Design of bidirectional converter in renewable energy systems

Abstract

Nowadays the usage of renewable energy sources has increased due to newlinethe demand for fossil fuel, gas and oil reserves in the global market. However, newlinethe fluctuation nature of most renewable energy resources like wind and solar newlinemakes them unsuitable for standalone operation. A common solution to newlineovercome this problem is to use an energy storage device besides the newlinerenewable energy resource to compensate for these fluctuations and maintain newlinea smooth and continuous power flow to the load. In medium power range, the newlinemost common and economical energy storage devices are batteries and supercapacitors.A DC-DC converter is always required to allow energy exchange newlinebetween a storage device and the rest of a system. Such a converter must have newlinea bidirectional power flow capability with flexible control in all operating newlinemodes. The modelling and the control of bi-directional DC-DC converters is newlinean important issue.Thus, the demand of BDC include smaller size, lighter weight and newlinehigher efficiency, etc. In order to minimize the size of BDC, the switching newlinefrequency must be increased. However, the increase of switching frequency newlineresults in higher switching losses. To solve this problem, many soft switching newlinetopologies have been introduced. However, the main function of the BDC is newlineto interface the system with an energy storage device. Hence, the converter newlinehas to be controlled to regulate the voltage within safe limits and to be newlinemaintained at a constant energy flow between the battery and the system. Due newlineto safety implications for the source and load, controllers have to be newlineimplemented. newline newline