Flyback converter and control method of flyback converter

A flyback converter and control method technology, applied in control/regulation systems, DC power input conversion to DC power output, instruments, etc., can solve the problem of low utilization rate of magnetic core, small negative excitation current, lower overall efficiency, etc. problem, to achieve the effect of reducing EMI interference, reducing the volume of the magnetic core, and increasing the utilization rate

Active Publication Date: 2015-01-21
MORNSUN GUANGZHOU SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This patented technology improves upon existing technologies by ensuring that it works well even at low loads or when there are heavy usage periods (lightly loaded). It also reduces electromagnetic Interference while still providing efficient operation for both normal mode and standby modes. Additionally, this design allows for higher-frequency inductors without increasing their sizes significantly.

Problems solved by technology

This technical problem addressed in this patented describes how to improve the design of a conventional flying type (FSC) pulse width modulated (PWM)-active clam loop clutch controllers without increasing their sizes due to increased quiescent period and impedances during regulation cycles.

Method used

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  • Flyback converter and control method of flyback converter
  • Flyback converter and control method of flyback converter
  • Flyback converter and control method of flyback converter

Examples

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Embodiment 1

[0043] A control method of a flyback converter of the present invention comprises the following steps,

[0044] Judging whether the converter is working in a small load state,

[0045] If so, control the clamping module to enter a non-complementary working mode. The non-complementary working mode is to send a narrow pulse control signal before the main switch is turned on and before the nanosecond-level dead time is left, and the rising edge of the narrow pulse Drive the conduction of the clamp switch tube, and control the turn-off of the clamp switch tube by the falling edge of the narrow pulse; after the clamp switch tube is turned off and there is a nanosecond dead time, control the main switch tube to turn on ;

[0046] If not, control the clamping module to enter the complementary working mode, the complementary working mode is to generate a wide pulse driving signal that is complementary to the main switching tube and has a nanosecond dead time, so as to be driven by th...

Embodiment 2

[0062] Figure 7 Shown is the circuit schematic diagram of the detection control circuit of the flyback converter in the second embodiment of the present invention, the detection feedback voltage VFB, the feedback voltage VFB changes with the load, the greater the load, the higher the voltage, at different VFB voltages Next, the voltage-controlled constant current source generates a changing current to charge the capacitor and generates a changing driving pulse width signal to output to the clamping switch tube. When the clamping switch tube is turned off, it outputs a driving signal to the main switch tube Sw. When entering The next cycle is repeated to realize that the conduction time of the clamp switch tube is different under different loads, and to realize that the source-clamp flyback converter operates in different operating modes under different loads.

[0063] Figure 7 Shown is the circuit schematic diagram of the detection control module of the flyback converter in...

Embodiment 3

[0066] Figure 8 Shown is the circuit schematic diagram of the detection control module of the flyback converter in the third embodiment of the present invention, the detection feedback voltage VFB, the feedback voltage VFB changes with the load, the greater the load, the higher the voltage, at different VFB voltages Next, the voltage-controlled constant current source generates a changing current to charge the capacitor and generates a changing driving pulse width signal to output to the clamping switch Sa. When the main switching tube Sw is turned off, a dead time is generated. When the main switching tube Sw is turned off And after the dead time is over, the clamp switch Sa is turned on, and the conduction time of the clamp switch Sa is adjusted by adjusting the dead time after the main switch Sw is turned off, so as to realize the active clamp flyback converter In different working modes under different loads.

[0067] Figure 8Shown is the circuit principle diagram of t...

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PUM

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Abstract

The invention provides a control method of a flyback converter. The control method is a control method in a mixed control mode; in other words, the flyback converter works in a non-complementation state under light loads, the clamp switch pipe on time is shortened through down conversion, and light load losses are effectively reduced through down conversion; flyback converter works in a fixed-frequency drive complementation state under heavy loads, and the clamp switch pipe on time is prolonged. Compared with the prior art, the control method has the advantages that the voltage stress of a main switch pipe and a clamp capacitor can be effectively reduced, the main switch pipe off losses can be reduced, the clamp circuit current change slope is decreased, the EMI interference is reduced, the secondary current change slope is decreased, and the longer detection reaction time is provided for synchronous rectification. Meanwhile, the working area of a magnetic core in the third quadrant is enlarged, the maximum flux density is reduced, and the size of the magnetic core is reduced.

Description

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Claims

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Application Information

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Owner MORNSUN GUANGZHOU SCI & TECH
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