Design of a Nonisolated Bidirectional Multiport DC‐DC Converter With Improved Efficiency for Photovoltaic Applications

ABSTRACT In this paper, a novel multiport and bidirectional converter is presented that possesses the capability to multiply the voltage gain and enhance overall efficiency. The converter integrates the input, energy storage, and load ports into a single unit for renewable energy applications. The circuit structure incorporates only a single coupled inductor; however, a significant issue arises from the energy stored in the leakage inductor, which leads to voltage spikes on the power switch and diodes. To solve this problem, a passive clamp circuit has been implemented. This auxiliary circuit not only limits the voltage on the power switch but also recovers the energy stored in the leakage inductor and transfers it to the output. To increase voltage gain, this method employs the technique of switched capacitor and voltage lift, along with adjustments to the winding turns ratio of the coupled inductor. As a result, it achieves high voltage gain with a low duty cycle. By reducing the duty cycle, the circulating current duration in the circuit is minimized, which improves the overall efficiency. In this study, the prominent design features of this converter are high voltage gain with a low duty cycle, low voltage stress on switches, low winding turns ratio of the coupled inductor, and high efficiency. The various operating stages for the three modes—single‐input single‐output (SISO), single‐input double‐output (SIDO), and double‐input single‐output (DISO)—are analyzed, and design requirements are presented theoretically. Eventually, to evaluate the veracity of the theoretical analysis and the stated equations, a laboratory prototype of the proposed converter has been constructed. The prototype has an input (PV) voltage of 30 V, battery voltage of 45 V, and an output voltage of 400 V with a rated power of 300 W.