A 50‐kW class three‐phase photovoltaic (PV) inverter typically applies a transformerless circuit configuration due to its high efficiency and small volume/size. On the other hand, the conventional PV inverter may suffer from the deterioration of solar panels due to a dc leakage current flowing through the stray capacitance of the solar panels. To solve this problem, this paper presents a transformerless three‐phase PV inverter consisting of multiple bidirectional choppers, which prevents the dc leakage current by maintaining a negative PV array voltage with respect to the ground potential to a dc voltage that is zero or higher. In addition, the size/volume of an ac filter can be reduced by applying the so‐called phase‐shifted PWM to the inverter. In this paper, the operating principles and control method of the inverter are discussed and the validity of the control method is verified by performing computer simulation using the “PSCAD/EMTDC” software package and conducting experiments using a 150‐V downscaled model.

中文翻译：

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使用多个双向斩波器的无变压器三相PV逆变器的运行

50 kW级的三相光伏（PV）逆变器由于效率高，体积/尺寸小，通常采用无变压器的电路配置。另一方面，由于流过太阳能电池板的寄生电容的直流泄漏电流，常规的PV逆变器可能遭受太阳能电池板的劣化的困扰。为解决此问题，本文提出了一种由多个双向斩波器组成的无变压器三相PV逆变器，该逆变器通过将相对于地电势的负PV阵列电压保持为零或更高的直流电压来防止直流泄漏电流。另外，可以通过对逆变器应用所谓的相移PWM来减小交流滤波器的尺寸/体积。在本文中，