Single-stage zero-current switch full-bridge boost DC converter and control method thereof

Abstract

The invention discloses a single-stage zero-current switch full-bridge boost DC converter and a control method thereof, a primary side of the converter is composed of a boost inductor, a full-bridge module, a group of reverse series switch tubes and an LC series resonant cavity, a secondary side of the converter is a voltage doubling rectifying circuit, and the primary side and the secondary side are connected through a high-frequency transformer. Two reverse series switch tube drives have the same duty ratio equal to 0.5, the phase difference is half a switching period, two switch tube drives of a leading bridge arm have the same duty ratio larger than 0.5, the phase difference is half a switching period, and the duty ratio and the phase difference of two switch tubes of a lagging bridge arm are the same as those of the leading bridge arm. The reverse series switch tube group and the same-direction switch tube of the leading bridge arm have the same opening starting point; and a phase shift angle is formed between the switch tube drives on the diagonal lines of the two bridge arms. The transmission power and the step-up ratio can be adjusted by controlling the phase shift angle, and zero-current switching of all semiconductor devices in a wide load range is realized through frequency conversion control.

Description

technical field [0001] The invention belongs to the technical field of power electronics, is mainly applied to single-stage collection of a medium-voltage direct current grid, and relates to a single-stage zero-current switch full-bridge step-up direct current converter. Background technique [0002] According to the "Global Renewable Energy Status Report 2021" released by REN21 (Century Renewable Energy Policy Network), in 2020, global solar photovoltaic (PV) and wind power will be about 760GW and 743GW, respectively. In terms of gathering such a large power, there are two methods of gathering medium voltage AC (MVAC) and medium voltage direct current (MVDC). The latter has the characteristics of high efficiency, strong controllability and reliability. At the same time, the output voltage of the current renewable energy is low, and a high-gain DC / DC converter is required to connect the generated power to the medium-voltage DC bus. It can be mainly divided into two types, na...

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Problems solved by technology

Literature (R. Suryadevara and L. Parsa, "Full-Bridge ZCS-Converter-Based High-Gain Modular DC-DC Converter for PV Integration With Medium-Voltage DC Grids," in IEEE Transactions on Energy Conversion, vol.34, no.1, pp.302-312, March 2019.) proposed a full-bridge boost converter that can realize zero-current switching of all main switch tubes. By using reverse blocking switch tubes, the current will not continue to reverse after the current drops to zero. To resonate, so as to meet the requirements of zero current switching of all switching tubes and diodes, but because the reverse blocking switching tube is composed of a diode and an insulated gate bipolar transistor (IGBT) in series, on the one hand, the cost is high, and at the same time, it is renewable In the case of such a high-power and low-voltage energy collection, it will cause a large conduction loss

Patent (Ning Guangfu, Xu Guo, Wang Hui, Liu Yonglu. Single-stage Boost full-bridge zero-current switching DC converter and its control method [P]. Hunan Province: CN111884521B, 2021-07-30) proposed a A boost converter that only needs to use two reverse blocking switch tubes and two IGBTs to form a hybrid full bridge to realize zero-current switching of all main switch tubes, which can effectively improve efficiency while reducing costs, but the patent uses fixed frequency control , it is practically impossible to achieve zero-current turn-on and turn-off of all semiconductor devices under light load

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