A New High Gain AC-Decoupled Transformerless Inverter for Photovoltaic Applications

Abstract

Transformerless inverters are prominently used in the single-phase grid-connected system due to their reduced size, weight, and high efficiency. Common-mode leakage current is the main issue of transformerless inverters, which has to be mitigated. An AC-decoupled high gain inverter is proposed in the inverter capable of attaining the gain more than ten times. Hence, even if the PV voltage is less, the inverter can continue to supply the grid. Unlike the two-stage inverters, the proposed inverter doesn’t require the DC-link capacitor, and it’s charging diode between the boosting and inverter stages. The AC-decoupling method used in the inverter helps to reduce the leakage current within the German standard limit VDE0126-1-1. A detailed steady-state analysis of the inverter is presented. The proposed inverter is simulated in the MATLAB Simulink platform to validate its working principle. The comparative loss and thermal analysis of the semiconductor switches made of three different materials (Gallium Nitride, Silicon Carbide, and Silicon) are made in the PLECS platform. The comparative analysis proves that the proposed inverter with Gallium Nitride made switches offers higher efficiency and reliability.

Keywords

• transformerless inverter
• common-mode voltage
• common-mode leakage current
• loss analysis