CN101212182B - Power circuit - Google Patents
Power circuit Download PDFInfo
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- CN101212182B CN101212182B CN2006100645863A CN200610064586A CN101212182B CN 101212182 B CN101212182 B CN 101212182B CN 2006100645863 A CN2006100645863 A CN 2006100645863A CN 200610064586 A CN200610064586 A CN 200610064586A CN 101212182 B CN101212182 B CN 101212182B
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- voltage
- power circuit
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- pwm controller
- frequency transformer
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Abstract
The invention provides a power supply circuit, which comprises a first rectifier-filter circuit, a pulse-width modulation controller, an isolated high-frequency transformer, a second rectifier-filter circuit, a transistor and an overvoltage protective circuit; wherein, the isolated high-frequency transformer comprises an auxiliary winding and the pulse-width modulation controller comprises an undervoltage protective end. Under the control of the transistor, the outside alternating voltage outputs the direct voltage through the first rectifier-filter circuit, the isolated high-frequency transformer and the second rectifier-filter circuit. When the output voltage exceeds the maximum output voltage allowed by the transistor, the inductive voltage of the auxiliary winding is feedback to the undervoltage protective end through the overvoltage protective circuit and the pulse-width modulation controller is stopped from working.
Description
Technical field
The present invention relates to a kind of power circuit.
Background technology
See also Fig. 1, it is a kind of electrical block diagram of prior art power circuit.This power circuit 10 comprises one first current rectifying and wave filtering circuit 11, an isolation high frequency transformer 14, one second current rectifying and wave filtering circuit 15, a transistor 17, an optical coupler 18, one first resistance 121, one second resistance 122, an overvoltage crowbar 16 and a PWM controller 19.Wherein, this first current rectifying and wave filtering circuit 11 comprises two inputs 111,112, a full bridge rectifier 113, a filter capacitor 114 and an output 115.This isolation high frequency transformer 14 comprises an elementary winding 141 and a level winding 142.This second current rectifying and wave filtering circuit 15 comprises two inputs 151,152 and an output 150.This overvoltage crowbar 16 comprises resistance R 1, resistance R 2, resistance R 3, a voltage stabilizing didoe 161, a controlled inverter 162 and an electric capacity 163.This optical coupler 18 comprises a light-emitting diode 181 and a phototransistor 182.This PWM controller 19 comprises a control end 191, a voltage sample end 192 and a under-voltage protection end 193.
Two inputs of this full bridge rectifier 113 i.e. two inputs 111,112 of this first current rectifying and wave filtering circuit, the positive output end of this full bridge rectifier 113 i.e. the output 115 of this first current rectifying and wave filtering circuit, the negative output terminal ground connection of this full bridge rectifier 113, this filter capacitor 114 is connected in parallel between the positive output end and negative output terminal of this full bridge rectifier 113.These elementary winding 141 1 ends of isolating high frequency transformer 14 are electrically connected with the output 115 of this first current rectifying and wave filtering circuit 11, and its other end is electrically connected with the source electrode of this transistor 17.This secondary winding 142 of isolating high frequency transformer 14 is electrically connected with two inputs 151,152 of this second current rectifying and wave filtering circuit 15.The grid of this transistor 17 is electrically connected with the control end 191 of this PWM controller 19, and the drain electrode of this transistor 17 is by a resistance 170 ground connection.The output 150 of this power circuit is connected with the positive electrical of this light-emitting diode 181 by resistance R 1, the negative pole of this light-emitting diode 181 is connected with the positive electrical of this controlled inverter 162, the minus earth of this controlled inverter 162, the control utmost point of this controlled inverter 162 is connected with the positive electrical of this voltage stabilizing didoe 161.The output 150 of this power circuit is connected with the negative electricity of this voltage stabilizing didoe 161 by resistance R 2 simultaneously, and the positive pole of this voltage stabilizing didoe 161 is by these resistance R 3 ground connection, and this electric capacity 163 is in parallel with this resistance R 3.The collector electrode of this phototransistor 182 is connected the grounded emitter of this phototransistor 182 by a resistance (not indicating) with the voltage sample end 192 of this PWM controller 19.The under-voltage protection end 193 of this PWM controller 19 is connected with the positive output end of this full bridge rectifier 113 by this first resistance 121, and it is simultaneously by these second resistance, 122 ground connection.
Under the control of this transistor 17, extraneous alternating voltage inputs to two inputs 111,112 of this first current rectifying and wave filtering circuit 11, and this first current rectifying and wave filtering circuit 11 of process, this isolation high frequency transformer 14 and this second current rectifying and wave filtering circuit 15 backs are from these output 150 output dc voltages.
When the voltage of input 111,112 is lower than its minimum voltage that allows input; the voltage of this second resistance 122 changes thereupon; this Voltage Feedback is to the under-voltage protection end 193 of this PWM controller 19, and this PWM controller 19 enters the clamper guard mode immediately.
When the voltage of output 150 surpasses its maximum voltage that allows output; these voltage stabilizing didoe 161 reverse-conductings; promptly can produce reverse-conduction current in this voltage stabilizing didoe 161; this electric current resistance R 3 of flowing through; resistance R 3 two ends produce voltage drop; at this moment; extremely corresponding generation one voltage signal of the control of this controlled inverter 162; these controlled inverter 162 conductings; at this moment; this output 150; this resistance R 1; this light-emitting diode 181; this controlled inverter 162 constitutes a loop with ground; this current in loop increases; the corresponding increase of the luminous intensity of this light-emitting diode 181, the also corresponding increase of the conducting electric current of this phototransistor 182 feeds back to the also corresponding increase of voltage of the voltage sample end 192 of this PWM controller 19; this PWM controller 19 reference voltage that this feedback voltage is inner with it compares; when being higher than its inner reference voltage, this PWM controller 19 quits work, thereby realizes over-voltage protecting function.
But this power circuit 10 need use controlled inverter 162 and optical coupler 18 is realized over-voltage protecting function, thereby the cost of this power circuit 10 is higher.
Summary of the invention
In order to solve the high problem of power circuit cost in the prior art, be necessary to provide a kind of lower-cost power circuit.
A kind of power circuit, it comprises one first current rectifying and wave filtering circuit, a PWM controller, an isolation high frequency transformer, one second current rectifying and wave filtering circuit, a transistor and an overvoltage crowbar.Wherein, this isolation high frequency transformer comprises an auxiliary winding, and this PWM controller comprises a under-voltage protection end.Under this transistorized control, output dc voltage behind extraneous this first current rectifying and wave filtering circuit of alternating voltage process, this isolation high frequency transformer and this second current rectifying and wave filtering circuit.When output voltage surpasses its maximum voltage that allows output; should assist the induced voltage of winding to feed back to this under-voltage protection end by this overvoltage crowbar; this PWM controller quits work; wherein; this power circuit also comprises one first resistance and one second resistance; the under-voltage protection end of this PWM controller is connected with an end of the elementary winding of this isolation high frequency transformer by this first resistance; it is simultaneously by this second grounding through resistance; when input voltage is lower than the minimum voltage of this power circuit permission input; second resistance feedback is with the under-voltage protection end of voltage to this PWM controller, and this PWM controller enters the clamper guard mode.
Compared with prior art, power circuit of the present invention adopts the overvoltage crowbar that is made of a diode, a bipolar transistor, a voltage stabilizing didoe and a small amount of resistance, electric capacity can realize over-voltage protecting function, thereby has reduced the cost of this power circuit.And this over-voltage protecting function utilization is the under-voltage protection end of this PWM controller, and the application of this PWM controller also is expanded.
Description of drawings
Fig. 1 is a kind of electrical block diagram of prior art power circuit.
Fig. 2 is the electrical block diagram of power circuit of the present invention.
Embodiment
See also Fig. 2, it is the electrical block diagram of power circuit of the present invention.This power circuit 20 comprises one first current rectifying and wave filtering circuit 21, a PWM controller 23, an isolation high frequency transformer 24, one second current rectifying and wave filtering circuit 25, a field-effect transistor 27, an overvoltage crowbar 29, one first resistance 221, one second resistance 222 and an output 250.Wherein, this first current rectifying and wave filtering circuit 21 comprises two inputs 211,212, a full bridge rectifier 213, a filter capacitor 214 and an output 215.This PWM controller 23 comprises a control end 231 and a under-voltage protection end 232.This isolation high frequency transformer 24 comprises an elementary winding 241, a level winding 242 and an auxiliary winding 243.This overvoltage crowbar 29 comprises resistance R 1, a bipolar transistor 292, a diode 293, a voltage stabilizing didoe 294 and resistance R 2.
Two inputs of this full bridge rectifier 213 are as two inputs 211,212 of this first current rectifying and wave filtering circuit 21, the positive output end of this full bridge rectifier 213 is as the output 215 of this first current rectifying and wave filtering circuit 21, the negative output terminal ground connection of this full bridge rectifier 21, this filter capacitor 214 is connected in parallel between the positive output end and negative output terminal of this full bridge rectifier 213.These elementary winding 241 1 ends of isolating high frequency transformer 24 are electrically connected with the output 215 of this first current rectifying and wave filtering circuit 21, and its other end is electrically connected with the source electrode of this field-effect transistor 27.These secondary winding 242 1 ends are connected its other end ground connection by this second current rectifying and wave filtering circuit 25 with this output 250.Should be electrically connected its other end ground connection with the under-voltage protection end 232 of this PWM controller 23 by this overvoltage crowbar 29 by auxiliary winding 243 1 ends.The drain electrode of this field-effect transistor 27 is by a current-limiting resistance 270 ground connection, and the grid of this field-effect transistor 27 is electrically connected with the control end 231 of this PWM controller 23.The under-voltage protection end 232 of this PWM controller 23 is connected with the positive output end of this full bridge rectifier 213 by this first resistance 221 simultaneously, and it is simultaneously by these second resistance, 122 ground connection, and an electric capacity (not indicating) is in parallel with this second resistance 222.
The positive pole of this diode 293 is connected with an end of the auxiliary winding 243 of this isolation high frequency transformer 24, and its negative pole is connected with the emitter of this bipolar transistor 292, and its negative pole is simultaneously by an electric capacity (not indicating) ground connection.The collector electrode of this bipolar transistor 292 is connected with the under-voltage protection end 232 of this PWM controller 23 by this resistance R 1, and its base stage is connected with the negative pole of this voltage stabilizing didoe 294.The positive pole of this voltage stabilizing didoe 294 is by these resistance R 2 ground connection.
Under the control of this field-effect transistor 27, extraneous alternating voltage inputs to two inputs 211,212 of this first current rectifying and wave filtering circuit 21, and this first current rectifying and wave filtering circuit 21 of process, this isolation high frequency transformer 24 and this second current rectifying and wave filtering circuit 25 backs are from these output 250 output dc voltages.
When the voltage of input 211,212 is lower than its minimum voltage that allows input; the voltage of this second resistance 222 changes thereupon; this Voltage Feedback is to the under-voltage protection end 232 of this PWM controller 23, and this PWM controller 23 enters the clamper guard mode immediately.
When the voltage of output 250 surpasses its maximum voltage that allows output; this isolates the corresponding rising of voltage of the secondary winding 242 of high frequency transformer 24; because this isolates the mutual inductance effect between high frequency transformer 24 each winding; should assist the also corresponding increase of voltage of winding 243; the voltage of these bipolar transistor 292 emitters increases thereupon; and this voltage stabilizing didoe 294 remains unchanged the base voltage of this bipolar transistor 292; so the emitter of this bipolar transistor 292 and the voltage difference between base stage increase; these bipolar transistor 292 meeting conductings; feed back to the also corresponding increase of voltage of the under-voltage protection end 232 of this PWM controller 23; this PWM controller 23 clamp voltage that this feedback voltage is inner with it compares; when being higher than its inner clamp voltage; this PWM controller 23 quits work, thereby realizes over-voltage protecting function.
Compared with prior art; power circuit 20 of the present invention adopts the overvoltage crowbar 29 that is made of this diode 293, this bipolar transistor 292, this voltage stabilizing didoe 294 and a small amount of resistance, electric capacity can realize over-voltage protecting function, thereby has reduced the cost of this power circuit 20.And this over-voltage protecting function utilization is the under-voltage protection end 232 of this PWM controller 23, and the application of this PWM controller 23 also is expanded.
Claims (7)
1. power circuit; it comprises one first current rectifying and wave filtering circuit; one PWM controller; one isolates high frequency transformer; one second current rectifying and wave filtering circuit and a transistor; under this transistorized control; extraneous alternating voltage is through this first current rectifying and wave filtering circuit; output dc voltage behind this isolation high frequency transformer and this second current rectifying and wave filtering circuit; it is characterized in that: this power circuit also comprises an overvoltage crowbar; this isolation high frequency transformer comprises an auxiliary winding; this PWM controller comprises a under-voltage protection end; when output voltage surpasses the maximum voltage of this power circuit permission output; should assist the induced voltage of winding to feed back to this under-voltage protection end by this overvoltage crowbar; this PWM controller quits work; wherein; this power circuit also comprises one first resistance and one second resistance; the under-voltage protection end of this PWM controller is connected with an end of the elementary winding of this isolation high frequency transformer by this first resistance; it is simultaneously by this second grounding through resistance; when input voltage is lower than the minimum voltage of this power circuit permission input; second resistance feedback is with the under-voltage protection end of voltage to this PWM controller, and this PWM controller enters the clamper guard mode.
2. power circuit as claimed in claim 1 is characterized in that: this transistor is a field-effect transistor.
3. power circuit as claimed in claim 2; it is characterized in that: this overvoltage crowbar comprises a resistance R 1, a bipolar transistor, a diode, a voltage stabilizing didoe and a resistance R 2; the positive pole of this diode is connected with an end of the auxiliary winding of this isolation high frequency transformer; its negative pole is connected with the emitter of this bipolar transistor; the collector electrode of this bipolar transistor is connected with the under-voltage protection end of this PWM controller by this resistance R 1; its base stage is connected with the negative pole of this voltage stabilizing didoe, and the positive pole of this voltage stabilizing didoe is by these resistance R 2 ground connection.
4. power circuit as claimed in claim 3 is characterized in that: the negative pole of this diode is by a capacity earth.
5. power circuit as claimed in claim 4 is characterized in that: the under-voltage protection end of this PWM controller is simultaneously by a capacity earth.
6. power circuit as claimed in claim 5, it is characterized in that: this power circuit also comprises two inputs and a current-limiting resistance, this isolation high frequency transformer also comprises an elementary winding, this PWM controller also comprises a control end, this two input is connected with an end of this elementary winding by this first current rectifying and wave filtering circuit, the other end of this elementary winding is electrically connected with the source electrode of this field-effect transistor, the grounded drain of this field-effect transistor, the grid of this field-effect transistor is connected with the control end of this PWM controller.
7. power circuit as claimed in claim 6, it is characterized in that: this first current rectifying and wave filtering circuit comprises a full bridge rectifier and a filter capacitor, two inputs of this full bridge rectifier are two inputs of this power circuit, the positive output end of this full bridge rectifier is connected with an end of the elementary winding of this isolation high frequency transformer, the negative output terminal ground connection of this full bridge rectifier, this filter capacitor are connected in parallel between the positive output end and negative output terminal of this full bridge rectifier.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2006100645863A CN101212182B (en) | 2006-12-29 | 2006-12-29 | Power circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2006100645863A CN101212182B (en) | 2006-12-29 | 2006-12-29 | Power circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101212182A CN101212182A (en) | 2008-07-02 |
| CN101212182B true CN101212182B (en) | 2010-04-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN2006100645863A Expired - Fee Related CN101212182B (en) | 2006-12-29 | 2006-12-29 | Power circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101212182B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102420529A (en) * | 2011-12-23 | 2012-04-18 | 崧顺电子（深圳）有限公司 | Voltage conversion circuit for forward design of auxiliary winding in flyback topology |
| CN103219880B (en) * | 2012-01-18 | 2015-07-08 | 伊顿制造（格拉斯哥）有限合伙莫尔日分支机构 | Transformer circuit provided with voltage feedback circuit with improved starting performance |
| TWI581535B (en) * | 2016-01-19 | 2017-05-01 | 群光電能科技股份有限公司 | Over voltage protection circuit |
| CN107681636A (en) * | 2017-11-22 | 2018-02-09 | 合肥惠科金扬科技有限公司 | A kind of overvoltage crowbar and Switching Power Supply |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000270549A (en) * | 1999-03-17 | 2000-09-29 | Fuji Elelctrochem Co Ltd | Switching power supply unit with protective circuit |
-
2006
- 2006-12-29 CN CN2006100645863A patent/CN101212182B/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000270549A (en) * | 1999-03-17 | 2000-09-29 | Fuji Elelctrochem Co Ltd | Switching power supply unit with protective circuit |
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| Publication number | Publication date |
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| CN101212182A (en) | 2008-07-02 |
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Granted publication date: 20100414 Termination date: 20191229 |
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| CF01 | Termination of patent right due to non-payment of annual fee |