges, M. Izák, and S. Liu, “Integrated current control, energy control and energy balancing of modular multilevel converters,” in Proc. 36th Annu. Conf. IEEE Ind. Electron. Soc. (IECON), Glendale, AZ, USA, 2010, pp. 150–155
[17] Karamanakos, Petros, and Tobias Geyer. "Guidelines for the design of finite control set model predictive controllers." IEEE Transactions on Power Electronics 35.7 (2019): 7434-7450.
[18] Wang, Yue, et al. "Model predictive control of modular multilevel converter with reduced computational load.
"2014 IEEE Applied Power Electronics Conference and Exposition-APEC 2014. IEEE, 2014.
[19] Q. Tu, Z. Xu, and L. Xu, “Reduced Switching-frequency modulation and circulating current suppression for modular multilevel converters,” IEEE Trans. Power Deliv., vol. 26, no. 3, pp. 2009–2017, 2011.
[20] M. Zygmanowski, B. Grzesik, and R. Nalepa, “Capacitance and inductance selection of the modular multilevel converter,” 2013 15th Eur. Conf. Power Electron. Appl. EPE 2013, 2013.