Design of a CLC Filter for Flyback-Type Micro-inverters of Grid-Connected Photovoltaic Systems

Abstract

ABSTRACT In this paper, the design method of CLC filter for current source inverter (CSI) is discussed. This inverter is basically for photovoltaic system with small power which is also called micro-inverter. For better performance of small power inverter, flyback-type converter-side topology is determined and it operates as CSI because it has inductor inside. The CLC filter is the output filter for this CSI. Mostly, the components’ capacity and system size are regarded as key factors when evaluating small-powered systems. The CLC filter is made with an additional capacitor to a conventional CL filter. The proposed CLC filter assures the same or the better performance on current ripple reduction than the CL filter. Hence, according to this output filter benefits, the micro-inverter system can be smaller and cost down. The passive damping methods are also analysed upon the positions of resistive damping in the filter circuit. Among four different damping methods according to the resisters’ position, the optimal damping method which has the lowest power consumption is applied to the proposed CLC filter and the effect of this method is also analysed. Performance of the proposed CLC filter is verified with simulation and experiment and the results also show the validity of passive damping method.