CN110277897A - A kind of constant-current control circuit and switching power circuit - Google Patents
A kind of constant-current control circuit and switching power circuit Download PDFInfo
- Publication number
- CN110277897A CN110277897A CN201910636071.3A CN201910636071A CN110277897A CN 110277897 A CN110277897 A CN 110277897A CN 201910636071 A CN201910636071 A CN 201910636071A CN 110277897 A CN110277897 A CN 110277897A
- Authority
- CN
- China
- Prior art keywords
- circuit
- constant
- signal
- current
- switching tube
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000005070 sampling Methods 0.000 claims abstract description 70
- 230000005347 demagnetization Effects 0.000 claims abstract description 43
- 238000001514 detection method Methods 0.000 claims abstract description 20
- 239000003990 capacitor Substances 0.000 claims description 20
- 230000005611 electricity Effects 0.000 claims description 12
- 238000010521 absorption reaction Methods 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 7
- 238000010586 diagram Methods 0.000 description 5
- 230000003321 amplification Effects 0.000 description 4
- 238000003199 nucleic acid amplification method Methods 0.000 description 4
- 230000001939 inductive effect Effects 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000004146 energy storage Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000011176 pooling Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/0003—Details of control, feedback or regulation circuits
- H02M1/0009—Devices or circuits for detecting current in a converter
Abstract
The present invention relates to current constant control technical fields, specifically disclose a kind of constant-current control circuit, wherein, constant-current control circuit includes: demagnetization detection circuit, sampling hold circuit, operational transconductance amplifying circuit, ratio buffer, PWM comparator and rest-set flip-flop, demagnetization detection circuit and sampling hold circuit are connect with the input terminal of operational transconductance amplifying circuit, the output end of operational transconductance amplifying circuit and the input terminal of ratio buffer connect, the output end of ratio buffer is connected to the inverting input terminal of PWM comparator, the output end of PWM comparator is connected to the input terminal of rest-set flip-flop, the output end feedback link of rest-set flip-flop to sampling hold circuit input terminal, the input terminal of sampling hold circuit and the non-inverting input terminal of PWM comparator are also used to input sample voltage signal.The invention also discloses a kind of switching power circuits.Constant-current control circuit provided by the invention can be realized the adjusting of output current precision, and then realize output high-precision current.
Description
Technical field
The present invention relates to current constant control technical field more particularly to a kind of constant-current control circuit and including current constant control electricity
The switching power circuit on road.
Background technique
The output electric current general expression of flyback topologies applied to primary-side-control are as follows:
Wherein, NpPrimary side the number of turns of indication transformer, NsSecondary side the number of turns of indication transformer, Ip,pkIndication transformer primary side
Peak point current, TdemIndicate demagnetization time, TswIndicate the switching tube duty cycle.
In existing conventional constant current control mode, the transformer primary pair side turn ratioWith sampling resistor RcsIt keeps not
Become, in current constant control loop, can be controlled by loop feedback ensures Vcs,pkWithFor constant, that is, it can guarantee output electric current
Mean value is steady state value.For example, in control circuit, it is assumed that the former secondary side turn ratio of the topology flyback transformerSampling electricity
Hinder Rcs=862.5m Ω.According to conventional constant current control mode, controlling two variables respectively is steady state value, then passes through feedback control loop
Control CS crest voltage Vcs,pk=500mV, while controlling the ratio of demagnetization time and periodIt is finally loaded defeated
Electric current can constant be 2A out.But under conventional constant current control mode, since variable needs individually to control, variable is respectively
There are its distributions and respectively impacted factor, and it is low that this will lead to final constant current output precision.For example, in the example above
In, due to Vcs,pkThe Variable Control of=500mV, andVariable Control be individually separate loop feedback control,
Final output situation often without Theoretical Design when it is so ideal, it is assumed that there are 1% deviations for respective final output, then actually
Obtained control variable Vcs,pk=495mV,Obtaining load output electric current is 1.96A, defeated with preset 2A electric current
There is 2% error out, i.e. the error of final output electric current is exaggerated.
Therefore, the output current precision how improved in constant-current control circuit is asked as technology instantly urgently to be resolved
Topic.
Summary of the invention
The present invention is directed at least solve one of the technical problems existing in the prior art, provide a kind of constant-current control circuit and
Switching power circuit including the constant-current control circuit, to solve the problems of the prior art.
As the first aspect of the invention, a kind of constant-current control circuit is provided, wherein the constant-current control circuit packet
It includes: demagnetization detection circuit, sampling hold circuit, operational transconductance amplifying circuit, ratio buffer, PWM comparator and rest-set flip-flop,
The demagnetization detection circuit and the sampling hold circuit are connect with the input terminal of the operational transconductance amplifying circuit, it is described across
The input terminal of the output end and the ratio buffer of leading operational amplification circuit connects, the output end connection of the ratio buffer
To the inverting input terminal of the PWM comparator, the output end of the PWM comparator is connected to the input terminal of the rest-set flip-flop,
Input terminal of the output end feedback link of the rest-set flip-flop to the sampling hold circuit, the input of the sampling hold circuit
The non-inverting input terminal of end and the PWM comparator is also used to input sample voltage signal；
The sampling hold circuit obtains sampling and keeps electricity for the sampled voltage signal to be sampled and kept
Pressure；
The demagnetization detection circuit is for exporting demagnetization time signal；
The operational transconductance amplifying circuit is used to keep voltage to control by the demagnetization time signal sampling
Sampled current signals are made；
The ratio buffer is used to carry out scaled down to the sampled current signals to control to obtain scaled down signal；
The PWM comparator is for being compared and being closed to the scaled down signal and the sampled voltage signal
Break signal；
The rest-set flip-flop is for being handled to obtain switching tube logic control signal to the cut-off signals to control function
The conducting and shutdown of rate switching tube.
Preferably, the constant-current control circuit further includes power tube Continuity signal generator, the power tube Continuity signal
Generator is for generating Continuity signal.
Preferably, the S input terminal of the rest-set flip-flop connects the power tube Continuity signal generator, the rest-set flip-flop
R input connect the output end of the PWM comparator, the rest-set flip-flop is used under the action of the Continuity signal to institute
Cut-off signals are stated to be handled to obtain the switching tube logic control signal.
Preferably, the constant-current control circuit further includes gate driving circuit, and the input terminal of the gate driving circuit connects
The output end of the rest-set flip-flop is connect, the gate driving circuit is for handle to the switching tube logic control signal
To switching tube driving signal, and export the switching tube driving signal.
Preferably, the constant-current control circuit further includes reference circuit, and the reference circuit is detected with the demagnetization respectively
Circuit, operational transconductance amplifying circuit, sampling hold circuit, ratio buffer are connected with PWM comparator, for providing reference voltage
Signal and reference current signal.
Preferably, the sampling hold circuit includes first switch tube and samples holding capacitor, the first switch tube
Driving end connects the output end of the rest-set flip-flop, and the first end of the first switch tube connects the one of the sampling holding capacitor
End, the second end of the first switch tube connect for inputting the sampled voltage signal, the other end of the sampling holding capacitor
Connect signal ground.
Preferably, the operational transconductance amplifying circuit includes: second switch, third switching tube and operational transconductance amplification
Device, the driving end of the second switch are connect with the output end of the demagnetization detection circuit, and the first of the second switch
The first end of end connection third switching tube, the second end of the second switch connect one end of the sampling holding capacitor, institute
The driving end for stating third switching tube connects the output end of the demagnetization detection circuit, and the second end of the third switching tube connects letter
The normal phase input end on number ground, the operational transconductance amplifier is used for input reference voltage signal, the operational transconductance amplifier
Inverting input terminal connects the first end of the second switch, and the output end of the operational transconductance amplifier is for exporting described adopt
Sample current signal.
Preferably, the ratio buffer includes: operational amplifier, the 4th switching tube, the first divider resistance and second point
Piezoresistance, the normal phase input end of the operational amplifier for inputting the sampled current signals, the operational amplifier it is anti-
Phase input terminal is connected to the second end of the 4th switching tube, and the output end of the operational amplifier connects the 4th switching tube
Driving end, the first end of the 4th switching tube connects input voltage signal, and the second end of the 4th switching tube connects institute
One end of the first divider resistance is stated, the other end of first divider resistance is by the second divider resistance connection signal.
Preferably, the first switch tube, second switch, third switching tube and the 4th switching tube include N-type switch
Pipe.
As the second aspect of the invention, a kind of switching power circuit is provided, wherein the switching power circuit packet
It includes: current rectifying and wave filtering circuit, RCD energy absorption circuit, transformer, output control circuit, power switch tube and previously described perseverance
Flow control circuit, the current rectifying and wave filtering circuit is connect with the RCD energy absorption circuit and the constant-current control circuit, described
The output end of constant-current control circuit is connect with the driving end of the power switch tube, the power switch tube and the RCD energy
Absorbing circuit is connect with the source side of the transformer, and the secondary side of the transformer is connect with the output control circuit, described
It is described to control that constant-current control circuit obtains switching tube logic control signal after capable of handling the sampled voltage signal
The conducting and shutdown of power switch tube.
Constant-current control circuit provided by the invention, by sampling hold circuit realize to sampled voltage signal carry out sampling and
It keeps, keeps voltage to carry out controlling proper sampling under the action of demagnetizing time signal sampling by operational transconductance amplifying circuit
Current signal passes through switching tube logic finally by being handled sampled current signals to obtain switching tube logic control signal
The control of the conducting and shutdown to power switch tube may be implemented in control signal, to switch when the constant-current control circuit is applied
It can be realized the adjusting of output current precision when in power circuit, and then realize output high-precision current.
Detailed description of the invention
The drawings are intended to provide a further understanding of the invention, and constitutes part of specification, with following tool
Body embodiment is used to explain the present invention together, but is not construed as limiting the invention.In the accompanying drawings:
Fig. 1 is the structural block diagram of constant-current control circuit provided by the invention.
Fig. 2 is the circuit structure diagram of switching power circuit provided by the invention.
Fig. 3 is the structure chart of sampling hold circuit provided by the invention and operational transconductance amplifying circuit.
Fig. 4 is the circuit diagram of ratio buffer and PWM comparator provided by the invention.
Fig. 5 a is a kind of embodiment structure figure of power tube Continuity signal generator provided by the invention.
Fig. 5 b is the another embodiment structure chart of power tube Continuity signal generator provided by the invention.
Fig. 6 is the waveform diagram of each signal in Fig. 1.
Fig. 7 is the waveform diagram of each signal in Fig. 5 a.
Specific embodiment
Below in conjunction with attached drawing, detailed description of the preferred embodiments.It should be understood that this place is retouched
The specific embodiment stated is merely to illustrate and explain the present invention, and is not intended to restrict the invention.
In order to realize the output current precision that can be improved in constant-current control circuit, the present invention is to be applied to work critical
For the isolated flyback converter of primary-side-control of conduction mode (BCM).Energy transmission is carried out between main coil and secondary coil；
Output information is transmitted in auxiliary winding by secondary coil, and the isolation output and input is realized using transformer.General switch
Power control system, there is power tube is switched on and off two processes.When power tube is opened, primary side inductance can be formed over the ground
One access, input terminal provides energy for transformer, while primary side inductance carries out energy storage, secondary side diode cut-off, load output
Energy is supplied by the energy stored in output capacitance；When power tube shutdown, transformer releases energy, secondary inductance release
Energy.The turn-on and turn-off of power tube are controlled by internal feedback circuitry, realize the constant of final output electric current.
Current formula can must be exported by system power grade control principle are as follows:
Wherein, NpPrimary side the number of turns of indication transformer, NsSecondary side the number of turns of indication transformer, Ip,pkIndication transformer primary side
Peak point current, TdemIndicate demagnetization time, TswIndicate the switching tube duty cycle.
It is found that it can be with by way of by using " unique " Variable Control the analysis to conventional constant current control mode principle
Realize the output of high-accuracy and constant constant current.Therefore, the present invention provides a kind of constant-current control circuit, public to control above-mentioned output electric current
In formulaThe product of three's variable be constant basis, herein can this three's variable product be referred to as " sampling
Value " is " unique " variable in Constant Current Control System.
Specifically, as the first aspect of the invention, a kind of constant-current control circuit 112 is provided, wherein as shown in Figure 1,
The constant-current control circuit 112 include: demagnetization detection circuit 206, sampling hold circuit 207, operational transconductance amplifying circuit 203,
Ratio buffer 204, PWM comparator 205 and rest-set flip-flop 208, the demagnetization detection circuit 206 and the sampling hold circuit
207 connect with the input terminal of the operational transconductance amplifying circuit 203, the output end of the operational transconductance amplifying circuit 203 with
The input terminal of the ratio buffer 204 connects, and the output end of the ratio buffer 204 is connected to the PWM comparator 205
Inverting input terminal, the output end of the PWM comparator 205 is connected to the input terminal of the rest-set flip-flop 208, the RS triggering
Input terminal of the output end feedback link of device 208 to the sampling hold circuit 207, the input of the sampling hold circuit 207
The non-inverting input terminal of end and the PWM comparator 205 is also used to input sample voltage signal；
The sampling hold circuit 207 obtains sampling and keeps for the sampled voltage signal to be sampled and kept
Voltage；
The demagnetization detection circuit 206 is for exporting demagnetization time signal；
The operational transconductance amplifying circuit 203 is used to keep voltage to carry out by the demagnetization time signal sampling
Control obtains sampled current signals；
The ratio buffer 204 is used to carry out the sampled current signals scaled down and controls to obtain scaled down letter
Number；
The PWM comparator 205 is for being compared the scaled down signal and the sampled voltage signal
To cut-off signals；
The rest-set flip-flop 208 is for being handled to obtain switching tube logic control signal to the cut-off signals to control
The conducting and shutdown of power switch tube.
Constant-current control circuit provided by the invention, by sampling hold circuit realize to sampled voltage signal carry out sampling and
It keeps, keeps voltage to carry out controlling proper sampling under the action of demagnetizing time signal sampling by operational transconductance amplifying circuit
Current signal passes through switching tube logic finally by being handled sampled current signals to obtain switching tube logic control signal
The control of the conducting and shutdown to power switch tube may be implemented in control signal, to switch when the constant-current control circuit is applied
It can be realized the adjusting of output current precision when in power circuit, and then realize output high-precision current.
Specifically, as shown in Figure 1, the constant-current control circuit 112 further includes power tube Continuity signal generator 202, institute
Power tube Continuity signal generator 202 is stated for generating Continuity signal.
Specifically, the S input terminal of the rest-set flip-flop 208 connects the power tube Continuity signal generator 112, the RS
The R input of trigger 208 connects the output end of the PWM comparator 205, and the rest-set flip-flop 208 is used in the conducting
The cut-off signals are handled under the action of signal to obtain the switching tube logic control signal.
Specifically, the constant-current control circuit 112 further includes gate driving circuit 219, the gate driving circuit 219
Input terminal connects the output end of the rest-set flip-flop 208, and the gate driving circuit 219 is used for the switching tube logic control
Signal is handled to obtain switching tube driving signal, and exports the switching tube driving signal.
Specifically, as shown in Figure 1, the constant-current control circuit 112 further includes reference circuit 201, the reference circuit 201
Respectively with the demagnetization detection circuit 206, operational transconductance amplifying circuit 203, sampling hold circuit 207, ratio buffer 204 and
PWM comparator 205 connects, for providing reference voltage signal and reference current signal.
It should be noted that the connection relationship between reference circuit 201 and other circuits is not shown in Fig. 1.
Specifically, as depicted in figs. 1 and 2, reference circuit 201, to generate required for the constant-current control circuit 112
Reference voltage Vref required for various reference voltages and reference current, such as operational transconductance amplifying circuit 203, the voltage determine
The value of " sampling mean value "；Demagnetization detection circuit 206 is extracted demagnetization time signal by FB signal；Sampling keeps electricity
Road 207 is sampled and is kept to the input voltage Vcs of the CS pin of constant-current control circuit 112；Operational transconductance amplifying circuit
203, electric current is converted to by demagnetization time signal control to the voltage that sampling hold circuit 207 is kept；Built-in compensation electricity
Hold 217, in the present embodiment, built-in compensating electric capacity size is 50pF；Ratio buffer circuit 204, to sampled current signals 213 into
Row scaled down simultaneously plays pooling feature；PWM comparator 205 compares scaled down signal 218 and sampled voltage signal 216
Cut-off signals 214 are exported afterwards；RS triggers 208 devices, receives conductivity control signal 215 and cut-off signals 214, finally generates switching tube
Logic control signal 210；Switching tube logic control signal 210 is converted to high-voltage power and opened by power tube gate driving circuit 219
Pipe driving signal 220 is closed, and is exported by the BD pin of constant-current control circuit 112, conducting and the pass of power switch tube 113 are controlled
It is disconnected.
Specifically, as shown in figure 3, the sampling hold circuit 207 includes first switch tube 301 and sampling holding capacitor
302, the driving end of the first switch tube 301 connects the output end of the rest-set flip-flop 208, the first switch tube 301
First end connects one end of the sampling holding capacitor 302, and the second end of the first switch tube 301 is for inputting the sampling
Voltage signal 216VCS, the other end connection signal of the sampling holding capacitor 302.
Specifically, as shown in figure 3, the operational transconductance amplifying circuit 203 includes: second switch 303, third switching tube
306 and operational transconductance amplifier 307, the output end at the driving end of the second switch 303 and the demagnetization detection circuit 206
Connection, the first end of the first end connection third switching tube 306 of the second switch 303, the of the second switch 303
Two ends connect one end of the sampling holding capacitor 302, and the driving end of the third switching tube 306 connects the demagnetization detection electricity
The output end on road 206, the second end connection signal of the third switching tube 306, the positive of the operational transconductance amplifier 307
Input terminal is used for input reference voltage signal 209, and the inverting input terminal connection described second of the operational transconductance amplifier 307 is opened
The first end of pipe 303 is closed, the output end of the operational transconductance amplifier 307 is for exporting the sampled current signals 213.
Preferably, the first switch tube 301, second switch 303 and third switching tube 306 all can be N-type switches
Pipe.
Fig. 3 by taking N type switch tube as an example, distinguish by the first switch tube 301, second switch 303 and third switching tube 306
It is controlled by the non-signal 305 of switching tube logic control signal 210, demagnetization signal 212 and demagnetization.
Primary side peak point current sampled signal is obtained by the pin CS of constant-current control circuit 112, and by after sampling resistor
Sampled voltage signal 216 is obtained, by the first switch tube 301 controlled by power tube logic control signal 210, to sampled voltage
Signal 216 is sampled.Then, average value operation is carried out in switch periods according to magnetizing inductance demagnetization time signal 212, from
And obtain average current.In 210 turn-on time of power tube logic control signal, sampling of the holding capacitor 302 to primary side is sampled
Voltage signal 216 is sampled, i.e. sampling holding capacitor 302 charges；In 210 deadline of power tube logic control signal
Interior, first switch tube 301 turns off, and sampling holding capacitor 302 keeps signal 211V by samplingsampleElectric discharge.In non-demagnetization
Interior, the non-signal 305 of demagnetization is high level, and demagnetization signal 212 is low level, and corresponding control third switching tube 306 is connected, corresponding
Second switch 303 turns off, and samples mean value signal 304V at this timeCS,sampleIt is grounded, compensating electric capacity 217 charges in piece；In demagnetization
In, demagnetization signal 212 is high level, and the non-signal 305 of demagnetization is low level, and corresponding control second switch 303 is connected, right
Third switching tube 306 is answered to turn off, compensating electric capacity 217 is discharged in piece.According in signal period, charge and discharge in compensating electric capacity 217 in piece
The principle of electric equilibrium, available following equation:
gm·(Vref-0)·(T-Tdem)+gm·(Vref-Vcs1)·Tdem=0,
Wherein, VrefIndicate reference voltage 209, T required for operational transconductance amplifying circuit 203demIndicate demagnetization time, T
Indicate switching tube duty cycle, VCS1Indicate the equal threshold voltage of sampling under the demagnetization time, gmIndicate the amplification of operational transconductance shown in Fig. 3
The equivalent transconductance value of device 307.
The interior mutual conductance g with OTA in discharge time when chargingmWhen remaining unchanged, following equation is obtained:
Compare previously described " sampling mean value "It can be found thatThis equation is constant current ring
Under road, " unique " variable of required control.ByEquation, under constant current topology of the present invention, it is desirable that mutual conductance fortune
(0~1V) under amplifier 307 changes in gamut is calculated, mutual conductance is invariable.Mutual conductance 307 generates needed for PWM comparator 205
Sampled current signals 213, after ratio buffer 204 carries out a certain proportion of scaling, PWM comparator 205 can be according to prime
The output of circuit and corresponding sampled voltage signal 216 are compared, and generate the cut-off signals of corresponding constant current loop.
As shown in figure 4, the ratio buffer 204 includes: operational amplifier 400, the 4th switching tube 401, first partial pressure
Resistance 402 and the second divider resistance 403, the normal phase input end of the operational amplifier 400 is for inputting the sample rate current letter
Numbers 213, the inverting input terminal of the operational amplifier 400 is connected to the second end of the 4th switching tube 401, and the operation is put
The output end of big device 400 connects the driving end of the 4th switching tube 401, and the first end connection of the 4th switching tube 401 is defeated
Entering voltage signal VDD, the second end of the 4th switching tube 401 connects one end of first divider resistance 402, and described first
The other end of divider resistance 402 is by 403 connection signal of the second divider resistance.
It should be noted that when the first switch tube 301, second switch 303, third switching tube 306 and the 4th are opened
When pass pipe 401 is N type switch tube, then the driving end of each switching tube is grid, and first end is drain electrode, and second end is source electrode.
As shown in figure 4, ratio buffer 204 be only an embodiment, using operational amplifier 400, the 4th switching tube 401,
First divider resistance 402 and the second divider resistance 403 are constituted, and the Y of node 405 locates output voltage with operational amplifier 400 just
The input voltage corresponding relationship of phase input terminal nodes X is as follows:
Wherein, VYIndicate that the voltage at the Y of node 405, i.e. ratio buffer output voltage, X indicate operational transconductance amplification
Device output voltage, RaIndicate the first divider resistance 402, RbIndicate the second divider resistance 403.
It should be noted that at node 405 by 404 connection signal of a filter capacitor.
Corresponding each node waveform is as shown in Figure 6.Thus the negative feedback closed loop control loop constituted, can be realized formulaReference voltage signal 209 is maintained, to obtain constant output electric current.
Fig. 5 a is a specific embodiment of power tube Continuity signal generator 202, and 508 indicate to come from reference circuit 201
Bias voltage；5th switching tube 501, the 6th switching tube 502, the 7th switching tube 504 and the 8th switching tube 505 collectively form electricity
Comparator is flowed, when output voltage feedback signal FB is negative voltage, quasi-resonance valley conduction signal (QR) 509 is low level；When
When FB is zero level or positive voltage, quasi-resonance valley conduction signal 509 is high level；9th switching tube 503 and the tenth switch
Pipe 506 collectively forms phase inverter, and output after 509 reverse phase of quasi-resonance valley conduction signal is obtained quasi-resonance valley conduction signal
The non-signal 510 of non-signal 510, quasi-resonance valley conduction signal exports final conductivity control signal by the first trigger 507
215.It is as shown in Figure 7 that each signal corresponds to waveform.
Fig. 5 b is another specific embodiment of power tube Continuity signal generator 202.Output voltage feedback pin FB electricity
Pressure and the reference voltage 514 from reference circuit 201, are compared by comparator 511, when FB voltage is higher than reference voltage 514,
The output signal 513 of comparator 511 is high level；When FB voltage is lower than reference voltage 514, output 513 is low level, is passed through
Second trigger 512 exports final conductivity control signal 215.
It should be noted that the 5th switching tube 501, the 6th switching tube 502 and the 9th switching tube 503 can be p-type
Switching tube, the 7th switching tube 504, the 8th switching tube 505 and the tenth switching tube 506 can be N type switch tube.
Final rest-set flip-flop 208 receives conductivity control signal 215 and cut-off signals 214, generates switching tube logic control letter
Numbers 210；Switching tube logic control signal 210 is converted to high-voltage circuit breaker pipe driving letter by power tube gate driving circuit 219
Numbers 220, and exported by the BD pin of constant-current control circuit 112, control the conducting and shutdown of power switch tube 113.
As the second aspect of the invention, a kind of switching power circuit is provided, wherein as shown in Fig. 2, the switch is electric
Source circuit includes: current rectifying and wave filtering circuit, RCD energy absorption circuit 111, transformer 115, output control circuit, power switch tube
113 and previously described constant-current control circuit 112, the current rectifying and wave filtering circuit and the RCD energy absorption circuit 111 and institute
State the connection of constant-current control circuit 112, the driving end of the output end of the constant-current control circuit 112 and the power switch tube 113
Connection, the power switch tube 113 and the RCD energy absorption circuit 111 are connect with the source side of the transformer 115, institute
The secondary side for stating transformer 115 is connect with the output control circuit, and the constant-current control circuit 112 can be to the sampled voltage
Signal obtains switching tube logic control signal to control the conducting and shutdown of the power switch tube after being handled.
Switching power circuit provided by the invention, since the constant-current control circuit of use above is as controller, by adopting
The realization of sample holding circuit is sampled and is kept to sampled voltage signal, keeps voltage to sampling by operational transconductance amplifying circuit
It carries out controlling proper sampled current signals under the action of demagnetizing time signal, be handled finally by sampled current signals
Switching tube logic control signal is obtained, conducting and shutdown to power switch tube may be implemented by switching tube logic control signal
Control, so as to realize output current precision adjusting, and then realize output high-precision current.
Specifically, as shown in Fig. 2, being the specific embodiment of the switching power circuit of a primary-side-control of the invention, the
One rectifier diode 101, the second rectifier diode 102, third rectifier diode 103, the 4th rectifier diode 104 and filtered electrical
Hold 105 and constitute current rectifying and wave filtering circuit, Vdc is indicated through over commutation, filtered high direct voltage；106 indicate high voltage startup resistance；
107, which are expressed as constant-current control circuit 112, provides the storage capacitor of electric energy；108 indication transformer auxiliary winding rectifier diodes；
109 and 110 be two divider resistances of output voltage feedback；111 indicate RCD energy absorption network；113 indicate external high pressure function
Rate switching tube；114 indication transformer primary side inductive current sampling resistance；115 be transformer；116 be transformer secondary output around
Group rectifier diode；117 be output filter capacitor；118 be output loading.Vout is output voltage.
After switching power circuit powers on, VIN charges to filter capacitor 107 by high voltage startup resistance 106, filtered electrical
Hold 107 voltages to gradually rise；After filter capacitor voltage rises to a certain preset value, constant-current control circuit 12 is started to work.BD
Foot exports high level control power tube 113 and is connected；After power tube 113 is connected, electric current flows through 115 primary side inductance Np of transformer storage
Energy；When power tube 113 is connected, secondary side rectifier diode 116 ends, and output load current in output capacitance 117 by storing
Energy provides.With the increase of inductive current, voltage is gradually increased on sampling resistor 114, when electric current reaches constant-current control circuit
After the current-limiting points being pre-designed inside 112, the BD output low level control power tube 113 of constant-current control circuit 112 ends；Secondary side
Rectifier diode 116 is connected；The energy of storage is passed through output winding Ns release by transformer 115 in the form of electric current；Output electricity
Stream is powered for load and output capacitance 117.Therefore, believed by the sampled voltage on sampling primary side inductive current sampling resistance 114
Number CS and output voltage feedback pin FB voltage FB, the conducting of the output waveform of the adjustable BD pin of constant-current control circuit 112
Time, and then the output power of control switch power circuit.
It is understood that the principle that embodiment of above is intended to be merely illustrative of the present and the exemplary implementation that uses
Mode, however the present invention is not limited thereto.For those skilled in the art, essence of the invention is not being departed from
In the case where mind and essence, various changes and modifications can be made therein, these variations and modifications are also considered as protection scope of the present invention.
Claims (10)
1. a kind of constant-current control circuit, which is characterized in that the constant-current control circuit includes: demagnetization detection circuit, sampling holding
Circuit, operational transconductance amplifying circuit, ratio buffer, PWM comparator and rest-set flip-flop, the demagnetization detection circuit and described are adopted
Sample holding circuit is connect with the input terminal of the operational transconductance amplifying circuit, the output end of the operational transconductance amplifying circuit with
The input terminal of the ratio buffer connects, and the reverse phase that the output end of the ratio buffer is connected to the PWM comparator is defeated
Enter end, the output end of the PWM comparator is connected to the input terminal of the rest-set flip-flop, the output end feedback of the rest-set flip-flop
It is connected to the input terminal of the sampling hold circuit, the same phase of the input terminal of the sampling hold circuit and the PWM comparator
Input terminal is also used to input sample voltage signal；
The sampling hold circuit obtains sampling and keeps voltage for the sampled voltage signal to be sampled and kept；
The demagnetization detection circuit is for exporting demagnetization time signal；
The operational transconductance amplifying circuit is used to keep voltage control by the demagnetization time signal sampling
To sampled current signals；
The ratio buffer is used to carry out scaled down to the sampled current signals to control to obtain scaled down signal；
The PWM comparator is used to be compared to obtain shutdown letter to the scaled down signal and the sampled voltage signal
Number；
The rest-set flip-flop is used to handle the cut-off signals to obtain switching tube logic control signal and be opened with controlling power
Close the conducting and shutdown of pipe.
2. constant-current control circuit according to claim 1, which is characterized in that the constant-current control circuit further includes power tube
Continuity signal generator, the power tube Continuity signal generator is for generating Continuity signal.
3. constant-current control circuit according to claim 2, which is characterized in that the S input terminal of the rest-set flip-flop connects institute
Power tube Continuity signal generator is stated, the R input of the rest-set flip-flop connects the output end of the PWM comparator, the RS
Trigger is for handling the cut-off signals under the action of Continuity signal to obtain the switching tube logic control
Signal.
4. constant-current control circuit according to claim 1, which is characterized in that the constant-current control circuit further includes that grid drives
Dynamic circuit, the input terminal of the gate driving circuit connect the output end of the rest-set flip-flop, and the gate driving circuit is used for
The switching tube logic control signal is handled to obtain switching tube driving signal, and exports the switching tube driving signal.
5. constant-current control circuit according to claim 1, which is characterized in that the constant-current control circuit further includes benchmark electricity
Road, the reference circuit are buffered with the demagnetization detection circuit, operational transconductance amplifying circuit, sampling hold circuit, ratio respectively
Device is connected with PWM comparator, for providing reference voltage signal and reference current signal.
6. constant-current control circuit according to claim 1, which is characterized in that the sampling hold circuit includes first switch
Pipe and sampling holding capacitor, the driving end of the first switch tube connects the output end of the rest-set flip-flop, the first switch
The first end of pipe connects one end of the sampling holding capacitor, and the second end of the first switch tube is for inputting the sampling electricity
Pressure signal, the other end connection signal of the sampling holding capacitor.
7. constant-current control circuit according to claim 6, which is characterized in that the operational transconductance amplifying circuit includes:
Two switching tubes, third switching tube and operational transconductance amplifier, the driving end of the second switch and the demagnetization detection circuit
Output end connection, the first end of the first end connection third switching tube of the second switch, the of the second switch
Two ends connect one end of the sampling holding capacitor, and the driving end of the third switching tube connects the defeated of the demagnetization detection circuit
Outlet, the second end connection signal of the third switching tube, the normal phase input end of the operational transconductance amplifier is for inputting
Reference voltage signal, the inverting input terminal of the operational transconductance amplifier connect the first end of the second switch, it is described across
The output end of operational amplifier is led for exporting the sampled current signals.
8. constant-current control circuit according to claim 7, which is characterized in that the ratio buffer includes: operation amplifier
Device, the 4th switching tube, the first divider resistance and the second divider resistance, the normal phase input end of the operational amplifier is for inputting institute
Sampled current signals are stated, the inverting input terminal of the operational amplifier is connected to the second end of the 4th switching tube, the fortune
The output end for calculating amplifier connects the driving end of the 4th switching tube, and the first end of the 4th switching tube connects input voltage
Signal, the second end of the 4th switching tube connect one end of first divider resistance, first divider resistance it is another
End is by the second divider resistance connection signal.
9. the constant-current control circuit according to any one of claim 8, which is characterized in that the first switch tube,
Two switching tubes, third switching tube and the 4th switching tube include N type switch tube.
10. a kind of switching power circuit, which is characterized in that the switching power circuit includes: current rectifying and wave filtering circuit, RCD energy
Current constant control described in any one of absorbing circuit, transformer, output control circuit, power switch tube and claim 1 to 9
Circuit, the current rectifying and wave filtering circuit are connect with the RCD energy absorption circuit and the constant-current control circuit, the constant current control
The output end of circuit processed is connect with the driving end of the power switch tube, the power switch tube and RCD energy absorption electricity
The source side of transformer described in Lu Junyu connects, and the secondary side of the transformer is connect with the output control circuit, the constant current control
Circuit processed obtains switching tube logic control signal after capable of handling the sampled voltage signal and is opened with controlling the power
Close the conducting and shutdown of pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910636071.3A CN110277897B (en) | 2019-07-15 | 2019-07-15 | Constant current control circuit and switching power supply circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910636071.3A CN110277897B (en) | 2019-07-15 | 2019-07-15 | Constant current control circuit and switching power supply circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110277897A true CN110277897A (en) | 2019-09-24 |
| CN110277897B CN110277897B (en) | 2023-12-29 |
Family
ID=67964465
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910636071.3A Active CN110277897B (en) | 2019-07-15 | 2019-07-15 | Constant current control circuit and switching power supply circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110277897B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111294034A (en) * | 2020-03-23 | 2020-06-16 | 广东美的白色家电技术创新中心有限公司 | Grid drive circuit, power switch circuit and electrical equipment |
| CN113630121A (en) * | 2021-08-19 | 2021-11-09 | 电子科技大学 | Sampling holding and knee point detection circuit |
| CN114499121A (en) * | 2022-04-14 | 2022-05-13 | 深圳市芯茂微电子有限公司 | Controller of switching power supply and switching power supply |
| CN117310262A (en) * | 2023-11-28 | 2023-12-29 | 成都市易冲半导体有限公司 | Primary side information detection circuit and detection chip of transformer |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101459381A (en) * | 2008-12-10 | 2009-06-17 | 浙江大学 | Control apparatus and method for Boost type switch converter |
| CN101471600A (en) * | 2007-11-29 | 2009-07-01 | 意法半导体股份有限公司 | Isolated voltage converter with feedback on the primary winding, and corresponding method for controlling the output voltage |
| CN103219884A (en) * | 2012-01-19 | 2013-07-24 | 美芯晟科技（北京）有限公司 | Control circuit and control method of primary side feedback constant current |
| CN103248227A (en) * | 2013-05-30 | 2013-08-14 | 杭州士兰微电子股份有限公司 | Switching power supply and switching power supply controller for realizing constant output current |
| CN103476180A (en) * | 2013-09-12 | 2013-12-25 | 杭州士兰微电子股份有限公司 | Transconductance amplifier and LED constant current drive circuit |
| CN103929849A (en) * | 2014-03-26 | 2014-07-16 | 无锡市晶源微电子有限公司 | Isolation led drive circuit |
| CN105245112A (en) * | 2015-11-17 | 2016-01-13 | 成都启臣微电子有限公司 | Self-adaptive high-precision constant current circuit and switching power supply |
| CN210297540U (en) * | 2019-07-15 | 2020-04-10 | 无锡硅动力微电子股份有限公司 | Constant current control circuit and switching power supply circuit |
-
2019
- 2019-07-15 CN CN201910636071.3A patent/CN110277897B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101471600A (en) * | 2007-11-29 | 2009-07-01 | 意法半导体股份有限公司 | Isolated voltage converter with feedback on the primary winding, and corresponding method for controlling the output voltage |
| CN101459381A (en) * | 2008-12-10 | 2009-06-17 | 浙江大学 | Control apparatus and method for Boost type switch converter |
| CN103219884A (en) * | 2012-01-19 | 2013-07-24 | 美芯晟科技（北京）有限公司 | Control circuit and control method of primary side feedback constant current |
| CN103248227A (en) * | 2013-05-30 | 2013-08-14 | 杭州士兰微电子股份有限公司 | Switching power supply and switching power supply controller for realizing constant output current |
| CN103476180A (en) * | 2013-09-12 | 2013-12-25 | 杭州士兰微电子股份有限公司 | Transconductance amplifier and LED constant current drive circuit |
| CN103929849A (en) * | 2014-03-26 | 2014-07-16 | 无锡市晶源微电子有限公司 | Isolation led drive circuit |
| CN105245112A (en) * | 2015-11-17 | 2016-01-13 | 成都启臣微电子有限公司 | Self-adaptive high-precision constant current circuit and switching power supply |
| CN210297540U (en) * | 2019-07-15 | 2020-04-10 | 无锡硅动力微电子股份有限公司 | Constant current control circuit and switching power supply circuit |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111294034A (en) * | 2020-03-23 | 2020-06-16 | 广东美的白色家电技术创新中心有限公司 | Grid drive circuit, power switch circuit and electrical equipment |
| CN111294034B (en) * | 2020-03-23 | 2024-04-02 | 广东美的白色家电技术创新中心有限公司 | Gate drive circuit, power switch circuit and electrical equipment |
| CN113630121A (en) * | 2021-08-19 | 2021-11-09 | 电子科技大学 | Sampling holding and knee point detection circuit |
| CN114499121A (en) * | 2022-04-14 | 2022-05-13 | 深圳市芯茂微电子有限公司 | Controller of switching power supply and switching power supply |
| CN117310262A (en) * | 2023-11-28 | 2023-12-29 | 成都市易冲半导体有限公司 | Primary side information detection circuit and detection chip of transformer |
| CN117310262B (en) * | 2023-11-28 | 2024-02-09 | 成都市易冲半导体有限公司 | Primary side information detection circuit and detection chip of transformer |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110277897B (en) | 2023-12-29 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110277897A (en) | A kind of constant-current control circuit and switching power circuit | |
| TWI483524B (en) | A system and method for adjusting a power conversion system | |
| US7522398B2 (en) | Method and apparatus for overcurrent protection in DC-DC power converters | |
| US10886854B2 (en) | Control circuit and related integrated circuit and switching-type converter | |
| US8953347B2 (en) | Capacitor discharging circuit and power converter | |
| CN102017378B (en) | Power converter, discharge lamp ballast and headlight ballast | |
| CN103887984A (en) | Isolating converter and switching power supply comprising same | |
| CN106341053A (en) | Flyback-based power conversion device | |
| CN1996732A (en) | Switch power device and semiconductor device using same | |
| CN101552570A (en) | Switch voltage stabilizing circuit with frequency limiting function and method | |
| CN108880296A (en) | power conversion system | |
| CN103248207A (en) | Constant-current and constant-voltage fly-back converter based on primary side feedback | |
| CN106992684B (en) | Flyback power supply system and its control method | |
| CN102237812A (en) | Primary side feedback (FB) switching power supply controller and switching power supply system | |
| CN105245112A (en) | Self-adaptive high-precision constant current circuit and switching power supply | |
| CN104716836A (en) | Control circuit and method for switching power converter | |
| JP2015053225A (en) | Led drive circuit | |
| CN105337513B (en) | power conversion device and over-power protection method thereof | |
| CN202424498U (en) | Protection circuit applicable to PWM (pulse-width modulation) power control circuit | |
| JP2002315331A (en) | Power supply equipped with dc-dc converter | |
| CN208209603U (en) | A kind of charge control system | |
| CN210297540U (en) | Constant current control circuit and switching power supply circuit | |
| US20140126088A1 (en) | Protection circuit, switch control circuit, and power supply device comprising the same | |
| KR102583398B1 (en) | Prestart control circuit for switching power converters | |
| CN114865595A (en) | Switching power supply protection control circuit and method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| CB03 | Change of inventor or designer information | ||
| CB03 | Change of inventor or designer information |
Inventor after: Zhu Qinwei Inventor after: Liye Inventor after: Huang Feiming Inventor before: Yu Nannan Inventor before: Zhu Qinwei Inventor before: Liye Inventor before: Huang Feiming |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant |