CN101989742A - No-load protection circuit for capacitor step-down - Google Patents
No-load protection circuit for capacitor step-down Download PDFInfo
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- CN101989742A CN101989742A CN2009100558534A CN200910055853A CN101989742A CN 101989742 A CN101989742 A CN 101989742A CN 2009100558534 A CN2009100558534 A CN 2009100558534A CN 200910055853 A CN200910055853 A CN 200910055853A CN 101989742 A CN101989742 A CN 101989742A
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Abstract
As a capacitor step-down circuit of an alternating current power supply is a current source circuit, when in no-load or an external circuit is open, the voltage at the output end can rise to a very high level till the peak value of the alternating current power supply, thereby damaging components in the circuit and even damaging a step-down capacitor. For the capacitor step-down circuit which is connected with an external load, the load open circuit often happens, thereby often causing the damages to the capacitor step-down circuit. A no-load protection circuit of the invention can realize that when the output voltage exceeds the maximum limit working voltage of the load during the no-load state of the capacitor step-down circuit, a sampling circuit can output a control signal to control the protection circuit which needs to be conducted during the no-load state, thereby conducting the protection circuit, limiting the rise of the voltage at the output end, safely and reliably protecting the components in the capacitor step-down circuit and avoiding damaging the components.
Description
Technical field
The present invention relates to the technical field of capacity voltage dropping circuit, particularly relate to the no-load protection circuit of capacitance decompression.
Background technology
The capacity voltage dropping circuit of AC power, owing to be current source circuit, so when unloaded, or external circuit is when opening a way, and output end voltage can rise very highly, until the peak value up to AC power, will damage the components and parts in the circuit like this, even decompression capacitor.For the capacity voltage dropping circuit of external load, load open circuit takes place through regular meeting, so just causes the damage of capacity voltage dropping circuit through regular meeting.
Summary of the invention
In order to solve the intrinsic problem of capacity voltage dropping circuit in the prior art, provide a kind of safe and reliable no-load protection circuit to society, the present invention proposes following technical scheme.
1. the no-load protection circuit of capacitance decompression, by capacity voltage dropping circuit (1), load (2), the protective circuit (3) of conducting when unloaded, sample circuit (4) is formed.Exchange input two ends; two inputs of input capacitance reduction voltage circuit (1); two outputs of capacity voltage dropping circuit (1) are connected to load (2); the protective circuit (3) of conducting and sample circuit (4) all are attempted by two ends of capacity voltage dropping circuit (1) output when unloaded; the control end of the protective circuit (3) of conducting when the output termination of sample circuit (4) is unloaded, the protective circuit (3) of conducting when control is unloaded.
2. its working point of described sample circuit (4) is set at: when capacity voltage dropping circuit (1) zero load; when its output voltage exceeds load greatest limit operating voltage; the protective circuit (3) of conducting made its conducting when the output control signal went to control zero load, had limited the rising of output end voltage.
3. the no-load protection circuit of capacitance decompression:
Described capacity voltage dropping circuit (1) comprises decompression capacitor (C), bridge rectifier diode (D1) (D2) (D3) (D4), filter capacitor (C1), current-limiting resistance (R1); Exchange input one end and connect the negative pole of bridge rectifier diode (D1) and the positive pole of diode (D2) through decompression capacitor (C), exchange the negative pole of another termination bridge rectifier diode (D3) of importing and the positive pole of diode (D4), the negative pole of bridge rectifier diode (D2) is connected with the negative pole of diode (D4), connect current-limiting resistance (R1) end after connecing filter capacitor (C1) end again, the other end of current-limiting resistance (R1) is as the cathode output end of capacity voltage dropping circuit (1), after the positive pole of the positive pole of bridge rectifier diode (D1) and diode (D3) is connected, connect the cathode output end of filter capacitor (C1) other end, formed a known resistance-capacitance depressurization circuit like this as capacity voltage dropping circuit (1).
Described load (2) is the LED lamp, and positive pole is connected on the cathode output end of capacity voltage dropping circuit (1), and negative pole is connected on the cathode output end of capacity voltage dropping circuit (1).
Described when unloaded the protective circuit (3) of conducting comprise protection current-limiting resistance (R2), controllable silicon (SCR); The anode of the one end serial connection controllable silicon (SCR) of protection current-limiting resistance (R2), the other end of protection current-limiting resistance (R2) and the negative electrode of controllable silicon (SCR) are connected on positive pole and negative pole end that capacity voltage dropping circuit (1) is exported respectively;
Described sample circuit (4) comprises voltage-stabiliser tube (DW), sampling current-limiting resistance (R3), divider resistance (R4); The anodal serial connection sampling of voltage-stabiliser tube (DW) current-limiting resistance (R3) end; one end of the other end serial connection divider resistance (R4) of sampling current-limiting resistance (R3); the other end of the negative pole of voltage-stabiliser tube (DW) and divider resistance (R4); be connected to the positive pole and the negative pole end of capacity voltage dropping circuit (1) output respectively; the tie point of sampling current-limiting resistance (R3) and divider resistance (R4) is as the sampling output; the protective circuit of conducting (3) control end, i.e. the control utmost point of controllable silicon (SCR) when being connected to zero load.
Described capacity voltage dropping circuit (1) is except the resistance-capacitance depressurization circuit of said structure, and is multiple in addition.Example: do following connection on former positive-negative output end: two triodes (BG1) (BG2) are made Darlington circuit and are connected, promptly the collector electrode of two pipes connects together and is connected on former output plus terminal, make this circuit output plus terminal, the emitter of first pipe (BG1) connects the base stage of second pipe (BG2), the emitter of second pipe (BG2) connects an end that connects sampling resistor (R5) behind the former output negative terminal again, make this circuit output negative terminal after the base stage of another termination first pipe (BG1) of sampling resistor (R5), in capacity voltage dropping circuit, just added surge absorbing circuit like this.
Beneficial effect of the present invention
The present invention is when the capacity voltage dropping circuit zero load; when its output voltage exceeds load greatest limit operating voltage; the protective circuit of conducting when sample circuit output control signal goes to control zero load; make its conducting; limited the rising of output end voltage; safe and reliable protection the components and parts in the capacity voltage dropping circuit, unlikely damage.
Description of drawings
Fig. 1 is an electric functional-block diagram of the present invention.
Fig. 2 is one of electrical schematic diagram of the present invention.
Fig. 3 is two of an electrical schematic diagram of the present invention.
The present invention is described in further detail below in conjunction with the drawings and specific embodiments.
Embodiment
Below, at first in conjunction with Fig. 1, to overall technological scheme of the present invention be described, description and interpretation.
The no-load protection circuit of capacitance decompression of the present invention is imported two ends by exchanging, two inputs of input capacitance reduction voltage circuit (1), and two outputs of capacity voltage dropping circuit (1) are connected to load (2), and this is known capacity voltage dropping circuit part.The protective circuit (3) of conducting and sample circuit (4) are connected in parallel on two ends of capacity voltage dropping circuit (1) output when unloaded; the control end of the protective circuit (3) of conducting when the output termination of sample circuit (4) is unloaded; when control is unloaded the protective circuit (3) of conducting this partly formed the no-load protection circuit; the high voltage of output makes sample circuit output control signal when zero load or load open circuit; with protective circuit (3) conducting; limit the rising of output voltage, played protective effect.
More than to overall technological scheme of the present invention be described, description and interpretation.Below, to embodiments of the invention further be described, description and interpretation.
Embodiment 1.
In conjunction with Fig. 2, carry out following description.
Exchange input one end and after decompression capacitor (C) step-down, connect the negative pole of bridge rectifier diode (D1) and the positive pole of diode (D2), exchange the negative pole of another termination bridge rectifier diode (D3) of importing and the positive pole of diode (D4), the negative pole of bridge rectifier diode (D2) is connected with the negative pole of diode (D4), the direct-flow positive voltage of output after rectification, connect filtering behind filter capacitor (C1) end again, connect current-limiting resistance (R1) end, through the resistance current limliting, the other end of current-limiting resistance (R1) is as the cathode output end of capacity voltage dropping circuit (1), after the positive pole of the positive pole of bridge rectifier diode (D1) and diode (D3) is connected, the negative DC voltage of output after rectification, connect the cathode output end of filter capacitor (C1) other end as capacity voltage dropping circuit (1), positive and negative two ends of this out-put supply are sent into positive and negative two ends of LED lamp, driving LED lamp.Output voltage raises when the LED lamp is opened a way; be connected in parallel on the voltage-stabiliser tube (DW) of LED two ends serial connection; sampling current-limiting resistance (R3); divider resistance (R4) conducting; voltage control controllable silicon (SCR) conducting on divider resistance (R4); because the anode of an end of protection current-limiting resistance (R2) serial connection controllable silicon (SCR); the other end of protection current-limiting resistance (R2) and the negative electrode of controllable silicon (SCR); be connected on the positive pole and the negative pole end of out-put supply respectively; like this with regard to short circuit output, limited the rising of output voltage.When the resistance of current-limiting resistance (R1) was enough big, protection current-limiting resistance (R2) value can be zero.
Embodiment 2.
In conjunction with Fig. 3, carry out following description.
Fig. 3 has been Duoed Darlington circuit and the sampling resistor of (BG2) being made up of two triodes (BG1) (R5) than Fig. 2, capacity voltage dropping circuit (1) is done following connection on Fig. 2 positive-negative output end: two triodes (BG1) (BG2) are made Darlington circuit and are connected, promptly the collector electrode of two pipes connects together and is connected on former output plus terminal, make this circuit output plus terminal, the emitter of first pipe (BG1) connects the base stage of second pipe (BG2), the emitter of second pipe (BG2) connects an end that connects sampling resistor (R5) behind the former output negative terminal again, makes this circuit output negative terminal after the base stage of another termination first pipe (BG1) of sampling resistor (R5).The electric current of LED lamp is imported the base stage of first triode (BG1) in the pressure drop of sampling resistor (R5), and when capacitance decompression produces surge current, Darlington circuit will absorb surge current.Protection current-limiting resistance (R2), the protective circuit (3) of conducting when unloaded that controllable silicon (SCR) is formed, and voltage-stabiliser tube (DW), sampling current-limiting resistance (R3), the sample circuit (4) that divider resistance (R4) is formed, the same Fig. 2 of the course of work.
Claims (4)
1. the no-load protection circuit of capacitance decompression is characterized in that comprising capacity voltage dropping circuit (1), load (2), the protective circuit (3) of conducting when unloaded, sample circuit (4); Exchange two inputs of input two termination capacitor reduction voltage circuits (1); two output termination loads (2) of capacity voltage dropping circuit (1); the protective circuit (3) of conducting and sample circuit (4) all are attempted by two ends of capacity voltage dropping circuit (1) output when unloaded, the control end of the protective circuit (3) of conducting when the output termination of sample circuit (4) is unloaded.
2. according to the no-load protection circuit of the capacitance decompression of claim 1, it is characterized in that described sample circuit (4) working point: when capacity voltage dropping circuit (1) zero load, when its output voltage exceeds load greatest limit operating voltage, the output control signal.
3. according to the no-load protection circuit of the capacitance decompression of claim 1, it is characterized in that:
Described capacity voltage dropping circuit (1) comprises decompression capacitor (C), bridge rectifier diode (D1) (D2) (D3) (D4), filter capacitor (C1), current-limiting resistance (R1); Exchange input one end and connect the negative pole of bridge rectifier diode (D1) and the positive pole of diode (D2) through decompression capacitor (C), exchange the negative pole of another termination bridge rectifier diode (D3) of importing and the positive pole of diode (D4), the negative pole of bridge rectifier diode (D2) is connected with the negative pole of diode (D4), connect current-limiting resistance (R1) end after connecing filter capacitor (C1) end again, the other end of current-limiting resistance (R1) is as the cathode output end of capacity voltage dropping circuit (1), after the positive pole of the positive pole of bridge rectifier diode (D1) and diode (D3) is connected, connect the cathode output end of filter capacitor (C1) other end as capacity voltage dropping circuit (1);
Described load (2) is the LED lamp, and positive pole is connected on the cathode output end of capacity voltage dropping circuit (1), and negative pole is connected on the cathode output end of capacity voltage dropping circuit (1);
Described when unloaded the protective circuit (3) of conducting comprise protection current-limiting resistance (R2), controllable silicon (SCR); The anode of the one end serial connection controllable silicon (SCR) of protection current-limiting resistance (R2) is protected the other end of current-limiting resistance (R2) and the negative electrode of controllable silicon (SCR), is connected to the positive pole and the cathode output end of capacity voltage dropping circuit (1) respectively;
Described sample circuit (4) comprises voltage-stabiliser tube (DW), sampling current-limiting resistance (R3), divider resistance (R4); The anodal serial connection sampling of voltage-stabiliser tube (DW) current-limiting resistance (R3) end; one end of the other end serial connection divider resistance (R4) of sampling current-limiting resistance (R3); the other end of the negative pole of voltage-stabiliser tube (DW) and divider resistance (R4); be connected to the positive pole and the cathode output end of capacity voltage dropping circuit (1) respectively; the tie point of sampling current-limiting resistance (R3) and divider resistance (R4) is as sampling output, the control utmost point of the controllable silicon (SCR) of the protective circuit of conducting (3) control end when being connected to zero load.
4. according to the no-load protection circuit of the capacitance decompression of claim 1; it is characterized in that described capacity voltage dropping circuit (1) does following connection on former positive-negative output end: two triodes (BG1) (BG2) are made Darlington circuit and are connected; promptly the collector electrode of two pipes connects together and is connected on former output plus terminal; make this circuit output plus terminal; the emitter of first pipe (BG1) connects the base stage of second pipe (BG2); the emitter of second pipe (BG2) connects an end that connects sampling resistor (R5) behind the former output negative terminal again, makes this circuit output negative terminal after the base stage of another termination first pipe (BG1) of sampling resistor (R5).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100558534A CN101989742A (en) | 2009-08-04 | 2009-08-04 | No-load protection circuit for capacitor step-down |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2009100558534A CN101989742A (en) | 2009-08-04 | 2009-08-04 | No-load protection circuit for capacitor step-down |
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| CN101989742A true CN101989742A (en) | 2011-03-23 |
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| CN2009100558534A Pending CN101989742A (en) | 2009-08-04 | 2009-08-04 | No-load protection circuit for capacitor step-down |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103841697A (en) * | 2012-11-23 | 2014-06-04 | 罗正华 | IC chip and control circuit of LED directly driven by electronic ballast |
| CN104080221A (en) * | 2013-03-26 | 2014-10-01 | 海洋王（东莞）照明科技有限公司 | LED (Light Emitting Diode) driving circuit and LED lamp |
| CN104201912A (en) * | 2014-08-15 | 2014-12-10 | 京东方科技集团股份有限公司 | Alternating current-direct current (AC-DC) converter, power panel and display device |
| CN104300522A (en) * | 2013-07-19 | 2015-01-21 | 天宝电子（惠州）有限公司 | Lightning protection device |
| CN107093892A (en) * | 2017-05-05 | 2017-08-25 | 郑州云海信息技术有限公司 | A kind of structure and method for solving point discharge |
| CN108832601A (en) * | 2018-09-03 | 2018-11-16 | 北京有感科技有限责任公司 | A kind of overvoltage crowbar and its application |
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| CN2058539U (en) * | 1989-08-02 | 1990-06-20 | 武汉洪山方大科技开发部 | Silicon controlled open circuit protector for electric power current transformer |
| CN1055261A (en) * | 1991-04-05 | 1991-10-09 | 刘运中 | Open-circuit protector for secondary loop of mutual inductor |
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| CN101001016A (en) * | 2006-01-13 | 2007-07-18 | 汤征宁 | Capacity voltage dropping surge absorption circuit |
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| WO2008086050A2 (en) * | 2007-01-04 | 2008-07-17 | Allegro Microsystems, Inc. | Electronic circuit for driving a diode load |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103841697A (en) * | 2012-11-23 | 2014-06-04 | 罗正华 | IC chip and control circuit of LED directly driven by electronic ballast |
| CN103841697B (en) * | 2012-11-23 | 2017-04-05 | 罗正华 | The IC chip and its control circuit of electric ballast direct drive LED |
| CN104080221A (en) * | 2013-03-26 | 2014-10-01 | 海洋王（东莞）照明科技有限公司 | LED (Light Emitting Diode) driving circuit and LED lamp |
| CN104300522A (en) * | 2013-07-19 | 2015-01-21 | 天宝电子（惠州）有限公司 | Lightning protection device |
| CN104201912A (en) * | 2014-08-15 | 2014-12-10 | 京东方科技集团股份有限公司 | Alternating current-direct current (AC-DC) converter, power panel and display device |
| CN104201912B (en) * | 2014-08-15 | 2017-12-26 | 京东方科技集团股份有限公司 | A kind of AC DC converters, power panel and display device |
| US10026372B2 (en) | 2014-08-15 | 2018-07-17 | Boe Technology Group Co., Ltd. | Alternating current-direct current converter, power supply board and display apparatus |
| CN107093892A (en) * | 2017-05-05 | 2017-08-25 | 郑州云海信息技术有限公司 | A kind of structure and method for solving point discharge |
| CN107093892B (en) * | 2017-05-05 | 2018-09-21 | 郑州云海信息技术有限公司 | A kind of structure and method solving point discharge |
| CN108832601A (en) * | 2018-09-03 | 2018-11-16 | 北京有感科技有限责任公司 | A kind of overvoltage crowbar and its application |
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Application publication date: 20110323 |