Design Analysis and Implementation of a Three Phase Seven Level PV Micro Inverter with Soft Switching

Abstract

This paper proposes a system of converters for the integration of a large photovoltaic (PV) plant with a utility AC grid. The system comprises of a central seven-level voltage-fed inverter (VFI) and a large number of PV modules with module-integrated DC-DC converter. The seven-level VFI consists of three three-phase, three-level VFI units connected in parallel on the AC-side. This paper also proposes a new solar power generation system, which is composed of a DC/DC & DC/AC power converter and a new seven-level inverter. This new seven-level inverter is configured using a capacitor selection circuit and a full-bridge power converter, connected in cascade. Seven level converts fed with PV modules provide a viable solution to mitigating harmonic related issues caused by diode or thyristor rectifier front-ends. To handle the large compensation currents and provide better thermal management, two or more paralleled semiconductor switching devices can be used. The proposed PV based seven level topology can also produce seven voltage levels, which significantly reduces the switching current ripple and the size of passive components. The performance of the proposed power converters system is studied using MATLAB/ Simulink.