A Novel Grid Connected Multi-Input Direct DC-AC Converter

摘要

The growing number of power-electronics equipment with non-sinusoidal currents and reactive power has given increased interest in active power filters (APF). APFs have been researched and put into practical use in power systems with nonlinear loads for harmonic current compensation, power factor correction, reactive power compensation and etc. Shunt APFs, connected in parallel with the power line, are more common than the series ones. This paper presents a bidirectional grid connected multi-input DC-AC converter that plays as a shunt APF integrated with Distributed Generation (DG) sources for power quality enhancement and supplying a part of loads. At the input port of this converter, Half Bridge Converters (HBC) is used to meet the requirement of different DGs, such as Photovoltaic (PV) and Fuel Cell (FC) systems and at the output port, a cycloconverter acts as a shunt APF to compensate current harmonics, reactive power of load and also supply a part of the load. In the proposed converter, High Frequency Transformer (HFT) is used instead of large power transformer. In the proposed converter, the cost, size and the volume of the converter can be reduced. The reduced conversion steps increase the efficiency of the converter. The converter is analyzed step by step to show the principles of the operation in providing an energy management system based on duty cycle variations. The system capability in different operation modes is simulated and simulation and experimental results validate the highly dynamic performance of the proposed controller. Dynamic analysis and controller design of the bidirectional DC-AC converter, which is presented based on non-linear Input-Output Feedback Linearization (IOFL) method, is presented, too.