Multiport Resonant Isolated Bidirectional DC-DC Converter Interfacing Photovoltaic System and Battery with reduced turns ratio

The multi port DC-DC converter handling the renewable energy sources and energy storage system provides a controlled power flow between the input sources and the load. An isolated converter is desirable where the isolation and large voltage step-up gain is needed. Traditional isolated multiport DC-DC converters utilize many switches which result in more switching losses and hence low efficiency. The advantages of existing LCL resonant isolated DC-DC converter is that using the least number (three) of switches at the primary side. In the proposed converter, constant output dc voltage can be obtained with the reduced transformer turns ratio from 1:3 to 1:1 ratio so that it minimizes the leakage inductance losses, improves the battery charging capacity and also improves the efficiency of the converter. The decrease in voltage gain of the converter due to reduction in transformer turn ratio is compensated by adjusting the gate pulse duty cycle of switches S1,S2,S3. Simulation is carried out using MATLAB (R2014A) and the results of proposed topology are compared with the existing topology and the constant step-up voltage gain at the output side is verified. In future, a prototype hardware model will be implemented for the proposed topology to verify the results.