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A self-driving drive circuit for a dual-transistor forward synchronous rectification circuit

A technology of synchronous rectification and drive circuit, which is applied in the direction of high-efficiency power electronic conversion, electrical components, output power conversion devices, etc., can solve the problems of reducing the efficiency of the converter, unable to provide driving voltage for the freewheeling tube, etc., to improve reliability Sexuality, easy implementation and practicality, effect of size reduction

Active Publication Date: 2020-01-21
MORNSUN GUANGZHOU SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The self-excitation driving method generally uses the voltage of the secondary winding of the transformer to directly or indirectly drive the synchronous rectifier. This driving method is relatively low in cost, but in some converters, the synchronous It provides a path for the output inductor current and transformer excitation current. At this time, the secondary winding of the transformer is equivalent to a short circuit, and the voltage of the drive winding is zero, which cannot provide a drive voltage for the freewheel tube. At this time, the output inductor current will pass through the body diode of the freewheel tube. for circulation, greatly reducing the efficiency of the converter

Method used

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  • A self-driving drive circuit for a dual-transistor forward synchronous rectification circuit
  • A self-driving drive circuit for a dual-transistor forward synchronous rectification circuit
  • A self-driving drive circuit for a dual-transistor forward synchronous rectification circuit

Examples

Experimental program
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Effect test

no. 1 example

[0028] figure 1 The circuit schematic diagram of the first embodiment is shown, following the connection relationship of the above-mentioned initial technical scheme, a self-driving drive circuit of a dual-tube forward synchronous rectification circuit, the dual-tube forward synchronous rectification circuit includes a transformer, and The double-transistor forward network on one side and the synchronous rectification transformation network on the secondary side of the transformer; the transformer includes the first primary winding Np1, the first secondary winding Ns1 and the second secondary winding Ns2, and the synchronous rectification transformation network on the secondary side of the transformer includes The first secondary winding Ns1, the freewheeling tube Q1 whose drain is connected to the same-named end of the first secondary winding Ns1, the inductor L1 connected to the drain of the freewheeling tube Q1 at one end, and the other end of the inductor L1 is the output o...

no. 2 example

[0037] figure 2 shows the schematic diagram of the circuit of the second embodiment, and the difference from the first embodiment is that in the first embodiment figure 1 On the basis of , a diode D2 is connected between the gate of the first P-type MOS transistor and the opposite terminal of the second secondary winding Ns2 of the transformer, which can accelerate the discharge of the gate-source voltage of the first P-type MOS transistor Q3, so that The first P-type MOS transistor Q3 is quickly turned on, so that the freewheeling transistor Q1 is quickly turned off. At the same time, a series circuit composed of a resistor R5 and a diode D3 is connected in parallel at both ends of the third resistor R3. The cathode of the diode D3 is connected between the opposite end of the second secondary winding Ns2 and the resistor R3, and the anode of the diode D3 is connected after the resistor R5. Connected between the resistor R3 and the first capacitor C1. In this way, the disch...

no. 3 example

[0039] image 3 shows the schematic diagram of the circuit of the third embodiment, the difference from the second embodiment is that in the second embodiment figure 2 On the basis of , the voltage regulator tube ZD1 is connected in parallel at both ends of the first capacitor C1, the anode of the voltage regulator tube ZD1 is connected to the gate connection point of the first capacitor C1 and the freewheeling tube Q1, and the cathode of the voltage regulator tube ZD1 is connected to the first capacitor C1 and the resistor The connection point of R3 and resistor R5, the presence of Zener tube ZD1 can control the maximum bias voltage at both ends of the first capacitor C1, preventing the bias voltage at both ends of the first capacitor C1 from being too high and causing the gate-source voltage of the freewheeling tube Q1 to be too low As a result, the freewheeling tube cannot be turned on normally.

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Abstract

The invention discloses a self-driving drive circuit of a double-tube forward synchronous rectification circuit. The double-tube forward synchronous rectification circuit includes a transformer, a double-tube forward network on the primary side of the transformer, and a synchronous rectification transformation network on the secondary side of the transformer. The transformer includes the first primary winding, the first secondary winding and the second secondary winding; the self-driving drive circuit of the double-tube forward synchronous rectification circuit is used to drive the freewheeling tube in the synchronous rectification transformation network, by controlling the self-driving Drive the working state of the first P-type MOS tube in the driving circuit to drive the rectifier tube in the synchronous rectification conversion network. The driving voltage provides a path for the output inductor of the subsequent stage, which can improve the efficiency of the converter. At the same time, the driving voltage of the freewheeling tube can be adjusted to make the control more flexible and reliable.

Description

technical field [0001] The invention relates to an AC-DC converter, in particular to a self-driving drive circuit for a double-transistor forward, single-transistor forward, full-bridge and other transformers whose winding voltage is zero. Background technique [0002] With the continuous development of society, switching converter technology is also developing towards low cost, miniaturization, high power density and high reliability. Under such a trend, synchronous rectification technology is particularly important. The power MOSFET with extremely low on-resistance is used to replace the rectifier diode to reduce rectification loss, which can greatly improve the efficiency of the converter and there is no dead zone voltage caused by the Schottky barrier voltage. [0003] In the isolated switching converter, there are two modes of synchronous rectification: self-excitation drive and external drive. The external drive generally has an additional drive chip to detect the volt...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M1/088H02M7/217
CPCH02M1/088H02M7/217H02M1/0058Y02B70/10
Inventor 杨志潘成章程志勇
Owner MORNSUN GUANGZHOU SCI & TECH
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