一种光伏发电用高增益多电平逆变器

针对传统的多电平逆变器存在有源器件数量较多、电容电压不平衡、结构复杂以及电压增益低的问题，提出一种降低器件数量且可扩展的多电平逆变器。该逆变器由开关电容单元和两个半桥组成，使用1个直流电源、3个电容、13个开关管，实现4倍电压增益和九电平交流输出电压。该逆变器通过2个半桥代替后端H桥转换输出电压极性，可以有效降低开关管总电压应力。在所提逆变器的扩展结构中，电容逐级充电的工作方式进一步提高了电压增益和输出电平数。首先，详细阐述了所提逆变器的工作模式、调制策略、电容分析、电压应力计算和电路参数设计。然后，与其他类似多电平逆变器进行了比较。最后，通过仿真与实验验证了所提逆变器的可行性和理论分析的正确性。

A high gain multilevel inverter for photovoltaic power generation

There are problems such as the large number of active components, unbalanced capacitor voltage, complex structure and low voltage gain in traditional multilevel inverters. Given these, this paper proposes a multilevel inverter that reduces the number of components and can be modularly expanded. The inverter is composed of a switched capacitor unit and two half bridges. It uses 1 DC power supply, 3 capacitors, and 13 switches to achieve 4 doubles voltage gain and a nine-level AC output voltage. Two half-bridges are used instead of the back-end H-bridge to convert the output voltage polarity. This can effectively reduce the total voltage stress of the switches. In the modular expansion structure of the proposed inverter, the step-by-step charging method of the capacitors further improves the voltage gain and the output level number. First, the working mode, modulation strategy, capacitance analysis, voltage stress calculation, and circuit parameter design of the proposed inverter are elaborated in detail. Then, it is compared with other similar multilevel inverters in recent literature. Finally, the feasibility of the proposed inverter and the correctness of the theoretical analysis are verified through simulation and experiment.