CN105610129A - Sampling circuit and overvoltage and under-voltage protection control circuit - Google Patents
Sampling circuit and overvoltage and under-voltage protection control circuit Download PDFInfo
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- CN105610129A CN105610129A CN201511002958.5A CN201511002958A CN105610129A CN 105610129 A CN105610129 A CN 105610129A CN 201511002958 A CN201511002958 A CN 201511002958A CN 105610129 A CN105610129 A CN 105610129A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC converters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/207—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage also responsive to under-voltage
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Abstract
The invention provides an overvoltage and under-voltage protection control circuit, which comprises a sampling circuit, an under-voltage control circuit, an overvoltage control circuit and a control signal output circuit, wherein the sampling circuit comprises a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5; a positive input voltage Vin flows back to the ground through the resistor R5, the resistor R4, the resistor R3, the resistor R2 and the resistor R1, which are connected with one another in series; a common node of the resistor R5 and the resistor R4 is led out as a first sampling point and is supplied to the under-voltage control circuit; and the common node of the resistor R4 and the resistor R3 is led out as a second sampling point and is supplied to the overvoltage control circuit. Compared with the prior art, the sampling circuit and the overvoltage and under-voltage return difference control circuit are flexible to design; and overvoltage and under-voltage trigger points and recovery points are easy to design and convenient to debug.
Description
Technical field
The present invention relates to circuit field, concrete, relate to one for switch power supply system, raising transducer reliabilitySample circuit and the overvoltage based on this sample circuit, under-voltage protection control circuit.
Background technology
In recent years, energy problem is increasingly serious, and the new forms of energy such as photovoltaic solar, wind-power electricity generation obtain national policy and support energetically,The sector development rapidly. Photovoltaic auxiliary electric power supply is a kind of switch converters, be used to photovoltaic solar, wind-power electricity generation,SVG dispatch control system provides stable, reliable DC voltage.
Affected by application scenario, photo-voltaic power supply operating voltage range is very wide, taking photovoltaic solar power station as example, is subject to illumination strongDegree impact, the output voltage in photovoltaic solar power station tens volts on kilovolt, corresponding auxiliary electric power supply operating voltageScope also tens volts on kilovolt. So wide input voltage range, requires switch converters must possess overvoltage, under-voltageDefencive function, while preventing that input voltage is too low, power device is crossed cause thermal damage, and when input voltage is too high, switching device overvoltage damages.
Over voltage function is integrated into controller inside by part semiconductor manufacturer, is simple and easy to use. But for there is no integrated being somebody's turn to doThe controller of function or particular application must design separately over voltage holding circuit, and existing scheme exists following askingTopic:
Patent publication No. is that CN104283193A discloses a kind of over voltage holding circuit, and trigger point and recovery point are sameElectrical voltage point, the risk facing is: if this trigger point and converter normal working voltage scope are too approaching, easily cause false touchSend out, therefore, between the converter normal range of operation of trigger point, need to retain certain allowance.
Patent publication No. is that CN101752829A discloses a kind of under-voltage protecting circuit, and this circuit possesses sluggish protection loop, adoptsWith TL431, as error amplification, comparator, existing problems are: at critical voltage points such as over voltage trigger point, recovery pointsNear meeting produces repeated switching phenomenon, easily causes logic control confusion, and return difference recovery point in kind and Theoretical Design existRelatively large deviation, occur that drift is abnormal near critical voltage point, reduce the reliability of loop of power circuit.
Patent publication No. is that CN103683206A discloses a kind of over voltage holding circuit, and this circuit is under overvoltage protection stateStart-up circuit is conducting always, is operational amplifier power supply, and power consumption is large, has reduced the reliability of start-up circuit.
Existing some other holding circuit, works at overvoltage protection state downconverter the state of having the hiccups, far super at input voltageIn the situation of over-voltage protection point, the switching device in inverter power loop still faces over-voltage breakdown risk, therefore, existingOver voltage holding circuit performance is needed further improvement badly.
For foregoing circuit exist distinct disadvantage, inventor herein analyses in depth isolated drive circuit, this case byThis generation.
Summary of the invention
Have in view of that, in order to tackle above-mentioned challenge, the object of the invention is to provide a kind of sampling and over voltage return difference control electricityThe sample circuit of road flexible design.
Corresponding therewith, another object of the present invention is to provide a kind of over voltage trigger point, recovery point is easy to design, is convenient toThe over voltage holding circuit of debugging.
In order to realize foregoing invention object, the invention provides a kind of sample circuit, be applicable to overvoltage, the under-voltage protection of converterControl circuit, in order to according to the situation of change of the anodal input voltage vin of converter, to owing of overvoltage, under-voltage protection control circuitPressure-controlled circuit and overvoltage control circuit provide sampled signal, and described sample circuit comprises resistance R 1, resistance R 2, resistanceR3, resistance R 4 and resistance R 5, wherein, anodal input voltage vin is by resistance R 5, resistance R 4, the electricity of connecting successivelyResistance R3, resistance R 2 and resistance R 1 are back to ground; Resistance R 5 is drawn as the first sampled point with the common node of resistance R 4,Be used for offering under-voltage control circuit; Resistance R 4 is drawn as the second sampled point with the common node of resistance R 3, for providingGive overvoltage control circuit.
The present invention also provides a kind of over voltage protection control circuit, for anodal input voltage vin, the direct current of converterAfter potential source VDD, reference voltage signal Vref connect, according to the situation of change of the anodal input voltage vin of converter, to conversionThe error comparator input output over voltage protection control signal of device master control IC, enters guard mode with control change device,Described over voltage protection control circuit, comprises that sample circuit, under-voltage control circuit, overvoltage control circuit and control signal are defeatedGo out circuit, described sample circuit, comprises resistance R 1, resistance R 2, resistance R 3, resistance R 4 and resistance R 5, wherein, and justUtmost point input voltage vin is back to ground by resistance R 5, resistance R 4, resistance R 3, resistance R 2 and the resistance R 1 of connecting successively;Resistance R 5 is drawn as the first sampled point with the common node of resistance R 4, for offering under-voltage control circuit; Resistance R 4Draw as the second sampled point with the common node of resistance R 3, for offering overvoltage control circuit; Described under-voltage control circuit,In the anodal input voltage vin of converter in the time that under-voltage protection trigger point voltage raises gradually, by resistance R 2, the resistance of connectingR3, resistance R 4 and total resistance of resistance R 6 in parallel determine to exit the recovery point voltage of under-voltage protection state; Described excessively voltage-controlledCircuit processed, in the anodal input voltage vin of converter in the time that overvoltage protection trigger point voltage reduces gradually, by the resistance of connectingTotal resistance of R1, resistance R 2, resistance R 3 determines to exit the recovery point voltage of overvoltage protection state.
Preferably, described under-voltage control circuit, comprises operational amplifier U1A, diode D1, N-type switching tube Q2, electricityResistance R6, resistance R 9 and resistance R 10, wherein, operational amplifier U1A in-phase input end connects reference voltage signal Vref,The inverting input of operational amplifier U1A is connected to capacitor C 1, resistance R 4, resistance R 5 threes' common node, and computing is putThe inverting input of large device U1A is also connected with the colelctor electrode of N-type switching tube Q2 by resistance R 6, N-type switching tube Q2'sGrounded emitter; Operational amplifier U1A output is by resistance R 9 and resistance R 10 ground connection of series connection; N-type switching tube Q2Base stage be connected to the common node of resistance R 9 and resistance R 10; The output of operational amplifier U1A also with diode D1Anode be connected, the negative electrode of diode D1 is as the output of under-voltage control circuit, for being connected with control signal output circuit.
Described overvoltage control circuit, comprises operational amplifier U1B, diode D2, direct voltage source VDD, N-type switchPipe Q4, N-type switching tube Q5, resistance R 11, resistance R 12, resistance R 13 and resistance R 14, wherein, operational amplifierU1B inverting input is connected with reference voltage signal Vref, operational amplifier U1B in-phase input end be connected to resistance R 4,The common node of resistance R 3; The output of operational amplifier U1B is connected with N-type switching tube Q5 base stage by resistance R 12,The grounded emitter of N-type switching tube Q5; Resistance R 11 be connected in parallel on N-type switching tube Q5 base stage and emitter stage between; DirectlyDD is by resistance R 13 and resistance R 14 ground connection of series connection for stream voltage source V, and resistance R 13 is divided with the common node of resistance R 14Be not connected the grounded emitter of N-type switching tube Q4 with the colelctor electrode of N-type switching tube Q5 and the base stage of N-type switching tube Q4;N-type switching tube Q4 colelctor electrode be connected with the common node of resistance R 1 and resistance R 2; The output of operational amplifier U1BEnd is also connected with the anode of diode D2, and the negative electrode of diode D2 is as the output of overvoltage control circuit, for believing with controlNumber output circuit connects.
Described control signal output circuit, comprises resistance R 7, resistance R 8 and N-type switching tube Q1, wherein, and resistance R 7One end is connected with the output of under-voltage control circuit and overvoltage control circuit, the other end of resistance R 7 and N-type switching tube Q1'sBase stage connects, the grounded emitter of N-type switching tube Q1; Resistance R 8 is connected in parallel on base stage and the emitter stage of N-type switching tube Q1Between; The colelctor electrode of N-type switching tube Q1 is drawn the output as control signal output circuit, for converter master control ICError comparator input connect.
As the further improvement of foregoing invention, described sample circuit, also comprises capacitor C 1, and capacitor C 1 is for filtering switchThe interfering signal of converter input, one end of capacitor C 1 is connected to the common node of resistance R 5 and resistance R 4, capacitor C 1Other end ground connection.
A step again as foregoing invention is improved, and described over voltage protection control circuit, also comprises over-voltage locking circuit, instituteState over-voltage locking circuit and comprise NPN type triode Q3 and start-up circuit control end, wherein, the collection of NPN type triode Q3Electrode is connected with start-up circuit control end, and the base stage of NPN type triode Q3 and the common node of resistance R 3 and resistance R 2 connectConnect the grounded emitter of NPN type triode Q3; In the anodal input voltage vin of converter from overvoltage protection trigger point voltageWhile being increased to gradually the over-voltage locking point voltage of setting, NPN type triode Q3 conducting, making start-up circuit control end is low electricityLevel state, quits work for controlling start-up circuit.
Preferably, above-mentioned N-type switching tube Q1, N-type switching tube Q2, N-type switching tube Q4 and N-type switching tube Q5 areNPN type triode or NPN type metal-oxide-semiconductor.
Compared with prior art, the present invention has following beneficial effect:
1) this programme sampling and over voltage return difference control circuit flexible design, over voltage trigger point, recovery point be easy to design,Be convenient to debugging.
2) drift can be overcome near the critical voltage points such as over voltage trigger point, recovery point abnormal, critical voltage point can be avoidedDrifting problem.
3) under guard mode, this programme antijamming capability is strong, stand-by power consumption is low, and reliability is high.
4) this programme circuit structure is simple, and components and parts number is few, flexible design, and cost has superiority.
Brief description of the drawings
Fig. 1 is the circuit theory diagrams of first embodiment of the invention over voltage protection control circuit;
Fig. 2 is circuit interdependent node voltage, the control signal waveform of first embodiment of the invention over voltage protection control circuit;
Fig. 3 is the circuit theory diagrams of second embodiment of the invention over voltage protection control circuit;
Fig. 4 is the circuit theory diagrams of third embodiment of the invention over voltage protection control circuit;
Fig. 5 is circuit interdependent node voltage, the control signal waveform of third embodiment of the invention over voltage protection control circuit;
Fig. 6 is the circuit theory diagrams of fourth embodiment of the invention over voltage protection control circuit.
Detailed description of the invention
The improvement of having done with respect to prior art in order to understand better the present invention, to two kinds of specific embodiment parties of the present inventionBefore formula is elaborated, the prior art of first mentioning in conjunction with background technology part, is illustrated improving thinking.
Thinking of the present invention is: adopt operational amplifier (as LM324) as sampled signal error computing comparator, avoidNear the critical voltage points such as over voltage trigger point, recovery point, produce repeated switching, by adjusting return difference control circuit,Near avoid occurring repeated switching the critical voltage points such as over voltage trigger point, recovery point anomaly, has improved guarantorProtection circuit accuracy of action; Operational amplifier number is two, wherein, and the under-voltage logic circuit of the first operational amplifier control,The second operational amplifier control overvoltage logic circuit; Under overvoltage condition, overvoltage crowbar is by the overvoltage protection of switch convertersState is set to two stages, pre-over pressure phase and over-voltage locking stage, reduce stand-by power consumption under overvoltage condition, and improve sampleMachine reliability.
Further, pre-overvoltage condition voltage triggered point is lower than over-voltage locking state trigger point.
The under-voltage protection state course of work is as follows: when input voltage triggers under-voltage protection point, and the high electricity of the first operational amplifier outputFlat signal, drives the first switch, second switch conducting, and wherein, the first switch in parallel is at PWM switch converters loop of power circuitThe error comparator input (taking UC3842 as example, this pin is comp pin) of controller, when the first switch conduction, drawsLow and to maintain this pin be low level state, PWM controller stops output pwm signal, and converter is in under-voltage protection state,No-output;
Further, second switch is connected in parallel on under-voltage sampling resistor two ends after connecting with the first resistance, after second switch conductingOne resistance and under-voltage sampling resistor are in parallel, and the resistance after parallel connection determines under-voltage condition recovery point, formation under-voltage protecting circuitReturn difference.
The overvoltage protection state course of work is as follows: when input voltage triggers pre-over-voltage protection point, the second operational amplifier output is highLevel signal, drives the first switch, the 4th switch conduction, herein the first switch process and under-voltage stage in full accord,No longer describe in detail, after the first switch conduction, converter no-output;
The 4th switch is adjusted the high and low of input voltage overvoltage condition sampled signal amplitude, after the 4th switch conduction, and input voltageOvervoltage condition sampled signal amplitude raises, and automatically sets pre-overvoltage condition recovery point, forms returning of the pre-overvoltage of overvoltage crowbarPoor;
In the time that input voltage is increased to triggering overvoltage condition keyed end, over-voltage locking circuit output control signal, controls and starts electricityRoad works in off state, and converter quits work, and now, Overall Power Consumption only comprises sample circuit part, the stand-by power consumption utmost pointLow and avoid the overvoltage of loop of power circuit switching tube to damage, improve switch converters reliability.
Especially, the present invention program's sampling and the design of over voltage return difference control circuit are very flexible, and the two shares input letterNumber sample circuit, by exporting control signal after the comparison operation of over voltage operational amplifier, automatically adjusts over voltage and recoversPoint, obviously distinguishes and is better than existing sampling and return difference control program.
In order to make object of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, to thisInvention is further elaborated.
The first embodiment
Fig. 1 shows the schematic block circuit diagram of first embodiment of the invention over voltage protection control circuit, a kind of over voltageHolding circuit: comprise sample circuit, reference voltage signal Vref, direct voltage source VDD, under-voltage comparison and return difference control thereofCircuit, overvoltage comparison and return difference control circuit thereof, over voltage control signal output circuit.
Sample circuit by the anodal input of switch converters Vin, capacitor C 1, resistance R 5, resistance R 4, resistance R 3, resistance R 2,Resistance R 1 forms, and wherein, one end of resistance R 5 is connected with the anodal input of converter Vin, one end of the other end and resistance R 4Be connected, the other end of resistance R 4 is connected with resistance R 3, and the other end of resistance R 3 is in series with resistance R 1 after resistance R 2,The other end of resistance R 1 is connected to input circuit (in Fig. 1, label is GND), and one end of capacitor C 1 is connected to resistance R 5With the common node of resistance R 4, the other end is connected to input circuit (in Fig. 1, label is GND).
Especially, the present invention program's over voltage comparison and return difference control circuit common input signal sample circuit thereof, designFlexibly, obviously distinguish and be better than existing sampling plan.
Further, capacitor C 1 can filtering switch converters input-terminal disturbance signal, avoids interference effect of signals sampled result,Thereby eliminate the over voltage protection misoperation that interfering signal triggers, greatly strengthened the anti-of over voltage protection control circuitInterference performance, has improved the reliability of circuit protection.
Under-voltage comparison and return difference control circuit thereof by operational amplifier U1A, diode D1, NPN type triode Q2, resistance R 6,Resistance R 9, resistance R 10, reference voltage signal Vref composition, wherein, reference voltage signal Vref concatenation operation amplifierU1A in-phase input end (one end of U1A mark "+" in Fig. 1), the inverting input (U1A in Fig. 1 of operational amplifier U1AOne end of mark "-") be connected to capacitor C 1, resistance R 4, resistance R 5 threes' common node, operational amplifier U1A'sOutput is connected with the anode of diode D1, the common node that this point is the two, and resistance R 9 one end are connected to operational amplifierThe common node of U1A output and diode D1 anode, the other end is connected to input circuit through resistance R 10, and (Fig. 1 gets the bidNumber be GND), one end of resistance R 6 connects capacitor C 1, resistance R 4, resistance R 5 threes' common node, the other end withThe colelctor electrode of NPN type triode Q2 is connected, and the base stage of NPN type triode Q2 is connected to the public affairs of resistance R 9 and resistance R 10Conode, the emitter stage of NPN type triode Q2 is connected to input circuit (in Fig. 1, label is GND).
Overvoltage comparison and return difference control circuit thereof are by operational amplifier U1B, diode D2, direct voltage source VDD, NPN type threeUtmost point pipe Q4, Q5, resistance R 11, resistance R 12, resistance R 13, resistance R 14 and reference voltage signal Vref composition, wherein,Reference voltage signal Vref concatenation operation amplifier U1B inverting input (one end of U1B mark "-" in Fig. 1), computingAmplifier U1B in-phase input end (one end of U1B mark "+" in Fig. 1) is connected to the common node of resistance R 4, resistance R 3,The output of operational amplifier U1B is connected with the anode of diode D2, the common node that this point is the two, one of resistance R 12End is connected to the common node of operational amplifier U1B output and diode D2 anode, and the other end is connected to defeated through resistance R 11Entry loop ground (in Fig. 1, label is GND), after resistance R 14 is in series with resistance R 13, the other end of resistance R 14 connectsTo direct voltage source VDD, the other end of resistance R 13 is connected to input circuit (in Fig. 1, label is GND), NPN typeTriode Q5 base stage is connected to the common node of resistance R 11 and resistance R 12, and the colelctor electrode of Q5 is connected to resistance R 14 and electricityThe common node of resistance R13, the emitter stage of Q5 is connected to input circuit (in Fig. 1, label is GND), NPN type triodeThe base stage of Q4 is connected to the common node of resistance R 13 and resistance R 14, and the colelctor electrode of Q4 is connected to resistance R 1 and resistance R 2Common node, the emitter stage of Q4 is connected to input circuit (in Fig. 1, label is GND).
Especially, diode D1, D2 negative electrode in over voltage comparison and return difference control circuit thereof are connected, and this point is the twoCommon node.
Over voltage control signal output circuit is by resistance R 7, resistance R 8, NPN type triode Q1, switch converters master control ICError comparator input (taking UC3842 as example, this pin is comp pin) composition, wherein, resistance R 7 and resistanceAfter R8 series connection, the other end of resistance R 7 is connected to the common node of diode D1, D2, and resistance R 8 other ends are connected to be inputted backGround, road (in Fig. 1, label is GND), the base stage of NPN type triode Q1 is connected to the public joint of resistance R 7 and resistance R 8Point, the colelctor electrode of Q1 is connected to the error comparator input of switch converters master control IC, and the emitter stage of Q1 is connected to inputGround, loop (in Fig. 1, label is GND).
Especially, the present invention program's over voltage return difference control circuit design is very flexible, and input sample signal passes through, owesAfter pressing operational amplifier comparison operation, export control signal, automatically adjust over voltage recovery point, obviously distinguish and be better than existingSampling and return difference control program.
The annexation of circuit shown in Figure 1, in conjunction with Fig. 2 circuit interdependent node voltage, control signal waveform, tells about oneThe operation principle of lower circuit of the present invention.
In Fig. 2,5, Vin is switch converters input voltage, and A, B, C, D, E, F, G represent respectively different defeatedEnter electrical voltage point, wherein, C, D represent respectively input voltage lower bound, the ceiling value of normal working voltage scope, V1A, V1BThe outputs level signals of operational amplifier U1A, U1B in presentation graphs 1 respectively, switch converters master in Comp presentation graphs 1Error comparator input (taking UC3842 as example, this pin is comp pin) the level signal amplitude of control IC.
Especially, numeral 1 represents high level signal, and numeral 0 represents low level signal.
The under-voltage protection state course of work: before the T0 moment, switch converters input voltage is C, T0 moment, input voltageGradually reduce, to the T1 moment, input voltage drops to an A, operational amplifier U1A in-phase input end voltage magnitude higher thanReverse input end voltage magnitude, U1A exports high level signal, NPN type triode Q1 emitter junction, the conducting of collector junction positively biased,The error comparator input of switch converters master control IC is that Comp pin level is pulled to low level signal, and circuit enters to be owedPress guard mode, voltage magnitude corresponding to some A is under-voltage protection state trigger point voltage.
In the same time, operational amplifier U1B in-phase input end voltage magnitude is lower than reverse input end voltage magnitude, and U1B output is lowLevel signal, NPN type triode Q5 emitter junction, the reverse-biased cut-off of collector junction, NPN type triode Q4 emitter junction, collector junctionConducting, resistance R 1 is by short circuit, because of U1A output high level signal, the conducting of NPN type triode Q2 collector junction, in the same time,Resistance R 2, R3, R4 connect afterwards and resistance R 6 is in parallel, and the resistance after parallel connection has determined converter input undervoltage guard modeUnder recovery point; Input voltage raises gradually, and in the T2 moment, input voltage rises to a B, and operational amplifier U1A homophase is defeatedEnter terminal voltage amplitude lower than reverse input end voltage magnitude, U1A output low level signal, NPN type triode Q1, Q2 send outPenetrate knot, the reverse-biased cut-off of collector junction, the error comparator input of switch converters master control IC is that Comp pin level rises toHigh level signal, circuit enters normal operating conditions, and voltage magnitude corresponding to some B is under-voltage protection state recovery point.
Under-voltage trigger point voltage VAAmplitude calculate as shown in Equation 1:
Under-voltage recovery point voltage VBAmplitude calculate as shown in Equation 2:
Get final product Exact Design under-voltage protection trigger point, recovery point according to formula 1,2.
The overvoltage protection state course of work: before the T3 moment, switch converters input voltage is D, T3 moment, input voltageRaise gradually, to the T4 moment, input voltage rises to a F, and operational amplifier U1B in-phase input end voltage magnitude is higher than insteadTo input terminal voltage amplitude, U1B exports high level signal, NPN type triode Q1 emitter junction, collector junction conducting, switchThe error comparator input of converter master control IC is that Comp pin level is pulled to low level signal, and circuit enters overvoltage and protectsProtect state, voltage magnitude corresponding to some F is overvoltage protection state trigger point voltage.
In the same time, the in-phase input end voltage magnitude of operational amplifier U1A is lower than reverse input end voltage magnitude, and U1A continuesKeep output low level state, because of the high level signal of U1B output, after resistance R 12, R11 dividing potential drop, be added in NPN type threeUtmost point pipe Q5 emitter junction two ends, the emitter junction of Q5, collector junction conducting, NPN type triode Q4 emitter junction is by short circuit, Q4 collectionThe reverse-biased cut-off of electricity knot, resistance R 1, resistance R 2, resistance R 3 are in series, and the all-in resistance after series connection determines overvoltage recovery point; T5In the moment, input voltage starts to decline gradually, and in the T6 moment, input voltage drops to an E, the input of operational amplifier U1B homophaseTerminal voltage amplitude is lower than reverse input end voltage magnitude, U1B output low level signal, NPN type triode Q1, Q5 transmittingKnot, the reverse-biased cut-off of collector junction, NPN type triode Q4 emitter junction, the conducting of collector junction positively biased, switch converters master control IC'sError comparator input is that Comp pin level rises to high level signal, and circuit enters normal operating conditions, some E correspondenceVoltage magnitude be overvoltage protection state recovery point.
Overvoltage trigger point voltage VFAmplitude calculate as shown in Equation 3:
Overvoltage recovery point voltage VEAmplitude calculate as shown in Equation 4:
Get final product Exact Design overvoltage protection trigger point, recovery point according to formula 3,4.
The second embodiment
The over voltage protection control circuit that is illustrated in figure 3 second embodiment of the invention, is from the different of the first embodiment,NPN type triode Q1 shown in Fig. 1, Q2, Q4, Q5 can be also NPN type metal-oxide-semiconductors, as shown in Figure 3, or are NPNType triode and metal-oxide-semiconductor combination (listing no longer one by one detailed combination herein), after adjusting, the operation principle of circuit and first in factExecute example just the same, can realize equal effect.
The 3rd embodiment
Fig. 4 shows the schematic block circuit diagram of the over voltage protection control circuit of third embodiment of the invention, and one is crossed, owedVoltage protection circuit, comprising: comprise sample circuit, reference voltage signal Vref, direct voltage source VDD, under-voltage comparison andReturn difference control circuit, overvoltage comparison and return difference control circuit thereof, over voltage control signal output circuit, over-voltage locking circuit.The present embodiment is compared with first, second embodiment, and difference is, increases over-voltage locking circuit, other parts completeCause. The concrete structure of the present embodiment over-voltage locking circuit is:
Over-voltage locking circuit comprises NPN type triode Q3, start-up circuit control signal, wherein, and the collection of NPN type triode Q3Electrode connects start-up circuit control signal, and the base stage of Q3 is connected to the common node of resistance R 2, R3, and the emitter stage of Q3 connectsTo input ground.
Start-up circuit control signal operation principle is: in the time that start-up circuit control signal is high level, and the work of start-up circuit itselfMake state unaffected; In the time that start-up circuit control signal is low level, start-up circuit quits work.
After adjusting, the difference of the present embodiment circuit working process and the first embodiment is only the over-voltage locking stage, in conjunction with Fig. 4 instituteThe coherent signal waveform showing, tells about the operation principle in over-voltage locking stage: duty and the embodiment of circuit before the T6 momentOne is just the same, and after the T6 moment, input voltage rises gradually, to T7 moment input voltage triggering over-voltage protection point, circuitEnter overvoltage protection state, defining this stage is the pre-overvoltage protection stage; After the T7 moment, input voltage continues to rise to T8Before moment, operational amplifier U1B continues output high level, the conducting of NPN type triode Q5 collector junction positively biased, Q4 collector junctionReverse-biased cut-off, samples to input voltage after resistance R 1, R2 series connection; Input voltage continues to rise, to the T8 moment, and NPN type threeUtmost point pipe Q3 emitter junction, the equal positively biased conducting of collector junction, start-up circuit control signal is low level state, start-up circuit quits work,Converter overvoltage is locked, quits work; Meanwhile, operational amplifier U1A, U1B all quit work, after 8 moment of definition of TThe duty of circuit is the locked stage of overvoltage.
Especially, before the T8 moment, start-up circuit control signal is exported equal high level state, the duty of start-up circuit itselfDo not affected;
Setting NPN type triode Q3 emitter junction voltage is Vd, overvoltage locking state corresponding voltage VLockAmplitude calculate as formulaShown in 5:
Get final product Exact Design overvoltage locking state point according to formula 5, avoid loop of power circuit switching tube to be damaged by overvoltage, meanwhile,Start-up circuit quits work, and reduces overvoltage condition stand-by power consumption and improves switch converters reliability.
The 4th embodiment
In the 3rd embodiment, the NPN type triode Q1 shown in Fig. 4, Q2, Q4, Q5 can be also NPN type metal-oxide-semiconductors, asShown in Fig. 6, or be NPN type triode and metal-oxide-semiconductor combination (listing no longer one by one detailed combination herein), circuit after adjustingOperation principle and the first embodiment just the same, can realize equal effect.
Below be only the preferred embodiment of the present invention, it should be pointed out that above-mentioned preferred embodiment should not be considered as thisBright restriction, for those skilled in the art, without departing from the spirit and scope of the present invention, also canTo make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention, no longer use embodiment hereRepeat, protection scope of the present invention should be as the criterion with claim limited range.
Claims (11)
1. an over voltage protection control circuit, for the anodal input voltage vin of converter, direct voltage source VDD,After reference voltage signal Vref connects, according to the situation of change of the anodal input voltage vin of converter, to converter master control IC'sError comparator input output over voltage protection control signal, enters guard mode with control change device, it is characterized in that:Comprise sample circuit, under-voltage control circuit, overvoltage control circuit and control signal output circuit,
Described sample circuit, comprises resistance R 1, resistance R 2, resistance R 3, resistance R 4 and resistance R 5, wherein, anodal defeatedEnter voltage Vin and be back to ground by resistance R 5, resistance R 4, resistance R 3, resistance R 2 and the resistance R 1 of connecting successively; ElectricityThe common node of resistance R5 and resistance R 4 is drawn as the first sampled point, for offering under-voltage control circuit; Resistance R 4 withThe common node of resistance R 3 is drawn as the second sampled point, for offering overvoltage control circuit;
Described under-voltage control circuit, in the anodal input voltage vin of converter in the time that under-voltage protection trigger point voltage raises gradually,Determine to exit under-voltage protection state by the resistance R 2 of connecting, resistance R 3, resistance R 4 and total resistance of resistance R 6 in parallelRecovery point voltage;
Described overvoltage control circuit, in the anodal input voltage vin of converter in the time that overvoltage protection trigger point voltage reduces gradually,Determined to exit the recovery point voltage of overvoltage protection state by total resistance of the resistance R 1 of connecting, resistance R 2, resistance R 3.
2. over voltage protection control circuit according to claim 1, is characterized in that: described under-voltage control circuit,Comprise operational amplifier U1A, diode D1, N-type switching tube Q2, resistance R 6, resistance R 9 and resistance R 10, wherein,Operational amplifier U1A in-phase input end connects reference voltage signal Vref, and the inverting input of operational amplifier U1A is connected toCapacitor C 1, resistance R 4, resistance R 5 threes' common node, the inverting input of operational amplifier U1A also passes through resistanceR6 is connected with the colelctor electrode of N-type switching tube Q2, the grounded emitter of N-type switching tube Q2; Operational amplifier U1A outputEnd is by resistance R 9 and resistance R 10 ground connection of series connection; The base stage of N-type switching tube Q2 is connected to resistance R 9 and resistance R 10Common node; The output of operational amplifier U1A is also connected with the anode of diode D1, the negative electrode conduct of diode D1The output of under-voltage control circuit, for being connected with control signal output circuit.
3. over voltage protection control circuit according to claim 1, is characterized in that: described overvoltage control circuit,Comprise operational amplifier U1B, diode D2, direct voltage source VDD, N-type switching tube Q4, N-type switching tube Q5, electricityResistance R11, resistance R 12, resistance R 13 and resistance R 14, wherein, operational amplifier U1B inverting input and reference voltageSignal Vref connects, and operational amplifier U1B in-phase input end is connected to the common node of resistance R 4, resistance R 3; Computing is putThe output of large device U1B is connected with N-type switching tube Q5 base stage by resistance R 12, and the emitter stage of N-type switching tube Q5 connectsGround; Resistance R 11 be connected in parallel on N-type switching tube Q5 base stage and emitter stage between; Direct voltage source VDD passes through series connectionResistance R 13 and resistance R 14 ground connection, the common node of resistance R 13 and resistance R 14 respectively with the current collection of N-type switching tube Q5The base stage of the utmost point and N-type switching tube Q4 connects, the grounded emitter of N-type switching tube Q4; N-type switching tube Q4 current collectionThe utmost point is connected with the common node of resistance R 1 and resistance R 2; The output of operational amplifier U1B also with the anode of diode D2Be connected, the negative electrode of diode D2 is as the output of overvoltage control circuit, for being connected with control signal output circuit.
4. over voltage protection control circuit according to claim 1, is characterized in that: described control signal outputCircuit, comprises resistance R 7, resistance R 8 and N-type switching tube Q1, wherein, one end of resistance R 7 and under-voltage control circuit andThe output of overvoltage control circuit connects, and the other end of resistance R 7 is connected with the base stage of N-type switching tube Q1, N-type switching tubeThe grounded emitter of Q1; Resistance R 8 is connected in parallel between the base stage and emitter stage of N-type switching tube Q1; N-type switching tube Q1'sColelctor electrode is drawn the output as control signal output circuit, for being connected with the error comparator input of converter master control IC.
5. over voltage protection control circuit according to claim 1, is characterized in that: described sample circuit, alsoComprise capacitor C 1, capacitor C 1 is for the interfering signal of filtering switch converters input, and one end of capacitor C 1 is connected to resistanceThe common node of R5 and resistance R 4, the other end ground connection of capacitor C 1.
6. over voltage protection control circuit according to claim 5, is characterized in that: described under-voltage control circuit,Comprise operational amplifier U1A, diode D1, N-type switching tube Q2, resistance R 6, resistance R 9 and resistance R 10, wherein,Operational amplifier U1A in-phase input end connects reference voltage signal Vref, and the inverting input of operational amplifier U1A is connected toCapacitor C 1, resistance R 4, resistance R 5 threes' common node, the inverting input of operational amplifier U1A also passes through resistanceR6 is connected with the colelctor electrode of N-type switching tube Q2, the grounded emitter of N-type switching tube Q2; Operational amplifier U1A outputEnd is by resistance R 9 and resistance R 10 ground connection of series connection; The base stage of N-type switching tube Q2 is connected to resistance R 9 and resistance R 10Common node; The output of operational amplifier U1A is also connected with the anode of diode D1, the negative electrode conduct of diode D1The output of under-voltage control circuit, for being connected with control signal output circuit.
7. over voltage protection control circuit according to claim 5, is characterized in that: described overvoltage control circuit,Comprise operational amplifier U1B, diode D2, direct voltage source VDD, N-type switching tube Q4, Q5, resistance R 11, electricityResistance R12, resistance R 13 and resistance R 14, wherein, operational amplifier U1B inverting input and reference voltage signal Vref connectConnect, operational amplifier U1B in-phase input end is connected to the common node of resistance R 4, resistance R 3; Operational amplifier U1B'sOutput is connected with N-type switching tube Q5 base stage by resistance R 12, the grounded emitter of N-type switching tube Q5; Resistance R 11Be connected in parallel on N-type switching tube Q5 base stage and emitter stage between; Direct voltage source VDD is by resistance R 13 and the electricity of series connectionResistance R14 ground connection, the common node of resistance R 13 and resistance R 14 respectively with colelctor electrode and the N-type switch of N-type switching tube Q5The base stage of pipe Q4 connects, the grounded emitter of N-type switching tube Q4; N-type switching tube Q4 colelctor electrode and resistance R 1 HeThe common node of resistance R 2 connects; The output of operational amplifier U1B is also connected with the anode of diode D2, diodeThe negative electrode of D2 is as the output of overvoltage control circuit, for being connected with control signal output circuit.
8. over voltage protection control circuit according to claim 5, is characterized in that: described control signal outputCircuit, comprises resistance R 7, resistance R 8 and N-type switching tube Q1, wherein, one end of resistance R 7 and under-voltage control circuit andThe output of overvoltage control circuit connects, and the other end of resistance R 7 is connected with the base stage of N-type switching tube Q1, N-type switching tubeThe grounded emitter of Q1; Resistance R 8 is connected in parallel between the base stage and emitter stage of N-type switching tube Q1; N-type switching tube Q1'sColelctor electrode is drawn the output as control signal output circuit, for being connected with the error comparator input of converter master control IC.
9. according to the over voltage protection control circuit described in any one in claim 1 to 8, it is characterized in that: described inOver voltage protection control circuit, also comprises over-voltage locking circuit, and described over-voltage locking circuit comprises NPN type triode Q3With start-up circuit control end, wherein, the colelctor electrode of NPN type triode Q3 is connected with start-up circuit control end, NPN type threeThe base stage of utmost point pipe Q3 is connected with the common node of resistance R 3 and resistance R 2, the grounded emitter of NPN type triode Q3;In the anodal input voltage vin of converter in the time that overvoltage protection trigger point voltage is increased to the over-voltage locking point voltage of setting gradually,NPN type triode Q3 conducting, making start-up circuit control end is low level state, quits work for controlling start-up circuit.
10. according to the over voltage protection control circuit described in any one in claim 1 to 8, it is characterized in that: described inN-type switching tube Q1, N-type switching tube Q2, N-type switching tube Q4 and N-type switching tube Q5 are NPN type triode or NPNType metal-oxide-semiconductor.
11. 1 kinds of sample circuits, are applicable to overvoltage, the under-voltage protection control circuit of converter, in order to according to converter positive poleThe situation of change of input voltage vin, provides to under-voltage control circuit and the overvoltage control circuit of overvoltage, under-voltage protection control circuitSampled signal, is characterized in that: described sample circuit, comprises resistance R 1, resistance R 2, resistance R 3, resistance R 4 and resistanceR5, wherein, anodal input voltage vin is by resistance R 5, resistance R 4, resistance R 3, resistance R 2 and the electricity of connecting successivelyResistance R1 is back to ground; Resistance R 5 is drawn as the first sampled point with the common node of resistance R 4, for offering under-voltage controlCircuit processed; Resistance R 4 is drawn as the second sampled point with the common node of resistance R 3, for offering overvoltage control circuit.
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| CN106253210A (en) * | 2016-08-09 | 2016-12-21 | 珠海格力电器股份有限公司 | Undervoltage protection circuit |
| CN106972461A (en) * | 2017-05-22 | 2017-07-21 | 中国电子科技集团公司第四十三研究所 | A kind of line under-voltage protection circuit inputted with retarding window wide scope |
| CN108270199A (en) * | 2018-03-28 | 2018-07-10 | 广州金升阳科技有限公司 | A kind of output overvoltage protection circuit |
| CN108683153A (en) * | 2018-07-24 | 2018-10-19 | 深圳市泛海三江电子股份有限公司 | Protection circuit capable of automatically recovering |
| CN109038529A (en) * | 2018-08-10 | 2018-12-18 | 维沃移动通信有限公司 | A kind of overvoltage crowbar, charger and electronic equipment |
| CN110069093A (en) * | 2018-01-24 | 2019-07-30 | 丰田自动车株式会社 | Power control |
| CN112117740A (en) * | 2020-08-21 | 2020-12-22 | 广州亚美智造科技有限公司 | Under-voltage protection trigger circuit, under-voltage protection device and power supply system |
| CN112542940A (en) * | 2019-09-23 | 2021-03-23 | 中车株洲电力机车研究所有限公司 | Input overvoltage protection circuit and power panel comprising same |
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| CN112117740A (en) * | 2020-08-21 | 2020-12-22 | 广州亚美智造科技有限公司 | Under-voltage protection trigger circuit, under-voltage protection device and power supply system |
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