Synchronous rectification BOOST converter, synchronous rectification control circuit and method

Abstract

The invention provides a synchronous rectification control circuit and method. The synchronous rectification control circuit comprises an output detection unit, an error amplifying unit, a logic control unit and a driving circuit unit; the output detection unit is connected between the output positive end of a main power unit and the first input end of the error amplifying unit; the output end ofthe error amplifying unit is connected with the first input end of the logic control unit; the first output end and the second output end of the logic control unit are connected with the first input end and the second input end of the driving circuit unit respectively; the first output end and the second output end of the driving circuit unit are connected with gates of switching tubes M1 and M2 respectively; the third output end of the driving circuit unit is connected with the drain of the switching tube M1 and the source of the switching tube M2 respectively; the synchronous rectification control circuit also comprises an input detection unit and a nonlinear modulation unit; the output end of the input detection unit is connected with the input end of the nonlinear modulation unit; andthe output end of the nonlinear modulation unit is connected with the second input end of the logic control unit.

Description

technical field [0001] The invention relates to the field of switching converters, in particular to a synchronous rectification control circuit and method for a synchronous rectification BOOST converter. Background technique [0002] With the rapid development of the field of power electronics, the application of switching converters is becoming more and more extensive, especially people put forward more requirements for switching converters with high power density, high reliability and small size, and the switches in the converter Loss is usually the main factor limiting the frequency increase and volume reduction of converters, so soft switching technology has attracted more and more attention from the industry. [0003] At present, synchronous rectification BOOST circuit is usually used in the boost converter to meet the soft switching characteristics, and its schematic diagram is as follows figure 1 shown. If the synchronous rectification switching tube M2 is turned o...

AI Technical Summary

Problems solved by technology

When the input voltage is wide, the monotonous increase or decrease of the frequency will cause the reverse current I of the inductor when the switch tube M2 is turned off within the entire input voltage range. l_min There are large fluctuations

Monotonically increasing frequency will cause reverse current I at high input voltage l_min The amplitude is too low, it is difficult to realize the ZVS characteristic, and the efficiency is low; the monotonous decrease of the frequency will cause the reverse current I when the input voltage is low l_min The amplitude is too high, the effective value of the current is large, and the efficiency is low

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