A New Three-Phase Non-Isolated Photovoltaic Inverter for Suppressing Leakage Current and THD

Abstract

A novel three-phase grid-tied photovoltaic (PV) non-isolated inverter with improved performance owing to common mode current suppression as well as constant common mode voltage is presented in this paper. To compensate unexpected oscillations in stray capacitor voltage, three additional diodes are used with the full bridge circuit of traditional B6 inverter. Therefore, using total six insulated gate bipolar transistors (IGBTs) and three diodes, the proposed inverter eliminates the pitfalls of conventional grid-tied non-isolated PV inverters. Unipolar sinusoidal pulse width modulation (SPWM) method is utilized here in order to control the power switches of the presented inverter. Because of less voltage oscillations in stray capacitor, common mode voltage is hold to be constant. Consequently, extra leakage current flow is reduced significantly. The peak leakage current is found 8.184 mA and 5.132 mA RMS leakage current is recorded. The total harmonic distortions (THDs) of phase voltage and phase current are also very low. 1.66% THD is measured for both phase voltage and current. To justify the effectiveness of the proposed inverter more accurately, dynamic load change behavior as well as variable input response are analyzed. The proposed inverter has been simulated and analyzed via MATLAB/Simulink software.