Isolation type direct-current buck converter with soft switching function and control method of isolation type direct-current buck converter

Abstract

The invention discloses an isolation type direct-current buck converter with the soft switching function and a control method of the isolation type direct-current buck converter, and belongs to the technical field of power electronic converters. The converter is composed of an input source (Uin), a first input filter capacitor (Cin1), a second input filter capacitor (Cin2), a first switching tube (S1), a second switching tube (S2), a third switching tube (S3), a fourth switching tube (S4), an inductor (Lf), a transformer (T), a first diode (D1), a second diode (D2), an output filter capacitor (C0) and a load (R0). The first switching tube (S1) and the second switching tube (S2) alternatively work, the first switching tube (S1) and the third switching tube (S3) work in a complementary mode, the second switching tube (S2) and the fourth switching tube (S4) work in a complementary mode, and therefore output voltage control is achieved. The isolation type direct-current buck converter with the soft switching function has the advantages that the voltage stress of the switching devices is small, and soft switching of all the switching tubes can be achieved within the whole load range; high-frequency efficient power switching can be achieved, the inductance and the size of the transformer can be effectively reduced, high power density can be achieved, and the isolation type direct-current buck converter with the soft switching function is easy to control, high in reliability and easy to achieve.

Description

Technical field [0001] The invention relates to an isolated soft-switching step-down DC converter and a control method thereof, and belongs to the technical field of power electronic converters. Background technique [0002] Isolated DC buck converters are suitable for occasions where electrical isolation of input and output is required and the output voltage is lower than the input voltage. This type of converter has a wide range of applications in various fields such as communication power supplies, server power supplies, and aerospace. [0003] Traditional isolated DC converters, such as forward converters, push-pull converters, half-bridge converters, full-bridge converters, etc., are all step-down DC converters. In applications where the output voltage is much lower than the input voltage, the half-bridge converter is most widely used. However, the traditional isolated buck DC converter represented by the half-bridge converter has the following problems: the voltage stress of...

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Problems solved by technology

However, the traditional isolated step-down DC converter represented by the half-bridge converter has the following problems: the voltage stress of the rectifier diode on the secondary side of the converter is high; the leakage inductance of the transformer is large and the leakage inductance energy cannot be effectively used, causing switching devices Voltage spikes and oscillations further aggravate the stress on switching devices, reducing reliability and efficiency

In addition, traditional DC converters usually cannot achieve soft switching of the switching tube, which limits the efficiency of the converter.

In recent years, the LLC resonant converter has gained wide attention and application due to its excellent soft switching, low voltage stress and other advantages. However, the LLC resonant converter needs to adopt frequency conversion control, and the design, implementation and control of the converter are more complicated than traditional converters. many

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