CN1889658A - Compensation loop for eliminating switch frequency change to generate electromagnetic interference phenomenon - Google Patents
Compensation loop for eliminating switch frequency change to generate electromagnetic interference phenomenon Download PDFInfo
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- CN1889658A CN1889658A CN 200610040783 CN200610040783A CN1889658A CN 1889658 A CN1889658 A CN 1889658A CN 200610040783 CN200610040783 CN 200610040783 CN 200610040783 A CN200610040783 A CN 200610040783A CN 1889658 A CN1889658 A CN 1889658A
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- sine wave
- filter cell
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Abstract
A compensating loop for eliminating electromagnetic interference phenomenon caused by switch frequency variation is prepared as transmitting power supply AC input signal to power supply conversion unit via input rectification-filter unit, inputting compensation sine wave to current control unit by input rectification-filter unit, providing compensated waveform to power supply conversion unit by current control unit, outputting required signal by power supply conversion unit through transformer and output rectification-filter unit after waveform signal is received power supply conversion unit.
Description
One, technical field
The present invention relates to the employed circuit of mains switch in a kind of display equipment, specifically a kind of switching frequency of eliminating changes and the compensation circuit of generation electromagnetic interference phenomenon.
Two, background technology
The employed circuit of mains switch comprises input rectifying and filter cell 11, power conversion unit 12, current control unit 13, accessory power supply 14, transformer unit 15 and output rectification and filter cell 16 in the existing display equipment, sees Fig. 1.During work, the power supply direct-flow input signal passes to power conversion unit 12 via input rectifying and filter cell 11; Simultaneously, current control unit 13 provides waveform shown in Fig. 2 a or Fig. 2 b by accessory power supply 14 power supply and to power conversion unit 12.By transformer unit 15 and output rectification and the required waveform signal of filter cell 16 outputs, the waveform of output is shown in Fig. 2 c or Fig. 2 d behind the waveform that power conversion unit 12 received current control units 13 provide.
The detailed circuit diagram of current control unit 13 is seen shown in 3 in the prior art, and wherein, the oscillator mode is that inside is furnished with R
T/ C
TTrigger the trigger oscillator, oscillator frequency is by element R
TAnd C
TDecision, promptly switching frequency is only by R
T/ C
TValue decide.
Capacitor C
TOn voltage by the input 5.0V voltage pass through resistor R
TAfter charge to 2.8V, by internal consumption current discharge 0.2V.
Capacitor C
TInterdischarge interval, oscillator produces the internal consumption pulse for the normal input of high-end trim of keeping not gate NOR Gate.This produces the output stuck phenomenon when making output be in low-end trim.
C
TAnd R
Tselectedly decide by oscillator frequency and output wave cycle.
Charging and discharge time are by following formula decision:
1/T＝f＝1.8/R
T·C
T
The mains switch that uses on the existing display equipment produces the electromagnetic interference phenomenon owing to switching frequency changes when opening or closing, thereby the generation switch noise also further causes the conductive switch noise on the whole loop.
Three, summary of the invention
The purpose of this invention is to provide a kind of switching frequency of eliminating changes and the compensation circuit of generation electromagnetic interference phenomenon, this compensation circuit can decay the switch noise that produces on the mains switch that uses on the display equipment and by and conductive switch noise on the whole loop that causes promptly compensates the frequency of initial switch device and the conduction noise of decaying.
The objective of the invention is to be achieved through the following technical solutions:
A kind of switching frequency of eliminating changes and the compensation circuit of generation electromagnetic interference phenomenon, comprise input rectifying and filter cell 1, power conversion unit 2, current control unit 3, transformer unit 5 and output rectification and filter cell 6, it is characterized in that: the power supply direct-flow input signal passes to power conversion unit 2 via input rectifying and filter cell 1; Input rectifying is connected with current control unit 3 with filter cell 1 and to current control unit 3 input offset sine waves; Export required signal by transformer unit 5 and output rectification and filter cell 6 behind the compensation sine wave signal that power conversion unit 2 received current control units 3 provide; This compensation is sinusoidal wave to be disperseed the output frequency noise and makes conductive switch sound attenuation on the whole loop.
Among the present invention, described compensation sine wave is 1/2 sine wave, and it changes R in the current control unit 3
T/ C
TGradient make the sine wave of output change frequency.
Formation of the present invention and operation principle are as follows, see Fig. 3:
In current control unit, because R
T/ C
TThe electric current of supplying with is certain, so R
T/ C
TThe frequency that produces is certain.In the present invention, after the DC power supply input, via input rectifying and filter cell to R
T/ C
TInput offset 1/2 sine wave, thus R changed
T/ C
TThe gradient of output waveform makes output driver be changed frequency by the electric current of sine wave.The waveform of input offset 1/2 sine wave is shown in Fig. 4 a; Output waveform after the change frequency is shown in Fig. 4 b.The present invention produces the 2nd outer frequency characteristic of normal working frequency by to current control unit input offset sine wave, makes the output driver frequency dispersion, promptly eliminates switching frequency and changes and generation electromagnetic interference phenomenon.
Four, description of drawings
Fig. 1 is the employed circuit diagram of mains switch in the existing display equipment;
Fig. 2 a, Fig. 2 b are the waveform schematic diagrames that current control unit provides to power conversion unit among Fig. 1;
Fig. 2 c, Fig. 2 d are the waveform schematic diagrames of exporting among Fig. 1;
Fig. 3 is a circuit diagram of the present invention;
Fig. 4 a is the oscillogram of input offset sine wave of the present invention;
Fig. 4 b is the output waveform figure after the change frequency among the present invention.
Five, embodiment
A kind of elimination switching frequency of the present invention changes and the compensation circuit of generation electromagnetic interference phenomenon, comprises input rectifying and filter cell 1, power conversion unit 2, current control unit 3, transformer unit 5 and output rectification and filter cell 6.The power supply direct-flow input signal passes to power conversion unit 2 via input rectifying and filter cell 1; Input rectifying is connected with current control unit 3 with filter cell 1 and to current control unit 3 input offset sine waves.The waveform signal of current control unit 3 after power conversion unit 2 affords redress; Export required signal by transformer unit 5 and output rectification and filter cell 6 behind the waveform signal after the compensation that power conversion unit 2 received current control units 3 provide.The compensation sine wave is 1/2 sine wave,
R in this 1/2 sinusoidal wave change current control unit 3
T/ C
TGradient make the sine wave of output change frequency.
During work, after the DC power supply input, the R in current control unit 3 via input rectifying and filter cell 1
T/ C
TInput offset 1/2 sine wave, thus R changed
T/ C
TThe gradient of output waveform makes output driver be changed frequency by the electric current of sine wave.The waveform of input offset 1/2 sine wave is shown in Fig. 4 a; Output waveform after the change frequency is shown in Fig. 4 b.The present invention passes through to R
T/ C
TThe input offset sine wave produces the 2nd outer frequency characteristic of normal working frequency, makes the output driver frequency dispersion, promptly eliminates switching frequency and changes and generation electromagnetic interference phenomenon.Thereby eliminate switch noise and further cause conductive switch noise on the whole loop by it.
The present invention not only is applicable in the display equipment in the employed circuit of mains switch, and other is changed by switching frequency and produces in the circuit of electromagnetic interference phenomenon and be suitable for too.Therefore, above-mentioned execution mode is an illustrative, and does not have limited.Those skilled in the art in the invention are under the prerequisite that does not change technical solution of the present invention, and how other implements and can go operation according to the understanding of oneself concrete form.The present invention and all be included within the scope of the present invention by all changes or form that close notion draws.
Claims (2)
1, a kind of switching frequency of eliminating changes and the compensation circuit of generation electromagnetic interference phenomenon, comprise input rectifying and filter cell (1), power conversion unit (2), current control unit (3), transformer unit (5) and output rectification and filter cell (6), it is characterized in that: the power supply direct-flow input signal passes to power conversion unit (2) via input rectifying and filter cell (1); Input rectifying is connected with current control unit (3) with filter cell (1) and to current control unit (3) input offset sine wave; Pass through transformer unit (5) and output rectification and the required signal of filter cell (6) output behind the compensation sine wave signal that power conversion unit (2) received current control unit (3) provides; This compensation is sinusoidal wave to be disperseed the output frequency noise and makes conductive switch sound attenuation on the whole loop.
2, elimination switching frequency according to claim 1 changes and the compensation circuit of generation electromagnetic interference phenomenon, it is characterized in that: described compensation sine wave is 1/2 sine wave and changes R in the current control unit 3
T/ C
TGradient make the sine wave of output change frequency.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100407831A CN100405833C (en) | 2006-06-01 | 2006-06-01 | Compensation loop for eliminating switch frequency change to generate electromagnetic interference phenomenon |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2006100407831A CN100405833C (en) | 2006-06-01 | 2006-06-01 | Compensation loop for eliminating switch frequency change to generate electromagnetic interference phenomenon |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1889658A true CN1889658A (en) | 2007-01-03 |
| CN100405833C CN100405833C (en) | 2008-07-23 |
Family
ID=37578916
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2006100407831A Expired - Fee Related CN100405833C (en) | 2006-06-01 | 2006-06-01 | Compensation loop for eliminating switch frequency change to generate electromagnetic interference phenomenon |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100405833C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103151915A (en) * | 2013-02-20 | 2013-06-12 | 合肥京东方光电科技有限公司 | Direct current (DC)/DC convertor, voltage modulating method and display device |
| CN113054850A (en) * | 2021-03-30 | 2021-06-29 | 上海喜坤电子科技有限公司 | Switch control circuit based on current transformer |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2565217B2 (en) * | 1995-01-30 | 1996-12-18 | ソニー株式会社 | Switching power supply |
| JPH09182423A (en) * | 1995-12-25 | 1997-07-11 | Matsushita Electric Works Ltd | Switching power supply circuit |
| CN2662529Y (en) * | 2003-08-26 | 2004-12-08 | 中国科学院电工研究所 | A positively exciting constant current source |
| WO2005076448A1 (en) * | 2004-02-03 | 2005-08-18 | Murata Manufacturing Co., Ltd. | Switching power supply device |
-
2006
- 2006-06-01 CN CNB2006100407831A patent/CN100405833C/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103151915A (en) * | 2013-02-20 | 2013-06-12 | 合肥京东方光电科技有限公司 | Direct current (DC)/DC convertor, voltage modulating method and display device |
| CN113054850A (en) * | 2021-03-30 | 2021-06-29 | 上海喜坤电子科技有限公司 | Switch control circuit based on current transformer |
Also Published As
| Publication number | Publication date |
|---|---|
| CN100405833C (en) | 2008-07-23 |
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Granted publication date: 20080723 |