基于飞跨电容桥臂动态均压的多电平变流器拓扑与控制研究

Study on the Topology and Control of Novel Multi-level Converter with Flying Capacitor Phase-leg to Form Dynamic Voltage Balancing

  • 摘要: 采用电容分压的二极管钳位型多电平变流器受限于复杂工况下电容电压波动带来的动态分压不均问题。采用动态控制分压的飞跨电容桥臂代替无源电容分压能有效解决这一问题。介绍了基于这一思路的拓扑演化和控制研究。基于三电平的二极管钳位型变流器,介绍了FC-NPC变流器及其控制方法并研发了原理样机,实现了不同调制方式下中点电压的动态平衡。针对2000 V光伏/储能变流需求,进一步演化出了四电平FC-NPC的拓扑结构及其控制方法。在FC-NPC变流器的拓扑下,设计了优化电磁干扰的新型调制方法。针对储能逆变器应用FC-NPC结构,进一步提出了基于飞跨电容的电压扰动方法实现电池阻抗在线辨识方法。

     

    Abstract: Diode-clamped multilevel converters employing capacitive voltage division suffer from dynamic imbalance in voltage distribution under complex operating conditions due to capacitor voltage fluctuations. Replacing capacitive voltage division with dynamically controlled voltage-sharing flying capacitor legs effectively resolves this issue. The topological evolution and control research is proposed based on this approach. Based on a three-level diode-clamped converter, the FC-NPC converter and its control methodology are introduced, with a prototype developed to achieve dynamic neutral point voltage balancing under various modulation schemes. Furthermore, to address 2 000 V photovoltaic/energy storage conversion requirements, a four-level FC-NPC topology and its control methodology are evolved. Within the FC-NPC converter topology, a novel modulation scheme optimized for electromagnetic interference mitigation is designed. Subsequently, for energy storage inverter applications employing the FC-NPC structure, a voltage disturbance method based on flying capacitors is proposed to achieve online battery impedance identification.

     

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