Flyback converter and its control method

A technology of flyback converter and controller, which is applied in the direction of control/regulation system, conversion equipment with intermediate conversion to AC, DC power input conversion to DC power output, etc., which can solve the problem of increasing system cost and size, flyback conversion To reduce the cost and size, optimize the circuit structure, and expand the application range

Active Publication Date: 2022-07-19
JOULWATT TECH INC LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the isolation device 6 and the auxiliary circuit structure set in the flyback converter increase the cost and size of the system, which limits the application of the flyback converter

Method used

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  • Flyback converter and its control method
  • Flyback converter and its control method
  • Flyback converter and its control method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0111] In this embodiment, the flyback converter works in the DCM mode, and the timing waveforms of some control signals in the flyback converter in the DCM mode are as follows image 3 shown.

[0112] In this embodiment, the timing signal generated by the control signal generating unit 43 can control the synchronous rectifier SR to turn on twice in one switching cycle (the first turn-on corresponds to the time period t12-t13, and the second turn-on corresponds to the time period t14-t15 ), at the same time, after the control synchronous rectifier SR is turned on for the first time, compared with the normal control sequence, the synchronous rectifier SR will be turned off earlier.

[0113] In this embodiment, the target time parameter corresponds to the interval time Toff between the first turn-off of the synchronous rectifier SR to the second turn-on, that is, the time period t13 to t14 . Therefore, in this embodiment, the first functional relationship stored separately in t...

Embodiment 2

[0125] In this embodiment, the flyback converter works in the BCM mode, and the timing waveforms of some control signals in the flyback converter in the BCM mode are as follows: Figure 4 shown.

[0126] In this embodiment, the timing signal generated by the control signal generating unit 43 can control the synchronous rectifier SR to be turned off with a delay in one switching cycle.

[0127] In this embodiment, the synchronous rectifier controller 4 controls the body diode of the synchronous rectifier SR to conduct in the interval after the power switch SW is turned off to before the synchronous rectifier SR is turned on in each cycle. And the target time parameter corresponds to the conduction time td of the body diode of the synchronous rectifier SR, that is, the time period t22-t23. Therefore, in this embodiment, the first functional relationship stored separately in the second computing unit 42, or the first functional relationship stored in both the first computing uni...

Embodiment 3

[0140] In this embodiment, the flyback converter works in the BCM mode, and the timing waveforms of some control signals in the flyback converter in the BCM mode are as follows: Figure 5 shown.

[0141] In this embodiment, the timing signal generated by the control signal generating unit 43 can control the synchronous rectifier SR to turn on twice in one switching cycle (the first turn-on corresponds to the time period t32-t33, and the second turn-on corresponds to the time period t34-t35 ), at the same time, the interval between the two turn-ons of the control synchronous rectifier SR (corresponding to the time period t33-t34) is less than the preset threshold, which can be equivalent to the normal control sequence of the synchronous rectifier SR. is turned off once during the turn-on period.

[0142] In this embodiment, the target time parameter corresponds to the first turn-on time T1 (corresponding to the time period t32-t33) or the second turn-on time T2 (corresponding ...

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Abstract

The invention discloses a flyback converter and a control method thereof. The flyback converter comprises: a transformer, a power switch tube, a synchronous rectifier tube, a primary side controller, and a synchronous rectifier controller, wherein the synchronous rectifier controller is used for according to The output voltage of the flyback converter obtains the error compensation signal, and provides the control sequence of the synchronous rectifier tube based on the error compensation signal and the first functional relationship; the primary side controller is used to sample the drain voltage of the power switch tube to obtain the corresponding target time parameter, and obtain the peak value of the inductor current based on the target time parameter and the second functional relationship, and the primary side controller controls the power switch tube of the primary side to turn off according to the peak value of the inductor current. The signal transmission between the primary and secondary sides is carried out through the transformer in the flyback converter topology, so that the on / off control of the primary side power switch tube and the secondary side synchronous rectifier tube can be realized without isolation devices, and the circuit structure is optimized. .

Description

technical field [0001] The invention relates to the technical field of power converters, in particular to a flyback converter and a control method thereof. Background technique [0002] A flyback converter is an isolated power converter commonly used for galvanically isolated AC-to-DC and DC-to-DC conversion between an input and one or more outputs. More precisely, a flyback converter is a buck / boost converter with inductive splitting, forming a transformer that multiplies the voltage ratio with the added advantage of isolation. In conventional flyback converters, synchronous rectifiers are usually used instead of diode rectifiers to improve efficiency. [0003] The typical structure of a flyback converter consists of a primary power switch coupled to the primary (or primary) transformer winding of the transformer, and a synchronous rectifier coupled to the secondary (or secondary) transformer winding of the transformer. The input voltage is provided through the primary wi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M3/335H02M3/28H02M1/08
CPCH02M3/33592H02M3/28H02M1/083Y02B70/10
Inventor 黄必亮
Owner JOULWATT TECH INC LTD
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