CN109039085A - A kind of control circuit and the Switching Power Supply using the circuit - Google Patents
A kind of control circuit and the Switching Power Supply using the circuit Download PDFInfo
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- CN109039085A CN109039085A CN201810888306.3A CN201810888306A CN109039085A CN 109039085 A CN109039085 A CN 109039085A CN 201810888306 A CN201810888306 A CN 201810888306A CN 109039085 A CN109039085 A CN 109039085A
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- 239000000284 extract Substances 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 12
- 230000008569 process Effects 0.000 description 7
- 238000002955 isolation Methods 0.000 description 6
- 230000005347 demagnetization Effects 0.000 description 5
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- BINCGEGLXIMJFO-JQSLHUNDSA-N rfa-2 Chemical compound C1([C@H]2N[C@H](CC3(N=C4C=5C6=C7O[C@](C6=O)(C)O/C=C/[C@@H]([C@H]([C@@H](OC(C)=O)[C@@H](C)[C@@H](O)[C@H](C)[C@@H](O)[C@@H](C)\C=C\C=C(C)/C(=O)NC(=C4N3)C(=O)C=5C(O)=C7C)C)OC)C2)C=2C=CC(F)=CC=2)=CC=C(F)C=C1 BINCGEGLXIMJFO-JQSLHUNDSA-N 0.000 description 2
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Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- 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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention discloses the Switching Power Supplies of a kind of control circuit and the application circuit, the isolating switch power for the secondary circuit that control circuit is suitable for being formed with the vice-side winding of the primary circuit and transformer that are formed by the primary side winding of transformer, it include: the detection judgment module positioned at secondary side, output voltage coding control module and feedback switch, and the auxiliary winding positioned at primary side, auxiliary winding voltage detects upper resistance and auxiliary winding voltage detects lower resistance, feedback switch state detection module, output voltage decoding feedback module and duty ratio modulation circuit, characterized by further comprising extract the current source module that auxiliary winding voltage detects upper resistance and auxiliary winding voltage detects lower electric resistance partial pressure sampled point, the present invention can ensure that output voltage changes setting value Δ V in high output voltageref﹤ divides the voltage change of sampled point, enables power-supply system steady operation, while feedback switch state detection module need to only use low-voltage device, can reduce power-supply system cost.
Description
Technical field
The present invention relates to switching power source control circuits, in particular to the high output voltage secondary side feedback control circuit of Magnetic isolation
And the Switching Power Supply using the circuit.
Background technique
In order to avoid loading interference and destruction to energization input, isolation type switch power has become various power supply systems
In indispensable part.It should realize that the isolation between output voltage and input voltage is again setting output voltage stabilization
Value is necessarily required to that control is adjusted to input side in the size feedback of output voltage using isolating device.Fig. 1 is common
The task of feedback is isolated by isolated amplifier that device TL431, optocoupler and additional device form to hold in secondary side feedback control technology
Load.Basic principle is: the trsanscondutance amplifier of the elements 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 larger, that is, flows through light
The electric current of coupling becomes larger, and the voltage of the port controller FB becomes smaller, so that the port controller GATE output duty cycle becomes smaller so that transformation
Device transmits smaller energy to secondary side output end, and output voltage starts to reduce；Conversely, if output voltage is relatively low, by error
Signal feeds back the increase to primary-side-control duty ratio to increase the transmission energy of transformer, to improve output voltage.It is so anti-
It is multiple constantly to adjust control output voltage stabilization in setting value.This feedback technique is electric in switch because of its detection and comparing element
The secondary side in source, i.e. load side, so being called secondary side feedback.This mode for directly detecting output voltage has with high accuracy
Feature, but since these detections, the presence of amplifier, isolation feedback device increase the space of power-supply system plate, it is clear that
There is no advantage in cost and volume.Especially optocoupler cannot work at high temperature, and be easy to aging, so that the high temperature of this power supply
Service life is short, is unable to satisfy some high temperature applications.
In order to solve the technical issues of above-mentioned encountered, 105610306 A of Publication No. CN, entitled " secondary side is anti-
Feedback control method and its control circuit " application for a patent for invention propose a kind of novel secondary side feedback circuit, it is suitable for tool
The disconnecting switch for the secondary circuit for thering is the vice-side winding of the primary circuit formed by the primary side winding of transformer and transformer to be 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 feedback switch
Corrugating figure, secondary side feedback switches power supply shown in Fig. 2, it includes: three-winding transformer, it is by primary side winding NP, pair
Side winding NS, these three windings of auxiliary winding NA composition, wherein winding NP includes 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 side modulator
It is made of output voltage coding control module, detection judgment module.Secondary side 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, source electrode port 135 and gate port ports containing drain electrode.Output voltage coding control module, it includes the
114 3 Single port 112, second port 113, third port ports；Judgment module is detected, it includes first port 115, second
119 5 port 116, third port 117, the 4th port 118, fifth port ports；Auxiliary winding voltage detects upper resistance, it
Include first port 120 and second port 121；Auxiliary winding voltage detects lower resistance, it includes first port 122 and second end
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 128,130 3 second port 129, third port ports.
Their connection relationship are as follows: port 102 is connected with the positive terminal 101 of input power, port 103 and 130 phase of port
Even；Port 104, port 131, port 119 are connected together, and tie point forms the positive 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 cathode 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 be it is the same, its difference exists
In how in degaussing phase from secondary side the change information of output voltage feedback to primary side.Its specific working principle is detailed in correlation
The 0086-0090 section of specification.
The feedback control of above scheme simplifies process are as follows: secondary frontier inspection is surveyed judgment module sampling and outputting voltage → output voltage and compiled
Code control module encodes → controls feedback switch resistance state variation → primary side feedback switch state detection module detection feedback switch
Resistance state variation → output voltage decoding feedback module decoding → duty ratio modulation circuit generates voltage modulated duty ratio.The program was both
It does not need optocoupler and does not need other additional isolation transmitter parts yet, to not only avoid brought by these devices itself
Some inherent shortcomings, there will not be for assist these devices work and add device, volume and cost can be reduced, make volume,
Cost, performance, which reach, 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 not
It can be the problem of secondary side be changed output voltage by control.
But above scheme need to guarantee the voltage change detected at the output voltage variation port setting value Δ Vref ﹤ 124
ΔV124, that is, feedback switch state detection module can judge this voltage jump.If power-supply system output voltage VOUT
=12V, the voltage V detected at port 124124=3V, output voltage change setting value Δ Vref=0.1V, feedback switch base stage
With the voltage V of transmitting interpolarBE=0.4V, feedback switch conduction voltage drop Vsdon=0.06V.
By formula:
It can obtain:
At this point, will lead to Δ Vref> Δ V124.Therefore, in high output voltage, feedback switch state detection module is difficult to
Detect whether the on state of feedback switch changes, output voltage decoding feedback module and duty ratio modulation circuit can not
The decoding of feedback switch on state and the adjustment of duty ratio are completed, and then power-supply system is caused to can not work normally；And it is
The ceiling voltage that feedback switch state detection module can be handled is improved, needs that resistance to height is added in feedback switch state detection module
The device of pressure, high tension apparatus will increase additional cost, and high tension apparatus also has certain pressure resistance limitation.
Summary of the invention
In view of this, the technical problem to be solved by the present invention is to propose a kind of secondary side feedback control suitable for high output voltage
The Switching Power Supply of circuit processed and the application circuit.
It is as follows that the present invention solves the control circuit technical solution that above-mentioned technical problem provides:
A kind of control circuit, suitable for having the secondary side of the primary circuit and transformer that are formed by the primary side winding of transformer
The isolating switch power for the secondary circuit that winding is formed, comprising: detection judgment module, output voltage coding-control positioned at secondary side
Module and feedback switch；And the auxiliary winding positioned at primary side, auxiliary winding voltage detect upper resistance, auxiliary winding voltage detection
Lower resistance, feedback switch state detection module, output voltage decoding feedback module and duty ratio modulation circuit；
The secondary side degaussing circuit of feedback switch and isolating switch power is in parallel；One end of auxiliary winding keeps apart for connecting
The negative pole end of mains input power source is closed, the other end of auxiliary winding successively detects upper resistance and auxiliary winding through auxiliary winding voltage
It is connected to the negative pole end of isolating switch power input power under voltage detecting after resistance, auxiliary winding voltage detects upper resistance and auxiliary
Winding voltage is helped to detect the tie point of lower resistance as partial pressure sampled point；
The output voltage of judgment module detection isolating switch power is detected, and the voltage and internal reference voltage are carried out
Compare, generates 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 the coding is sent to the control terminal of feedback switch, control the working condition of feedback switch；
Feedback switch state detection module passes through auxiliary winding electricity in the designated time of the degaussing phase of each switch periods
Pressure detects upper resistance, auxiliary winding voltage detects the partial pressure of lower resistance to sample the voltage of auxiliary winding, and current detection
Voltage be compared with the voltage detected before, obtain the amplitude of variation of voltage and the change direction of voltage, output feedback
The information of switch working state variation, and send it to output voltage decoding feedback module；
Output voltage decoding feedback module receives the information of feedback switch working condition variation, according to the communication protocol of agreement
It is decoded, judges that output voltage is higher or relatively low, export modulation voltage, and send it to duty ratio modulation circuit；
Duty ratio modulation circuit receives modulation voltage, and according to the size modulations duty ratio of this voltage, modulation voltage increases
Then increase duty ratio, it is on the contrary then reduce duty ratio；
It is characterized by also including current source modules, and the electric current of partial pressure sampled point is extracted by adjusting current source module, will
The voltage stabilization of sampled point is divided in a setting value, so that the voltage of partial pressure sampled point is not as isolating switch power exports electricity
The increase of pressure and increase.
Preferably, it is more than setting value that feedback switch working condition change information, which is increased amplitude, then it is assumed that feedback switch
High-impedance state has been jumped to by low resistance state；Conversely, it is more than setting value that feedback switch working condition change information, which is reduced amplitude, then
Think that the working condition of feedback switch has jumped to low resistance state by high-impedance state.
Preferably, output voltage decoding feedback this period of module is decoded the result is that " output voltage is higher ", then gradually subtract
Small modulation voltage, until appearance " output voltage is relatively low "；Conversely, if this period is decoded the result is that " output voltage is inclined
It is low ", then modulation voltage is gradually increased, until appearance " switch power source output voltage is higher ".
Preferably, the feedback switch is metal-oxide-semiconductor.
Accordingly, the present invention also proposes the Switching Power Supply using above-mentioned control circuit, it is characterised in that: the main power of Switching Power Supply
The duty ratio of switching tube is provided by duty ratio modulation circuit.
Above-mentioned relational language is explained as follows:
It is secondary in degaussing circuit: degaussing circuit provides logical when secondary in the application for the transformer demagnetization of isolating switch power
Road.Secondary side degaussing circuit is in the conductive state in transformer degaussing phase, provides for the energy storage of transformer to output capacitance charging
Path；It is in high-impedance state in the non-degaussing phase of transformer, prevents the charge of output capacitance from flowing backward.
The communication protocol of agreement: referring to and the switch power source output voltage sampled be numbered according to scheduled rule,
Default 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: referring to that secondary side feedback switch is about scheduled on certain moment or the period movement of degaussing phase,
The detection module of primary side senses that this movement just thinks effective in this predetermined time period.
The control terminal of feedback switch: the conducting of control feedback switch and the port of cut-off refer to metal-oxide-semiconductor such as 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 that electric current flows into refers to such as metal-oxide-semiconductor
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 collector of triode is referred to, in conducting, electric current is by electricity
High collector is pressed to flow to the low emitter of voltage.
The conducting electric current outflow end of feedback switch: after feedback switch conducting, the port of electric current outflow refers to such as metal-oxide-semiconductor
Be metal-oxide-semiconductor source electrode；For triode, the emitter of triode is referred to.
On state: being to show feedback switch driving voltage appropriate to make its work in high-impedance state or low resistance state, high-impedance state
It is boundary opposite rather than that setting is absolute with low resistance state, their difference, which is only that, controls voltage caused by feedback switch
It can be detected in primary side and correctly judge the variation of its resistance state.
Particularly, it in order to allow people to be easier to understand the working principle in the present invention, is patrolled in cataloged procedure in embodiment
The relationship of collecting has used specific form to indicate, such as " output voltage is higher " this information uses " feedback switch is in high-impedance state "
It represents, " output voltage is higher " this information also can be used " feedback switch is in low resistance state " to hold in the realization of actual product
It carries, merely to preferably illustrate the present invention, rather than for limiting the present invention.
Compared with prior art, the invention has the following advantages:
(1) isolated amplifier of more traditional TL431, optocoupler and additional device composition realize the technical side of secondary side control
For case, the application does not need optocoupler and does not need other additional isolation transmitter parts yet, to not only avoid these devices
Some inherent shortcomings brought by part itself, there will not be the device added to assist these devices to work, reduce volume and
Cost reaches volume, cost, performance and optimizes, and the scope of application is wider.
(2) for more existing more popular primary side feedback technology, the output voltage precision of primary side feedback technology is not had
It is low and cannot secondary side by control be changed output voltage the problem of.
(3) current source module is increased, the electric current of partial pressure sampled point is extracted by adjusting current source module, partial pressure is sampled
The voltage stabilization of point is in a setting value, so that the voltage of partial pressure sampled point is not with the increase of isolating switch power output voltage
And increase.In high output voltage using consistent with low output voltageThe electricity detected at port 124
Press changing value Δ V124Still conform to formulaIt can ensure that output voltage variation is set
Definite value Δ Vref﹤ divides the voltage change of sampled point, makes power-supply system steady operation, realizes the secondary side feedback of high output voltage
Control circuit, while feedback switch state detection module need to only use low-voltage device, can reduce power-supply system cost.
Relative theory analysis, which is designed and calculated with specific Switching Power Supply in embodiment part, to be shown.
Detailed description of the invention
Fig. 1 is the Switching Power Supply typical circuit figure using traditional secondary side feedback controller；
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 node 124 of Fig. 2 electronic feedback switch；
Fig. 4 is the Switching Power Supply functional block diagram using the secondary side feedback control circuit of first embodiment of the invention.
Specific embodiment
In order to which the present invention is more clearly understood, with reference to the accompanying drawings and embodiments, 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
It is flyback converter, it includes: three winding transformation as shown in figure 4, being the circuit diagram of the present embodiment Switching Power Supply
Device, it is made of primary side winding NP, vice-side winding NS, auxiliary winding NA these three windings, and wherein primary side winding NP includes first
Port 102 and second port 103, vice-side winding NS include first port 104 and second port 105, and auxiliary winding NA includes the
Single port 106 and second port 107.Secondary side modulator is made of compression module and output voltage coding control module, wherein is added
Die block, including secondary side degaussing circuit and feedback switch, feedback switch are pressurizer, secondary side degaussing circuit, it includes first
111 two ports in port 110 and second port；Output capacitance COUT, it includes first port 131 and second port 132 two ends
Mouthful；Feedback switch, it includes 134 3 port 133, source electrode port 135 and gate port ports of drain electrode.Output voltage coding control
Molding block, it includes first port 112,114 3 second port 113, third port ports；Secondary sampler device, using detection
Judgment module, it includes first port 115, second port 116, third port 117, the 4th port 118, fifth port 119 5
A port；Auxiliary winding voltage detects upper resistance RFA1, it includes first port 120 and second port 121；Auxiliary winding voltage
Detect lower resistance RFA2, it includes first port 122 and second port 123；Current source module, it includes first port, this first
Port connectivity port 133；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 130 3 first port 128, second port 129, third port ports.
Their connection relationship are as follows: port 102 is connected with the positive terminal 101 of input power, port 103 and 130 phase of port
Even；Port 104, port 131, port 119 are connected together, and tie point forms the positive 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 cathode port 109；Port 113
It is connected with port 116；Port 114 is connected with port 117；Port 120 is connected with port 106；Port 121, port 122, port
124, port 133 is 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 the negative pole end of input power.
It should be noted that Fig. 4 show functional block diagram, and in actual circuit design process, port 103 and port
The master power switch pipe of Switching Power Supply is connected between 130, the connection of port 130 is the control of Switching Power Supply master power switch pipe
End, Fig. 3 is also such.
What feedback switch was selected in Fig. 4 is metal-oxide-semiconductor, low-resistance step response when opening using metal-oxide-semiconductor, reduces secondary side demagnetization
The pressure drop of circuit both ends；High resistant step response when not opened using metal-oxide-semiconductor increases secondary side degaussing circuit both ends pressure drop.
The excitation process of the flyback sourse converter and traditional flyback converter are the same, it differs in that such as
Where degaussing phase is fed back the change information of output voltage to primary side from secondary side.Specific working principle is:
The effect of secondary side degaussing circuit: it is in the conductive state in transformer degaussing phase, it is the energy storage of transformer to output
Capacitor COUTCharging provides path；It is in high-impedance state in the non-degaussing phase of transformer, prevents output capacitance COUTCharge flow backward.
Two detections for detecting judgment module act on: first, by the output voltage of 119 detection switch power supply of port, and
The voltage is compared with internal reference voltage, comparison result can determine feedback switch metal-oxide-semiconductor in transformer demagnetization rank
Whether section is open-minded.If detecting the output voltage of Switching Power Supply lower than internal reference voltage, feedback switch by port 119
Metal-oxide-semiconductor is open-minded in transformer degaussing phase；If being higher than internal benchmark electricity by the output voltage of 119 detection switch power supply of port
Pressure, then feedback switch metal-oxide-semiconductor is not open-minded in transformer degaussing phase；Second, demagnetization is detected by 110 ports and 111 ports
The conduction voltage drop of access, degaussing phase port 110 pressure drop ratio port 111 it is smaller, with this determine power-supply system be in disappear
The magnetic stage.
Two effects of output voltage coding control module: first, Coding Effects arrange coding rule --- output voltage
Feedback switch need to change to low resistance state from high-impedance state when from higher state change to Lower state, conversely, output voltage is from relatively low
Feedback switch need to change to high-impedance state from low resistance state when state change is to higher state.So, feedback is opened when output voltage is higher
Pass should be at high-impedance state, and feedback switch drive level is encoded as low level；Feedback switch should be at low when output voltage is relatively low
Resistance state, feedback switch drive level are encoded as high level.Second, control action controls feedback switch grid in degaussing phase
In corresponding code level, i.e., port 112 exports low level when output voltage is higher, and port 112 is defeated when output voltage is relatively low
High level out.
Preferably coding rule are as follows: feedback switch working condition change information is that increased amplitude is more than setting value, then recognizes
High-impedance state has been jumped to by low resistance state for feedback switch；Conversely, feedback switch working condition change information is super for reduced amplitude
Cross setting value, then it is assumed that the working condition of feedback switch has jumped to low resistance state by high-impedance state.
The reason of selecting above-mentioned coding rule is: in general circuit of reversed excitation, output voltage is higher, then is gradually reduced modulation
Voltage, output voltage are begun to decline to setting value；Output voltage is relatively low, then gradually increases modulation voltage, on output voltage starts
Rise to setting value.By adjusting modulation voltage, power-supply system output voltage stabilization can be maintained.
The transmission process of transformer: because there is output capacitance COUTThe presence of energy storage effect, converter are even several at one
Biggish mutation will not occur for output voltage in period, so can ignore capacitor C in a short timeOUTVoltage VOUTVariation.
According to the present invention known to content, it is now desired in VOUTOne control voltage of upper superposition, we are using rectification diode conduct thus
Secondary side demagnetization access, as shown in figure 4, this is most simply to be also most common mode.Because V drops in the knot pressure of diodeBEPresence,
Feedback switch metal-oxide-semiconductor is not when degaussing phase is opened, vice-side winding NSThe pressure difference minimum value of port 104 and port 105 is (VOUT+
VBE)；Feedback switch metal-oxide-semiconductor is when degaussing phase is opened, vice-side winding NSThe pressure difference of port 104 and port 105 is (VOUT+
Vsdon), wherein VsdonPressure difference when being the conducting of feedback switch metal-oxide-semiconductor between source electrode and drain electrode, because feedback switch metal-oxide-semiconductor is interior
Hinder small, VsdonLess than VBE.As it can be seen that degaussing phase feedback switch metal-oxide-semiconductor being connected and being not turned on so that the pressure difference at winding both ends is sent out
Biggish mutation has been given birth to, by conversion, the voltage change size at the port of feedback switch state detection module 124 are as follows:WhereinIt is the ratio between winding NA and winding NS the number of turns.
The detection deterministic process of feedback switch state detection module: in order to allow people more intuitively to understand this transmission process,
Design a supply convertor specifically below to illustrate.Select VBE=0.4V, feedback switch metal-oxide-semiconductor conduction voltage drop Vsdon=
0.06V, So feedback MOS switch pipe is connected and is not turned on, and detects at port 124
Voltage change is Δ V124=(0.4V-0.06V) × 3 × 0.2=0.2V.The voltage of each cycle detection port 124, if this
The voltage that period obtains is higher by output voltage variation setting value Δ Vref=0.1V than the voltage in previous period, then may determine that
Feedback switch has changed to high resistance area from low-resistance region out；Conversely, it is low then to may determine that feedback switch has been changed to from high resistance area
Hinder area.It in order to keep this correct judgment errorless, is guaranteed by following two requirement, first is exactly Δ Vref < Δ V124,
Namely detection module can judge this voltage jump；Second be the voltage to compare be separated by periodicity cannot be excessive, because
V can just be ignored for only having time is shortOUTThe variation of voltage, avoids because of VOUTLarge change and generate erroneous judgement.
If VOUT=12V, V124Voltage reaches 7.2V, instead
The ceiling voltage that feedback switch state detection module can be handled is 4V.To improve the highest that feedback switch state detection module can be handled
Voltage needs to be added high voltage bearing device in feedback switch state detection module, and high tension apparatus will increase additional cost, and
High tension apparatus also has certain pressure resistance limitation.
V124With VOUTIncrease and increase, the customary means of those skilled in the art is in feedback switch state-detection
The device of resistance to more high pressure is added in module；Present inventor abandons usual solution, seeks to break through, and adds at node 124
Enter current source module, it is ensured that in output voltage VOUT=12V or V when higher voltage124=3V, specific formula for calculation are as follows:
It can obtain
Value RFA1=40K, RFA2=10K, VBE=0.4V, VOUT=12V, V124=
3V can be calculated I=0.555mA.For more high output voltage VOUT, setting V124=3V.By above-mentioned calculation formula, calculating current source module extracts the electric current I at 124, can
Ensure Δ Vref < Δ V124, realize that the secondary side feedback control circuit for being suitable for high output voltage is to apply the switch electricity of open circuit
Source.
Under high output voltage, whether the on state that feedback switch state detection module can detecte feedback switch is sent out
Raw to change, the decoding of feedback switch on state and the adjustment of duty ratio are completed in decoding with duty ratio modulation module, realize power supply
System worked well.
Decoding and duty ratio modulation process: according to the coding rule arranged in cataloged procedure, it should about definite decoding rule is,
Correspondingly decoded when receiving the judging result of " feedback switch changes to low resistive state from high-impedance state " " output voltage from
Higher state change is to Lower state ", conversely, when the judgement that receive " feedback switch changes to high-impedance state from low resistive state "
" output voltage changes to higher state from Lower state " is correspondingly decoded when as a result.If decoding result be " output voltage from
Higher state change is to Lower state ", show that output voltage is higher before variation, current output voltage be it is relatively low, directly
To receiving opposite state change again；Conversely, can learn that current output voltage is higher.As long as it can be seen that according to this
Two communication protocols arranged and constituted are controlled and are transmitted, and the size of isolating transformer pair side output voltage can be fed back
To its primary side.Modulation voltage is gradually reduced when output voltage is higher, modulation voltage control duty ratio is gradually reduced, thus
Output voltage is caused to reduce；It is increased again conversely, gradually increasing duty ratio when output voltage is relatively low.Repeatedly, defeated
Voltage stabilization is in setting value out.
Preferably decoding with duty ratio modulation scheme is: output voltage decoding feedback this period of module it is decoded the result is that
" output voltage is higher ", then be gradually reduced modulation voltage, until appearance " output voltage is relatively low "；Conversely, if this periodic solution
Code the result is that " output voltage is relatively low ", then gradually increase modulation voltage, until appearance " switch power source output voltage is higher " is
Only.
Select the reason of above-mentioned decoding is with duty ratio modulation scheme is same to be: in general circuit of reversed excitation, output voltage is inclined
Height, then be gradually reduced modulation voltage, and output voltage is begun to decline to setting value；Output voltage is relatively low, then gradually increases modulation electricity
Pressure, output voltage are begun to ramp up to setting value.By adjusting modulation voltage, power-supply system output voltage stabilization can be maintained.
The above is only the preferred embodiment of the present invention, it is noted that above-mentioned preferred embodiment is not construed as pair
Limitation of the invention, protection scope of the present invention should be defined by the scope defined by the claims..For the art
For those of ordinary skill, without departing from the spirit and scope of the present invention, several improvements and modifications can also be made, these change
It also should be regarded as protection scope of the present invention into retouching.
Claims (5)
1. a kind of control circuit, suitable for have the secondary side of the primary circuit and transformer that are formed by the primary side winding of transformer around
The isolating switch power for the secondary circuit that group is formed, comprising: detection judgment module, output voltage coding-control mould positioned at secondary side
Block and feedback switch；And the auxiliary winding positioned at primary side, auxiliary winding voltage detect under upper resistance, auxiliary winding voltage detection
Resistance, feedback switch state detection module, output voltage decoding feedback module and duty ratio modulation circuit；
The secondary side degaussing circuit of feedback switch and isolating switch power is in parallel；One end of auxiliary winding keeps apart powered-down for connection
The negative pole end of source input power, the other end of auxiliary winding successively detect upper resistance and auxiliary winding voltage through auxiliary winding voltage
Detect the negative pole end that isolating switch power input power is connected to after lower resistance, auxiliary winding voltage detect upper resistance and auxiliary around
The tie point of resistance is partial pressure sampled point under group voltage detecting；
The output voltage of judgment module detection isolating switch power is detected, and the voltage and internal reference voltage are compared
Compared with, generation output voltage change information, and send it to output voltage coding control module；
Output voltage coding control module is encoded according to the voltage change information received according to the communication protocol of agreement,
And the coding is sent to the control terminal of feedback switch, control the working condition of 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, auxiliary winding voltage detect the partial pressure of lower resistance to sample the voltage of auxiliary winding in survey, and the electricity of current detection
Pressure is compared with the voltage detected before, obtains the amplitude of variation of voltage and the change direction of voltage, exports feedback switch
The information of working condition variation, and send it to output voltage decoding feedback module；
Output voltage decoding feedback module receives the information of feedback switch working condition variation, is carried out according to the communication protocol of agreement
Decoding, judges that output voltage is higher or relatively low, exports modulation voltage, and send it to duty ratio modulation circuit；
Duty ratio modulation circuit receives modulation voltage, and according to the size modulations duty ratio of this voltage, modulation voltage increase then increases
Add duty ratio, it is on the contrary then reduce duty ratio；
It is characterized by also including current source modules, and the electric current of partial pressure sampled point is extracted by adjusting current source module, will be divided
The voltage stabilization of sampled point is in a setting value, so that the voltage of partial pressure sampled point is not with isolating switch power output voltage
Increase and increases.
2. control circuit according to claim 1, it is characterised in that: feedback switch working condition change information is increased
Amplitude is more than setting value, then it is assumed that feedback switch has jumped to high-impedance state by low resistance state；Conversely, feedback switch working condition changes
Information is that reduced amplitude is more than setting value, then it is assumed that the working condition of feedback switch has jumped to low resistance state by high-impedance state.
3. control circuit according to claim 1, it is characterised in that: output voltage decoding feedback this period of module is decoded
The result is that " output voltage is higher ", then be gradually reduced modulation voltage, until appearance " output voltage is relatively low "；Conversely, if originally
Cycle decoder the result is that " output voltage is relatively low ", then gradually increase modulation voltage, until " switch power source output voltage is inclined for appearance
It is high " until.
4. control circuit according to claim 1, it is characterised in that: feedback switch is metal-oxide-semiconductor.
5. a kind of Switching Power Supply using any one of Claims 1-4 control circuit, it is characterised in that: the main power of Switching Power Supply
The duty ratio of switching tube is provided by duty ratio modulation circuit.
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| CN201810888306.3A CN109039085B (en) | 2018-08-07 | 2018-08-07 | Control circuit and switching power supply using same |
| PCT/CN2019/084987 WO2020029614A1 (en) | 2018-08-07 | 2019-04-29 | Control circuit and switched-mode power supply using circuit |
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| CN201810888306.3A CN109039085B (en) | 2018-08-07 | 2018-08-07 | Control circuit and switching power supply using 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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| WO2020029614A1 (en) * | 2018-08-07 | 2020-02-13 | 广州金升阳科技有限公司 | Control circuit and switched-mode power supply using circuit |
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| WO2020029614A1 (en) | 2020-02-13 |
| CN109039085B (en) | 2024-05-17 |
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