A High Step-Up PWM Non-Isolated DC-DC Converter With Soft Switching Operation

A high step-up PWM non-isolated dc-dc converter with soft switching is proposed in this paper. The converter has minimum auxiliary elements to achieve high power density and high voltage gain. The ZVS operation of the main power switch results in negligible capacitive turn-on losses. Since the duty cycle of the auxiliary switch is narrow and its operation is under ZCS condition, the losses that the auxiliary circuit imposes are not significant. Also, all the diodes are operated under soft-switching conditions solving the reverse recovery problem. All the inductors are coupled on only one magnetic core, reducing size and conduction losses. Compared to the hard switched counterpart, the electromagnetic interference of the proposed converter is reduced. Furthermore, the output voltage of the proposed converter is controlled by an integral sliding mode control strategy during the load variations. Also, the proposed integral sliding mode control strategy has been compared with the PI control strategy, improving the transient response and the robustness under load variations while the switching frequency is constant. The effectiveness and accuracy of the proposed converter are verified by practical laboratory results which are obtained from a 250W prototype.