**Step-Up Series Resonant DC–DC Converter with Bidirectional-Switch-Based Boost Rectifier for Wide Input Voltage Range Photovoltaic Applications**

#### **Abualkasim Bakeer, Andrii Chub \* and Dmitri Vinnikov \***

Department of Electrical Power Engineering and Mechatronics, Power Electronics Group, Tallinn University of Technology, 19086 Tallinn, Estonia; abbake@taltech.ee

**\*** Correspondence: andrii.chub@taltech.ee (A.C.); dmitri.vinnikov@taltech.ee (D.V.)

Received: 25 June 2020; Accepted: 17 July 2020; Published: 21 July 2020

**Abstract:** This paper proposes a high gain DC–DC converter based on the series resonant converter (SRC) for photovoltaic (PV) applications. This study considers low power applications, where the resonant inductance is usually relatively small to reduce the cost of the converter realization, which results in low-quality factor values. On the other hand, these SRCs can be controlled at a fixed switching frequency. The proposed topology utilizes a bidirectional switch (AC switch) to regulate the input voltage in a wide range. This study shows that the existing topology with a bidirectional switch has a limited input voltage regulation range. To avoid this issue, the resonant tank is rearranged in the proposed converter to the resonance capacitor before the bidirectional switch. By this rearrangement, the dependence of the DC voltage gain on the duty cycle is changed, so the proposed converter requires a smaller duty cycle than that of the existing counterpart at the same gain. Theoretical analysis shows that the input voltage regulation range is extended to the region of high DC voltage gain values at the maximum input current. Contrary to the existing counterpart, the proposed converter can be realized with a wide range of the resonant inductance values without compromising the input voltage regulation range. Nevertheless, the proposed converter maintains advantages of the SRC, such as zero voltage switching (ZVS) turn-on of the primary-side semiconductor switches. In addition, the output-side diodes are turned o ff at zero current. The proposed converter is analyzed and compared with the existing counterpart theoretically and experimentally. A 300 W experimental prototype is used to validate the theoretical analysis of the proposed converter. The peak e fficiency of the converter is 96.5%.

**Keywords:** photovoltaic (PV); DC–DC converter; series resonance converter; wide range converter; bidirectional switch; conversion e fficiency
