Voltage Balancing Control Based on Flexible Hybrid Virtual SPWM Method for a Five-Level Converter With Lower Total Blocking Voltage

• Published in: IEEE transactions on power electronics 2024-12, Vol.39 (12), p.15493-15505
• Main Authors: Wen, Chuangping, Chen, Hua, Xing, Xiangyang, Liu, Chang, Ren, Qiguang, Zhang, Rui
• Format: Article
• Language: English
• Subjects: Capacitors; Control systems; FC five-level inverter; Flying capacitor (FC) voltage balance; low frequency; Modulation; Switches; Thermal stability; Topology; total blocking voltage; Voltage control
• ISSN: 0885-8993; 1941-0107
• DOI: 10.1109/TPEL.2024.3431704

Flying-capacitor (FC) five-level topology with lower total blocking voltage is a potential topology in the medium-voltage application. Still, under high modulation indexes, conventional modulation methods cannot guarantee the stability of the FC voltage, resulting in increased volume and capacity of passive components and limiting its application. To achieve capacitor voltage balance at various modulation indexes with a modulation method, this article proposes a hybrid virtual SPWM method that modifies the carrier and modulation waves based on conventional SPWM, achieving FC voltage balance under full-modulation and full-frequency conditions. Due to the advantage of the topology without neutral point voltage control, HVSPWM can be seamlessly switched to the hybrid virtual DPWM, which can achieve different control objectives while satisfying the stability of the FC voltage. The proposed method has the same expansion capability as the topology, meeting the requirements of the future development. The effectiveness of the proposed method is verified by the simulations and experiments.