Abstract:Fuel cell is a kind of clean energy with high efficiency and high power density, which has a good application prospect in automobile, aerospace and other fields. This paper presents a new type of resonant converter with high gain and soft switching for fuel cell. The resonant converter uses the coupling inductor to improve the voltage gain. The topology mainly consists of two parts: Boost circuit and resonant circuit. The resonant circuit is superimposed on the Boost circuit, and the output voltage of the two is superimposed to increase the voltage gain. The Boost circuit consists of the magnetic inductance of the coupled inductor and two switches, the auxiliary switches are equivalent to ordinary Boost diodes. The circuit is a unidirectional high-gain circuit. The purpose of using MOSFETs in the auxiliary switches is not to achieve bidirectional energy flow, but to ensure that the main switches can realize zero voltage opening and improve efficiency. The active clamping technique is used for the primary soft switch and synchronous rectification to reduce losses. The resonant circuit is composed of the auxiliary side of the coupled inductor, the leakage inductance of the coupled inductor, the resonant capacitor, two diodes and the output capacitance. The voltage boost ratio depends not only on the duty ratio, but also on the variation ratio of the coupling inductor, which has the advantage of high gain. In addition, due to the active clamp technology, the energy in the leakage inductance can be recovered and utilized to provide energy for the charging and discharging of the junction capacitor of the switches, so as to realize the soft switching. Due to the coupled inductor, the proposed converter can achieve higher output voltage at lower voltage stress, so low voltage devices with low on-resistance can be used to improve the efficiency of the system. In this paper, the operation principle of the proposed converter is analyzed, and the expressions are derived theoretically. On this basis, the conditions of obtaining soft switch of the converter are analyzed theoretically. Besides, the voltage and current stress of each device of the converter are analyzed and the selection method of the output capacitor is given, which provides a theoretical basis for device selection. In the experiment, a 1 kW rated prototype is made, and the experiment is carried out for the performance of the proposed converter, such as high step-up, soft switching, low voltage stress, high efficiency and etc. The input voltage is 40V and the output voltage is 380 V, which can realize the 9.5 voltage gain. All switching tubes can realize ZVS soft switching operation, and all diodes can realize ZCS operation. Because all switches have soft switching operation, and the switching current stress is small, the peak efficiency of the proposed converter is about 97.5% under 10 times Boost ratio which verifies the superiority of the proposed topology.
王哲, 李驰, 郑泽东, 李永东. 一种基于耦合电感的高增益软开关谐振变换器[J]. 电工技术学报, 2024, 39(1): 194-205.
Wang Zhe, Li Chi, Zheng Zedong, Li Yongdong. A High Step-Up ZVS/ZCS Resonant Converter Based on Coupled Inductor. Transactions of China Electrotechnical Society, 2024, 39(1): 194-205.
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