Synchronous rectification circuit of reverse excitation circuit provided with adjustable dead time

Abstract

The invention discloses a synchronous rectification circuit of a reverse excitation circuit provided with adjustable dead time, which comprises a main switching tube time delay driving circuit and a secondary side synchronous rectification driving circuit; wherein, the main switching tube Q1 time delay driving circuit comprises resistances R5, R6 and R7, a capacitance C3, PNP triode VT2 and N channel MOS tube Q3; a gate drive circuit of a secondary side synchronous rectifying tube Q2 comprises a capacitance C2, resistances R2, R3 and R4, diodes D1 and D2 and PNP triode VT1; a driving transformer Tr1 can realize the isolation and transmission of a primary side PWM driving signal. The invention utilizes a simple and discrete component circuit to realize the modulation of the dead time for opening and closing the main switching tube Q1 and the synchronous rectifying tube Q2, so as to avoid the compatible phenomenon; meanwhile, the invention can ensure the slope coefficients of rising edge and falling edge of the driving signal not to be affected, so as to reduce the switching loss. The synchronous rectification circuit has the advantages of simple circuit, high transfer efficiency, strong universality and high reliability.

Description

A Synchronous Rectification Circuit of Flyback Circuit with Adjustable Dead Time technical field The invention relates to a synchronous rectification circuit of a flyback circuit, in particular to a synchronous rectification circuit of a flyback circuit whose dead time can be adjusted. Background technique The flyback converter circuit is widely used in low-power isolated power supplies because of its simple circuit structure, fewer components, and low cost. At present, the power supply used in the communication field is more and more widely used to output low voltage and high current. If the traditional diode rectification is still used, the loss on the rectifier diode will be very large. To maintain the high efficiency of power conversion, mainly use Secondary side synchronous rectification technology. The key to the synchronous rectification technology is the driving mode. At present, there are generally two ways: self-driving or other driving. Although the structure...

AI Technical Summary

Problems solved by technology

In view of this, the present invention is to provide a synchronous rectification circuit of a flyback circuit with an adjustable dead time, so as to solve the problems of large switching loss and complex structure of the driving circuit for adjusting the dead time.

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