Driving circuit and driving method applied to flyback-type converter and quasi-resonant soft-switching flyback-type converter applying same

Abstract

The invention provides a driving circuit and a driving method applied to a flyback-type converter and a quasi-resonant soft-switching flyback-type converter applying the same. According to a driving circuit applied to the flyback-type converter, differential coefficient of the drain-source voltage of a main power switch tube in the flyback-type converter is worked out by a differential circuit, thus leading the time when the drain-source voltage achieves valley floor to correspond to the time when the differential voltage passes the zero point in positive direction. A valley floor voltage detecting circuit is connected with the differential circuit and receives a differential voltage signal; when the drain-source voltage of the main power switch tube achieves the valley floor, a valley floor control signal is output, thus controlling the driving circuit to drive the main power switch tube, and further exactly realizing the aim of conducting the valley floor of the main power switch tube. By adopting the driving circuit, the aim of controlling a quasi-resonant soft switch of the main power switch tube is realized precisely, the driving circuit of the flyback-type converter is optimized so that the controlling effect and the reliability are greatly improved, and the realizing cost is reduced.

Description

technical field [0001] The invention relates to a driving circuit, in particular to a driving circuit and a driving method in a flyback converter, and a quasi-resonant soft-switching flyback converter using the same. Background technique [0002] The high frequency of the switch is an important direction for the development of modern switching power supplies. The reason is that the high frequency of the switch can greatly reduce the volume and weight of the switching converter, thereby increasing the power density of the converter. At the same time, increasing the switching frequency can also reduce the Audio noise from switching power supplies, improving dynamic response. To achieve high frequency, switching loss must be reduced, and soft switching technology is one of the important methods to reduce switching loss. Through the principle of resonance, the voltage or current of the switching tube in the switching converter changes according to the sinusoidal or quasi-sinuso...

AI Technical Summary

Problems solved by technology

It can be seen that with this implementation method, although the quasi-resonant soft switching control of the main power switch can be realized, the circuit design is relatively complicated and the implementation cost is also high

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