This article proposes a multilevel inverter topology with single dc-link and series-connected capacitors as stacked voltage sources for multilevel voltage generation. The voltage deviation of a dc-link capacitor will occur whenever a phase terminal connects to the balanced neutral points (NPs: terminal joints of dc-link capacitors). On the contrary, if the voltage of a dc-link capacitor deviates from the nominal voltage, the same phase currents can be utilized to balance these NPs. This new technique is being proposed for the first time in the literature. Any voltage disturbance of the dc-link capacitors is balanced using the motor phase currents, irrespective of load power factor and modulation indices. For the balanced NPs, whenever a phase connects to an NP, the other phase terminal tapping positions are varied on the dc link to establish iA+iB+iC=0i_{A}+i_{B}+i_{C}=0 for that NP. The pole voltage level variation at motor phase terminals is undisturbed by adding extra cascaded H-bridges (CHBs) at each phase leg. The voltages of CHB capacitors are controlled conventionally by inverter pole voltage redundancies. The detailed experimental results for open-loop V/f and closed-loop field-oriented control on an induction motor are presented using a nine-level laboratory prototype.

中文翻译：

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采用单个直流母线和低压电容器作为堆叠电压源的九电平逆变器，具有电容器电压控制（与负载功率因数无关）


本文提出了一种多电平逆变器拓扑，采用单个直流链路和串联电容器作为用于多电平电压生成的堆叠电压源。每当相端子连接到平衡中性点（NP：直流母线电容器的端子接头）时，就会出现直流母线电容器的电压偏差。相反，如果直流母线电容器的电压偏离标称电压，则可以利用同相电流来平衡这些NP。这项新技术是首次在文献中提出。直流母线电容器的任何电压扰动均使用电机相电流进行平衡，而与负载功率因数和调制指数无关。对于平衡 NP，每当一相连接到 NP 时，直流链路上另一相端子抽头位置就会发生变化，从而建立 iA+iB+iC=0i_{A}+i_{B}+i_{C}=0那个 NP。通过在每个相脚添加额外的级联 H 桥 (CHB)，电机相端子处的极电压电平变化不会受到干扰。 CHB 电容器的电压通常通过逆变器极电压冗余来控制。使用九级实验室原型展示了感应电机开环 V/f 和闭环磁场定向控制的详细实验结果。