CN201075823Y - Compensation type switch power source - Google Patents
Compensation type switch power source Download PDFInfo
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- CN201075823Y CN201075823Y CNU2007200079926U CN200720007992U CN201075823Y CN 201075823 Y CN201075823 Y CN 201075823Y CN U2007200079926 U CNU2007200079926 U CN U2007200079926U CN 200720007992 U CN200720007992 U CN 200720007992U CN 201075823 Y CN201075823 Y CN 201075823Y
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Abstract
A novel compensation switch power of the utility model relates to a switch power for pulse-width modulation which solves the problem that an output voltage and an output circuit are adjusted in equal proportion when a load resistance is changed. One end of a primary grade of a transformer is connected with a high-voltage DC output end of an input rectification filtering circuit and the other end is connected with a high-voltage DC groundwire of the input rectification filtering circuit by a pulse-width modulation switch. A secondary grade of the transformer is connected with two AC input ends of an output rectification filtering circuit. A low-voltage DC output end of the output rectification filtering circuit is connected with one end of a load, a power input end of a sampling circuit and a power input end of a voltage reference circuit. A low-voltage DC ground wire of the output rectification filtering circuit is connected with the ground terminal of the voltage reference circuit and is connected with the ground terminal of the load through a current sampling resistance. The ground terminal of the sampling circuit is connected with the ground terminal of the load and the output end is connected with the control input end of the pulse-width modulation switch through a photocoupler. The output end of the voltage reference circuit is connected with a sampling reference end of the sampling circuit.
Description
Technical field
The utility model relates to a kind of Switching Power Supply of direct current output, particularly relates to the Switching Power Supply of a kind of pulse-width modulation, direct current output.
Background technology
The Switching Power Supply of existing direct current output is generally the Switching Power Supply that DC voltage-stabilizing is exported, and adopts pulse width modulated voltage regulator circuit structure shown in Figure 1 more.Input rectifying filter circuit 1 ' with electric main be transformed to high voltage direct current be added to transformer 2 ' elementary 21 ' an end, transformer 2 ' elementary 21 ' the other end through a pwm switch 3 ' connect high voltage direct current ground wire.Pwm switch 3 ' control transformer 2 ' elementary 21 ' energising or outage; Transformer 2 ' secondary 22 ' induction output through output rectifier and filter 4 ' be transformed to low-voltage direct deliver to load 5 '.Sample circuit 6 ' input be connected on output rectifier and filter 4 ' output, sample circuit 6 ' output connect photoelectric coupling circuit 7 ' input, photoelectric coupling circuit 7 ' output connect pwm switch 3 ' the control input end.The low-voltage direct ground wire of the high voltage direct current ground wire of photoelectric coupling circuit 7 ' isolating transformer 2 ' elementary 21 ' one sides and transformer 2 ' secondary 22 ' one sides.Reduce at load 5 ' resistance, output rectifier and filter 4 ' the output current of output increase, when voltage reduces: the voltage signal of sample circuit 6 ' output reduces; Photoelectric coupling circuit 7 ' elementary lumination of light emitting diode brightness reduces, and the tube voltage drop of secondary phototriode increases; Pwm switch 3 ' the control end current potential improve; The duty ratio increase of pwm switch 3 ' make transformer 2 ' elementary 21 ' high voltage direct current energising is that effective pulsewidth broadens; Transformer 2 ' secondary 22 ' induction output increase through the direct voltage of output rectifier and filter 4 ' conversion, remedied deliver to originally load 5 ' the composition that reduces of direct voltage, make deliver to load 5 ' direct voltage keep stable.Increase at load 5 ' resistance, output rectifier and filter 4 ' the output current of output reduce, when voltage increases: the voltage signal increase of sample circuit 6 ' output, photoelectric coupling circuit 7 ' elementary lumination of light emitting diode brightness increases, and the tube voltage drop of secondary phototriode reduces; Pwm switch 3 ' the control end current potential reduce; Pwm switch 3 ' make transformer 2 ' duty ratio of elementary 21 ' high voltage direct current energising reduces is that effective pulsewidth narrows down; Transformer 2 ' secondary 22 ' induction output reduce through the direct voltage of output rectifier and filter 4 ' conversion, remedied deliver to originally load 5 ' the composition that increases of direct voltage, make deliver to load 5 ' direct voltage keep stable.That is to say in the power bracket that this Switching Power Supply allows, no matter how load 5 ' resistance changes, deliver to load 5 ' direct voltage total energy trend stable.
But in some application scenario, load resistance alters a great deal in running, require Switching Power Supply along with the increase of load resistance is that output current reduces and reduces to deliver to the direct voltage of load, perhaps conversely along with load resistance to reduce be that output current increases and increases the direct voltage of delivering to load.Obviously, the Switching Power Supply of the direct current of prior art output can't realize the specific (special) requirements of these application scenarios.
The utility model content
The offset-type Switching Power Supply of the utility model aims to provide a kind of load resistance when changing output current and the adjustment of output voltage equal proportion.
The technical solution of the utility model is: the offset-type Switching Power Supply, and the high voltage direct current output end of input rectifying filter circuit connects an end of primary, and the primary other end connects the high voltage direct current ground wire of input rectifying filter circuit through pwm switch; Two corresponding two ac input ends that connect output rectifier and filter of induction output of transformer secondary output, the low-voltage direct output of output rectifier and filter connects the power input of load and the power input of sample circuit; Corresponding two inputs that connect photoelectric coupling circuit of two outputs of sample circuit, the output of photoelectric coupling circuit connects the control input end of pwm switch; Current sampling resistor is serially connected between the earth terminal of the low-voltage direct ground wire of output rectifier and filter and load; The power input of voltage reference circuit connects the low-voltage direct output of output rectifier and filter, the earth terminal of voltage reference circuit connects the low-voltage direct ground wire of output rectifier and filter, and the output of voltage reference circuit connects the sampling reference edge of sample circuit; The earth terminal of sample circuit connects the earth terminal of load.This Switching Power Supply is introduced the minus deviation voltage that produces when negative bias voltage that voltage reference circuit provides and load current change at the sampling reference edge of sample circuit on current sampling resistor; The feedback control signal that sample circuit provides to pwm switch through photoelectric coupling circuit not only comprises the deviation information of the low-voltage direct output end voltage of output rectifier and filter, the information that also has load current to change.Along with load resistance to reduce be that output current increases, the minus deviation voltage at current sampling resistor two ends increases.The increase of minus deviation voltage causes the sampling reference edge current potential of sample circuit to descend, reduce identical effect because the decline of sampling reference edge current potential has with the voltage of output rectifier and filter low-voltage direct output, the feedback control signal that sample circuit provides increases the duty ratio of primary high voltage direct current energising through photoelectric coupling circuit control pwm switch; The induction output of transformer secondary output increases through the direct voltage of output rectifier and filter conversion, and the direct voltage of delivering to load increases.Otherwise along with the increase of load resistance is that output current reduces, the minus deviation voltage at current sampling resistor two ends reduces.The sampling reference edge current potential lifting that reduces to cause sample circuit of minus deviation voltage, increase identical effect because the raising of sampling reference edge current potential has with the voltage of output rectifier and filter low-voltage direct output, the feedback control signal that sample circuit provides reduces the duty ratio of primary high voltage direct current energising through photoelectric coupling circuit control pwm switch; The induction output of transformer secondary output reduces through the direct voltage of output rectifier and filter conversion, and the direct voltage of delivering to load reduces.Adjust the resistance of current sampling resistor and the voltage of voltage reference circuit output, can adjust the rate of change of load curve of output.
In the embodiment of an optimization: described sample circuit comprises output branch road that is formed by first error amplifier and first current-limiting resistance serial connection and the dividing potential drop branch road that is formed by two resistance serial connections; The negative pole of first error amplifier is connected with an end of first current-limiting resistance and is that an output of sample circuit, the other end of first current-limiting resistance are another output and the power input of sample circuit in the output branch road; The earth terminal of the just very sample circuit of first error amplifier; Dividing point connects the reference edge of first error amplifier in the output branch road in the dividing potential drop branch road of sample circuit, the free end of a resistance connects the low-voltage direct output of output rectifier and filter in the dividing potential drop branch road, and the free end of another resistance is the sampling reference edge of sample circuit in the dividing potential drop branch road; Described voltage reference circuit comprises constant voltage branch road that is formed by second error amplifier and second current-limiting resistance serial connection and the dividing potential drop branch road that is formed by two resistance serial connections; The earth terminal of the just very voltage reference circuit of second error amplifier in the constant voltage branch road, the negative pole of second error amplifier is connected with the reference edge of second error amplifier and is connected an end of second current-limiting resistance, and the other end of second current-limiting resistance is the power input of voltage reference circuit; The free end of two resistance connects the positive pole and the negative pole of constant voltage branch road second error amplifier respectively in the dividing potential drop branch road of voltage reference circuit, and dividing point is the sampling reference edge of the output connection sample circuit of voltage reference circuit in the dividing potential drop branch road.Second error amplifier of voltage reference circuit uses by the mode of voltage-stabiliser tube, and the voltage source that the constant voltage branch road provides high stable extracts the be added to sampling reference edge of sample circuit of the minus deviation voltage of negative bias voltage on current sampling resistor by the dividing potential drop branch road.Dividing point provides control signal to the reference edge of output branch road first error amplifier in the dividing potential drop branch road of sample circuit, and control flows is through the electric current of first error amplifier; Flow through the first level led luminous quantity of the Current Control photoelectric coupling circuit of first error amplifier and first current-limiting resistance in the output branch road of sample circuit.Load resistance reduces, when flowing through the electric current increase of current sampling resistor, the current potential of the low-voltage direct ground wire of load is raise, the current potential of the sampling reference edge of sample circuit and dividing potential drop branch road dividing point reduces, cause that the first error amplifier conducting degree reduces in the output branch road of sample circuit, the electric current that flows through first error amplifier and first current-limiting resistance reduces; The voltage at the first level led two ends of photoelectric coupling circuit is reduced, luminous quantity reduces, the conducting degree of secondary light lotus root triode reduces, the control end voltage of pwm switch rises, thereby change the duty ratio of pwm switch output, transformer secondary output is risen through the output voltage that output rectifier and filter offers load.Otherwise load resistance increases, and when the electric current that flows through current sampling resistor reduced, the current potential of the low-voltage direct ground wire of load reduced.The current potential of the sampling reference edge of sample circuit and dividing potential drop branch road dividing point raises, and causes that the first error amplifier conducting degree increases in the output branch road of sample circuit, and the electric current that flows through first error amplifier and first current-limiting resistance increases; The voltage at the first level led two ends of photoelectric coupling circuit is increased, luminous quantity increases, the conducting degree of secondary light lotus root triode increases, the control end voltage of pwm switch reduces, the duty ratio of pwm switch output reduces, and transformer secondary output is reduced through the output voltage that output rectifier and filter offers load.
Particularly: the voltage stabilizing value of first error amplifier is identical with the voltage stabilizing value of second error amplifier in the voltage reference circuit in the described sample circuit.Adjust the voltage of voltage reference circuit output, can adjust the rate of change of load curve of output significantly.
The utility model offset-type Switching Power Supply is provided with a current sampling resistor in the ground wire of output, and increasing a voltage reference circuit that is connected with current sampling resistor at the sampling reference edge of sample circuit, the earth terminal current potential of this voltage reference circuit is lower than the earth terminal current potential of load.The minus deviation voltage that on current sampling resistor, produces when utilizing negative bias voltage that voltage reference circuit provides and load current to change, the feedback control signal that sample circuit is provided to pwm switch through photoelectric coupling circuit not only comprises the deviation information of the low-voltage direct output end voltage of output rectifier and filter, the information that also has load current to change.And then make Switching Power Supply can along with load resistance to reduce be that output current increases and increases the direct voltage of delivering to load; Perhaps along with the increase of load resistance is that output current reduces and reduces to deliver to the direct voltage of load.Particularly adopt voltage reference circuit that the mode of negative bias is provided, can obtain adjusting the effect of load curve of output rate of change, and expanded the scope of application of Switching Power Supply of the present utility model thus.Switching Power Supply add ons of the present utility model is few, easy to implement.
Description of drawings
Fig. 1 is the circuit box structure schematic diagram of common pulse-width modulation voltage-stabilizing switch power source.
Fig. 2 is the circuit box structure schematic diagram of the utility model offset-type Switching Power Supply.
Fig. 3 is the electrical block diagram of an embodiment of the utility model offset-type Switching Power Supply.
Fig. 4 is the load curve comparison diagram of Fig. 3 embodiment and linear transformer and common pulse-width modulation voltage-stabilizing switch power source.
Embodiment
The circuit box structure of the utility model offset-type Switching Power Supply, as shown in Figure 2.Please comparison diagram 1, common pulse-width modulation voltage-stabilizing switch power source directly is connected the sampling reference edge of sample circuit 6 with the low-voltage direct output of output rectifier and filter 4; The utility model offset-type Switching Power Supply has increased current sampling resistor 8 and voltage reference circuit 9 between two outputs 403,404 of the sampling reference edge 605 of sample circuit 6 and output rectifier and filter 4; The current potential of voltage reference circuit 9 earth terminals 902 is lower than the current potential of load 5 earth terminals 502.Thereby introduce the minus deviation voltage that on current sampling resistor 8, produces when negative bias voltage that voltage reference circuits 9 provide and load current change at the sampling reference edge 605 of sample circuit 6.The feedback control signal that sample circuit 6 provides to pwm switch 3 through photoelectric coupling circuit 7 not only comprises the deviation information of low-voltage direct output 403 voltages of output rectifier and filter 4, the information that also has load 5 electric currents to change.By the FEEDBACK CONTROL of 6 pairs of pwm switch 3 of sample circuit, output current and the adjustment of output voltage equal proportion when making the resistance variations of load 5.
Please see Figure 2: the input 101 of the input rectifying filter circuit 1 of the utility model offset-type Switching Power Supply is connected with the live wire of electric main, and another input 102 is connected with the zero line of electric main.The high voltage direct current output end 103 of input rectifying filter circuit 1 connects an end 211 of transformer 2 elementary 21, and the other end 212 of transformer 2 elementary 21 connects the output 302 of pwm switch 3.The high voltage direct current ground wire 104 of input rectifying filter circuit 1 connects the earth terminal 304 of pwm switch 3 and the earth terminal 704 of 7 levels of photoelectric coupling circuit respectively.The control input end 303 of pwm switch 3 connects the output 703 of 7 levels of photoelectric coupling circuit.
Two induction outputs, 221,222 corresponding two ac input ends 401,402 that connect output rectifier and filter 4 of 2 levels 22 of transformer.The low-voltage direct output 403 of output rectifier and filter 4 connects the power input 501 of load 5; The low-voltage direct ground wire 404 of output rectifier and filter 4 connects the earth terminal 502 of load 5 through a current sampling resistor 8.The power input 601 of sample circuit 6 is connected on the low-voltage direct output 403 of output rectifier and filter 4, and the earth terminal 602 of sample circuit 6 connects the earth terminal 502 of load 5.Two outputs, 603,604 corresponding two inputs 701,702 that connect photoelectric coupling circuit 7 of sample circuit 6.The output 903 of voltage reference circuit 9 connects the sampling reference edge 605 of sample circuit 6.The power input 901 of voltage reference circuit 9 connects the low-voltage direct output 403 of output rectifier and filter 4, and the earth terminal 902 of voltage reference circuit 9 connects the low-voltage direct ground wire 404 of output rectifier and filter 4.
Input rectifying filter circuit 1 is transformed to high voltage direct current with electric main, pwm switch 3 is switched on or switched off off and on, makes the termination 212 of transformer 2 elementary 21 be connected to the high voltage direct current ground wire 104 of input rectifying filter circuit 1 off and on through pwm switch 3; High voltage direct current flows through off and at elementary 21 of transformer 2.The variation of secondary 22 inductive primary, 21 electric currents of transformer 2, secondary 22 output is transformed to low-voltage DC through output rectifier and filter 4 and delivers to load 5.Sample circuit 6 is by means of the output voltage and the output current of voltage reference circuit 9 and current sampling resistor 8 monitoring output rectifier and filters 4, and the control end voltage by photoelectric coupling circuit 7 control pwm switch 3, thereby the duty ratio of control pwm switch 3 outputs, the resistance variations that makes 2 levels 22 of transformer offer the relative load 5 with electric current of output voltage of load 5 through output rectifier and filter 4 is made corresponding adjustment.
If the resistance of load 5 changes: along with load 5 resistance to reduce be that output rectifier and filter 4 output currents increase, the minus deviation voltage at current sampling resistor 8 two ends increases, the increase of minus deviation voltage causes the current potential of load 5 earth terminals 502 to promote; For the earth terminal 502 of load 5, sampling reference edge 605 current potentials of sample circuit 6 descend.Reduce identical effect because the decline of sampling reference edge 605 current potentials has with the voltage of output rectifier and filter 4 low-voltage direct outputs 403, the feedback control signal that sample circuit 6 provides increases the duty ratio of transformer 2 elementary 21 high voltage direct current energisings through photoelectric coupling circuit 7 control pwm switch 3; The induction output of 2 levels 22 of transformer increases through the direct voltage of output rectifier and filter 4 conversion, and the direct voltage of delivering to load 5 increases.Otherwise along with the resistance increase of load 5 is that output current reduces, the minus deviation voltage at current sampling resistor 8 two ends reduces.The sampling reference edge 605 current potential lifting for the earth terminal 502 of load 5 that reduces to cause sample circuit 6 of minus deviation voltage, increase identical effect because the raising of sampling reference edge 605 current potentials has with the voltage of output rectifier and filter 4 low-voltage direct outputs 403, the feedback control signal that sample circuit 6 provides reduces the duty ratio of transformer 2 elementary 21 high voltage direct current energisings through photoelectric coupling circuit 7 control pwm switch 3; The induction output of 2 levels 22 of transformer reduces through the direct voltage of output rectifier and filter 4 conversion, and the direct voltage of delivering to load 5 reduces.Along with the resistance variations of load 5, the output current of output rectifier and filter 4 and output voltage can produce the equal proportion adjustment of identical change trend automatically.Adjust the resistance of current sampling resistor 8 and the voltage of voltage reference circuit 9 outputs, can adjust the rate of change of load 5 curves of output.
Circuit structure of optimizing embodiment of the utility model offset-type Switching Power Supply, please referring to Fig. 3:
Input rectifying filter circuit 1 is made up of bridge rectifier and the electrochemical capacitor C1 that four rectifier diode D1-D4 constitute.The input 101 of input rectifying filter circuit 1 is connected with the live wire L of electric main, and another input 102 is connected with the zero line N of electric main.The high voltage direct current output end 103 of input rectifying filter circuit 1 connects the termination 211 of transformer 2 elementary 21, and the high voltage direct current ground wire 104 of input rectifying filter circuit 1 connects the earth terminal 304 of pwm switch 3 and the earth terminal 704 of 7 levels of photoelectric coupling circuit respectively.
Rectifier diode D7, electrochemical capacitor C5 and inductance L 1 are formed output rectifier and filter 4.The positive pole of rectifier diode D7 connects the induction output 221 of 2 levels 22 of transformer as an ac input end 401 of output rectifier and filter 4.The negative pole of electrochemical capacitor C5 connects the induction output 222 of 2 levels 22 of transformer as another ac input end 402 of output rectifier and filter 4.One end of inductance L 1 connects the positive pole of electrochemical capacitor C5 and the negative pole of rectifier diode D7, and the other end of inductance L 1 connects the power input 501 of load 5 as the low-voltage direct output 403 of output rectifier and filter 4.The negative pole of electrochemical capacitor C5 is again the low-voltage direct ground wire 404 of output rectifier and filter 4, connects the earth terminal 502 of load 5 through current sampling resistor 8.Electrochemical capacitor C6 and load 5 are in parallel.
The model of photoelectric coupling circuit 7 is EL817 in the present embodiment, and first level led positive pole is connected to a current-limiting resistance R7; The free end of current-limiting resistance R7 is the input 701 of photoelectric coupling circuit 7, and first level led negative pole is the input 702 of photoelectric coupling circuit 7.The current collection of secondary light lotus root triode is the output 703 of photoelectric coupling circuit 7 very; The emission of light lotus root triode is the earth terminal 704 of 7 levels of photoelectric coupling circuit very.
In present embodiment when work: input rectifying filter circuit 1 is transformed to high voltage direct current with electric main, and pwm switch 3 is switched on or switched off off and on, makes high voltage direct current flow through elementary 21 of transformer 2 off and on; The alternating signal of 2 levels of transformer, 22 inductions is transformed to low-voltage DC through current sampling resistor 8 supply loads 5 through output rectifier and filter 4.Because the electric current of output rectifier and filter 4 outputs can form potential difference at the two ends of current sampling resistor 8, the current potential of output rectifier and filter 4 low-voltage direct ground wires 404 is lower than the current potential of load 5 earth terminals 502, that is to say that the current potential of voltage reference circuit 9 earth terminals 902 is lower than the current potential of sample circuit 6 earth terminals 602.Because the error amplifier Z2 of voltage reference circuit 9 uses by the mode of voltage-stabiliser tube, 2.5 volts voltage sources that the constant voltage branch road provides high stable are by the be added to sampling reference edge 605 of sample circuit 6 of the minus deviation voltage of dividing potential drop branch road extraction negative bias voltage on current sampling resistor 8 again.At sample circuit 6 in real time in the process of the voltage and current of monitoring output rectifier and filters 4 output low-voltage DCs, dividing point 607 provides control signal to the reference edge of output branch road error amplifier U2 in the dividing potential drop branch road of sample circuit 6, when the potential difference of dividing point 607 and sample circuit 6 earth terminals 602 is higher than 2.5 volts of the voltage stabilizing values of error amplifier U2, there is electric current to flow through between the positive pole of error amplifier U2 and negative pole; The potential difference control flows of dividing point 607 and sample circuit 6 earth terminals 602 is crossed the electric current of error amplifier U2.The electric current that flows through error amplifier U2 and current-limiting resistance R8 in the output branch road of sample circuit 6 provides control for photoelectric coupling circuit 7 elementary.The first level led luminance of photoelectric coupling circuit 7 influences the conducting state of secondary light lotus root triode, be the control end voltage of pwm switch 3, thereby the duty ratio of control pwm switch 3 outputs makes 2 levels 22 of transformer make adjustment through the variation (being load 5 changes in resistance) that output rectifier and filter 4 offers the relative output current of output voltage of load 5.
For example load 5 resistance reduce, when flowing through the electric current increase of current sampling resistor 8, the earth terminal 502 of load 5 is that the current potential of sample circuit 6 earth terminals 602 raises, the current potential of the sampling reference edge 605 of sample circuit 8 and dividing potential drop branch road dividing point 607 is temporarily constant, dividing point 607 descends with the potential difference of sample circuit 6 earth terminals 602, cause that error amplifier U2 conducting degree reduces in the output branch road of sample circuit 6, the electric current that flows through error amplifier U2 and current-limiting resistance R8 reduces and makes the voltage reduction at the first level led two ends of photoelectric coupling circuit 7, electric current reduces, and luminous quantity weakens; Secondary light lotus root triode end conducting degree reduces, and control end 303 voltages of pwm switch 3 rise, thereby changes the duty ratio of pwm switch 3 outputs, and 2 levels 22 of transformer are risen through the output voltage that output rectifier and filter 4 offers load 5.Otherwise, load resistance increases, when the electric current that flows through current sampling resistor 8 reduces, load 5 earth terminals 502 are that the current potential of sample circuit 6 earth terminals 602 reduces, the current potential of the sampling reference edge 605 of sample circuit 6 and dividing potential drop branch road dividing point 607 is temporarily constant, dividing point 607 increases with the potential difference of sample circuit 6 earth terminals 602, cause that error amplifier U2 conducting degree increases in the output branch road of sample circuit 6, the electric current that flows through error amplifier U2 and current-limiting resistance R8 increases and makes the voltage increase at the first level led two ends of photoelectric coupling circuit 7, electric current increases, and luminous quantity strengthens; Secondary light lotus root triode end conducting degree increases, and control end 303 voltages of pwm switch 3 descend, and the duty ratio of pwm switch 3 outputs is reduced, and 2 levels 22 of transformer descend through the output voltage that output rectifier and filter 4 offers load 5.
Please referring to Fig. 4, it is acclivitous straight line that the load curve B of present embodiment compares with the load curve A of common pulse-width modulation voltage-stabilizing switch power source.The same trend of output voltage and output current, equal proportion ground change.
Special needs to be pointed out is: the model of error amplifier U2 is identical with the model of error amplifier Z2 in the voltage reference circuit 9 in the present embodiment sample circuit 6, and their voltage stabilizing value is identical, is 2.5 volts.Adjust in the voltage reference circuit 9 dividing potential drop branch roads ratio of the resistance value of two resistance R 12, R13, not only influence the voltage of voltage reference circuit 9 outputs, can also adjust the rate of change of load curve of output significantly.
The above only is preferred embodiment of the present utility model, does not limit the scope that the utility model is implemented with this, and the equivalence of doing according to the technical solution of the utility model and description changes and modification, all should belong to the scope that the utility model is contained.
Claims (3)
1. offset-type Switching Power Supply, the high voltage direct current output end of input rectifying filter circuit connects an end of primary, and the primary other end connects the high voltage direct current ground wire of input rectifying filter circuit through pwm switch; Two corresponding two ac input ends that connect output rectifier and filter of induction output of transformer secondary output, the low-voltage direct output of output rectifier and filter connects the power input of load and the power input of sample circuit; Corresponding two inputs that connect photoelectric coupling circuit of two outputs of sample circuit, the output of photoelectric coupling circuit connects the control input end of pwm switch; It is characterized in that: current sampling resistor is serially connected between the earth terminal of the low-voltage direct ground wire of output rectifier and filter and load; The power input of voltage reference circuit connects the low-voltage direct output of output rectifier and filter, the earth terminal of voltage reference circuit connects the low-voltage direct ground wire of output rectifier and filter, and the output of voltage reference circuit connects the sampling reference edge of sample circuit; The earth terminal of sample circuit connects the earth terminal of load.
2. offset-type Switching Power Supply according to claim 1 is characterized in that: described sample circuit comprises output branch road that is formed by first error amplifier and first current-limiting resistance serial connection and the dividing potential drop branch road that is formed by two resistance serial connections; The negative pole of first error amplifier is connected with an end of first current-limiting resistance and is that an output of sample circuit, the other end of first current-limiting resistance are another output and the power input of sample circuit in the output branch road; The earth terminal of the just very sample circuit of first error amplifier; Dividing point connects the reference edge of first error amplifier in the output branch road in the dividing potential drop branch road of sample circuit, the free end of a resistance connects the low-voltage direct output of output rectifier and filter in the dividing potential drop branch road, and the free end of another resistance is the sampling reference edge of sample circuit in the dividing potential drop branch road; Described voltage reference circuit comprises constant voltage branch road that is formed by second error amplifier and second current-limiting resistance serial connection and the dividing potential drop branch road that is formed by two resistance serial connections; The earth terminal of the just very voltage reference circuit of second error amplifier in the constant voltage branch road, the negative pole of second error amplifier is connected with the reference edge of second error amplifier and is connected an end of second current-limiting resistance, and the other end of second current-limiting resistance is the power input of voltage reference circuit; The free end of two resistance connects the positive pole and the negative pole of constant voltage branch road second error amplifier respectively in the dividing potential drop branch road of voltage reference circuit, and dividing point is the sampling reference edge of the output connection sample circuit of voltage reference circuit in the dividing potential drop branch road.
3. offset-type Switching Power Supply according to claim 2 is characterized in that: the voltage stabilizing value of first error amplifier is identical with the voltage stabilizing value of second error amplifier in the voltage reference circuit in the described sample circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200079926U CN201075823Y (en) | 2007-08-15 | 2007-08-15 | Compensation type switch power source |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2007200079926U CN201075823Y (en) | 2007-08-15 | 2007-08-15 | Compensation type switch power source |
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| CN201075823Y true CN201075823Y (en) | 2008-06-18 |
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| CNU2007200079926U Expired - Fee Related CN201075823Y (en) | 2007-08-15 | 2007-08-15 | Compensation type switch power source |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102244951A (en) * | 2010-05-10 | 2011-11-16 | 冠捷投资有限公司 | Light emitting diode (LED) drive circuit |
| CN103049028A (en) * | 2012-11-28 | 2013-04-17 | 华中科技大学 | Constant current source for high voltage magnetic switch resetting |
| CN103731618A (en) * | 2013-11-27 | 2014-04-16 | 乐视致新电子科技（天津）有限公司 | Display device and standby control circuit thereof |
| TWI505060B (en) * | 2013-05-23 | 2015-10-21 | Artilect Green Co Ltd | Voltage regulator with buck light emitting diode |
| CN105425889A (en) * | 2015-11-09 | 2016-03-23 | 华北电力大学（保定） | High-precision voltage and current stability control circuit based on high-frequency power supply pre-regulation level |
| WO2017107452A1 (en) * | 2015-12-22 | 2017-06-29 | 乐视控股（北京）有限公司 | Switch voltage stabilization power source |
-
2007
- 2007-08-15 CN CNU2007200079926U patent/CN201075823Y/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102244951A (en) * | 2010-05-10 | 2011-11-16 | 冠捷投资有限公司 | Light emitting diode (LED) drive circuit |
| CN103049028A (en) * | 2012-11-28 | 2013-04-17 | 华中科技大学 | Constant current source for high voltage magnetic switch resetting |
| CN103049028B (en) * | 2012-11-28 | 2014-07-23 | 华中科技大学 | Constant current source for high voltage magnetic switch resetting |
| TWI505060B (en) * | 2013-05-23 | 2015-10-21 | Artilect Green Co Ltd | Voltage regulator with buck light emitting diode |
| CN103731618A (en) * | 2013-11-27 | 2014-04-16 | 乐视致新电子科技（天津）有限公司 | Display device and standby control circuit thereof |
| CN103731618B (en) * | 2013-11-27 | 2017-12-12 | 乐视致新电子科技（天津）有限公司 | Display device and its readiness control circuit |
| CN105425889A (en) * | 2015-11-09 | 2016-03-23 | 华北电力大学（保定） | High-precision voltage and current stability control circuit based on high-frequency power supply pre-regulation level |
| WO2017107452A1 (en) * | 2015-12-22 | 2017-06-29 | 乐视控股（北京）有限公司 | Switch voltage stabilization power source |
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Granted publication date: 20080618 Termination date: 20110815 |