An isolated single-switch high step-up DC/DC converter with three-winding transformer for solar photovoltaic applications

Abstract

An isolated single-switch high step-up DC/DC converter for solar photovoltaic applications is presented in this paper. The proposed isolated converter consists of a single switch, two voltage doubler circuits and a three-winding transformer. The four capacitors in the voltage doubler circuits are charged in parallel and are discharged in series by the secondary and tertiary winding of the three-winding transformer to attain a high step-up voltage gain. In addition, the voltage doubler circuits absorb energy in parallel, which, in turn, significantly alleviates the voltage stress on the switch with low turns ratio and low duty cycle. The converter operation principle and steady-state analysis of the isolated high gain converter for continuous conduction mode are presented in detail. Laboratory tests and simulation using MATLAB/Simulink are carried out with a prototype of 80 W converter. The predicted and test results establish a close agreement between the validity of the analysis and the viability of the proposed circuit.