CN101997434A - Synchronous rectification device - Google Patents
Synchronous rectification device Download PDFInfo
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- CN101997434A CN101997434A CN2009101896434A CN200910189643A CN101997434A CN 101997434 A CN101997434 A CN 101997434A CN 2009101896434 A CN2009101896434 A CN 2009101896434A CN 200910189643 A CN200910189643 A CN 200910189643A CN 101997434 A CN101997434 A CN 101997434A
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Abstract
The invention discloses a synchronous rectification device which comprises a control circuit unit, a switch tube, a power switch transformer, a synchronous rectification unit, a current transformer and a driving control unit. The control circuit unit is connected in series with the switch tube and used for performing pulse width modulation control on the switch tube; the source electrode of the switch tube is connected in series with the control circuit unit; a primary coil winding of the power switch transformer is connected in series with the grid electrode of the switch tube, and a secondary coil winding of the power switch transformer is connected is series with an output terminal; the synchronous rectification unit is connected in series with the secondary coil winding of the power switch transformer; the current transformer is connected in series with the synchronous rectification unit and used for detecting the current of the output end of the synchronous rectification unit; and the driving control unit is connected in parallel with the current transformer and the synchronous rectification unit and used for converting a current signal output by the secondary coil winding of the current transformer into a voltage signal and controlling the switching on or off of the synchronous rectification unit according to the converted voltage signal. The implementation of the invention realizes the synchronous rectification control of a flyback power supply and achieves the purpose of reducing synchronous rectification consumption.
Description
Technical field
The present invention relates to electronic applications, relate in particular to a kind of synchronous rectificating device.
Background technology
Along with the development in power supply market, the demand of big electric current, low-voltage being exported the DC-DC isolating switch power also increases considerably thereupon.Traditional circuit of reversed excitation (promptly with the circuit of reversed excitation of Schottky diode as the output rectifier diode) because its circuit structure is simple, use very extensive in the small-power buffer circuit by reason such as the components and parts number is few, and is with low cost.But develop rapidly along with the Modern High-Speed very lagre scale integrated circuit (VLSIC), the supply voltage of integrated circuit descends thereupon, operating current but increases thereupon, because when low-voltage, high-current is exported, if still adopt Schottky diode as the output rectifier diode, the conduction loss on the output diode can be very big so.And because the low-voltage power metal oxide semiconductor field-effect transistor (Metal OxideSemiconductor Field Effect Transistor, conducting resistance MOSFET) is very little, and for example the conducting resistance of the power MOSFET of 20A only is 6-8m Ω.Promptly be applied to the DC-DC Switching Power Supply of low pressure output the beginning of the eighties successively, be called synchronous rectifier (Synchronous Rectifier, SR).
In general, the synchronous rectification mode of existing inverse-excitation type switch power-supply adopts the mode of rectifying tube rectifier system or employing synchronous rectification control chip.Adopt the rectifier system of rectifying tube, though do not need control circuit, cost is lower, and rectification efficiency is very low, and adopts the mode of synchronous rectification control chip, though can improve rectification efficiency, controls the electric wire complexity, and cost is higher.
Summary of the invention
In view of above-mentioned existing in prior technology problem, the embodiment of the invention provides a kind of synchronous rectificating device, by
The invention provides a kind of synchronous rectificating device, comprising:
Control circuit unit, the switching tube of connecting is used for described switching tube is carried out pulse width modulation controlled;
Switching tube, the source electrode of described switching tube is connected with described control circuit unit;
Power switch transformer, the primary coil winding of described power switch transformer is connected with the grid of described switching tube, and the secondary coil winding of described power switch transformer is connected with lead-out terminal;
The synchronous rectification unit is with the secondary coil windings in series of described power switch transformer;
Current transformer with described synchronous rectification units in series, is used to detect the electric current of described synchronous rectification unit output;
Driving control unit, in parallel with described current transformer and described synchronous rectification unit, be used for the current signal of described current transformer secondary output is converted to voltage signal, and control described synchronous rectification cell conduction or close according to the voltage signal after the described conversion.
Implement the embodiment of the invention, have following beneficial effect: control circuit unit control switch pipe is in cut-off state, this moment, source current flowed to the synchronous rectification unit behind the process electric capacity rectifying and wave-filtering again by power switch transformer, make the diode elder generation conducting in the synchronous rectification cell cube, current transformer detects after the electric current, the secondary current of current transformer flows to driving control unit, control the conducting of synchronous rectification unit by driving control unit, synchronous rectification this moment begins, and has realized the anti-synchronous rectification control that swashs power supply, and it is low to reach cost, the efficient height, the reliability height, the simple effect of outside line has reduced the loss of synchronous rectification.
Description of drawings
In order to be illustrated more clearly in the embodiment of the invention or technical scheme of the prior art, to do to introduce simply to the accompanying drawing of required use in embodiment or the description of the Prior Art below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the structural representation of synchronous rectificating device of the present invention;
Fig. 2 is the schematic diagram of synchronous rectificating device circuit of the present invention;
Fig. 3 is the movement oscillogram of synchronous rectificating device of the present invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the invention, the technical scheme in the embodiment of the invention is clearly and completely described, obviously, described embodiment only is the present invention's part embodiment, rather than whole embodiment.Based on the embodiment among the present invention, those of ordinary skills belong to the scope of protection of the invention not making the every other embodiment that is obtained under the creative work prerequisite.
Referring to Fig. 1, Fig. 1 is the structural representation of synchronous rectificating device of the present invention, this synchronous rectificating device comprises control circuit unit 11, switching tube 12, power switch transformer 13, synchronous rectification unit 14, current transformer 15 and driving control unit 16, this control circuit unit 11 series connection one switching tube 12, be used for switching tube 12 is carried out pulse width modulation controlled, concrete, this control circuit unit is pulse-width modulation (Pulse WidthModulation, PWM) controller.The primary coil winding of power switch transformer 13 is connected with the grid of switching tube 12, and the secondary coil winding of power switch transformer 13 connects with lead-out terminal, is used to reduce the voltage of described switching tube 12 outputs.Synchronous rectification unit 14 is connected with the secondary coil windings in series of power switch transformer 13, and is concrete, and synchronous rectification unit 14 is the MOSFET pipe.Current transformer 15 is connected with synchronous rectification unit 14, be used to detect the electric current of synchronous rectification unit 14 outputs, concrete, the coil windings ratio of this current transformer 15 is 1: 100, such as, when the electric current that flows through when the former limit of flowing through current transformer 15 was 1A, the electric current that the secondary of current transformer 15 flows through just was 10mA.Driving control unit 16 is in parallel with current transformer 15 and synchronous rectification unit 14, is used for the current signal of current transformer 15 secondary output is converted to voltage signal, and according to control synchronous rectification unit 14 conductings of the voltage signal after the conversion or close.
Need to prove, this synchronous rectificating device also comprises electric capacity 17, be arranged between the secondary coil winding and synchronous rectification unit 14 of power switch transformer 13, be used to carry out rectifying and wave-filtering, the number of electric capacity 17 is two and is connected in parallel in the middle of actual mechanical process.
Need to prove, when the connected switching tube 12 of control circuit unit 11 controls is conducting, behind the power initiation, will pass through the elementary winding of power switch transformer 13 with current direction switching tube 12, this moment, the secondary winding of power switch transformer 13 did not have electric current to flow through, do not have the transmission of energy in the circuit, this moment, the MOSFET pipe was in cut-off state.When control circuit unit 11 control and its switching tube 12 in succession for by the time, the electric current of input will pass through the secondary winding of power switch transformer 13 with current direction electric capacity 17, by electric capacity 17 electric current is carried out rectifying and wave-filtering, then with filtered current direction synchronous rectification unit 14, make the diode elder generation conducting in the MOSFET body, this moment, the current direction current transformer 15, current transformer 15 detects the size of current of the diode output in the MOSFET body, when the electric current that detects the current transformer 15 of flowing through is enough big, the secondary of current transformer 15 outputs to driving control unit 16 with electric current, driving control unit 16 is converted to voltage signal with the current signal of current transformer 15 outputs, and according to the conducting of the voltage signal control MOSFET pipe after the conversion, synchronous rectification this moment begins.When current transformer 15 detects the electric current of flowing through too hour, driving control unit 16 is turn-offed the MOSFET pipe, and synchronous rectification this moment finishes.
Referring to Fig. 2, Fig. 2 is the schematic diagram of synchronous rectificating device circuit of the present invention, this synchronous rectificating device circuit comprises PWM controller 21, switching tube Q1, power switch transformer T1, capacitor C 2, capacitor C 3, synchronous rectification MOSFET pipe Q2, current transformer T2 and driving control unit 22, this PWM controller 21 switching tube Q1 that is connected in series, switching tube Q1 is carried out pulse width modulation controlled, power switch transformer T1 is connected between lead-out terminal with the grid series connection of switching tube Q1 mutually, reduce the voltage of switching tube Q1 output, capacitor C 2 and C3 are arranged between power switch transformer T1 and the synchronous rectification MOSFET pipe Q2, carry out rectifying and wave-filtering, reduce output voltage, make output voltage stabilization, synchronous rectification MOSFET pipe Q2 is connected with the secondary coil windings in series of power switch transformer T1, conducting when having electric current in the circuit, current transformer 14 is connected in series with synchronous rectification MOSFET pipe Q2, detect the electric current of synchronous rectification MOSFET pipe Q2 output, concrete, the coil windings ratio of this current transformer 14 is 1: 100, such as, when the electric current that flows through when the former limit of flowing through current transformer 14 was 1A, the electric current that the secondary of current transformer 14 flows through just was 10mA.Driving control unit 22 is connected in parallel with current transformer T2 and synchronous rectification MOSFET pipe Q2, the current signal of current transformer T2 secondary output is converted to voltage signal, and according to the conducting of the control of the voltage signal after conversion synchronous rectification MOSFET pipe Q2 or close.
Need to prove, when PWM controller 21 connected switching tube Q1 are conducting, behind the power initiation, will pass through the elementary winding of power switch transformer T1 with current direction switching tube Q1, this moment, the secondary winding of power switch transformer T1 did not have electric current to flow through, do not have the transmission of energy in the circuit, this moment, MOSFET pipe Q2 was in cut-off state.When PWM controller 21 control and its switching tube Q1 in succession for by the time, the electric current of input will pass through the secondary winding of power switch transformer T1 with current direction capacitor C 2, by capacitor C 2 electric current is carried out rectifying and wave-filtering, then with filtered current direction MOSFET pipe Q2, make the diode elder generation conducting in the MOSFET pipe Q2 body, this moment current direction current transformer T2, current transformer T2 detects the size of current of the diode output in the MOSFET pipe Q2 body, when the electric current that detects the current transformer T2 that flows through is enough big, the secondary of current transformer T2 outputs to driving control unit 22 with electric current, driving control unit 22 is converted to voltage signal with the current signal of current transformer T2 output, and make MOSFET pipe Q2 conducting according to the voltage signal after the conversion, synchronous rectification this moment begins, its working waveform figure as shown in Figure 3, A is the current waveform of switching tube Q1 among the figure, and B is the current waveform of MOSFET pipe Q2 secondary, and C is a MOSFET pipe Q2 drive waveforms.When switching tube Q1 opens, electric current is linear to be increased, this moment, MOSFET pipe Q2 secondary did not have electric current to flow through, when switching tube Q1 ends, MOSFET pipe Q2 secondary flows through electric current, current transformer T2 detects this electric current, driving control unit 22 is opened MOSFET pipe Q2 (seeing the Q2 drive waveforms), synchronous rectification begins, along with the linearity of MOSFET pipe Q2 secondary current reduces, the current signal that detects up to current transformer T2 can not driving control unit 22, at this moment, MOSFET pipe Q2 turn-offs diode current flow in the body.When current transformer T2 detects the electric current of flowing through too hour, driving control unit 22 is turn-offed MOSFET pipe Q2, and synchronous rectification this moment finishes.
In sum, control circuit unit control switch pipe Q1 is in cut-off state, this moment, source current was managed Q2 through flowing to MOSFET behind capacitor C 2 rectifying and wave-filterings again by power switch transformer, make the diode elder generation conducting in the MOSFET pipe Q2 body, current transformer detects after the electric current, the secondary current of current transformer flows to driving control unit, control the conducting of MOSFET pipe Q2 by driving control unit, synchronous rectification this moment begins, and has realized the anti-synchronous rectification control that swashs power supply, and it is low to reach cost, the efficient height, the reliability height, the simple effect of outside line has reduced the loss of synchronous rectification.
Above disclosed is a kind of preferred embodiment of the present invention only, can not limit the present invention's interest field certainly with this, and therefore the equivalent variations of doing according to claim of the present invention still belongs to the scope that the present invention is contained.
Obviously, those skilled in the art can carry out various changes and modification to the present invention and not break away from the spirit and scope of the present invention.Like this, if of the present invention these are revised and modification belongs within the scope of claim of the present invention and equivalent technologies thereof, then the present invention also is intended to comprise these changes and modification interior.
Claims (3)
1. a synchronous rectificating device is characterized in that, comprising:
Control circuit unit, the switching tube of connecting is used for described switching tube is carried out pulse width modulation controlled;
Switching tube, the source electrode of described switching tube is connected with described control circuit unit;
Power switch transformer, the primary coil winding of described power switch transformer is connected with the grid of described switching tube, and the secondary coil winding of described power switch transformer is connected with lead-out terminal;
The synchronous rectification unit is with the secondary coil windings in series of described power switch transformer;
Current transformer with described synchronous rectification units in series, is used to detect the electric current of described synchronous rectification unit output;
Driving control unit, in parallel with described current transformer and described synchronous rectification unit, be used for the current signal of described current transformer secondary output is converted to voltage signal, and control described synchronous rectification cell conduction or close according to the voltage signal after the described conversion.
2. device as claimed in claim 1 is characterized in that, described device also comprises:
Be provided with electric capacity between the secondary coil winding of described power switch transformer and the described synchronous rectification unit.
3. device as claimed in claim 1 or 2 is characterized in that, described synchronous rectification unit is a mos field effect transistor.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101896434A CN101997434A (en) | 2009-08-25 | 2009-08-25 | Synchronous rectification device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009101896434A CN101997434A (en) | 2009-08-25 | 2009-08-25 | Synchronous rectification device |
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| CN101997434A true CN101997434A (en) | 2011-03-30 |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103475195A (en) * | 2013-08-29 | 2013-12-25 | 华为技术有限公司 | Synchronous rectification control circuit and synchronous rectification control method |
| CN103546046A (en) * | 2012-07-12 | 2014-01-29 | 凹凸电子（武汉）有限公司 | Rectifying circuit and rectifying method |
| CN103683953A (en) * | 2013-12-02 | 2014-03-26 | 华南理工大学 | Adaptive drive method for synchronous rectification of flyback converter |
| CN104767407A (en) * | 2015-04-20 | 2015-07-08 | 成都岷创科技有限公司 | Synchronous rectification circuit |
| CN106664080A (en) * | 2014-07-01 | 2017-05-10 | 华为技术有限公司 | Unit and method for synchronous rectification control |
| CN112787512A (en) * | 2019-11-04 | 2021-05-11 | 海信视像科技股份有限公司 | Display device and control circuit |
| CN114038400A (en) * | 2021-10-21 | 2022-02-11 | 重庆康佳光电技术研究院有限公司 | Light emitting diode driving circuit and method, display panel and driving method thereof |
| CN114094846A (en) * | 2021-11-24 | 2022-02-25 | 深圳市群芯科创电子有限公司 | Synchronous rectification control circuit for realizing high-stability parallel application |
| US11900855B2 (en) | 2019-11-04 | 2024-02-13 | Hisense Visual Technology Co., Ltd. | Display apparatus |
-
2009
- 2009-08-25 CN CN2009101896434A patent/CN101997434A/en active Pending
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103546046A (en) * | 2012-07-12 | 2014-01-29 | 凹凸电子（武汉）有限公司 | Rectifying circuit and rectifying method |
| US9391534B2 (en) | 2013-08-29 | 2016-07-12 | Huawei Technologies Co., Ltd. | Comparator based synchronous rectifier control circuit and synchronous rectifier control method |
| WO2015027759A1 (en) * | 2013-08-29 | 2015-03-05 | 华为技术有限公司 | Synchronous rectification control circuit and synchronous rectification control method |
| CN103475195B (en) * | 2013-08-29 | 2016-04-13 | 华为技术有限公司 | A kind of synchronous commutating control circuit and synchronous rectification control method |
| CN103475195A (en) * | 2013-08-29 | 2013-12-25 | 华为技术有限公司 | Synchronous rectification control circuit and synchronous rectification control method |
| CN103683953A (en) * | 2013-12-02 | 2014-03-26 | 华南理工大学 | Adaptive drive method for synchronous rectification of flyback converter |
| CN106664080A (en) * | 2014-07-01 | 2017-05-10 | 华为技术有限公司 | Unit and method for synchronous rectification control |
| CN104767407A (en) * | 2015-04-20 | 2015-07-08 | 成都岷创科技有限公司 | Synchronous rectification circuit |
| CN112787512A (en) * | 2019-11-04 | 2021-05-11 | 海信视像科技股份有限公司 | Display device and control circuit |
| CN112787512B (en) * | 2019-11-04 | 2022-05-13 | 海信视像科技股份有限公司 | Display device and control circuit |
| US11900855B2 (en) | 2019-11-04 | 2024-02-13 | Hisense Visual Technology Co., Ltd. | Display apparatus |
| CN114038400A (en) * | 2021-10-21 | 2022-02-11 | 重庆康佳光电技术研究院有限公司 | Light emitting diode driving circuit and method, display panel and driving method thereof |
| CN114094846A (en) * | 2021-11-24 | 2022-02-25 | 深圳市群芯科创电子有限公司 | Synchronous rectification control circuit for realizing high-stability parallel application |
| CN114094846B (en) * | 2021-11-24 | 2023-09-08 | 深圳市群芯科创电子有限公司 | Synchronous rectification control circuit for realizing high-stability parallel application |
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Application publication date: 20110330 |