Closed-Loop Common-Mode Voltage Injection Control for Hybrid Clamped Converter Based on Capacitor Voltage Difference Extraction
Pan Jianyu1,2, Guo Yujia1,2, Fu Xiaojie1,2, Yan Sheng1,2, Xiao Junwei1,2
1. State Key Laboratory of Power Transmission Equipment Technology Chongqing University Chongqing 400044 China; 2. National Innovation Center for Industry-Education Integration of Energy Storage Technology Chongqing University Chongqing 400044 China
Abstract:The hybrid clamped converter (HCC) has a broad application prospect in medium and high- voltage variable-frequency speed control systems due to its simple structure, low current harmonics, and small number of devices. However, under low-frequency operation, the DC-link capacitor voltage experiences severe fluctuations, while under high-frequency conditions, its voltage stability is prone to disturbances caused by abrupt operational changes. Additionally, issues such as insufficient utilization of the DC-link voltage remain. The current vector control method is widely employed in variable-frequency drive systems. However, the introduction of current closed-loop control complicates the capacitor voltage fluctuation mechanism in HCC systems, potentially leading to control failure when handling resistive-inductive (RL) loads. A mathematical model of HCC under closed-loop load current control is established. Then, a closed-loop common-mode voltage injection balancing method based on capacitor voltage difference extraction is proposed to suppress violent capacitor voltage fluctuations under low-frequency operating conditions. A third-harmonic common-mode voltage angle compensation strategy is introduced for high-frequency operation, which enhances DC-link voltage utilization while maintaining capacitor voltage balancing capability. Finally, the proposed methods are validated through simulations and experiments. The results demonstrate that the proposed control method outperforms the conventional PW-PWM control method and open-loop common-mode voltage injection approaches in suppressing capacitor voltage fluctuations across a wide frequency range. Under closed-loop output current operation, the proposed method achieves robust capacitor voltage balancing in multiple scenarios, including extreme 0 Hz conditions. It maintains DC output capability. The introduced third-harmonic common-mode voltage angle compensation strategy enables the formation of a saddle wave effect in the superimposed reference waveform, thereby enhancing the utilization of the DC-link voltage. Furthermore, the proposed control method maintains a stable capacitor voltage while accurately tracking current and speed during four-quadrant motor operation. In addition, a three-phase HCC experimental platform was established. Comparative tests were conducted with the open-loop common-mode voltage injection method under open-loop and closed-loop output current conditions. In contrast, dynamic performance tests and angle compensation strategy validation were performed under closed-loop output current conditions. The results show that the proposed method demonstrates enhanced operational adaptability and superior dynamic capacitor voltage balancing capability. With the incorporation of the angle compensation strategy under high-frequency, high-modulation conditions, the DC-link voltage utilization rate was improved by approximately 14%.
潘建宇, 郭禹伽, 付孝杰, 闫升, 肖俊伟. 基于电容电压差值提取的闭环共模电压注入的混合式钳位变换器控制方法[J]. 电工技术学报, 2026, 41(2): 635-648.
Pan Jianyu, Guo Yujia, Fu Xiaojie, Yan Sheng, Xiao Junwei. Closed-Loop Common-Mode Voltage Injection Control for Hybrid Clamped Converter Based on Capacitor Voltage Difference Extraction. Transactions of China Electrotechnical Society, 2026, 41(2): 635-648.
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