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Primary feedback closed-loop control circuit of isolation type flyback converters

A technology of closed-loop control circuit and flyback converter, which is applied in the direction of control/regulation system, conversion of DC power input to DC power output, instruments, etc. It can solve the problems of many peripheral devices, optocoupler CTR attenuation, and large circuit volume. To achieve the effect of simplifying the peripheral circuit and reducing the volume

Active Publication Date: 2011-07-20
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a primary-side feedback closed-loop control circuit for isolated flyback converters to overcome the existing isolated flyback converters that have optocoupler CTR attenuation, large circuit volume, and many peripheral devices. question

Method used

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  • Primary feedback closed-loop control circuit of isolation type flyback converters
  • Primary feedback closed-loop control circuit of isolation type flyback converters
  • Primary feedback closed-loop control circuit of isolation type flyback converters

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Embodiment Construction

[0011] The present invention will be further described below with reference to the drawings and embodiments.

[0012] Reference figure 1 , The primary side feedback closed-loop control circuit of the isolated flyback converter, the flyback converter includes a transformer T1, an absorption circuit F5 connected in parallel with the primary side of the transformer, a switch tube S1 connected to the primary side of the transformer and a secondary side of the transformer Diode D1, the primary feedback closed-loop control circuit includes sample-and-hold circuit F1, arithmetic circuit F3, current compensation circuit F2, and PWM control and drive circuit F4. The closed-loop feedback control point is the connection point between the transformer T1 primary coil and the drain of the switch S1 , The input end of the sample and hold circuit F1 is connected to the drain of the switch S1, the output end of the sample and hold circuit F1 is connected to the positive input end of the arithmetic...

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Abstract

The invention discloses a primary feedback closed-loop control circuit of isolation type flyback converters, wherein the flyback converter comprises a transformer, an absorber circuit connected with the primary side of the transformer in parallel, a switching tube connected with the primary side of the transformer and a diode connected with the secondary side of the transformer, and the primary feedback closed-loop control circuit comprises a sample hold circuit, an arithmetic circuit, a current compensation circuit and a PWM control and driving circuit. The switching tube is finally controlled by the PWM control and driving circuit by using the drain voltage when the sample switching tube of the sample hold circuit is disconnected and using the arithmetic circuit to successively subtractvoltage component and current compensating voltage. Optical coupling and auxiliary winding are not used in the invention, thereby simplifying the transformer without the problem of optical coupling CTR attenuation, and being capable of simplifying peripheral circuit by integrating the control circuit into main control chip.

Description

Technical field [0001] The invention relates to a primary side feedback closed loop control circuit of an isolated flyback converter. It belongs to the field of power electronics technology. Background technique [0002] At present, the feedback circuit of most isolated flyback converters is composed of optocoupler and voltage reference, or is composed of auxiliary winding and sampling filter circuit. The former takes the output voltage, divides it and compares it with the voltage reference, so that the voltage reference cathode potential changes, thereby changing the current flowing through the optocoupler diode, thereby changing the optocoupler transistor current, and finally changing the error voltage of the error amplifier. This kind of circuit has a good voltage stabilization effect, but the current transfer ratio (CTR) of the optocoupler will decay over time and high temperature, making the circuit unstable, and there are many peripheral components and inconvenient to use ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M3/335
Inventor 何湘宁肖建国吴建德李武华
Owner ZHEJIANG UNIV