CN107370384A - The Switching Power Supply of secondary side feedback control circuit and the application circuit - Google Patents
The Switching Power Supply of secondary side feedback control circuit and the application circuit Download PDFInfo
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- CN107370384A CN107370384A CN201710618319.4A CN201710618319A CN107370384A CN 107370384 A CN107370384 A CN 107370384A CN 201710618319 A CN201710618319 A CN 201710618319A CN 107370384 A CN107370384 A CN 107370384A
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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
- 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
- H02M3/33569—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 having several active switching elements
- H02M3/33576—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 having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
-
- 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
- H02M1/00—Details of apparatus for conversion
- H02M1/32—Means for protecting converters other than automatic disconnection
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses a kind of secondary side feedback control circuit, suitable for the isolating switch power of the secondary circuit formed with the primary circuit formed by the primary side winding of transformer and the vice-side winding of transformer, including：Secondary degaussing circuit, detection judge module, output voltage coding control module, feedback switch, the upper resistance of auxiliary winding voltage detection, auxiliary winding voltage detection lower resistance, feedback switch state detection module, output voltage decoding feedback module and duty ratio modulation circuit, because feedback switch is connected with secondary degaussing circuit, power-supply system also can steady operation in high output voltage by the present invention, and can prevent the electric charge of output capacitance from pouring in down a chimney, reduce feedback switch control difficulty, while feedback switch need to only use low-voltage device, can reduce power-supply system cost.
Description
Technical field
The present invention relates to switch power controller, more particularly to the high output voltage secondary side feedback control circuit of Magnetic isolation and
Using the Switching Power Supply of the circuit.
Background technology
In order to avoid loading interference and destruction to energization input, isolation type switch power turns into various electric power systems
In indispensable part.It should realize that the isolation between output voltage and input voltage is again setting output voltage stabilization
Value, be necessarily required to using isolating device the size of output voltage feed back to input side control is adjusted.Fig. 1 is conventional
Secondary side feedback control technology, isolate isolated amplifier that the task of feedback is made up of device TL431, optocoupler and additional device to hold
Load.General principle is：The trsanscondutance amplifier of the element such as TL431 and sampling resistor R1, R2 composition is output voltage and reference voltage
Error voltage signal be enlarged into current signal, the electric current that TL431 is flowed through when output voltage is higher becomes big, that is, flows through light
The electric current of coupling becomes big, and the voltage of controller FB ports diminishes, so as to which controller output duty cycle diminishes so that transformer transmits more
Small energy starts to reduce to secondary output end, output voltage；Conversely, if output voltage is relatively low, by the way that error signal is fed back
Increase the transmission energy of transformer to the increase of primary-side-control dutycycle, so as to improve output voltage.So once and again
Adjustment control is output voltage stabilization in setting value.This feedback technique is because its detection and comparing element are in the pair of Switching Power Supply
Side, that is, side is loaded, so being called secondary side feedback.The mode of this directly detection output voltage has the characteristics of precision is high,
But because these detections, amplifier, the presence of isolating feedback device add the space of power-supply system plate, it is clear that in cost and
There is no advantage in volume.Particularly optocoupler can not work at high temperature, and be easy to aging so that the high temperature service life of this power supply
It is short, some high temperature applications can not be met.
In order to solve above-mentioned run into technical problem, Publication No. CN 105610306 A are entitled《Secondary is anti-
Present control method and its control circuit》Application for a patent for invention propose a kind of new secondary side feedback circuit, it be applied to tool
The disconnecting switch for the secondary circuit that the vice-side winding for having the primary circuit formed by the primary side winding of transformer and transformer is formed
Power supply.Fig. 2 Fig. 6 from foregoing invention application example IV, Fig. 3 are electricity at the working condition and 124 of Fig. 2 electronic feedbacks switch
Corrugating figure, the secondary side feedback switches power supply shown in Fig. 2, it includes：Three-winding transformer, it is by main limit winding NP, pair
Side winding NS, assists winding NA these three windings compositions, wherein winding NP include first port 102 and second port 103, winding
NS includes first port 104 and second port 105, and winding NA includes first port 106 and second port 107.Secondary modulator
It is made up of output voltage coding control module, detection judge module.Secondary degaussing circuit, it includes first port 110 and second
The port of port 111 two；Output capacitance, it includes 132 two ports of first port 131 and second port；Feedback switch, it is wrapped
134 3 port 133 containing drain electrode, source electrode port 135 and gate port ports.Output voltage coding control module, it includes the
Single port 112, second port 113, the port of the 3rd port 114 3；Judge module is detected, it includes first port 115, second
119 5 port 116, the 3rd port 117, the 4th port 118, fifth port ports；The upper resistance of auxiliary winding voltage detection, it
Include first port 120 and second port 121；The lower resistance of auxiliary winding voltage detection, it includes the end of first port 122 and second
Mouth 123；Feedback switch state detection module, it includes 125 two ports of first port 124 and second port；Output voltage solution
Code feedback module, it includes 127 two ports of first port 126 and second port；Duty ratio modulation circuit, it includes first end
Mouth 128, second port 129, the port of the 3rd port 130 3.
Their annexation is：Port 102 is connected with the positive terminal 101 of input power, port 103 and the phase of port 130
Even；Port 104, port 131, port 119 are connected together, and tie point forms the positive pole port 108 of switch power source output voltage；End
Mouth 105, port 110, the drain electrode port 133 of feedback switch, port 115 are connected together；Port 111, port 118, feedback switch
Source electrode port 135, port 132 be connected together, tie point formed switch power source output voltage negative pole port 109；Feedback is opened
The gate port 134 of pass is connected together with port 112；Port 113 is connected with port 116；Port 114 is connected with port 117；End
Mouth 120 is connected with port 106；Port 121, port 122, port 124 are connected together；Port 125 is connected together with port 126；
Port 127 is connected together with port 128；Port 129, port 123, port 107 are connected together, and tie point forms input power
Negative pole end.The excitation process of the flyback sourse Switching Power Supply and traditional reverse exciting switching voltage regulator are the same, and its difference exists
In how in degaussing phase the change information of output voltage being fed back to primary side from secondary.Its specific operation principle refers to correlation
The 0086-0090 sections of specification.
The feedback control of switch power supply such scheme simplifies process：Secondary sampler output voltage → coding →
Control feedback switch resistance state change → primary side detection resistance state change → decoding → generation voltage modulated dutycycle.The program was both not required to
Optocoupler is wanted also without other extra isolation transmitter parts, so as to not only avoid these devices more caused in itself
Inherent shortcoming, there will not be to aid in the device that adds of these devices work, volume and cost can be reduced, make volume, cost,
Performance, which reaches, to be optimized, and the scope of application is wider.The output voltage precision that there will not be primary side feedback technology simultaneously is low and can not be
The problem of secondary is changed output voltage by control.
But such scheme need to ensure Δ Vref ﹤ Δs V124, that is, detection module can interpolate that out this voltage jump.If
Power-supply system output voltage VOUT=12V, V124=3V, VBE=3V, Δ Vref=0.1V, feedback switch conduction voltage drop Vsdon=
0.06V。
By formula：
It can draw：
Cause Δ Vref＞ Δs V124.Therefore, in high output voltage, feedback switch state detection module is difficult to detect instead
Whether the conducting state of feedback switch changes, and decoding can not complete the solution of feedback switch conducting state with duty ratio modulation module
The adjustment of code and dutycycle, and then cause power-supply system can not normal work.In addition, feedback switch in the static exciter stage and
Demagnetization can not open after terminating, and otherwise occur that the electric charge of output capacitance pours in down a chimney, may cause power system failure, feedback switch
Working timing figure as shown in figure 3, wherein H represents the port output high level of output voltage coding control module 112, open by drive feedback
Conducting is closed, feedback switch is in low-resistance region；L represents the port output low level of output voltage coding control module 112, drive feedback
Switch is closed, and because the source electrode port 135 of feedback switch is connected to the negative pole port 109 of switch power source output voltage, feedback is opened
High resistance area is in when closing.The static exciter stage is 0~t1, t4~t5, if transformer degaussing phase t1~t3, t5~
Need to open feedback switch in the t6 periods, detection judge module is also needed by voltage at the detection of port 115 133, in port 133
Place's voltage closes feedback switch when reaching threshold value, i.e., feedback switch is closed at t2, avoids transformer demagnetization from terminating rear t3~t4, t6
The electric charge that~t7 periods internal feedback switch is not closed and output capacitance occurs in time now pours in down a chimney.Feedback switch control is relatively multiple
It is miscellaneous.Because feedback switch is in parallel with degaussing circuit, feedback switch need to use high pressure resistant device, increase power-supply system cost.
The content of the invention
The technical problem to be solved in the present invention is to propose a kind of secondary side feedback control circuit suitable for high output voltage, is opened
Powered-down source.
The technical scheme that the present invention solves above-mentioned technical problem is as follows：
A kind of secondary side feedback control circuit, suitable for the primary circuit and transformation formed by the primary side winding of transformer
The isolating switch power for the secondary circuit that the vice-side winding of device is formed, including：Secondary degaussing circuit, detection judge module, output
Voltage code control module, feedback switch, the upper resistance of auxiliary winding voltage detection, the lower resistance of auxiliary winding voltage detection, feedback
On off state detection module, output voltage decoding feedback module and duty ratio modulation circuit；
Secondary degaussing circuit is in the conduction state in transformer degaussing phase, is that the energy storage of transformer is charged to output capacitance
Path is provided；High-impedance state is in the non-degaussing phase of transformer, prevents the electric charge of output capacitance from pouring in down a chimney；
The output voltage of judge module detection isolating switch power is detected, and the voltage and internal reference voltage are carried out
Compare, output voltage change information, and send it to output voltage coding control module；
Output voltage coding control module is compiled according to the voltage change information received according to the communication protocol of agreement
Code, and according to the working condition of the coding-control feedback switch；
Feedback switch state detection module passes through assists winding electricity in the designated time of the degaussing phase of each switch periods
The upper resistance of pressure detection, the partial pressure of auxiliary winding voltage detection lower resistance sample the voltage of assists winding, and current detection
Voltage compared with the voltage detected before, obtain the amplitude of variation of voltage and the change direction of voltage, output feedback
Switch working state change information, and send it to output voltage decoding feedback module；
Output voltage decoding feedback module receives feedback switch working condition change information, is entered according to the communication protocol of agreement
Row decoding, judges that output voltage is higher or relatively low, exports modulation voltage, and send it to dutycycle and be adjusted to circuit；
Duty ratio modulation circuit receives modulation voltage, and according to the size modulations transformer primary winding excitation of this voltage
Dutycycle, modulation voltage increase then increase dutycycle, on the contrary then reduce dutycycle；
It is characterized in that：The control terminal connection output voltage coding control module of feedback switch, the electric conduction of feedback switch
Stream outflow end connection secondary degaussing circuit, the conducting electric current of feedback switch flow into the negative pole end of end connecting valve electric power output voltage
Mouthful.
Preferably, feedback switch working condition change information is that increased amplitude exceedes setting value, then it is assumed that feedback switch
Working condition saturation region has been jumped to by linear zone；Conversely, feedback switch working condition change information surpasses for the amplitude reduced
Cross setting value, then it is assumed that the working condition of feedback switch has jumped to linear zone by saturation region.
Preferably, the result of this cycle decoder of output voltage decoding feedback module is " output voltage is higher ", then gradually subtracts
Small modulation voltage, untill there is " output voltage is relatively low "；Conversely, if the result of this cycle decoder is that " output voltage is inclined
It is low ", then gradually increase modulation voltage, untill there is " switch power source output voltage is higher ".
Preferably, described feedback switch is metal-oxide-semiconductor.
As the specific embodiment of the isolating switch power of application the technical program, including：Three-winding transformer, it
It is made up of main limit winding NP, vice-side winding NS, assists winding NA these three windings, they include first port and the second end respectively
Mouthful；Secondary degaussing circuit, it includes two ports of first port and second port；Output capacitance, it includes first port and the
Two ports of Two-port netwerk；Feedback switch, it includes three drain electrode port, source electrode port and gate port ports；Output voltage is compiled
Code control module, it includes first port, second port；Judge module is detected, it includes first port, second port；Auxiliary
The upper resistance of winding voltage detection, it includes first port and second port；The lower resistance of auxiliary winding voltage detection, it includes first
Port and second port；Feedback switch state detection module, it includes first port and second port；Output voltage decoding feedback
Module, it includes two ports of first port and second port；Duty ratio modulation circuit, it include first port, second port,
3rd port of port three；
Its annexation is：Main limit winding NP first port is connected with input power positive pole, second port and dutycycle
3rd port of modulation circuit is connected；Vice-side winding NS first port, the first port of output capacitance, detect judge module
First port is connected together, and tie point forms the positive pole port of switch power source output voltage；Vice-side winding NS second port, pair
The first port of side degaussing circuit is connected together；The second port of secondary degaussing circuit, the source electrode port of feedback switch are connected；It is defeated
The second port for going out voltage code control module is connected with detecting the second port of judge module；The drain electrode port of feedback switch,
The second port of output capacitance is connected together, and tie point forms the negative pole port of switch power source output voltage；The grid of feedback switch
Extreme mouth is connected with the first port item of output voltage coding control module；The first port of the upper resistance of auxiliary winding voltage detection
It is connected with assists winding NA first port；The second port of the upper resistance of auxiliary winding voltage detection, auxiliary winding voltage detection
First port, the first port of feedback switch state detection module of lower resistance are connected together；Feedback switch state detection module
Second port be connected together with the first port of output voltage decoding feedback module；The second of output voltage decoding feedback module
Port is connected together with the first port of duty ratio modulation circuit；The second port of duty ratio modulation circuit, auxiliary winding voltage
Second port, the assists winding NA second port of the lower resistance of detection are connected together, and tie point forms the negative pole end of input power.
Preferably, described feedback switch is metal-oxide-semiconductor.
Above-mentioned relational language is explained as follows：
The communication protocol of agreement：Refer to the switch power source output voltage sampled is numbered according to predetermined rule,
Give tacit consent to this coding rule again in the decoding process of primary side, it is therefore an objective to may determine that whether output voltage is higher or relatively low.Tool
The coding and decoding process of body can be understood by the detailed explanation of embodiment.
The designated time of degaussing phase：Refer to that secondary side feedback switch is about scheduled on certain moment or the period action of degaussing phase,
The detection module of primary side senses that this action just thinks effective in this predetermined time period.
The control terminal of feedback switch：Feedback switch conducting and the port of cut-off are controlled, such as metal-oxide-semiconductor, refers to metal-oxide-semiconductor
Grid；For triode, the base stage of triode is referred to.
The conducting electric current of feedback switch flows into end：After feedback switch conducting, the port of electric current inflow, such as metal-oxide-semiconductor, refer to
Be metal-oxide-semiconductor drain electrode, no matter N-channel, P-channel, enhanced or depletion type MOS tube, conducting when, electric current is all by voltage
High drain electrode flows to the low source electrode of voltage；For triode, the colelctor electrode of triode is referred to, in conducting, electric current is by electricity
High colelctor electrode is pressed to flow to the low emitter stage of voltage.
The conducting electric current outflow end of feedback switch：After feedback switch conducting, the port of electric current outflow, such as metal-oxide-semiconductor, refer to
Be metal-oxide-semiconductor source electrode；For triode, the emitter stage of triode is referred to.
Feedback switch working condition：It is that appropriate driving voltage of showing feedback switch makes it be operated in saturation region or linear
Area, saturation region and linear zone are relative rather than the absolute boundary of setting, they differ only in feedback switch produced by
Control voltage can be detected in primary side and correctly judge the change of its working condition.
Especially, in order to allow people to be easier to understand the operation principle in the present invention, patrolled in the cataloged procedure in embodiment
The relation of collecting has used specific form to represent, such as " output voltage is higher " this information uses " feedback switch is in saturation region "
To represent, " output voltage is higher " this information also can use " feedback switch is in linear zone " to hold in the product of reality is realized
Carry, merely to the present invention is preferably illustrated, rather than for limiting the present invention.
Compared with prior art, the invention has the advantages that：
(1) optocoupler is not needed also without other extra isolation transmitter parts, so as to not only avoid these devices
Some inherent shortcomings caused by itself, there will not be to aid in the device that the work of these devices add, reduction volume and into
This, reaches volume, cost, performance and optimizes, the scope of application is wider.
(2) at the same there will not be primary side feedback technology output voltage precision it is low and can not secondary by control be changed
The problem of becoming output voltage.
(3) Δ V is can ensure that in high output voltageref﹤ Δs V124, make power-supply system steady operation, relative theory analysis exists
Design and calculate with specific Switching Power Supply and be shown in embodiment part.
(4) in addition, feedback switch and demagnetization paths connected in series in the invention, disappear after terminating in static exciter stage and demagnetization
Magnetic circuit can voluntarily end to prevent the electric charge of output capacitance from pouring in down a chimney, the working state figure sequential of feedback switch as shown in figure 5, its
Middle H represents the port output high level of output voltage coding control module 112, drive feedback switch conduction, and feedback switch works in
Linear zone；L represents the port output low level of output voltage coding control module 112, due to the drain electrode of feedback switch in the present invention
Feedback switch works in saturation region when 135 ports of negative pole port 109,112 for being connected to switch power source output voltage are low level.
The static exciter stage is 0~t1, t3~t4, and demagnetization ending phase is t2~t3, t5~t6.
(5) judge module is detected without being to judge transformer by sampling the voltage at secondary degaussing circuit first port
It is no to be in degaussing phase t1~t2, t4~t5, only it need to pass through the positive pole port detection switch power supply of switch power source output voltage
Output voltage, and the voltage compared with the reference voltage of inside, result of the comparison determines feedback switch working condition, drop
Low feedback switch controls difficulty, and this is its outstanding advantages.
(6) feedback switch in the present invention need to only use low-voltage device, reduce power-supply system cost.
Brief description of the drawings
Fig. 1 is the Switching Power Supply typical circuit figure of the traditional secondary side feedback controller of application；
Fig. 2 is the Switching Power Supply typical circuit figure of new application secondary side feedback control circuit；
Fig. 3 is voltage oscillogram at the working condition and 124 of Fig. 2 electronic feedbacks switch；
Fig. 4 is the Switching Power Supply theory diagram using the secondary side feedback control circuit of first embodiment of the invention；
Fig. 5 is voltage oscillogram at the working condition and 124 of feedback switch of the present invention.
Embodiment
In order that the present invention is more clearly understood, below in conjunction with drawings and Examples, the present invention is described in more detail.
It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not intended to limit the present invention.
Embodiment one
Fig. 4 is using the Switching Power Supply theory diagram of the secondary side feedback control circuit of first embodiment of the invention, the switch
Power supply includes：Three-winding transformer, it is made up of main limit winding NP, vice-side winding NS, assists winding NA these three windings, wherein
Winding NP includes first port 102 and second port 103, and winding NS includes first port 104 and second port 105, winding NA
Include first port 106 and second port 107；Secondary degaussing circuit, it includes first port 110 and second port 111 two
Port；Output capacitance, it includes 132 two ports of first port 131 and second port；Feedback switch, it includes drain electrode port
135th, 134 3 ports in source electrode port 133 and gate port；Output voltage coding control module, it include first port 112,
Second port 114；Judge module is detected, it includes first port 119, second port 117；The upper resistance of auxiliary winding voltage detection
RFA1, it includes first port 120 and second port 121；The lower resistance R of auxiliary winding voltage detectionFA2, it includes first port
122 and second port 123；Feedback switch state detection module, it includes 125 two ports of first port 124 and second port；
Output voltage decoding feedback module, it includes 127 two ports of first port 126 and second port；Duty ratio modulation circuit, it
Include first port 128, second port 129, the port of the 3rd port 130 3.
Their annexation is：Port 102 is connected with the positive terminal 101 of input power, port 103 and the phase of port 130
Even；Port 104, port 131, port 119 are connected together, and tie point forms the positive pole port 108 of switch power source output voltage；End
Mouth 105, port 110 are connected together；Port 111, the source electrode port 133 of feedback switch are connected together；The drain electrode end of feedback switch
Mouth 135, port 132 are connected together, and tie point forms the negative pole port 109 of switch power source output voltage；The grid of feedback switch
Port 134, port 112 are connected together；Port 114 is connected with port 117；Port 120 is connected with port 106；Port 121, end
Mouth 122, port 124 are connected together；Port 125 is connected together with port 126；Port 127 is connected together with port 128；Port
129th, port 123, port 107 are connected together, and tie point forms the negative pole end of input power.
Specifically operation principle is：
Detection judge module is act as：By the output voltage of the detection switch power supply of port 119, and the voltage with it is interior
The reference voltage in portion is compared, and result of the comparison can determine whether feedback switch changes working condition, and this information is passed through
Its ports port 117 passes to output voltage coding control module.
Output voltage coding control module includes two effects：First, Coding Effects, set coding rule --- output electricity
Feedback switch working condition need to change to linear zone from saturation region when pressure is from higher state change to Lower state, conversely, output
Voltage from Lower state change to higher state when feedback switch working condition need to change to saturation region from linear zone.So, it is defeated
Go out voltage it is higher when feedback switch working condition should be at saturation region, feedback switch drive level is low level；Output voltage is inclined
Feedback switch should be at linear zone when low, and feedback switch drive level is high level.Second, control action, controls feedback switch
Grid is in corresponding code level, i.e., port 112 exports low level, port when output voltage is relatively low when output voltage is higher
112 output high level.
The transmitting procedure of transformer：Because there is output capacitance COUTThe presence of energy storage effect, Switching Power Supply are even several at one
Output voltage is that larger mutation will not occur in the individual cycle, so can ignore electric capacity C in a short timeOUTVoltage VOUTChange
Change.It can be seen from present invention, it is now desired in VOUTOne control voltage of upper superposition, for this, we use rectification diode
As secondary demagnetization path, as shown in figure 4, this is most simply to be also the most frequently used mode.Because the knot pressure drop V of diodeBE's
In the presence of when degaussing phase works in linear zone, the pressure difference minimum value of winding NS ports 104 and port 105 is feedback switch
(VOUT+VBE+Vdson), wherein VdsonIt is pressure difference when feedback switch works in linear zone between drain electrode and source electrode；Feedback switch exists
When degaussing phase works in saturation region, the pressure difference of winding NS ports 104 and port 105 is (VOUT+VBE+VDS), wherein VDSIt is
Pressure difference when feedback switch works in saturation region between drain electrode and source electrode.It can be seen that degaussing phase feedback MOS switch works in linearly
Area or saturation region may be such that the pressure difference at winding both ends there occurs larger mutation, by conversion, in feedback switch state-detection mould
Voltage change size is at the port 124 of block：
Wherein nA/nSIt is the ratio between winding NA and the winding NS numbers of turn.
The detection deterministic process of feedback switch state detection module：In order to allow people more intuitively to understand this transmitting procedure,
A power switch power supply is specifically designed below to illustrate.Select VOUT=12V, V124=3V, Δ Vref=0.1V, VBE=
0.4V, feedback switch pipe work in the conduction voltage drop V of saturation regionDS=3V, feedback switch pipe work in the conduction voltage drop of linear zone
Vdson=0.06V.
By formula：
It can draw：
ΔVref＜ Δs V124, it can be determined that go out feedback switch working condition and change to saturation region from linear zone；Conversely, then
It may determine that feedback switch working condition has changed to linear zone from saturation region.
Decoding and duty ratio modulation process：According to the coding rule set in cataloged procedure, it should set decoding rule as,
" output electricity is correspondingly decoded when receiving the judged result of " feedback switch working condition changes to linear zone from saturation region "
Pressure is from higher state change to Lower state ", conversely, " feedback switch working condition changes to saturation from linear zone when receiving
Correspondingly decoded during the judged result in area " " output voltage changes to higher state from Lower state ".If decoded result is " defeated
Go out voltage from higher state change to Lower state ", show that output voltage is higher before change, current output voltage is inclined
Low, the state change until receiving opposite direction again；Conversely, it can learn that current output voltage is higher.It can be seen that
As long as the communication protocol formed according to the two settings is controlled and transmitted, can be isolating transformer secondary output voltage
Size feed back to its primary side.Modulation voltage V is gradually reduced when output voltage is highercrl, it controls dutycycle gradually to subtract
It is small, so as to cause output voltage to reduce；It is set to raise again conversely, gradually increasing dutycycle when output voltage is relatively low.It is so anti-
It is multiple, output voltage stabilization in setting value.
Linear zone or full is worked in by detecting judge module and output voltage coding control module feedback switch pipe
And area, increase the change amplitude of voltage at port 124 so that power-supply system is in high output voltage, the inspection of feedback switch state
The change of feedback switch working condition can reliably be detected by surveying module, and then adjust dutycycle after decoding, and output voltage is steady
It is scheduled on setting value.
It the above is only the preferred embodiment of the present invention, it is noted that above-mentioned preferred embodiment is not construed as pair
The limitation of the present invention, protection scope of the present invention should be defined by claim limited range.For the art
For those of ordinary skill, without departing from the spirit and scope of the present invention, some improvements and modifications can also be made, these change
Enter and retouch and also should be regarded as protection scope of the present invention.
Claims (6)
- A kind of 1. secondary side feedback control circuit, suitable for the primary circuit and transformer formed by the primary side winding of transformer Vice-side winding formed secondary circuit isolating switch power, including：Secondary degaussing circuit, detection judge module, output electricity Pressure coding control module, feedback switch, the upper resistance of auxiliary winding voltage detection, the lower resistance of auxiliary winding voltage detection, feedback are opened Off status detection module, output voltage decoding feedback module and duty ratio modulation circuit；Secondary degaussing circuit is in the conduction state in transformer degaussing phase, is provided for the energy storage of transformer to output capacitance charging Path；High-impedance state is in the non-degaussing phase of transformer, prevents the electric charge of output capacitance from pouring in down a chimney；The output voltage of judge module detection isolating switch power is detected, and the voltage and the reference voltage of inside are compared Compared with, output voltage change information, and send it to output voltage coding control module；Output voltage coding control module is encoded according to the communication protocol of agreement according to the voltage change information received, And according to the working condition of the coding-control feedback switch；Feedback switch state detection module is examined in the designated time of the degaussing phase of each switch periods by auxiliary winding voltage Resistance in survey, the partial pressure of auxiliary winding voltage detection lower resistance sample the voltage of assists winding, and the electricity of current detection Pressure obtains the amplitude of variation of voltage and the change direction of voltage compared with the voltage detected before, exports feedback switch work Make state change information, and send it to output voltage decoding feedback module；Output voltage decoding feedback module receives feedback switch working condition change information, is solved according to the communication protocol of agreement Code, judges that output voltage is higher or relatively low, exports modulation voltage, and send it to dutycycle and be adjusted to circuit；Duty ratio modulation circuit receives modulation voltage, and the duty of the size modulations transformer primary winding excitation according to this voltage Then increase dutycycle than, modulation voltage increase, it is on the contrary then reduce dutycycle；It is characterized in that：The control terminal connection output voltage coding control module of feedback switch, the conducting electric current stream of feedback switch Go out end connection secondary degaussing circuit, the conducting electric current of feedback switch flows into the negative pole port of end connecting valve electric power output voltage.
- 2. secondary side feedback control circuit according to claim 1, it is characterised in that：Feedback switch working condition change information Exceed setting value for increased amplitude, then it is assumed that the working condition of feedback switch has jumped to saturation region by linear zone；It is conversely, anti- Feedback switch working state change information exceedes setting value for the amplitude reduced, then it is assumed that the working condition of feedback switch is by saturation region Linear zone is jumped to.
- 3. secondary side feedback control circuit according to claim 1, it is characterised in that：Output voltage decoding feedback module this week The phase result of decoding is " output voltage is higher ", then modulation voltage is gradually reduced, untill there is " output voltage is relatively low "；Instead It, if the result of this cycle decoder is " output voltage is relatively low ", gradually increases modulation voltage, and until occurring, " Switching Power Supply is defeated It is higher to go out voltage " untill.
- 4. secondary side feedback control circuit according to claim 1, it is characterised in that：Feedback switch is metal-oxide-semiconductor.
- 5. the Switching Power Supply of secondary side feedback control circuit described in application claim 1, it is characterised in that：Including：Three winding transformation Device, it is made up of main limit winding NP, vice-side winding NS, assists winding NA these three windings, they respectively comprising first port and Second port；Secondary degaussing circuit, it includes two ports of first port and second port；Output capacitance, it includes first end Mouth and two ports of second port；Feedback switch, it includes three drain electrode port, source electrode port and gate port ports；Output Voltage code control module, it includes first port, second port；Judge module is detected, it includes first port, the second end Mouthful；The upper resistance of auxiliary winding voltage detection, it includes first port and second port；The lower resistance of auxiliary winding voltage detection, it Include first port and second port；Feedback switch state detection module, it includes first port and second port；Output voltage Decoding feedback module, it includes two ports of first port and second port；Duty ratio modulation circuit, it include first port, Second port, the port of the 3rd port three.Its annexation is：Main limit winding NP first port is connected with input power positive pole, second port and duty ratio modulation 3rd port of circuit is connected；Vice-side winding NS first port, the first port of output capacitance, the first of detection judge module Port is connected together, and tie point forms the positive pole port of switch power source output voltage；Vice-side winding NS second port, secondary disappear The first port of magnetic circuit is connected together；The second port of secondary degaussing circuit, the source electrode port of feedback switch are connected；Output electricity The second port of coding control module is pressed to be connected with detecting the second port of judge module；The drain electrode port of feedback switch, output The second port of electric capacity is connected together, and tie point forms the negative pole port of switch power source output voltage；The gate terminal of feedback switch Mouth is connected with the first port of output voltage coding control module；The first port and auxiliary of the upper resistance of auxiliary winding voltage detection Winding NA first port is connected；The second port of the upper resistance of auxiliary winding voltage detection, the lower resistance of auxiliary winding voltage detection First port, the first port of feedback switch state detection module is connected together；The second of feedback switch state detection module Port is connected together with the first port of output voltage decoding feedback module；The second port of output voltage decoding feedback module with The first port of duty ratio modulation circuit is connected together；Under the second port of duty ratio modulation circuit, auxiliary winding voltage detect Second port, the assists winding NA second port of resistance are connected together, and tie point forms the negative pole end of input power.
- 6. Switching Power Supply according to claim 5, it is characterised in that：Feedback switch is metal-oxide-semiconductor.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710618319.4A CN107370384A (en) | 2017-07-26 | 2017-07-26 | The Switching Power Supply of secondary side feedback control circuit and the application circuit |
| PCT/CN2018/090364 WO2019019814A1 (en) | 2017-07-26 | 2018-06-08 | Secondary side feedback control circuit and switching power supply using the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710618319.4A CN107370384A (en) | 2017-07-26 | 2017-07-26 | The Switching Power Supply of secondary side feedback control circuit and the application circuit |
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| CN107370384A true CN107370384A (en) | 2017-11-21 |
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| CN201710618319.4A Withdrawn CN107370384A (en) | 2017-07-26 | 2017-07-26 | The Switching Power Supply of secondary side feedback control circuit and the application circuit |
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| Country | Link |
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| CN (1) | CN107370384A (en) |
| WO (1) | WO2019019814A1 (en) |
Cited By (4)
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| CN108880270A (en) * | 2018-09-19 | 2018-11-23 | 重庆线易电子科技有限责任公司 | Electric power converter control circuit |
| WO2019019814A1 (en) * | 2017-07-26 | 2019-01-31 | 广州金升阳科技有限公司 | Secondary side feedback control circuit and switching power supply using the same |
| CN109831107A (en) * | 2019-02-28 | 2019-05-31 | 华为技术有限公司 | A kind of power conversion unit and the method for controlling power conversion unit output impedance |
| CN113285607A (en) * | 2021-05-20 | 2021-08-20 | 深圳慧能泰半导体科技有限公司 | Isolated power supply circuit, control method of isolated power supply and isolated power supply |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2019019814A1 (en) * | 2017-07-26 | 2019-01-31 | 广州金升阳科技有限公司 | Secondary side feedback control circuit and switching power supply using the same |
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| CN109831107A (en) * | 2019-02-28 | 2019-05-31 | 华为技术有限公司 | A kind of power conversion unit and the method for controlling power conversion unit output impedance |
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| CN113285607A (en) * | 2021-05-20 | 2021-08-20 | 深圳慧能泰半导体科技有限公司 | Isolated power supply circuit, control method of isolated power supply and isolated power supply |
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| WO2019019814A1 (en) | 2019-01-31 |
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Application publication date: 20171121 |