CN202424500U - Soft switching circuit for active clamp forward synchronous rectification - Google Patents
Soft switching circuit for active clamp forward synchronous rectification Download PDFInfo
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- CN202424500U CN202424500U CN2011204931860U CN201120493186U CN202424500U CN 202424500 U CN202424500 U CN 202424500U CN 2011204931860 U CN2011204931860 U CN 2011204931860U CN 201120493186 U CN201120493186 U CN 201120493186U CN 202424500 U CN202424500 U CN 202424500U
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The utility model discloses a soft switching circuit for active clamp forward synchronous rectification. The soft switching circuit consists of a shutdown control signal (control), a current mirror, a resistor (R15), a capacitor (C38) and a transistor (Q6), wherein the shutdown control signal (control) is connected with the current mirror, and a base of the transistor (Q6) is connected with the current mirror; one end of the resistor (R15) is connected with the base of the transistor (Q6) and the other end of the resistor (R15) is connected with a reference power supply; and one end of the capacitor (C38) is connected with the base of the transistor (Q6) and the other end of the capacitor (C38) is grounded. Compared with the prior art, the utility model has the advantages that the soft switching circuit can fulfill the aim of soft shutdown, is novel in concept, low in cost and high in generality, and has a simple structure.
Description
Technical field
The utility model relates to the technical field of synchronous rectification, specifically, is meant the soft switch circuit of the positive exciting synchronous rectification of a kind of active clamp.
Background technology
Synchronous rectification is the key technology of low-voltage, high-current switch converters; Secondary (secondary) at switch converters; Adopt synchronous rectification MOS transistor (MOSFET) to replace Schottky (Schottky) diode to carry out rectification, can effectively reduce on-state loss, improve the efficient of switch converters.For synchronous rectification, key is the mode and the performance of its drive circuit.Synchronous rectification type of drive commonly used at present has self-powered, he drives or both combine, because self-powered has advantage with low cost, thereby obtains using the most widely.Particularly active clamp normal shock self-device synchronous rectification circuit because cost performance is very high, in the power supply of middle low power, is used very general.
As shown in Figure 1, in existing active clamp normal shock self-device synchronous rectification circuit, it is 3843 classical chip that pwm chip often adopts the very strong model of versatility; Remove to drive the main switch Q3 and the clamper tube Q4 of active clamp normal shock again through a chip for driving DRIVER IC, secondary synchronous rectification is often adopted from type of drive, because the function of pwm chip 3843 is limit; Shutdown mode is normal to adopt hard shutdown, physical circuit to see among Fig. 1 shown in the frame of broken lines, when shutting down the state when load is zero load or underloading under; The CONTROL signal is a high level, produces a voltage through resistance R 22 and R14 dividing potential drop and removes to drive Q7, the Q7 saturation conduction; Thereby bleed off the electric charge on the C38 rapidly, the also very fast saturation conduction of triode Q6, the COM signal is forced at once and drags down; Thereby close duty cycle signals at once, main switch Q3 is in off state, but the electric charge on this thing clamp capacitor C2 does not bleed off; Through transformer coupled, the continued flow tube Q1 of output still has drive signal, and continued flow tube Q1 still is in conducting state; Because MOSFET has two-way admittance property, the energy that output capacitance C goes up storage can pass through outputting inductance L reverse circulated, if when exporting rectifying tube Q2 and continued flow tube Q1 and all turn-offing at this moment; This reverse current can be through the junction capacitance charging of inductance to rectifying tube Q2 and continued flow tube Q1, because the junction capacitance of rectifying tube Q2 and continued flow tube Q1 is generally all very little, much smaller than the appearance value of output filter capacitor C; So can produce very high due to voltage spikes this moment on the junction capacitance of rectifying tube Q2 and continued flow tube Q1; Can damage rectifying tube Q2 and continued flow tube Q1 under the serious situation, reduce the reliability of power supply, also influence the practice of this circuit structure.
The utility model content
The purpose of the utility model is to provide the soft switch circuit of the positive exciting synchronous rectification of a kind of active clamp, and it can overcome above-mentioned defective, can not produce due to voltage spikes during shutdown, improves the reliability of power supply.
For realizing above-mentioned purpose, the utility model adopts following structure:
The soft switch circuit of the positive exciting synchronous rectification of a kind of active clamp; It includes and closes machine control signal (control), mirror current source, resistance (R15), electric capacity (C38) and triode (Q6) composition; Described pass machine control signal (control) links to each other with mirror current source, and the base stage of described triode (Q6) links to each other with mirror current source; Described resistance (R15) end links to each other with the base stage of triode (Q6), and the other end links to each other with reference power source; Described electric capacity (C38) end links to each other other end ground connection with the base stage of triode (Q6).
Above-mentioned mirror current source is made up of four resistance (R96, R31, R27, R115), diode (D31), two triodes (Q21, Q22), and an end of described resistance (R96) links to each other with power supply, and the other end links to each other with diode (D31) is anodal; The positive pole of described diode (D31) links to each other with pass machine control signal (control), and the negative pole of diode (D31) links to each other with the collector electrode and the base stage of triode (Q21); The base stage of two triodes (Q21, Q22) links to each other; The emitter of described triode (Q21) links to each other with an end of resistance (R31), described resistance (R31) other end ground connection; One end of described resistance (R27) links to each other other end ground connection with the emitter of triode (Q22); The collector electrode of described triode (Q22) links to each other with an end of resistance (R115), and the other end of resistance (R115) links to each other with triode (Q6).
Two above-mentioned triodes (Q21, Q22) are NPN type triode.
Above-mentioned triode (Q6) is the PNP triode, and the other end of described resistance (R115) links to each other with the base stage of triode (Q6).
After adopting technique scheme, during use, when off signal produces; The control signal uprises, and mirror current source starts, and can adjust the collector current of triode Q21 through the resistance of adjustment resistance R 96, R31; Operation principle according to mirror current source; The operating current of triode Q22 collector electrode equals the operating current of triode Q21 collector electrode, so the discharging current that the resistance through adjustment resistance R 96, R31 just can control capacitance C38 has also just been controlled discharge time of capacitor C 38; Because the interdischarge interval in capacitor C 38 is exactly the process that the COM signal diminishes gradually; Also be that duty ratio is varied down to zero process gradually, so almost be exactly the time of soft-off the discharge time of capacitor C 38, thus the purpose of realization soft-off.Compared with prior art, this new-type circuit not only can realize the purpose of soft-off, and novel, simple in structure, cost is low, highly versatile.
Description of drawings
Fig. 1 is existing circuit of synchronous rectification figure;
Fig. 2 is the circuit diagram of the utility model.
Embodiment
For the purpose, technical scheme and the advantage that make the utility model is clearer,, the utility model is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the utility model, and be not used in qualification the utility model.
With reference to shown in Figure 2, the utility model discloses the soft switch circuit of the positive exciting synchronous rectification of a kind of active clamp, it includes: closes machine control signal control, mirror current source, resistance R 15, capacitor C 38 and triode Q6 and forms, wherein:
Mirror current source is made up of resistance R 96, R31, R27, R115, diode D31, triode Q21, Q22, and wherein, an end of resistance R 96 links to each other with power supply, and the other end links to each other with the positive pole of diode D31; The positive pole of diode D31 links to each other with pass machine control signal control, and triode Q21, Q22 are NPN type triode, and the negative pole of diode D31 links to each other with collector electrode and the base stage of triode Q21; The base stage of triode Q21, Q22 links to each other; The emitter of triode Q21 links to each other with an end of resistance R 31, resistance R 31 other end ground connection; One end of resistance R 27 links to each other other end ground connection with the emitter of triode Q22; The collector electrode of triode Q22 links to each other with an end of resistance R 115, and the other end of resistance R 115 links to each other with triode Q6;
Triode Q6 is the PNP triode, and the other end of resistance R 115 links to each other with the base stage of triode Q6;
One end of capacitor C 38 links to each other other end ground connection with the base stage of triode Q6;
One end of resistance R 15 links to each other with the base stage of triode Q6, and the other end links to each other with VREF (reference power source).
During use, when off signal produced, the control signal uprised; Mirror current source starts; Resistance through adjustment resistance R 96, R31 can be adjusted the collector current of triode Q21, and according to the operation principle of mirror current source, the operating current of triode Q22 collector electrode equals the operating current of triode Q21 collector electrode; So discharging current that the resistance through adjustment resistance R 96, R31 just can control capacitance C38; Also just having controlled the discharge time of capacitor C 38, because be exactly the process that the COM signal diminishes gradually at the interdischarge interval of capacitor C 38, also is that duty ratio is varied down to zero process gradually; So almost be exactly the time of soft-off the discharge time of capacitor C 38, thus the purpose of realization soft-off.
Compared with prior art, this new-type circuit not only can realize the purpose of soft-off, and novel, simple in structure, cost is low, highly versatile.
The above; Be merely the preferable embodiment of the utility model; But the protection range of the utility model is not limited thereto; Any technical staff who is familiar with the present technique field is in the technical scope that the utility model discloses, and the variation that can expect easily or replacement all should be encompassed within the protection range of the utility model.Therefore, the protection range of the utility model should be as the criterion with the protection range of claim.
Claims (4)
1. the soft switch circuit of the positive exciting synchronous rectification of active clamp; It is characterized in that: it includes and closes machine control signal (control), mirror current source, resistance (R15), electric capacity (C38) and triode (Q6) composition; Described pass machine control signal (control) links to each other with mirror current source, and the base stage of described triode (Q6) links to each other with mirror current source; Described resistance (R15) end links to each other with the base stage of triode (Q6), and the other end links to each other with reference power source; Described electric capacity (C38) end links to each other other end ground connection with the base stage of triode (Q6).
2. the soft switch circuit of the positive exciting synchronous rectification of active clamp according to claim 1; It is characterized in that: described mirror current source is made up of four resistance (R96, R31, R27, R115), diode (D31), two triodes (Q21, Q22); One end of described resistance (R96) links to each other with power supply, and the other end links to each other with diode (D31) is anodal; The positive pole of described diode (D31) links to each other with pass machine control signal (control), and the negative pole of diode (D31) links to each other with the collector electrode and the base stage of triode (Q21); The base stage of two triodes (Q21, Q22) links to each other; The emitter of described triode (Q21) links to each other with an end of resistance (R31), described resistance (R31) other end ground connection; One end of described resistance (R27) links to each other other end ground connection with the emitter of triode (Q22); The collector electrode of described triode (Q22) links to each other with an end of resistance (R115), and the other end of resistance (R115) links to each other with triode (Q6).
3. the soft switch circuit of the positive exciting synchronous rectification of active clamp according to claim 2 is characterized in that: described two triodes (Q21, Q22) are NPN type triode.
4. the soft switch circuit of the positive exciting synchronous rectification of active clamp according to claim 2 is characterized in that: described triode (Q6) is the PNP triode, and the other end of described resistance (R115) links to each other with the base stage of triode (Q6).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204931860U CN202424500U (en) | 2011-12-01 | 2011-12-01 | Soft switching circuit for active clamp forward synchronous rectification |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204931860U CN202424500U (en) | 2011-12-01 | 2011-12-01 | Soft switching circuit for active clamp forward synchronous rectification |
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| Publication Number | Publication Date |
|---|---|
| CN202424500U true CN202424500U (en) | 2012-09-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2011204931860U Expired - Fee Related CN202424500U (en) | 2011-12-01 | 2011-12-01 | Soft switching circuit for active clamp forward synchronous rectification |
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| CN (1) | CN202424500U (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105071658A (en) * | 2014-12-26 | 2015-11-18 | 中国船舶重工集团公司第七一九研究所 | Control method for reducing bi-directional forward converter switching tube voltage spike and loop current |
| CN106230265A (en) * | 2016-08-24 | 2016-12-14 | 国网江苏省电力公司电力科学研究院 | A kind of current mode DC DC isolates conversion control circuit |
| CN112993995A (en) * | 2021-04-01 | 2021-06-18 | 国能朔黄铁路发展有限责任公司 | Bypass device |
-
2011
- 2011-12-01 CN CN2011204931860U patent/CN202424500U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105071658A (en) * | 2014-12-26 | 2015-11-18 | 中国船舶重工集团公司第七一九研究所 | Control method for reducing bi-directional forward converter switching tube voltage spike and loop current |
| CN106230265A (en) * | 2016-08-24 | 2016-12-14 | 国网江苏省电力公司电力科学研究院 | A kind of current mode DC DC isolates conversion control circuit |
| CN112993995A (en) * | 2021-04-01 | 2021-06-18 | 国能朔黄铁路发展有限责任公司 | Bypass device |
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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: 20120905 Termination date: 20161201 |
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| CF01 | Termination of patent right due to non-payment of annual fee |