CN105553303B - Standby control system for primary side feedback AC DC Switching Power Supplies - Google Patents
Standby control system for primary side feedback AC DC Switching Power Supplies Download PDFInfo
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- CN105553303B CN105553303B CN201510998458.5A CN201510998458A CN105553303B CN 105553303 B CN105553303 B CN 105553303B CN 201510998458 A CN201510998458 A CN 201510998458A CN 105553303 B CN105553303 B CN 105553303B
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- 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
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M7/219—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
-
- 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
- H02M3/33515—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 digital control
-
- 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
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a kind of standby control system for primary side feedback AC DC Switching Power Supplies, and it introduces various control state, meet the power match demand of a wide range of load change by carrying out structural adjustment to Isobarically Control loop；The present invention makes standby pulse width be not only restricted to the lead-edge-blanking time by increasing line voltage detecting unit, standby pulse width control unit, standby pulse count unit, constant pressure impulse control unit, constant voltage/constant current mode selecting unit；Relative to traditional control method, the present invention reduce further the width of standby switches pulse under conditions of standby switches frequency is not reduced, so as to reach the purpose of low standby power loss in the case where not influenceing dynamic response characteristic.
Description
Technical field
The invention belongs to Switching Power Supply control technology field, and in particular to a kind of primary side feedback AC-DC Switching Power Supplies are treated
Machine control system.
Background technology
As global energy is increasingly in short supply, people propose higher and higher requirement for the energy saving of everyday devices.Wherein,
A large amount of popularizations of consumer-elcetronics devices in recent years are bringing people conveniently, while pleasant, also become a huge energy
Consume group.For the charging equipment corresponding with electronic equipment, not only requiring nothing more than it has very high conversion efficiency, also
Ask stand-by power consumption low.Energy Star as authenticating authority standard has brought up to five-pointed star certification mark from a star Valuation Standard
Standard, require very harsh for the stand-by power consumption of AC-DC Switching Power Supplies.
Primary side feedback (PSR) AC-DC Switching Power Supplies, because it has, peripheral system component is few, and cost is low, simple in construction,
The advantages such as stand-by power consumption is low, receive and are widely applied.Because its sampling for output voltage has periodically, it is therefore necessary to
Ensure a minimum switching frequency to maintain normal work.In addition, also there is phase for dynamic performance in current application
The requirement answered, compared with secondary side feedback (SSR) AC-DC Switching Power Supplies, primary side feedback AC-DC Switching Power Supplies are because of its sampling period property
Minimum frequency can not be too low when determining standby, therefore stand-by power consumption is bigger than secondary side feedback AC-DC Switching Power Supplies.At present, drop
In terms of low standby power loss, whether pulse frequency modulated mode (PFM) or pulse width modulation (PWM) and mixed type
Control mode, it is to realize low standby power loss using reducing standby switches frequency and reducing control circuit power consumption mode.
Fig. 1 gives control and the application block diagram of existing primary side feedback AC-DC Switching Power Supplies.As shown in figure 1, primary side feedback
AC-DC Switching Power Supplies mainly include control chip, transformer and power switch pipe, and transformer includes primary side winding Np, auxiliary around
Group NaAnd secondary windings Ns, control chip include secondary ON time detecting unit, constant current frequency control unit, Isobarically Control
Unit, constant voltage/constant current mode selecting unit, rest-set flip-flop, driver element, lead-edge-blanking unit, peak point current comparing unit with
And built-in power module.
In the primary side feedback AC-DC Switching Power Supplies formed using this control chip, FB pins are assists winding Na electricity
Pressure feedback introduces pin, and from resistance R1With resistance R2Form in bleeder circuit and obtain voltage division signal.Inside control chip, FB draws
Pin is connected to the input of output voltage detecting unit and secondary ON time detecting unit, secondary ON time detecting unit
Output is connected to constant current frequency control unit, and the output end of output voltage detecting unit is connected to constant voltage frequency control unit.CS
Pin is primary side winding NpCurrent detection signal introduces pin, from NMOS tube source resistance RsUpper acquirement signal.In control chip
Portion, CS pins are connected to the input of lead-edge-blanking unit, and it is more single that the output end of lead-edge-blanking unit is connected to peak point current
The input of member.The output signal of constant current frequency control unit and constant voltage frequency control unit connects constant voltage/constant current pattern respectively
Two inputs of selecting unit.The output end (i.e. open signal) and peak point current of constant voltage/constant current mode selecting unit compare
The output end (i.e. cut-off signals) of unit is connected respectively to the S ends and R ends of rest-set flip-flop, and the output end of rest-set flip-flop is that Q ends connect
Driver element is connected to, the output end of driver element and the GATE pins of control chip connect, and the output of GATE pins is connected to NMOS tube
Grid, for drive outside power NMOS tube.VCC pin is the power pins of control chip, for controlling core to be whole
Piece accesses external power source；FB pins are used as constant current frequency control signal and constant voltage frequency control signal, its constant current frequency control simultaneously
Make for detecting assists winding NaON time, so as to constant current frequency control unit adjustment work cycle in proportion so that secondary
Level winding NsOutputting current steadily realizes constant current function in the value of setting；Its constant voltage frequency is controlled for detecting secondary conducting
When assists winding voltage, indirectly reflection output winding voltage, and then reflect the size of output voltage indirectly, and according to being detectd
The voltage swing measured carrys out adjusting switch frequency so that output voltage stabilization is in setting value.CS is primary side winding NpCurrent sense
Pin, for detecting primary side winding NpPeak point current during conducting, to realize, primary side peak point current is equal to institute in each periodic process
The threshold value of setting.
When the systems are operating normally, due to transformer primary side winding NpPolarity with respect to assists winding NaWith secondary windings Ns
Same Name of Ends is on the contrary, therefore in primary side winding NpDuring conducting, FB pins are negative voltage；When in secondary windings NsDuring conducting phase, by
In assists winding NaWith secondary windings NsSame Name of Ends polarity is identical, therefore FB voltages are positive voltage, now transformer secondary winding electricity
Press as Vs=Vo+Vz, auxiliary winding voltage Va=Vs*(Na/Ns)=Vfb*R2/(R1+R2), therefore Vo=Vfb*R2*Ns/[(R1+
R2)*Na]-Vz, that is, output voltage is feedback voltage VfbFunction, chip adjusts V by constant voltage frequency control unit 7fb
To setting value, you can so that output voltage VoStabilization is operated in constant voltage mode in setting value, now system；When system is operated in perseverance
During stream mode, secondary ON time detecting unit can determine secondary windings N by detecting the time that FB pins are positive voltages's
ON time Tons, and determine the work period T=K*T of system on this basisons, wherein K is proportionality coefficient.Due to system
Work and discontinuous mode, each cycle are intended to make primary side winding NpThe energy of storage is all in secondary windings NsRelease, it is so secondary
Winding NsPeak point current during conducting, IppFor primary side winding NpPeak point current during conducting, NsFor secondary windings NsThe number of turns, Np
For primary side winding NpThe number of turns.As long as so set IppWith K and transformer parameter, then secondary windings NsOutput current just
It is a steady state value.
When system be operated in underloading or it is unloaded when, because each cycle primary side peak point current immobilizes, therefore each
Periodic transfer is constant to the energy estimate methods of secondary, so when output is completely unloaded, due to ceaselessly there is energy to be transmitted to secondary,
Secondary output voltage can be constantly elevated, and be higher than setting value, in order to solve the problem, it usually needs be added to secondary output end
One fictitious load R4, the energy that comes for consuming each periodic transfer so that output voltage maintains setting value.
Add fictitious load R4What is brought is the increase of stand-by power consumption, in order to reduce stand-by power consumption, it is necessary to reduce control chip
Lowest operating frequency Fmin, it is turned on number reduction in same time, so as to reduce the energy of transmission, can thus increase
Big R4Resistance reduces stand-by power consumption.But FminExtreme influence can be produced to the dynamic characteristic of system again, when load is suddenly from zero
Full load is jumped to by FminLimitation, chip can not make primary side conducting supplement energy immediately, but have to wait for maximum shut-off
Time Tmax(Tmax=1/Fmin) crossed and can just turn on primary side, so, in TmaxBecause output end load is very big in this period,
And energy does not also transmit, therefore output voltage can decline rapidly, and its drop-out value depends entirely on Tmax, TmaxIt is bigger, i.e. FminMore
Low then stand-by power consumption is smaller, but dynamic characteristic is poorer, therefore the F in the case where meeting certain dynamic characteristicminIt can not drop again
It is low.
The content of the invention
For the above-mentioned technical problem present in prior art, the invention provides a kind of primary side feedback AC-DC switch electricity
The standby control system in source, the stand-by power consumption of AC-DC Switching Power Supplies can be reduced under conditions of dynamic property is not influenceed.
The standby control system of the primary side feedback AC-DC Switching Power Supplies, including：Auxiliary winding voltage feedback introduces pin FB
Pin, power pins VCC pin, primary side winding current sense introduce pin CS pins, drive power switch in AC-DC Switching Power Supplies
The GATE pins of pipe, the FB pins are connected respectively to secondary ON time detecting unit, output voltage detecting unit and line electricity
The input of detecting unit, the output connection constant current frequency control unit of secondary ON time detecting unit are pressed, output voltage is detectd
The output for surveying unit connects constant voltage frequency control unit, standby pulse width control unit, standby pulse count unit and constant pressure respectively
The input of pulse control unit；The output end of line voltage detecting unit is sequentially connected standby pulse width control unit, standby preparation
Pulse signal generation unit, standby pulse count unit；It is more single that CS pins by lead-edge-blanking unit are connected to peak point current
The input of member；The output end of constant current frequency control unit and peak point current comparing unit connects the S of the first rest-set flip-flop respectively
End and R ends, the input of the Q ends connection constant voltage/constant current mode selecting unit of the first rest-set flip-flop；Constant voltage frequency control unit and
The output end of peak point current comparing unit connects the S ends and R ends of the second rest-set flip-flop, the output of constant voltage frequency control unit respectively
End is also connected with the input of standby preparation pulse signal generation unit, the Q ends of the second rest-set flip-flop and standby pulse count unit
Output end connection constant pressure impulse control unit input, constant pressure impulse control unit output end connection constant voltage/constant current mould
The input of formula selecting unit, the output end connection driver element of constant voltage/constant current mode selecting unit, the output of driver element connect
Connect GATE pins；VCC pin connects built-in power subsystem, is powered for whole system；
The secondary ON time detecting unit, the assists winding voltage division signal of transformer in AC-DC Switching Power Supplies is gathered,
And therefrom detection obtains the secondary ON time T of AC-DC Switching Power Suppliesreset；
The constant current frequency control unit, according to secondary ON time TresetConstruction obtains constant current FREQUENCY CONTROL letter all the way
Number；
The lead-edge-blanking unit, collection flow through the primary current signal of power switch pipe in AC-DC Switching Power Supplies, and shield
The signal is covered in current spikes caused by power switch pipe conducting moment；
The peak point current comparing unit, by the primary current signal after shielding burr and given current reference ITCarry out
Compare, export peak point current comparison signal；
First rest-set flip-flop, inputted using described peak point current comparison signal as R, with described constant current frequency control
Signal processed inputs as S, so as to output constant current control signal；
The output voltage detecting unit, the assists winding voltage division signal is gathered, and therefrom detection obtains AC-DC switches
The output voltage feedback quantity V of power supplyf；
The constant voltage frequency control unit, according to output voltage feedback quantity VfConstruction obtains constant voltage frequency control letter all the way
Number；
The line voltage detecting unit, the assists winding voltage division signal is gathered, and therefrom detection obtains AC-DC switch electricity
The line voltage feedback quantity U in sourcef；
The standby pulse width control unit, according to output voltage feedback quantity VfWith line voltage feedback quantity Uf, generate constant pressure all the way
Pulse-width control signal；
The standby preparation pulse signal generation unit, according to the high pulse width T of the constant pressure pulse-width control signalonWith
The frequency f of constant voltage frequency control signalsGenerate standby preparation pulse signal；
The standby pulse count unit, using every N number of pulse as one group from standby preparation pulse signal, for any
Group screen covers several pulses therein, and N is the natural number more than 1；
Second rest-set flip-flop, inputted using described peak point current comparison signal as R, with described constant voltage frequency control
Signal processed inputs as S, so as to export Isobarically Control signal；
The constant pressure impulse control unit, judge output voltage feedback quantity VfWhether given voltage reference V is more thanT2：If
It is then to make the standby preparation pulse signal after shielding processing as output signal；If it is not, then make described Isobarically Control signal
For output signal；
The constant voltage/constant current mode selecting unit, judge output voltage feedback quantity VfWhether given voltage reference is more than
VT3：Exported if so, then making constant pressure impulse control unit obtain output signal as drive signal；If it is not, then make described constant current control
Signal processed exports as drive signal；
The driver element, exported after carrying out power amplification to drive signal, for controlling the work(in AC-DC Switching Power Supplies
Rate switching tube.
Described secondary ON time TresetCorrespond to the duration of positive voltage linear segment in assists winding voltage division signal.
The cycle T of the constant current frequency control signalperiodWith secondary ON time TresetRelation it is as follows：
Wherein：IoOutput current for AC-DC Switching Power Supplies and be expected setting, NpAnd NsRespectively AC-DC switch electricity
The number of turn of transformer primary side winding and vice-side winding in source.
Described output voltage feedback quantity VfHanded over for positive voltage linear segment in assists winding voltage division signal and resonance portion
The magnitude of voltage of boundary's point.
The frequency f of the constant voltage frequency control signalsWith output voltage feedback quantity VfRelation it is as follows：
Wherein：LmFor the primary side magnetizing inductance of transformer in AC-DC Switching Power Supplies, RLFor the load electricity of AC-DC Switching Power Supplies
Resistance, VoFor the output voltage of AC-DC Switching Power Supplies, R1And R2Two of transformer assists winding respectively in AC-DC Switching Power Supplies
Divider resistance resistance, NaAnd NsTransformer assists winding and the number of turn of vice-side winding respectively in AC-DC Switching Power Supplies.Auxiliary around
Resistance R is passed through in one end of group respectively1And R2Ground connection, FB pins are connected to resistance R1And R2Tie point.
Described line voltage feedback quantity UfFor the average voltage level of negative voltage linear segment in assists winding voltage division signal.
The high pulse width T of the constant pressure pulse-width control signalonWith output voltage feedback quantity VfWith line voltage feedback quantity Uf
Relation it is as follows：
Wherein：LmFor the primary side magnetizing inductance of transformer in AC-DC Switching Power Supplies, RLFor the load electricity of AC-DC Switching Power Supplies
Resistance, VoFor the output voltage of AC-DC Switching Power Supplies, VlineFor the AC line voltage of transformer primary side in AC-DC Switching Power Supplies, R1
And R2Two divider resistance resistances of transformer assists winding, N respectively in AC-DC Switching Power Suppliesa、NpAnd NsRespectively AC-DC
The number of turn of transformer assists winding, primary side winding and vice-side winding in Switching Power Supply.
The specific method of described standby pulse count unit shielding pulse is：For any of standby preparation pulse signal
Group pulse, judge since first pulse in the group, i.e., be compared immediately after current PRF terminates：If output voltage
Feedback quantity VfMore than given voltage reference VT1, then all pulses follow-up in shielding group；Otherwise, next pulse is judged.
For any group pulse, remaining pulse number M meets following relation in its group after shielding processing：
Wherein：LmFor the primary side magnetizing inductance of transformer in AC-DC Switching Power Supplies, RLFor the load electricity of AC-DC Switching Power Supplies
Resistance, VoFor the output voltage of AC-DC Switching Power Supplies, VlineFor the AC line voltage of transformer primary side in AC-DC Switching Power Supplies,
Ton_minFor the high pulse width of constant pressure pulse-width control signal under constant pressure holding state, R1And R2Respectively in AC-DC Switching Power Supplies
Two divider resistance resistances of transformer assists winding, Na、NpAnd NsTransformer assists winding respectively in AC-DC Switching Power Supplies,
The number of turn of primary side winding and vice-side winding.
Described voltage reference VT1Slightly above output voltage feedback quantity Vf, voltage reference VT2Slightly above output voltage feedback quantity
VfAnd it is less than voltage reference VT1, voltage reference VT3It is slightly less than output voltage feedback quantity Vf。
It is an advantage of the invention that：The standby control system of the present invention is drawn by carrying out structural adjustment to Isobarically Control loop
Enter various control state, meet the power match demand of a wide range of load change；The present invention by increase line voltage detecting unit,
Standby pulse width control unit, standby pulse count unit, constant pressure impulse control unit, constant voltage/constant current mode selecting unit, make to treat
Machine pulse width is not only restricted to the lead-edge-blanking time；Relative to traditional control method, the present invention is not reducing standby switches frequency
Under conditions of reduce further the width of standby switches pulse, so as to reach low in the case where not influenceing dynamic response characteristic
The purpose of stand-by power consumption.
Brief description of the drawings
Fig. 1 is the structural representation of existing primary side feedback AC-DC Switching Power Supplies and its control system.
Fig. 2 is the structural representation of primary side feedback AC-DC Switching Power Supplies of the present invention and its standby control system.
Fig. 3 is the waveform diagram of assists winding voltage division signal in AC-DC Switching Power Supplies.
Fig. 4 is the working state schematic representation of control system of the present invention.
Fig. 5 is the waveform diagram of constant pressure frequency modulation state primary side peak point current.
Fig. 6 is that the signal shielding of standby pulse count unit handles schematic diagram.
Embodiment
In order to more specifically describe the present invention, below in conjunction with the accompanying drawings and embodiment is to technical scheme
It is described in detail.
As shown in Fig. 2 present embodiments provide a kind of unloaded control system of primary side feedback AC-DC Switching Power Supplies.This hair
It is bright consistent with the pin of original control chip, including：Auxiliary winding voltage feedback introducing pin FB pins, power pins VCC pin,
Primary side winding current sense introduces pin CS pins, drives the GATE pins of power switch pipe in AC-DC Switching Power Supplies.
In internal system, the FB pins are connected respectively to secondary ON time detecting unit 1, output voltage detecting unit
6 and the input of line voltage detecting unit 8, the output connection constant current frequency control unit 2 of secondary ON time detecting unit 1,
The output of output voltage detecting unit 6 connects constant voltage frequency control unit 7, standby pulse width control unit 9, standby pulsimeter respectively
The input of counting unit 11 and constant pressure impulse control unit 13；The output end of line voltage detecting unit 8 is sequentially connected standby pulsewidth
Control unit 9, standby preparation pulse signal generation unit 10, standby pulse count unit 11；CS pins pass through lead-edge-blanking list
Member 3 is connected to the input of peak point current comparing unit 4；The output of constant current frequency control unit 2 and peak point current comparing unit 4
End connects the S ends and R ends of the first rest-set flip-flop 5, the Q ends connection constant voltage/constant current mode selecting unit of the first rest-set flip-flop 5 respectively
14 input；Constant voltage frequency control unit 7 and the output end of peak point current comparing unit 4 connect the second rest-set flip-flop 12 respectively
S ends and R ends, the output end of constant voltage frequency control unit 7 is also connected with the input of standby preparation pulse signal generation unit 10,
The Q ends of second rest-set flip-flop 12 connect the input of constant pressure impulse control unit 13 with the output end of standby pulse count unit 11
End, the input of the output end connection constant voltage/constant current mode selecting unit 14 of constant pressure impulse control unit 13, constant voltage/constant current mould
The output end connection driver element 15 of formula selecting unit 14, the output connection GATE pins of driver element 15；In VCC pin connection
Power subsystem 16 is built, is powered for whole system.
The secondary ON time detecting unit 1, gather the assists winding partial pressure letter of transformer in AC-DC Switching Power Supplies
Number, and therefrom detection obtains the secondary ON time T of AC-DC Switching Power Suppliesreset；
The constant current frequency control unit 2, according to secondary ON time TresetConstruction obtains constant current FREQUENCY CONTROL letter all the way
Number；
The lead-edge-blanking unit 3, collection flow through the primary current signal of power switch pipe in AC-DC Switching Power Supplies, and
The signal is shielded in current spikes caused by power switch pipe conducting moment；
The peak point current comparing unit 4, by the primary current signal after shielding burr and given current reference ITEnter
Row compares, and exports peak point current comparison signal；
First rest-set flip-flop 5, inputted using described peak point current comparison signal as R, with described constant current frequency
Control signal inputs as S, so as to output constant current control signal；
The output voltage detecting unit 6, gathers the assists winding voltage division signal, and therefrom detection obtains AC-DC and opened
The output voltage feedback quantity V in powered-down sourcef；
The constant voltage frequency control unit 7, according to output voltage feedback quantity VfConstruction obtains constant voltage frequency control letter all the way
Number；
The line voltage detecting unit 8, the assists winding voltage division signal is gathered, and therefrom detection obtains AC-DC switches
The line voltage feedback quantity U of power supplyf；
The standby pulse width control unit 9, according to output voltage feedback quantity VfWith line voltage feedback quantity Uf, generate permanent all the way
Press pulse-width control signal；
The standby preparation pulse signal generation unit 10, according to the high pulse width T of the constant pressure pulse-width control signalon
With the frequency f of constant voltage frequency control signalsGenerate standby preparation pulse signal；
The standby pulse count unit 11, using every N number of pulse as one group from standby preparation pulse signal, for appointing
One group screen covers several pulses therein, and N is the natural number more than 1；
Second rest-set flip-flop 12, inputted using described peak point current comparison signal as R, with described constant voltage frequency
Control signal inputs as S, so as to export Isobarically Control signal；
The constant pressure impulse control unit 13, judge output voltage feedback quantity VfWhether given voltage reference V is more thanT2：
If so, then make the standby preparation pulse signal after shielding processing as output signal；If it is not, then make described Isobarically Control signal
As output signal；
The constant voltage/constant current mode selecting unit 14, judge output voltage feedback quantity VfWhether given voltage base is more than
Quasi- VT3：Exported if so, then making constant pressure impulse control unit 13 obtain output signal as drive signal；If it is not, then make described perseverance
Flow control signals export as drive signal；
The driver element 15, exported after carrying out power amplification to drive signal, for controlling in AC-DC Switching Power Supplies
Power switch pipe.
The specific method that described standby pulse count unit 11 shields pulse is：For appointing for standby preparation pulse signal
A set of pulses, judge since first pulse in the group, i.e., be compared immediately after current PRF terminates：If output electricity
Press feedback quantity VfMore than given voltage reference VT1, then all pulses follow-up in shielding group；Otherwise, next pulse is judged.
The operation principle of present embodiment circuit is as follows：Current constant control loop of the present invention is similar with Fig. 1 traditional control methods,
By the secondary ON time detecting unit 1, constant current frequency control unit 2, lead-edge-blanking unit 3, peak point current comparing unit
4th, the first rest-set flip-flop 5 forms., can be by its point according to actual conditions and Isobarically Control loop is different compared with Fig. 1 traditional control methods
For three states, it is referred to as：Constant pressure frequency modulation, constant pressure amplitude modulation, constant pressure are standby.Wherein：
1. constant pressure frequency modulation：Primary side peak point current is constant, and switching frequency changes according to load.
2. constant pressure amplitude modulation：Primary side peak point current changes according to load, and switching frequency is constant.
3. constant pressure is standby：Primary side peak point current is constant, and switching pulse frequency is constant caused by system, but is selected during final output
Selecting property skips partial pulse.
As shown in figure 3, output voltage detecting unit can detect FB pin waveforms at the Sample_T1 moment, obtaining voltage isWherein R2, R1, Na, NsAll it is fixed amount, therefore output voltage V can be judged according to the voltageoSize.Such as Fig. 4
It is shown, work as Vo<V3When, system is in current constant control state (after startup).Work as Vo>V3When, system enters Isobarically Control state.
When heavier loads, i.e. Iout>Iout2, system are in constant pressure frequency modulation state, and now the constant voltage frequency control is single
Member can adjust the frequency that the unit produces signal according to output voltage specific size, while the shut-off moment of drive signal is by described
The output of peak point current comparing unit 4 determines, one fixed reference voltage of the inner setting of peak point current comparing unit 4,
So as to ensure that primary side peak point current is constant.System capacity conservation formula is as follows：
Wherein：LmFor the transformer primary side magnetizing inductance, VTFor the internal reference voltage of peak point current comparing unit 4,
RsFor primary current sampling resistor shown in Fig. 2, fsFor switching frequency, VoFor system output voltage, RLFor equivalent load resistance.
It can be seen that work as VTIt is switching frequency f after fixed valuesWith equivalent load resistance RLThere is one-to-one relationship.Switching frequency fsWith equivalent
Load resistance RLChange and change.Due to switching frequency fsMaximum f in the design be presents_maxWith minimum value fs_min, therefore
As load resistance RLFurther increase, that is, load current further reduce, switching frequency fsIt is reduced to minimum value fs_minWhen
Conservation of energy condition can not still be met, then system will enter constant pressure amplitude modulation state.
When load becomes middle load by heavy duty, i.e. Iout1<Iout<Iout2, system are in constant pressure amplitude modulation state, now institute
State constant voltage frequency control unit output signal frequency and be reduced to minimum fs_min, and keep constant, while the shut-off of drive signal
Moment is exported by the standby pulse width control unit 9 and determined.System capacity conservation formula is as follows：
Wherein：VlineFor the system line voltage shown in Fig. 2, TonIt is effective ON time of switching drive signal.Such as Fig. 3
Shown, the line voltage detecting unit to FB leg signals in Sample_T2 instance samples by obtainingDue to R1, R2, Na, NpIt is constant, therefore the value and VlineIt is directly proportional.The standby pulse-width controlled list
Member 9 can automatically adjust T after the line voltage detecting unit output is receivedonTo meet that power output matching requires.Wherein Ton
The same maximum and minimum value with setting, under the constant pressure amplitude modulation state, power output is smaller, TonIt is smaller.To realize
The power smooth transition of constant pressure frequency modulation state and constant pressure amplitude modulation state, has：
The maximum of T of standby pulsewidthon_maxIt can be determined by above formula.
As shown in figure 5, in constant pressure frequency modulation state, system is by detecting whether primary current reaches threshold value decision switch arteries and veins
The punching shut-off moment.Because primary current has current spikes opening moment, easily cause comparator false triggering, therefore would generally
There is the lead-edge-blanking unit bucking current burr stage, so in this case, when pulse is greater than lead-edge-blanking
Between.And in constant pressure amplitude modulation state, the generation of pulsewidth can eliminate lead-edge-blanking not by the way of primary side peak point current compares
The limitation of time.The minimum value T of i.e. standby pulsewidthon_minIt is smaller than the lead-edge-blanking time.Concrete numerical value is by specific system requirements institute
It is fixed.
When load from it is middle load be changed into underloading even it is standby when, i.e. Iout<Iout1, system are in constant pressure holding state, now
Described constant voltage frequency control unit is identical with constant pressure amplitude modulation state, exports low-limit frequency fs_minPulse.The standby arteries and veins
Wide control unit 9 exports the minimum value T of standby pulsewidthon_min.The other standby pulse count unit 11 will be shielded selectively
Partial pulse signal.As shown in fig. 6, under constant pressure holding state, system presses low-limit frequency fs_minWith minimum standby pulsewidth Ton_min
Send continuous impulse, by way of example, detect output voltage V when m-th pulse arrivesoMore than the threshold value V of restrictionburst
(Vburst>V3), then Systematic selection masks ensuing pulse signal until n-th end-of-pulsing.Wherein N is that internal system is set
Fixed fixed constant.According to the difference of load, the pulse number of shielding is also different.System capacity formula is accordingly：
When in holding state, the equivalent frequency of system is fs_min/N.It can change the equivalent of system standby by adjusting N
Frequency, so as to adjust dynamic effect.
Constant pressure impulse control unit 13 receives peak point current comparing unit 4, constant voltage frequency control unit 7, standby pulsewidth control
Unit 9 processed, the output signal of standby pulse count unit 11, carry out logical process, so as to realize constant pressure frequency modulation, constant pressure amplitude modulation,
The switching of the standby three kinds of states of constant pressure controls with system.
The above-mentioned description to embodiment is understood that for ease of those skilled in the art and using this hair
It is bright.Person skilled in the art obviously can easily make various modifications to above-described embodiment, and described herein
General Principle is applied in other embodiment without by performing creative labour.Therefore, the invention is not restricted to above-described embodiment,
For those skilled in the art according to the announcement of the present invention, the improvement made for the present invention and modification all should be in the protections of the present invention
Within the scope of.
Claims (9)
1. introduce pin FB for the standby control system of primary side feedback AC-DC Switching Power Supplies, including auxiliary winding voltage feedback and draw
Pin, power pins VCC pin, primary side winding current sense introduce pin CS pins, drive power switch pipe in AC-DC Switching Power Supplies
GATE pins, it is characterised in that
The FB pins are connected respectively to secondary ON time detecting unit (1), output voltage detecting unit (6) and line voltage and detectd
Survey the input of unit (8), the output connection constant current frequency control unit (2) of secondary ON time detecting unit (1), output electricity
The output of pressure detecting unit (6) connects constant voltage frequency control unit (7), standby pulse width control unit (9), standby pulsimeter respectively
The input of counting unit (11) and constant pressure impulse control unit (13)；The output end of line voltage detecting unit (8), which is sequentially connected, to be treated
Machine pulse width control unit (9), standby preparation pulse signal generation unit (10), standby pulse count unit (11)；CS pins pass through
Cross the input that lead-edge-blanking unit (3) is connected to peak point current comparing unit (4)；The output of constant current frequency control unit (2)
The S ends of end the first rest-set flip-flop of connection (5), the output end of peak point current comparing unit (4) connect the R of the first rest-set flip-flop (5)
End, the input of the Q ends connection constant voltage/constant current mode selecting unit (14) of the first rest-set flip-flop (5)；Constant voltage frequency control unit
(7) output end connects the S ends of the second rest-set flip-flop (12), and the output end of peak point current comparing unit (4) connects the 2nd RS and touched
The R ends of device (12) are sent out, the output end of constant voltage frequency control unit (7) is also connected with standby preparation pulse signal generation unit (10)
Input, the Q ends of the second rest-set flip-flop (12) connect constant pressure impulse control list with the output end of standby pulse count unit (11)
The input of first (13), the output end of constant pressure impulse control unit (13) connect the defeated of constant voltage/constant current mode selecting unit (14)
Enter end, the output end connection driver element (15) of constant voltage/constant current mode selecting unit (14), the output connection of driver element (15)
GATE pins；VCC pin connects built-in power subsystem (16), is powered for whole system；
The secondary ON time detecting unit (1), the assists winding voltage division signal of transformer in AC-DC Switching Power Supplies is gathered,
And therefrom detection obtains the secondary ON time T of AC-DC Switching Power Suppliesreset；
The constant current frequency control unit (2), according to secondary ON time TresetConstruction obtains constant current frequency control signal all the way；
The lead-edge-blanking unit (3), collection flow through the primary current signal of power switch pipe in AC-DC Switching Power Supplies, and shield
The signal is covered in current spikes caused by power switch pipe conducting moment；
The peak point current comparing unit (4), by the primary current signal after shielding burr and given current reference ITCompared
Compared with output peak point current comparison signal；
First rest-set flip-flop (5), inputted using described peak point current comparison signal as R, with described constant current frequency control
Signal processed inputs as S, so as to output constant current control signal；
The output voltage detecting unit (6), the assists winding voltage division signal is gathered, and therefrom detection obtains AC-DC switches
The output voltage feedback quantity V of power supplyf；
The constant voltage frequency control unit (7), according to output voltage feedback quantity VfConstruction obtains constant voltage frequency control signal all the way；
The line voltage detecting unit (8), the assists winding voltage division signal is gathered, and therefrom detection obtains AC-DC switch electricity
The line voltage feedback quantity U in sourcef；
The standby pulse width control unit (9), according to output voltage feedback quantity VfWith line voltage feedback quantity Uf, generate constant pressure all the way
Pulse-width control signal；
The standby preparation pulse signal generation unit (10), according to the high pulse width T of the constant pressure pulse-width control signalonWith
The frequency f of constant voltage frequency control signalsGenerate standby preparation pulse signal；
The standby pulse count unit (11), using every N number of pulse as one group from standby preparation pulse signal, for any
Group screen covers several pulses therein, and N is the natural number more than 1；
Second rest-set flip-flop (12), inputted using described peak point current comparison signal as R, with described constant voltage frequency control
Signal processed inputs as S, so as to export Isobarically Control signal；
The constant pressure impulse control unit (13), judges output voltage feedback quantity VfWhether given voltage reference V is more thanT2：If
It is then to make the standby preparation pulse signal after shielding processing as output signal；If it is not, then make described Isobarically Control signal
For output signal；
The constant voltage/constant current mode selecting unit (14), judges output voltage feedback quantity VfWhether given voltage reference is more than
VT3：Exported if so, then making constant pressure impulse control unit (13) obtain output signal as drive signal；If it is not, then make described perseverance
Flow control signals export as drive signal；
The driver element (15), exported after carrying out power amplification to drive signal, for controlling the work(in AC-DC Switching Power Supplies
Rate switching tube.
2. the standby control system according to claim 1 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
Described secondary ON time TresetCorrespond to the duration of positive voltage linear segment in assists winding voltage division signal.
3. the standby control system according to claim 1 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
The cycle T of the constant current frequency control signalperiodWith secondary ON time TresetRelation it is as follows：
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Wherein：IoOutput current for AC-DC Switching Power Supplies and be expected setting, NpAnd NsRespectively in AC-DC Switching Power Supplies
The number of turn of transformer primary side winding and vice-side winding.
4. the standby control system according to claim 1 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
Described output voltage feedback quantity VfFor positive voltage linear segment in assists winding voltage division signal and the electricity of resonance portion point of interface
Pressure value.
5. the standby control system according to claim 1 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
The frequency f of the constant voltage frequency control signalsWith output voltage feedback quantity VfRelation it is as follows：
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Wherein：LmFor the primary side magnetizing inductance of transformer in AC-DC Switching Power Supplies, RLFor the load resistance of AC-DC Switching Power Supplies,
VoFor the output voltage of AC-DC Switching Power Supplies, R1And R2Two points of transformer assists winding respectively in AC-DC Switching Power Supplies
Resistance R is passed through in piezoresistance resistance, one end of assists winding successively1And R2Ground connection, the other end ground connection of assists winding, FB pins connect
It is connected to resistance R1And R2Tie point, NaAnd NsThe respectively circle of transformer assists winding and vice-side winding in AC-DC Switching Power Supplies
Number.
6. the standby control system according to claim 1 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
Described line voltage feedback quantity UfFor the average voltage level of negative voltage linear segment in assists winding voltage division signal.
7. the standby control system according to claim 1 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
The high pulse width T of the constant pressure pulse-width control signalonWith output voltage feedback quantity VfWith line voltage feedback quantity UfRelation such as
Under：
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Wherein：LmFor the primary side magnetizing inductance of transformer in AC-DC Switching Power Supplies, RLFor the load resistance of AC-DC Switching Power Supplies,
VoFor the output voltage of AC-DC Switching Power Supplies, VlineFor the AC line voltage of transformer primary side in AC-DC Switching Power Supplies, R1And R2
Two divider resistance resistances of transformer assists winding respectively in AC-DC Switching Power Supplies, one end of assists winding is passed through successively
Resistance R1And R2Ground connection, the other end ground connection of assists winding, FB pins are connected to resistance R1And R2Tie point, Na、NpAnd NsPoint
Not Wei in AC-DC Switching Power Supplies transformer assists winding, primary side winding and vice-side winding the number of turn.
8. the standby control system according to claim 1 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
The method of described standby pulse count unit (11) shielding pulse is：Any group pulse for standby preparation pulse signal,
Judge since first pulse in the group, i.e., be compared immediately after current PRF terminates：If output voltage feedback quantity
VfMore than given voltage reference VT1, then all pulses follow-up in shielding group；Otherwise, next pulse is judged.
9. the standby control system according to claim 8 for primary side feedback AC-DC Switching Power Supplies, it is characterised in that：
For any group pulse, remaining pulse number M meets following relation in its group after shielding processing：
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Wherein：LmFor the primary side magnetizing inductance of transformer in AC-DC Switching Power Supplies, RLFor the load resistance of AC-DC Switching Power Supplies,
VoFor the output voltage of AC-DC Switching Power Supplies, VlineFor the AC line voltage of transformer primary side in AC-DC Switching Power Supplies, Ton_min
For the high pulse width of constant pressure pulse-width control signal under constant pressure holding state, R1And R2Respectively transformer in AC-DC Switching Power Supplies
Resistance R successively is distinguished in two divider resistance resistances of assists winding, one end of assists winding1And R2Ground connection, assists winding it is another
End ground connection, FB pins are connected to resistance R1And R2Tie point, Na、NpAnd NsTransformer aids in respectively in AC-DC Switching Power Supplies
The number of turn of winding, primary side winding and vice-side winding.
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| CN106849675B (en) * | 2017-03-28 | 2019-07-05 | 无锡芯朋微电子股份有限公司 | The control circuit and its method of Switching Power Supply |
| US9979285B1 (en) * | 2017-10-17 | 2018-05-22 | Crane Electronics, Inc. | Radiation tolerant, analog latch peak current mode control for power converters |
| CN113488975B (en) * | 2021-08-12 | 2023-08-25 | 上海晶丰明源半导体股份有限公司 | Output short-circuit protection method, power management chip and switching power supply |
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