Design and Implementation of a High Step-Up Grid-Connected PV Inverter

This paper describes a novel design of a high-performance, grid-connected inverter. The proposed inverter is particularly suitable for small P V systems that are required to feed power to the grid with a number of critical features, i.e. unity power factor, high step-up and high system efficiency. The topology of the proposed inverter is formed by a modified flyback DC/DC converter with a controlled output current source and a full-bridge converter operating with line-frequency switching techniques. With this special circuit arrangement, the proposed inverter is able to recycle the leakage inductance energy with a clamped capacitor and cascade the secondary winding inductor via the converter output path to achieve high efficiency and high step-up characteristics. For the convenience of conducting experiments in the laboratory and eliminating the possible effects of the weather conditions, a PV module emulator realized with a half bridge converter is also developed to replace the real P V module in the hardware tests carried out in this paper. An 80W prototype PV inverter system is built based on the proposed design method. The feasibility and effectiveness of the proposed inverter system are confirmed with some PSIM simulations and experimental results. Copyright (C) 2010 Praise Worthy Prize S.r.l. - All rights reserved.