Analysis and control of battery‐integrated dc/dc converters for renewable energy applications

Abstract

In this study, conventional dc/dc converters are integrated with a battery for renewable energy applications. The proposed battery-integrated dc/dc converters (BICs) can be compact size because these converters comprise just two switches and two diodes. Smaller size and desirable efficiency of the proposed BICs make it possible to use BICs in grid-connected (on-grid) distributed photovoltaic (PV) systems. The proposed BICs provide constant output power (less fluctuation) in different irradiance levels in distributed PV systems resulting in a constant output voltage at the connection point of BICs to the DC link. Besides extracting maximum power from the renewable source, output voltage is properly regulated on reference voltage in the proposed BICs. Depending on the utilisation states of the battery in grid-connected distributed PV systems, the operation of BICs is described in three scenarios. A linear quadratic regulator (LQR) control is applied to regulate output voltage and power of renewable source on references for three scenarios. Finally, the performance of the proposed BICs with LQR controller is verified by simulation (in PSCAD) and experimental results.