Direct-current boost converter and control method thereof

Abstract

The invention belongs to the technical field of direct-current converters, particularly relates to a direct-current boost converter and a control method thereof, and aims to solve the problems of highloss and narrow working range of a traditional direct-current boost converter. The direct-current boost converter comprises an input power supply interface, a coupling inductor unit, a half-bridge unit, a bus support capacitor, a pre-charging diode, an isolation transformer, a rectifying and filtering circuit and a power supply output interface, wherein the input power supply interface can be used for inputting wide-voltage-range power supplies such as photovoltaic or fuel cells; the coupling inductor unit comprises an A-phase coupling inductor and a B-phase coupling inductor; the half-bridgeunit comprises a first bridge arm and a second bridge arm; and the rectifying and filtering circuit comprises diodes D1-D4 and a capacitor Co. The two primary side boost circuits are connected in parallel to complement and share power loss, the current ripple frequency is twice of the switching frequency of the main switching tube, a transformer with a simple structure can be adopted to provide ahigh step-up ratio, the switching stress of the converter can be reduced through resonant soft switching, and the performance of the converter is improved.

Description

technical field [0001] The invention belongs to the technical field of DC converters, and in particular relates to a DC boost converter and a control method thereof. Background technique [0002] Photovoltaic grid-connected power generation is one of the important ways to utilize solar energy. With the development of high-power power electronic semiconductor devices, the cost of DC transmission is gradually reduced, and flexible DC transmission technology has been developed rapidly. Due to the multi-terminal flexible DC system The characteristics of flexibility, reliability and economy are more suitable for distributed power generation and power market, and become an important utilization form of photovoltaic power generation in the future. [0003] Photovoltaic cells have the characteristics of soft output characteristics, low voltage levels, and large voltage fluctuation ranges. Therefore, they need to be boosted into stable DC high voltages after DC / DC power conversion wi...

AI Technical Summary

Problems solved by technology

The traditional isolated full-bridge Boost converter has the advantages of high step-up ratio and wide input range, but it needs to be equipped with an active clamp circuit that requires high control timing to absorb the energy of the transformer leakage inductance. In high-power applications, The leakage inductance of the transformer and the parasitic inductance of the clamping circuit will increase the voltage stress of the switching tube in the circuit, and this topology has problems such as complicated start-up process

The double-inductor half-bridge isolated Boost converter uses two half-bridge boost converters interleaved in parallel, which reduces the current stress of the switch tube and reduces the input current ripple, but it works in a hard switching state, and the voltage stress of the main switch tube is relatively high. High, and large switching losses limit the efficiency of the converter, not suitable for high-power applications

The Boost push-pull forward converter combines the Boost push-pull structure with the forward topology, which has the advantages of fewer components, high core utilization and good voltage output characteristics. However, the voltage stress of the switch tube is 2 times that of the full-bridge circuit. times, it is not suitable for applications with high input voltage, and the problem of DC bias will cause excessive excitation current of high-frequency transformer or even damage the switch tube

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