An Efficient High-Step-Up Soft-Switching Boost Converter for Photovoltaic Application

In this paper an efficient high step-up converter with a coupled- inductor with soft- switching operation is presented. The proposed topology includes a coupled-inductor boost converter for raising the voltage gain. Moreover, a simple auxiliary resonant circuit composed of an auxiliary switch, a clamping diode and a resonant tank (inductor, capacitor), is adopted in this paper. The coupled-inductor boost converter presents poor efficiency because of hard switching and switch losses. All switches in the adopted circuit perform zero-current switching at turn-on, and zero-voltage switching at turn-off. This soft-switching operation reduces the switching losses and diode reverse-recovery problems. The converter uses PWM method for switching and it is controlled by a PI controller to improve its dynamic output response. The paper presents detailed analysis of the converter operational modes. A 225W dc-dc converter used in PV application is designed and evaluated by simulations. The results are presented to confirm the theoretical analysis.