CN102970797A - Secondary output current limiting circuit and device - Google Patents
Secondary output current limiting circuit and device Download PDFInfo
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- CN102970797A CN102970797A CN2012104605589A CN201210460558A CN102970797A CN 102970797 A CN102970797 A CN 102970797A CN 2012104605589 A CN2012104605589 A CN 2012104605589A CN 201210460558 A CN201210460558 A CN 201210460558A CN 102970797 A CN102970797 A CN 102970797A
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Abstract
The invention provides a secondary output current limiting circuit and a device. The secondary output current limiting circuit comprises a primary coil winding, a secondary coil winding and a control circuit, wherein the output end of the control circuit is connected with the primary coil winding; the secondary output current limiting circuit further comprises an auxiliary coil winding, a voltage sampling voltage and a feedback circuit, wherein the auxiliary coil winding and the secondary coil winding are connected in parallel; the voltage acquiring circuit is connected between the auxiliary coil winding and the feedback circuit; and the feedback circuit is further connected with the input end of the control circuit. According to the secondary output current limiting circuit and the secondary output current limiting device disclosed by the invention, part of output voltage is acquired by the voltage acquiring circuit, and the voltage acquired by the voltage acquiring voltage acts on the control circuit by the feedback circuit; when the acquired voltage exceeds a value, the primary winding voltage on the primary coil winding is reduced by the control circuit, so that the maximum output voltage and the maximum output current are limited.
Description
Technical field
The present invention relates to a kind of Limited Current circuit and device thereof, relate in particular to the secondary output current circuit of a kind of restriction and device.
Background technology
LED be a kind of can be the semiconductor of visible light with electric energy conversion, it has changed the principle that the incandescent lamp tungsten filament is luminous and the electricity-saving lamp tricolor powder is luminous, and adopts electroluminescence.LED is with respect to traditional lighting, has long, the advantages such as light efficiency is high, radiationless and low-power consumption of life-span, thereby has been subject to using more and more widely.
Existing led drive circuit as shown in Figure 1, be connected with semiconductor triode Q1 on the primary coil winding T, when transistor Q1 conducting, meeting generation current on the emitter of transistor Q1, then can produce voltage at R7, voltage on the R7 is the base voltage of another transistor Q2, when the voltage on the R7 is higher than the base-on voltage of transistor Q2, transistor Q2 conducting, after the transistor Q2 conducting, transistor Q1 base voltage is dragged down, and when being lower than conducting voltage, transistor Q1 turn-offs, the pass primary coil winding T voltage decreases of having no progeny, and then output current reduces, and the Current Control of exporting as can be known from said process is to do the current detecting benchmark by the base stage pressure drop of transistor Q2, and since in this circuit the datum mark voltage of R7 constant, therefore when input voltage is too high, whole input power can increase, and causes output voltage too high or output current is excessive, can damage load.When zero load, because circuit is open loop situations at this moment, output voltage is very high, and input power is larger, causes product loss when zero load larger.
Summary of the invention
Main purpose of the present invention is to provide a kind of secondary output current circuit of restriction and device that can limit output voltage and electric current when input voltage is too high.
In order to achieve the above object, the present invention proposes the secondary output current circuit of a kind of restriction, comprise: primary coil winding, secondary coil winding and control circuit, the output of described control circuit links to each other with described primary coil winding, also comprise: the ancillary coil winding, adopt volt circuit and feedback circuit, described ancillary coil winding and described secondary coil winding parallel, the described volt circuit of adopting is connected between described ancillary coil winding and the feedback circuit, and described feedback circuit also is connected with the input of described control circuit.
Preferably, the described volt circuit of adopting comprises rectifier diode D5, filter capacitor, voltage-stabiliser tube and resistance R 11, the positive pole of described rectifier diode D5 is connected with described ancillary coil winding one end, ground connection after the negative pole of described rectifier diode D5 passes through described filter capacitor and the described ancillary coil winding other end links to each other, the negative pole of described rectifier diode D5 also connects the negative pole of described voltage-stabiliser tube, and the positive pole of described voltage-stabiliser tube is through described resistance R 11 ground connection.
Preferably, described control circuit comprises transistor Q1 and transistor Q2; The collector electrode of described transistor Q1 links to each other with described primary coil winding, the base stage of described transistor Q1 links to each other with the collector electrode of described transistor Q2, the emitter of described transistor Q1 is through resistance R 7 ground connection, the grounded emitter of described transistor Q2.
Preferably, described feedback circuit comprises resistance R 9 and rectifier diode D2, described resistance R 9 one ends are connected between described voltage-stabiliser tube and the described resistance R 11, described resistance R 9 other ends connect the base stage of described transistor Q2, the negative pole of described rectifier diode D2 connects the base stage of described transistor Q2, and the positive pole of described rectifier diode D2 connects the emitter of described transistor Q1.
The present invention also proposes a kind of device, comprises the secondary output current circuit of restriction; The secondary output current circuit of described restriction comprises: primary coil winding, secondary coil winding and control circuit, the output of described control circuit links to each other with described primary coil winding, it is characterized in that, the secondary output current circuit of described restriction also comprises: the ancillary coil winding, adopt volt circuit and feedback circuit, described ancillary coil winding and described secondary coil winding parallel, the described volt circuit of adopting is connected between described ancillary coil winding and the feedback circuit, and described feedback circuit also is connected with the input of described control circuit.
Preferably, the described volt circuit of adopting comprises rectifier diode D5, filter capacitor, voltage-stabiliser tube and resistance R 11, the positive pole of described rectifier diode D5 is connected with described ancillary coil winding one end, ground connection after the negative pole of described rectifier diode D5 passes through described filter capacitor and the described ancillary coil winding other end links to each other, the negative pole of described rectifier diode D5 also connects the negative pole of described voltage-stabiliser tube, and the positive pole of described voltage-stabiliser tube is through described resistance R 11 ground connection.
Preferably, described control circuit comprises transistor Q1 and transistor Q2; The collector electrode of described transistor Q1 links to each other with described primary coil winding, the base stage of described transistor Q1 links to each other with the collector electrode of described transistor Q2, the emitter of described transistor Q1 is through resistance R 7 ground connection, the grounded emitter of described transistor Q2.
Preferably, described feedback circuit comprises resistance R 9 and rectifier diode D2, described resistance R 9 one ends are connected between described voltage-stabiliser tube and the described resistance R 11, described resistance R 9 other ends connect the base stage of described transistor Q2, the negative pole of described rectifier diode D2 connects the base stage of described transistor Q2, and the positive pole of described rectifier diode D2 connects the emitter of described transistor Q1
The secondary output current circuit of a kind of restriction and device that the present invention proposes, by adopting volt circuit collecting part output voltage, the voltage of adopting the volt circuit collection acts on the control circuit through feedback circuit, when gathering voltage above certain value, control circuit reduces the armature winding voltage on the primary coil winding, thereby restriction maximum output voltage and electric current have limited floating voltage simultaneously.
Description of drawings
Fig. 1 is existing led drive circuit figure;
Fig. 2 is the secondary output current circuit diagram of the restriction of preferred embodiment of the present invention;
In order to make technical scheme of the present invention clearer, clear, be described in further detail below in conjunction with accompanying drawing.
Embodiment
With reference to Fig. 1, conventional led drive circuit comprises: primary coil winding T, secondary coil winding and control circuit 1, control circuit 1 comprise transistor Q1 and transistor Q2; The collector electrode of the output transistor Q1 of control circuit 1 links to each other with primary coil winding T, the base stage of transistor Q1 links to each other with the collector electrode of transistor Q2, the emitter of transistor Q1 is through resistance R 7 ground connection, the grounded emitter of transistor Q2.When transistor Q1 conducting, meeting generation current on the emitter of transistor Q1, then can produce voltage at R7, voltage on the R7 is the base voltage of transistor Q2, when the voltage on the R7 is higher than the base-on voltage of transistor Q2, transistor Q2 conducting, after the transistor Q2 conducting, transistor Q1 base voltage is dragged down, when being lower than conducting voltage, transistor Q1 turn-offs, the pass armature winding voltage decreases of having no progeny, and then output current reduces, and the Current Control of exporting as can be known from said process is to do the current detecting benchmark by the base stage pressure drop of transistor Q2, and since in this circuit the datum mark voltage of R7 constant, therefore when input voltage is too high, whole input power can increase, and causes output voltage too high or output current is excessive, can damage load.When zero load, because circuit is open loop situations at this moment, output voltage is very high, and input power is larger, causes product loss when zero load larger.
The present invention improves Fig. 1 in order to overcome defective of the prior art, and as shown in Figure 2, Fig. 2 is the secondary output current circuit diagram of the restriction of preferred embodiment of the present invention.
As shown in Figure 2, present embodiment proposes the secondary output current circuit of a kind of restriction, comprise: primary coil winding T, secondary coil winding N1 and control circuit 1, control circuit 1 comprises transistor Q1 and transistor Q2, the base stage of transistor Q1 links to each other with the collector electrode of transistor Q2, the output of control circuit 1 is the collector electrode of transistor Q1, the input of control circuit 1 is the base stage of transistor Q2, the output of control circuit 1 links to each other with primary coil winding T, the emitter of transistor Q1 is through resistance R 7 ground connection, the grounded emitter of transistor Q2; The secondary output current circuit of restriction also comprises in the present embodiment: ancillary coil winding N2, adopt volt circuit 2 and feedback circuit 3, ancillary coil winding N2 is in parallel with secondary coil winding N1, adopt volt circuit 2 and be connected between ancillary coil winding N2 and the feedback circuit 3, feedback circuit 3 also is connected with the input of control circuit 1.
Concrete, adopt volt circuit 2 in the present embodiment and comprise rectifier diode D5, filter capacitor C6, voltage-stabiliser tube ZD and resistance R 11, the positive pole of rectifier diode D5 is connected with ancillary coil winding N2 one end, ground connection after the D5 negative pole of rectifier diode passes through filtering capacitor C 6 and the ancillary coil winding N2 other end links to each other, the negative pole of rectifier diode D5 also connects the negative pole of voltage-stabiliser tube ZD, and the positive pole of voltage-stabiliser tube ZD is through resistance R 11 ground connection.
In the present embodiment, when input voltage raises, ancillary coil winding N2 voltage also raises, after the halfwave rectifier effect of the high frequency ac signal of ancillary coil winding N2 through rectifier diode D5 and filter capacitor C6, signal is rectified into the d. c. voltage signal of more convenient detection, rising along with ancillary coil winding N2 voltage, this direct voltage also raises, because voltage-stabiliser tube ZD both end voltage is constant, therefore the upper voltage of R11 is that the FB point voltage raises, the FB point voltage also is to adopt the sampled voltage that volt circuit 2 sends feedback circuit 3 to, the FB point voltage is sent to the input of control circuit 1 by the resistance R 9 of feedback circuit 3, the input of control circuit 1 is the base stage of transistor Q2, feedback circuit 3 also comprises rectifier diode D2, this rectifier diode D2 can do the electricity isolation to the current signal of FB point signal and primary coil winding T, prevents that FB point signal is sent on the R7, thereby upsets control circuit 1; Along with the FB point voltage raises, the base voltage of transistor Q2 also raises, when the base voltage of transistor Q2 is higher than its conducting voltage, transistor Q2 conducting, after the transistor Q2 conducting, because transistor Q2 collector electrode links to each other with transistor Q1 base stage, transistor Q1 base voltage is dragged down, when transistor Q1 base voltage is lower than its conducting voltage, transistor Q1 turn-offs, and closes the voltage decreases of primary coil winding T of having no progeny, thereby output voltage is reduced, the output voltage of this moment is the maximum output voltage of secondary coil winding, thereby reaches the effect of restriction secondary output voltage.
Further, because the characteristic of transformer, the voltage ratio of coil equals number of turns ratio, when the maximum output voltage of ancillary coil winding N2 fixedly the time, accordingly, the maximum output voltage of loading coil winding N3 also can be fixed, and therefore can recently obtain according to the number of turns of regulating N2 and N3 the maximum output voltage of required loading coil winding N3, in the situation that the load on the loading coil winding N3 is fixed, can limit maximum output current according to maximum output voltage.
In addition, adopt the size of voltage stabilizing didoe ZD on the volt circuit 2 by adjusting, can regulate the size of sampled voltage, thereby regulate the maximum output voltage of ancillary coil winding N2, therefore, also can regulate by the size of regulating voltage stabilizing didoe ZD the maximum output voltage size of required loading coil winding N3.
In addition, the present invention also proposes the secondary current output device of a kind of restriction, and this device can adopt the secondary output current circuit of the restriction in above-described embodiment, and its circuit structure please refer to above-described embodiment, does not repeat them here.
The secondary output current circuit of a kind of restriction and device that the present invention proposes, by adopting volt circuit 2 collecting part output voltages, the voltage of adopting volt circuit 2 collections acts on the control circuit 1 through feedback circuit 3, when gathering voltage above certain value, control circuit 1 reduces the armature winding voltage on the primary coil winding T, thus restriction maximum output voltage and electric current.
The above only is the preferred embodiments of the present invention; be not so limit claim of the present invention; every equivalent structure or flow process conversion that utilizes specification of the present invention and accompanying drawing content to do; or directly or indirectly be used in other relevant technical field, all in like manner be included in the scope of patent protection of the present invention.
Claims (8)
1. one kind is limited secondary output current circuit, comprise: primary coil winding, secondary coil winding and control circuit, the output of described control circuit links to each other with described primary coil winding, it is characterized in that, also comprise: the ancillary coil winding, adopt volt circuit and feedback circuit, described ancillary coil winding and described secondary coil winding parallel, the described volt circuit of adopting is connected between described ancillary coil winding and the feedback circuit, and described feedback circuit also is connected with the input of described control circuit.
2. the secondary output current circuit of restriction according to claim 1, it is characterized in that, the described volt circuit of adopting comprises rectifier diode D5, filter capacitor, voltage-stabiliser tube and resistance R 11, the positive pole of described rectifier diode D5 is connected with described ancillary coil winding one end, ground connection after the negative pole of described rectifier diode D5 passes through described filter capacitor and the described ancillary coil winding other end links to each other, the negative pole of described rectifier diode D5 also connects the negative pole of described voltage-stabiliser tube, and the positive pole of described voltage-stabiliser tube is through described resistance R 11 ground connection.
3. the secondary output current circuit of restriction according to claim 1 and 2 is characterized in that, described control circuit comprises transistor Q1 and transistor Q2; The collector electrode of described transistor Q1 links to each other with described primary coil winding, the base stage of described transistor Q1 links to each other with the collector electrode of described transistor Q2, the emitter of described transistor Q1 is through resistance R 7 ground connection, the grounded emitter of described transistor Q2.
4. the secondary output current circuit of restriction according to claim 3, it is characterized in that, described feedback circuit comprises resistance R 9 and rectifier diode D2, described resistance R 9 one ends are connected between described voltage-stabiliser tube and the described resistance R 11, described resistance R 9 other ends connect the base stage of described transistor Q2, the negative pole of described rectifier diode D2 connects the base stage of described transistor Q2, and the positive pole of described rectifier diode D2 connects the emitter of described transistor Q1.
5. the secondary current output device of restriction comprises the secondary output current circuit of restriction; The secondary output current circuit of described restriction comprises: primary coil winding, secondary coil winding and control circuit, the output of described control circuit links to each other with described primary coil winding, it is characterized in that, the secondary output current circuit of described restriction also comprises: the ancillary coil winding, adopt volt circuit and feedback circuit, described ancillary coil winding and described secondary coil winding parallel, the described volt circuit of adopting is connected between described ancillary coil winding and the feedback circuit, and described feedback circuit also is connected with the input of described control circuit.
6. the secondary current output device of restriction according to claim 5, it is characterized in that, the described volt circuit of adopting comprises rectifier diode D5, filter capacitor, voltage-stabiliser tube and resistance R 11, the positive pole of described rectifier diode D5 is connected with described ancillary coil winding one end, ground connection after the negative pole of described rectifier diode D5 passes through described filter capacitor and the described ancillary coil winding other end links to each other, the negative pole of described rectifier diode D5 also connects the negative pole of described voltage-stabiliser tube, and the positive pole of described voltage-stabiliser tube is through described resistance R 11 ground connection.
7. according to claim 5 or the secondary current output device of 6 described restrictions, it is characterized in that described control circuit comprises transistor Q1 and transistor Q2; The collector electrode of described transistor Q1 links to each other with described primary coil winding, the base stage of described transistor Q1 links to each other with the collector electrode of described transistor Q2, the emitter of described transistor Q1 is through resistance R 7 ground connection, the grounded emitter of described transistor Q2.
8. the secondary current output device of restriction according to claim 7, it is characterized in that, described feedback circuit comprises resistance R 9 and rectifier diode D2, described resistance R 9 one ends are connected between described voltage-stabiliser tube and the described resistance R 11, described resistance R 9 other ends connect the base stage of described transistor Q2, the negative pole of described rectifier diode D2 connects the base stage of described transistor Q2, and the positive pole of described rectifier diode D2 connects the emitter of described transistor Q1.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012104605589A CN102970797A (en) | 2012-11-15 | 2012-11-15 | Secondary output current limiting circuit and device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2012104605589A CN102970797A (en) | 2012-11-15 | 2012-11-15 | Secondary output current limiting circuit and device |
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| CN102970797A true CN102970797A (en) | 2013-03-13 |
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| CN2012104605589A Pending CN102970797A (en) | 2012-11-15 | 2012-11-15 | Secondary output current limiting circuit and device |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103220838A (en) * | 2013-04-23 | 2013-07-24 | 广州市隆都电子有限公司 | Light-emitting diode (LED) ballast driving circuit |
| CN105682287A (en) * | 2016-01-29 | 2016-06-15 | 深圳和而泰照明科技有限公司 | Power supply circuit applied to fixed load and LED illuminating apparatus |
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| US20100157636A1 (en) * | 2008-12-23 | 2010-06-24 | Iwatt Inc. | Controller for switching power converter driving bjt based on primary side adaptive digital control |
| US20110156615A1 (en) * | 2009-12-30 | 2011-06-30 | Delta Electronics, Inc. | Backlight driving circuit for use in lcd panel |
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| CN103220838A (en) * | 2013-04-23 | 2013-07-24 | 广州市隆都电子有限公司 | Light-emitting diode (LED) ballast driving circuit |
| CN103220838B (en) * | 2013-04-23 | 2016-03-02 | 陈经湛 | LED ballast driven circuit |
| CN105682287A (en) * | 2016-01-29 | 2016-06-15 | 深圳和而泰照明科技有限公司 | Power supply circuit applied to fixed load and LED illuminating apparatus |
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Application publication date: 20130313 |