CN201821259U - Leakage inductance damping circuit of flyback transformer - Google Patents
Leakage inductance damping circuit of flyback transformer Download PDFInfo
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- CN201821259U CN201821259U CN2010205468551U CN201020546855U CN201821259U CN 201821259 U CN201821259 U CN 201821259U CN 2010205468551 U CN2010205468551 U CN 2010205468551U CN 201020546855 U CN201020546855 U CN 201020546855U CN 201821259 U CN201821259 U CN 201821259U
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Abstract
The utility model relates to a clamping damping circuit of a flyback transformer, which comprises a clamping diode, a clamping capacitor, a bleeder resistor and a damping resistor. The clamping damping circuit is characterized in that one end of the clamping capacitor and one end of the bleeder resistor are connected between a rectifier filter circuit and a transformer leakage inductor of a flyback power source, the other end of the clamping capacitor and the other end of the bleeder resistor are connected with a negative end of the damping resistor and a negative end of the clamping diode, and a positive end of the clamping diode is connected with a drain of a control switch tube and a transformer input end of the flyback power source. The clamping damping circuit is capable of completely damping resonance generated by the flyback transformer leakage inductor and a switch tube drain capacitor so as to reduce common mode noise, thereby facilitating adoption of a cheaper common mode inductor and increasing product competiveness.
Description
Technical field
The utility model relates to a kind of leakage inductance antihunt circuit of Flyback transformer, is applicable to the power supply and the relevant consumer electronics product of Flyback structure.
Background technology
At present in the Flyback electric power loop of using on each consumer product, often adopt the RCD clamp circuit to absorb that the switching tube drain electrode is gone up because the spike that transformer leakage inductance and switching tube capacitance of drain generation resonance produce.
Though this RCD clamp circuit is simple, low cost, the energy that is stored in during the switching tube conducting in the transformer leakage inductance can not be absorbed fully at the switching tube blocking interval; And the energy that Disabled stays in the transformer leakage inductance is had no progeny and will be carried out resonance with the switching tube capacitance of drain in the clamp diode pass, and this high-frequency resonant will produce bigger common-mode noise.And, must increase common mode inductance sensibility reciprocal and Y capacitance this common-mode noise that decays in order to meet the electromagnetic compatibility standard requirement, cause cost to increase.
As shown in Figure 1, Fig. 1 is traditional RCD damping circuit schematic diagram, and as we know from the figure: when Q1 ended, D1 began conducting, and the energy of storing in the primary inductance charges to C_out by secondary diode D1; But the energy that is stored among the transformer leakage inductance Lk when the Q1 conducting can not be sent to secondary side when Q1 turn-offs.So when Q1 turn-offs, the energy of storing among the leakage inductance Lk will rise the Vds voltage of Q1 to the output capacitance Coss1 charging of Q1.
As Vds during greater than Vin+Vc, the Dc conducting, Lk charges to Cc, and the Vds of switching tube Q1 is by the Cc clamper; Flow through the electric current of clamp diode Dc
i DcDescend again after being climbed to maximum earlier;
When
i DcWhen dropping to zero, the voltage on the clamp capacitor Cc reaches maximum Vc_max;
Clamp diode enters the reverse recovery stage subsequently, because the junction capacitance stored charge effect of diode PN junction, clamp diode Dc keeps reverse-conducting, and simultaneously the voltage on the clamp capacitor Cc begins to descend, when the reverse current of the clamp diode Dc that flows through reaches maximum I
RMThe time, the stored charge of clamp diode PN junction is zero, begins to turn-off, the voltage on the clamp capacitor Cc is denoted as Vc_m at this moment;
The reverse current of clamp diode Dc flow through subsequently from I
RMBegin to descend, up to zero, and meanwhile, switching tube Q1 capacitance of drain Coss1 and transformer leakage inductance Lk resonance, the positive terminal voltage of clamp diode Dc descends, and produces turn-off power loss simultaneously.
Traditional RCD damping circuit, when clamp diode turn-offs, voltage Vc_m on the clamp capacitor Cc is mapped to elementary voltage n*Vo greater than the transformer output voltage, here, the turns ratio of transformer primary and secondary is n:1, so the transformer leakage inductance Lk energy that Disabled stays when clamp diode turn-offs is: 1/2* (Vc_m-n*Vo)
2/ Lk.And the energy that this Disabled stays among the leakage inductance Lk is had no progeny beginning resonance with switching tube capacitance of drain Coss1 in the clamp diode pass, produces strong common-mode noise.
Concrete test waveform as shown in Figure 2, wherein passage 1: the DS pole tension Vds1 of switching tube Q1; Passage 2: the electric current that flows through clamp diode Dc
i Dc
Summary of the invention
In view of the deficiency of above-mentioned technology, the purpose of this utility model provides a kind of leakage inductance antihunt circuit of Flyback transformer, and the resonance of damping Flyback transformer leakage inductance and switching tube capacitance of drain formation reduces common-mode noise fully.
Adopt following means to realize in the utility model one examples of implementation: a kind of clamper damping circuit of Flyback power circuit, comprise a clamp diode, a clamp capacitor, a bleeder resistance and a damping resistance, it is characterized in that: an end of described clamp capacitor and bleeder resistance is connected between the current rectifying and wave filtering circuit and transformer leakage inductance of Flyback power supply, the other end links to each other with the negative terminal of clamp diode through described damping resistance, and the anode of described clamp diode links to each other with the drain electrode of a control switch pipe and the transformer input of Flyback power supply.
Adopt following means to realize in another examples of implementation of the present utility model: a kind of clamper damping circuit of Flyback power circuit, comprise a clamp diode, one clamp capacitor, one bleeder resistance and a damping resistance, it is characterized in that: an end of described clamp capacitor and bleeder resistance is connected between the current rectifying and wave filtering circuit and transformer leakage inductance of Flyback power supply, the other end of described clamp capacitor links to each other with the other end of bleeder resistance and the negative terminal of clamp diode through described damping resistance, and the anode of described clamp diode links to each other with the drain electrode of a control switch pipe and the transformer input of Flyback power supply.
The utility model does not need the Flyback power supply is carried out very big transformation, as long as damping resistance of series connection can be realized in the clamp diode branch road in damping circuit, the residual energy of transformer leakage inductance when this resistance can be regulated the diode shutoff is easily controlled it and is produced common-mode noise.
Description of drawings
Fig. 1 is the traditional principle schematic of RCD damping circuit in the Flyback power supply.
Fig. 2 is Fig. 1 RCD damping circuit test waveform schematic diagram.
Fig. 3 is the leakage inductance antihunt circuit schematic diagram of the utility model embodiment one Flyback transformer.
Fig. 4 is the test waveform schematic diagram of the leakage inductance antihunt circuit of embodiment one.
Fig. 5 is the leakage inductance antihunt circuit schematic diagram of the utility model embodiment two Flyback transformers.
Associated component explanation in the accompanying drawing:
BD901: rectifier bridge;
C_bulk: power frequency electric capacity;
Cc: clamp capacitor, its both end voltage Vc;
Rc: the bleeder resistance of clamp circuit;
Dc: the clamp diode of clamp circuit;
Rd: the damping resistance of clamp circuit;
The main switch of Q1:Flyback circuit;
Coss1: the capacitance of drain of switching tube Q1;
The transformer of T901:Flyback circuit, its primary and secondary turn ratio is n:1;
D1: inferior utmost point rectifier diode;
Cout: secondary output filter capacitor;
R_load: load resistance.
Embodiment
As shown in Figure 3, the utility model provides a kind of clamper damping circuit of Flyback power circuit, comprise a clamp diode, a clamp capacitor, a bleeder resistance and a damping resistance, it is characterized in that: an end of described clamp capacitor and bleeder resistance is connected between the current rectifying and wave filtering circuit and transformer leakage inductance of Flyback power supply, the other end links to each other with the negative terminal of clamp diode through described damping resistance, and the anode of described clamp diode links to each other with the drain electrode of a control switch pipe and the transformer input of Flyback power supply.
Briefly, the utility model is damping resistance Rd of series connection in the clamp diode Dc branch road in damping circuit, and its course of work is as follows:
As Vds during greater than Vin+Vc, the Dc conducting, Lk charges to Cc, and the Vds of switching tube Q1 is by the Cc clamper; The current i dc that flows through clamp diode Dc descends after being climbed to maximum earlier again;
When idc dropped to zero, the voltage on the clamp capacitor Cc reached maximum Vc_max;
Clamper two utmost points enter the reverse recovery stage subsequently, because the junction capacitance stored charge effect of diode PN junction, clamp diode Dc keeps reverse-conducting, voltage on the clamp capacitor Cc begins to descend simultaneously, when the reverse current of the clamp diode Dc that flows through reaches maximum IRM, the stored charge of clamp diode PN junction is zero, begins to turn-off, and the voltage on the clamp capacitor Cc is denoted as Vc_m at this moment; This moment, the DS pole tension of switching tube Q1 was: Vds1=Vin+Vc_m-IRM*Rd; From transformer branch road: Vds1=Vin+n*Vo+VLk.Regulate the resistance of Rd, make the VLk=0 of this moment.
The reverse current of clamp diode Dc of flowing through subsequently begins to descend from IRM, up to zero, and this moment owing to do not have energy in the leakage inductance, and Vds1=Vin+n*Vo is so turn-off power loss is very little, and the almost not vibration of the capacitance of drain of transformer leakage inductance Lk and switching tube Q1.After tested, the DS pole tension Vds1 of the sub-switching tube Q1 of present embodiment and the electric current that flows through clamp diode Dc
i DcWaveform as shown in Figure 4.
In addition, in another examples of implementation of the present utility model, as shown in Figure 5, described damping resistance Rd also can be placed on the clamp capacitor branch road, and promptly the one end links to each other with clamp capacitor Cc, and the negative terminal of the other end and clamp diode links to each other.
The above only is preferred embodiment of the present utility model, and all equalizations of being done according to the utility model claim change and modify, and all should belong to covering scope of the present utility model.
Claims (2)
1. the clamper damping circuit of a Flyback power circuit, comprise a clamp diode, a clamp capacitor, a bleeder resistance and a damping resistance, it is characterized in that: an end of described clamp capacitor and bleeder resistance is connected between the current rectifying and wave filtering circuit and transformer leakage inductance of Flyback power supply, the other end links to each other with the negative terminal of clamp diode through described damping resistance, and the anode of described clamp diode links to each other with the drain electrode of a control switch pipe and the transformer input of Flyback power supply.
2. the clamper damping circuit of a Flyback power circuit, comprise a clamp diode, a clamp capacitor, a bleeder resistance and a damping resistance, it is characterized in that: an end of described clamp capacitor and bleeder resistance is connected between the current rectifying and wave filtering circuit and transformer leakage inductance of Flyback power supply, the other end of described clamp capacitor links to each other with the other end of bleeder resistance and the negative terminal of clamp diode through described damping resistance, and the anode of described clamp diode links to each other with the drain electrode of a control switch pipe and the transformer input of Flyback power supply.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010205468551U CN201821259U (en) | 2010-09-29 | 2010-09-29 | Leakage inductance damping circuit of flyback transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010205468551U CN201821259U (en) | 2010-09-29 | 2010-09-29 | Leakage inductance damping circuit of flyback transformer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN201821259U true CN201821259U (en) | 2011-05-04 |
Family
ID=43919201
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2010205468551U Expired - Fee Related CN201821259U (en) | 2010-09-29 | 2010-09-29 | Leakage inductance damping circuit of flyback transformer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN201821259U (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101924473A (en) * | 2010-09-29 | 2010-12-22 | 福建捷联电子有限公司 | Leakage inductance damping circuit of Flyback transformer |
| CN112928904A (en) * | 2019-12-06 | 2021-06-08 | 仪鼎仪器股份有限公司 | Buffer circuit for reducing power consumption of flyback converter |
-
2010
- 2010-09-29 CN CN2010205468551U patent/CN201821259U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101924473A (en) * | 2010-09-29 | 2010-12-22 | 福建捷联电子有限公司 | Leakage inductance damping circuit of Flyback transformer |
| CN112928904A (en) * | 2019-12-06 | 2021-06-08 | 仪鼎仪器股份有限公司 | Buffer circuit for reducing power consumption of flyback converter |
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| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20110504 Termination date: 20150929 |
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| EXPY | Termination of patent right or utility model |