CN109980945A - A kind of adaptive lead-edge-blanking control circuit based on current sample - Google Patents

A kind of adaptive lead-edge-blanking control circuit based on current sample Download PDF

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Publication number
CN109980945A
CN109980945A CN201910287250.0A CN201910287250A CN109980945A CN 109980945 A CN109980945 A CN 109980945A CN 201910287250 A CN201910287250 A CN 201910287250A CN 109980945 A CN109980945 A CN 109980945A
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current
edge
signal
blanking
primary
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CN109980945B (en
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罗萍
邓成达
张辽
王强
唐天缘
凌荣勋
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University of Electronic Science and Technology of China
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University of Electronic Science and Technology of China
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00Details of apparatus for conversion
    • H02M1/36Means for starting or stopping converters
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion 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
    • H02M3/325Conversion 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
    • H02M3/335Conversion 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
    • H02M3/33507Conversion 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
    • H02M3/33523Conversion 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

Abstract

A kind of adaptive lead-edge-blanking control circuit based on current sample, belongs to integrated circuit fields and field of switch power.Including adaptive lead-edge-blanking circuit and primary current sample conversion circuit, adaptive lead-edge-blanking circuit generates enable signal of the adaptive lead-edge-blanking signal as primary current sample conversion circuit, and the enabled width of adaptive lead-edge-blanking signal is directly proportional in the load current information of previous switch periods to application system;Primary current sample conversion circuit samples sampled voltage when adaptive lead-edge-blanking signal is not enabled, stop sampling sampled voltage when adaptive lead-edge-blanking signal is enabled, the output signal of primary current sample conversion circuit is after impulse modulation and enhancing driving for controlling being switched on and off for switching tube in application system.The present invention can reduce accidentally sampled probability, improve stability;It can be realized low-power consumption and high efficiency simultaneously.

Description

A kind of adaptive lead-edge-blanking control circuit based on current sample
Technical field
The invention belongs to integrated circuit fields and field of switch power, are related to a kind of adaptive forward position based on current sample Blanking control circuit.
Background technique
In flyback converter, secondary side feedback regulative mode increases system cost, and framework is complicated, and primary side feedback is adjusted Mode has broader practice range.It, must when the control chip of primary side feedback flyback converter obtains system power information The current sample to electrical isolation outlet side therewith must be realized in system input side.Fig. 1 is traditional primary side feedback flyback converter The architecture diagram of system, wherein connect sampling resistor R between the source electrode of switching tube S and primary side groundCS, in switching tube S conducting phase, To sampling resistor RCSUpper terminal voltage signal VCSSampling, converted through a series of circuit computings, can feedback system load current letter Breath, and then control system constant current output, or realize constant pressure using functions such as lower output overcurrent protections.In addition, to pulse frequency is used In the system of rate modulation, also often according to the turn-on time of system load current information control switch pipe, in conclusion primary side feedback The high-precision of flyback converter current sample is most important.
There are leakage inductances for transformer in primary side feedback flyback converter, and when switching tube S is connected, leakage inductance energy is on primary current It rises and increases, switching tube S shutdown moment, most leakage inductance energies will be by D in Fig. 11、CCLAMP、RCLAMPThe resistance-of three's composition Capacitor-diode clamping circuit (RCD circuit) absorbs consumption, but due to diode D1Itself forward conduction voltage drop, Reverse recovery The factors such as effect, leakage inductance energy can not be consumed by RCD circuit completely, some total leakage inductance energy is left, and be stored in system In parasitic inductance, capacitor.When switching tube S is connected again, be stored in parasitic inductance, the leakage inductance of capacitor leaves energy will be by opening Pipe S release is closed, causes switching tube S conducting initial stage primary current to generate spike oscillation, may cause switching tube current information and accidentally adopt Sample finally causes system output current sampling precision to decline.Since leakage inductance storage energy and primary side peak point current are positively correlated, because This, leakage inductance is left energy and will also be changed therewith in each switch periods, causes in next switch periods, and primary current is first in conducting The damped oscillation time of phase is also not fixed.
In conjunction with above-mentioned analysis, to avoid the unfixed spike vibration of primary current time present in switching tube S conducting initial stage The influence to system power sampling precision is swung, conventional solution is when one section of fixed lead-edge-blanking being arranged in sample circuit Between, initial stage current oscillation is connected in mask switch pipe, however, when system input voltage rises or loads increasing, too short forward position Blanking time may be not enough to the oscillation of bucking current spike, and the too long lead-edge-blanking time is arranged and not only will lead to system power dissipation Rise with it, be more likely to cause it is lower in system input voltage, or load it is smaller when, by the voltage of primary current sampling resistor Waveform masks completely, influences system feedback adjusting.
Traditional adaptive lead-edge-blanking circuit is controlled in same switch periods by obtaining current switch period load information The sample circuit lead-edge-blanking time, but the influence that previous switch periods leakage inductance leaves energy is had ignored in this way, primary current The lead-edge-blanking adaptive performance of sample conversion is poor, reduces the accuracy of current sample.
Summary of the invention
For be difficult to existing for the tradition fixed lead-edge-blanking time bucking current spike oscillation effect, control power consumption and It influences to balance between system feedback adjusting, and the adaptive lead-edge-blanking circuit of tradition is ignored previous switch periods leakage inductance and left The problem of energy affect, the present invention propose a kind of adaptive lead-edge-blanking control circuit based on current sample, are using application System generates the adaptive lead-edge-blanking signal of adaptive application system load in the load current information of previous switch periods, from And control current switch period to the sampling blanking time of the sampled voltage comprising application system load current information, it can be fine Ground solves the negative effect of traditional lead-edge-blanking control circuit, improves the accuracy of system power intelligence sample, while reducing electricity Road power consumption is particularly suitable in primary side feedback flyback converter controlling for lead-edge-blanking.
The technical solution of the present invention is as follows:
A kind of adaptive lead-edge-blanking control circuit based on current sample, including adaptive lead-edge-blanking circuit and primary side Current sample conversion circuit, the adaptive lead-edge-blanking circuit is for generating adaptive lead-edge-blanking signal as the primary side The enable signal of current sample conversion circuit, the enabled width and application system of the adaptive lead-edge-blanking signal are previous The load current information of switch periods is directly proportional;The primary current sample conversion circuit is in the adaptive lead-edge-blanking signal Control down-sampling application system in switching tube the sampled voltage that is obtained after resistance of electric current, when adaptive lead-edge-blanking is believed The sampled voltage is sampled when number not enabled, is stopped when adaptive lead-edge-blanking signal is enabled to the sampled voltage It is sampled;The output signal of the primary current sample conversion circuit is answered after impulse modulation and enhancing driving for controlling It is switched on and off with switching tube in system.
Specifically, the adaptive lead-edge-blanking circuit includes the first phase inverter, the second phase inverter, third phase inverter, the One switch, first capacitor and the first current source, the input terminal of the first phase inverter connect the grid signal of switching tube in application system, Its output end connects the control terminal of the first switch;One end of first switch connects the input terminal and the first electricity of the second phase inverter Stream source and by being grounded after first capacitor, other end ground connection;The current value and application system of first current source are opened previous Close the inversely proportional relationship of current value of the load current information in period;The input terminal of third phase inverter connects the defeated of the second phase inverter Outlet, output end export the adaptive lead-edge-blanking signal.
Specifically, first current source is subtracted by a fixed reference current by the primary current sample conversion electricity The current signal that the output voltage on road is converted to obtains.
Specifically, the application system is primary side feedback flyback converter, the switching tube drain electrode connection primary side feedback is anti- Primary side Motor Winding Same Name of Ends in exciting converter, source electrode export the sampled voltage and by being grounded after sampling resistor;
The primary current sample conversion circuit includes that primary side peak point current sampled voltage keeps module, voltage-to-current to turn It changes the mold block, sample integration module, dump block and sampled voltage and keeps module,
It includes second switch and the second capacitor, one end of second switch that the primary side peak point current sampled voltage, which keeps module, The sampled voltage is connected, the other end exports the primary side peak point current sampled voltage and keeps the output voltage of module and pass through It is grounded after second capacitor, control terminal connects the adaptive lead-edge-blanking signal;
The Voltage-current conversion module is used to keep the primary side peak point current sampled voltage output voltage of module It is converted to current signal and connects the input terminal of the sample integration module;
The sample integration module includes third switch and third capacitor, and one end of third switch connects the sample integration The input terminal of module, the other end as the sample integration module output end and by being grounded after third capacitor, control End connection vice-side winding erasing time signal, the vice-side winding erasing time signal are the primary side feedback flyback converter Secondary current from maximum value be reduced to zero this period length pulse width signal;
The dump block include the 4th switch, the 4th switch one end connect the sample integration module output end and The sampled voltage keeps the input terminal of module, other end ground connection, and control terminal connects narrow pulse signal;
It includes operational amplifier, the 5th switch and the 4th capacitor that the sampled voltage, which keeps module, and operational amplifier is just The input terminal that the sampled voltage keeps module is connected to input terminal, and negative input connects its output end and the 5th switch One end;The other end of 5th switch exports the output signal of the primary current sample conversion circuit and is followed by by the 4th capacitor Ground, control terminal connect the grid signal of the switching tube.
Specifically, the grid signal of the switching tube passes through generate after odd number phase inverter and even number of inverters respectively Two signals again mutually with obtain the narrow pulse signal.
The invention has the benefit that the present invention leaves the influence of energy in view of previous switch periods leakage inductance, it can Adaptively change in the sampled voltage of the load current information of previous switch periods to sampling electricity according to comprising application system The sampling blanking time of pressure can reduce mistake sampled probability and avoid switching tube from leading so that system power intelligence sample is more accurate High-frequency noise existing for logical early period causes accidentally to sample, and improves the job stability of application system;Self adaptive control electric current is adopted simultaneously The lead-edge-blanking time during sample can reduce current sampling circuit underloading power consumption, improve the efficiency of sampling.
Detailed description of the invention
Fig. 1 is the circuit block diagram of traditional primary side feedback flyback converter.
Fig. 2 is anti-using a kind of primary side of the adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention Present flyback converter circuit block diagram.
Fig. 3 is adaptive forward position in a kind of adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention A kind of realization circuit diagram of blanking circuit.
Fig. 4 is that primary current is adopted in a kind of adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention A kind of realization circuit diagram of sample conversion circuit.
Fig. 5 is anti-using a kind of primary side of the adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention It presents flyback converter and is lightly loaded working example waveform diagram.
Fig. 6 is anti-using a kind of primary side of the adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention Present flyback converter heavy duty work example waveform figure.
Specific embodiment
It is specific to of the invention one below in conjunction with Figure of description in order to make the public have a better understanding the present invention Embodiment is described in detail and analyzes, and introduces the working principle of the invention and the practicality, but the present invention is not limited to this tool Body embodiment.Modification, alternative and the scheme that present invention encompasses any in inventive concept and range.
In the primary side feedback flyback converter course of work, when previous switch periods switching tube S is turned off, leakage inductance leaves energy It is stored in circuit parasitic capacitance;When new switch periods arrive, the energy of switching tube S conducting, parasitic capacitance passes through switching tube S Release generates the oscillation of primary current spike, obtains currently by the way that specific theory analysis, circuit simulation verification and object test are comprehensive Lead-edge-blanking time of switch periods primary current sample conversion circuit and previous switch periods primary side peak current level at Proportional relationship.It will be applied to below with a kind of adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention The course of work that the present invention will be described in detail for primary side feedback flyback converter, but adaptive lead-edge-blanking of the invention controls electricity Road can be applied not only to primary side feedback flyback converter, and can also be applied to sampling in other circuits includes system load electric current The voltage signal of information, and system is further improved according to the voltage of sampling.
As shown in Fig. 2, in primary side feedback flyback converter, input voltage VIN, busbar voltage VBUS, output voltage is VOUT.Using a kind of primary side feedback flyback change of the adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention Parallel operation includes by primary side winding NP, vice-side winding NSWith auxiliary winding NAThe transformer T of composition, connect with primary side winding Same Name of Ends Switching tube S, the rectifier diode D being connect with vice-side winding Same Name of Ends2;Rectifier diode D2Anode connects vice-side winding Same Name of Ends, Cathode welding system output end, the clamp capacitor C being connect with switching tube S drain electrode and primary side winding different name endCLAMP, clamp resistance RCLAMPWith clamp diode D1
A kind of adaptive lead-edge-blanking control circuit based on current sample proposed by the present invention includes that adaptive forward position disappears Hidden circuit 201 and primary current sample conversion circuit 202, adaptive lead-edge-blanking circuit 201 are received comprising application system preceding The information of voltage of the load current information of one switch periods, the information of voltage can be primary current sample conversion circuit 202 The previous switch periods of sampling include the voltage signal V of primary side feedback flyback converter primary side peak current informationsample, root Load current information, that is, previous switch periods according to application system in previous switch periods sample resulting reflection primary side peak The voltage signal for being worth current information generates adaptive lead-edge-blanking signal VLEB, for controlling primary current in current switch period The sampling time of signal, so that the lead-edge-blanking time during controlling primary current sample conversion, improves system power sampling On the one hand precision can make system power intelligence sample more accurate, avoid switching tube that high-frequency noise existing for early period is connected It causes accidentally to sample, meanwhile, the lead-edge-blanking time during self adaptive control current sample, it is light current sampling circuit can be reduced Carry power consumption.Adaptive 201 input data of lead-edge-blanking circuit is the output of primary current sample conversion circuit 202 in the present embodiment Voltage signal Vsample, output data is adaptive lead-edge-blanking signal VLEB, and it is sent into primary current sample conversion circuit 202.
The sampling resistor R of 202 switch tube S source electrode of primary current sample conversion circuitCSUpper terminal voltage signal samples electricity Press VCSSampling, 202 input data of primary current sample conversion circuit are sampled voltage VCSWith adaptive lead-edge-blanking signal VLEB, According to adaptive lead-edge-blanking signal VLEB, export accurate sampled voltage signal i.e. output signal Vsample, output signal Vsample For the voltage signal comprising previous switch periods load current information, and it is sent into pulse modulated circuit.Wherein sampled voltage VCS Interconnected system output end payload size situation, as the adaptive lead-edge-blanking signal V of adaptive lead-edge-blanking circuit 201 outputLEB Enabled i.e. adaptive lead-edge-blanking signal VLEBWhen for high level, primary current sample conversion circuit 202 stops the source switch tube S Pole sampling resistor RCSUpper terminal voltage signal VCSSampling, as adaptive lead-edge-blanking signal VLEBNot enabled i.e. adaptive lead-edge-blanking Signal VLEBWhen for low level, 202 switch tube S source electrode sampling resistor R of primary current sample conversion circuitCSUpper terminal voltage signal VCSSampling, the adaptive lead-edge-blanking signal V that adaptive lead-edge-blanking circuit 201 exportsLEBEnabled width and previous switch week Phase primary side peak point current is directly proportional.
Pulse modulated circuit input data is the output signal V of primary current sample conversion circuit 202sample, according to sampling Resulting voltage signal VsampleModulation obtains corresponding switching signal waveform VPWMIt is output to driving circuit.
Driving circuit input data is the pwm signal of pulse modulated circuit output, according to VPWMWaveform generates switch control letter Number VGATEAs driving signal, the conducting and shutdown of control switch pipe S.
When primary side feedback flyback converter input voltage become larger or load change weight when, switching tube S peak point current rise, then under In one switch periods, initial stage, the sampling resistor R of switching tube S source series is connected in switching tube SCSUpper end sampled voltage VCSWaveform vibration It swings amplitude to become larger, die-away time is elongated, and adaptive lead-edge-blanking control circuit sampling proposed by the present invention includes system load electricity The sampled voltage V of stream informationCSThe lead-edge-blanking time adaptive synchronicity of Shi Suoxu is elongated, avoids oscillation that voltage is caused accidentally to sample. When primary side feedback flyback converter input voltage become smaller or load lighten when, the decline of switching tube S peak point current, then next switch is all In phase, initial stage, the sampling resistor R of switching tube S source series is connected in switching tube SCSUpper end sampled voltage VCSOscillating waveform amplitude becomes Small, die-away time shortens, and adaptive lead-edge-blanking control circuit sampling proposed by the present invention includes system load current information Sampled voltage VCSThe lead-edge-blanking time adaptive synchronicity of Shi Suoxu shortens.When primary side feedback flyback converter underloading or zero load are defeated When out, the current sample of relatively fixed lead-edge-blanking time, lower power consumption, system effectiveness gets a promotion, and reduces system mistake Sampled probability improves the job stability of primary side feedback flyback converter.
A kind of way of realization of adaptive lead-edge-blanking circuit 201, including the first phase inverter U are given as shown in Figure 31、 Second phase inverter U2, third phase inverter U3, first switch S1, first capacitor C1With the first current source I1, the first phase inverter U1It is defeated Enter the grid signal V of switching tube S in end connection primary side feedback flyback converterGATE, output end connection first switch S1Control End;First switch S1One end connect the second phase inverter U2Input terminal and the first current source I1And pass through first capacitor C1It is followed by Ground, other end ground connection;First current source I1Current value and application system previous switch periods load current information The inversely proportional relationship of current value, the first current source I in the present embodiment1Current value and previous switch periods primary side peak value electricity The inversely proportional relationship of size is flowed, one reference current source fixed can be subtracted into the defeated of primary current sample conversion circuit 202 Signal V outsampleThe electric current generated after conversion can be obtained and is inversely proportional with previous switch periods primary side peak current level First current source I of example relationship1.Third phase inverter U3Input terminal connect the second phase inverter U2Output end, output end output Adaptive lead-edge-blanking signal VLEB
First switch S1With first capacitor C1Parallel connection, the first current source I1To first capacitor C1Charging, first capacitor C1On Voltage is VC1;Second phase inverter U2Input terminal is first capacitor C1On voltage be VC1;VC1With the second phase inverter U2Itself threshold value Voltage is made comparisons, VC1Higher than the second phase inverter U2By V when itself threshold voltageC1Carry out reverse phase;Second phase inverter U2Output letter Number pass through third phase inverter U3Reverse phase shaping generates adaptive lead-edge-blanking signal VLEB;In this example, the grid of switching tube Control signal VGATEBy the first phase inverter U1Control first switch S1Switch state.
A kind of way of realization of primary current sample conversion circuit 202, including primary side peak point current are given as shown in Figure 4 Sampled voltage keeps module, Voltage-current conversion module, sample integration module, dump block and sampled voltage to keep module,
Primary side peak point current sampled voltage keeps module to receive sampled voltage VCS, in switching tube S conducting, to sampled voltage VCSSampling, in switching tube S shutdown, the voltage retention value of primary side peak point current sampled voltage holding circuit 202 is sampled voltage Peak value.It includes second switch S that primary side peak point current sampled voltage, which keeps module,2With the second capacitor C2, second switch S2One end connect Meet sampled voltage VCS, the output voltage V of other end output primary side peak point current sampled voltage holding moduleCS-PKAnd pass through the Two capacitor C2After be grounded, control terminal connects adaptive lead-edge-blanking signal VLEB
Voltage-current conversion module is used to keep primary side peak point current sampled voltage the output voltage V of moduleCS-PKConversion For the current signal I for matching the information of voltage2And connect the input terminal of sample integration module.
Sample integration module receives vice-side winding erasing time signal VDISWith the electric current of current/charge-voltage convertor output Signal I2, the voltage signal V of reaction load current information is obtained by capacitance integralCT.Sample integration module includes third switch S3With third capacitor C3, third switch S3One end connection sample integration module input terminal, the other end is as sample integration mould The output end of block simultaneously passes through third capacitor C3After be grounded, control terminal connect vice-side winding erasing time signal VDIS, vice-side winding Erasing time signal VDISFor primary side feedback flyback converter secondary current from maximum value be reduced to zero this period length pulsewidth Signal.
Dump block generates a narrow pulse signal V at the switching tube S shutdown momentRT, to the output number of sample integration module According to clearing, prepare for the voltage sample holding in next period.Dump block includes the 4th switch S4, the 4th switch S4One end The output end and sampled voltage that connect sample integration module keep the input terminal of module, other end ground connection, control terminal connection Narrow pulse signal VRT.Wherein narrow pulse signal VRTThe grid signal V of switching tube S can be passed throughGATEIt is generated by logic circuit;It will The grid signal V of switching tube SGATETwo voltage signals are obtained after even number of inverters and odd number phase inverter respectively, Again by the two voltage signals by with Men Xiangyu, and then obtain narrow pulse signal VRT
Sampled voltage keeps module to receive the voltage signal V after sample integration moduleCT, and completely output includes load The voltage sampling signal of current information, that is, adaptive lead-edge-blanking control circuit output signal Vsample.Sampled voltage keeps mould Block includes operational amplifier U4, the 5th switch S5With the 4th capacitor C4, operational amplifier U4Positive input connect sampled voltage The input terminal of module is kept, negative input connects its output end and the 5th switch S5One end;5th switch S5The other end Export the output signal V of primary current sample conversion circuit 202sampleAnd pass through the 4th capacitor C4After be grounded, control terminal connection The grid signal V of switching tubeGATE
Second switch S2Pass through the grid signal V of switching tubeGATEIts switch state is controlled, as second switch S2When closure, adopt Sample voltage VCSIt is transferred to the second capacitor C2, voltage VCS-PK;Second capacitor C2Voltage VCS-PKIt is by current/charge-voltage convertor VI conversion circuit is converted to comprising VCS-PKSecond current source I of information of voltage2;Third switch S3Pass through the vice-side winding erasing time Signal VDISIts switch state is controlled, as third switch S3When closure, the second current source I2To third capacitor C3Integral, obtains third Capacitor C3Upper terminal voltage signal VCT;4th switch S4Pass through narrow pulse signal VRTIts switch state is controlled, in next switch week It is interim to third capacitor C3On voltage VCTIt resets;5th switch S5Pass through the grid signal V of switching tubeGATEIt controls it and switchs shape State, as the 5th switch S5When closure, third capacitor C3On voltage VCTBy the operational amplifier U for being connected into voltage follower form4 It is transmitted to the 4th capacitor C4In, the 4th capacitor C4Voltage be Vsample
Attached drawing 5 is the working example waveform diagram under the present embodiment underloading, and circuit works under discontinuous mode, opens Close pipe peak point current IPPKSmaller, when switching tube S turns off the moment, it is smaller that transformer leakage inductance leaves energy, therefore circuit parasitic parameter The energy of middle storage is also relatively small, and in next switch periods, initial stage, switching tube S source electrode sampling resistor R is connected in switching tube SCSOn The sampled voltage signal V at endCSOscillation amplitude is smaller, and die-away time is shorter, and the lead-edge-blanking time of systematic sampling is shorter, so that inspection Slowdown monitoring circuit can accurately detect primary current information.
Attached drawing 6 is the working example waveform diagram under the heavy duty of the present embodiment circuit, and circuit works in discontinuous mode Under, switching tube peak point current IPPKLarger, when switching tube S turns off the moment, it is larger that transformer leakage inductance leaves energy, therefore circuit is posted The energy stored in raw parameter is also relatively large, and in next switch periods, initial stage, sampled voltage V is connected in switching tube SCSVibrate width It is worth larger, die-away time is longer, and the lead-edge-blanking time of systematic sampling is longer, avoids primary current information and accidentally samples.
Primary side feedback flyback is become from above-mentioned specific embodiment it is found that leaving energy in view of previous switch periods leakage inductance The influence of parallel operation, the present embodiment generate adaptive lead-edge-blanking signal according to previous switch periods primary side peak current information, To which adaptive change is to the sampling blanking time of sampled voltage, in the case of avoiding extraneous input factor and load change, System power information accidentally samples, and can reduce accidentally sampled probability, improve the job stability of application system;Application is reduced simultaneously System power dissipation improves the rate of application system effect;A kind of adaptive lead-edge-blanking control based on current sample proposed by the present invention Circuit processed is applicable to the primary side feedback flyback converter system of any occasion.
Above by a specific embodiment, to the adaptive lead-edge-blanking control circuit of a kind of current sample of the invention into It has gone and has been described in detail and analyzes, it is worth noting that the present invention can be not only used for switching in sampling primary side feedback flyback converter The sampled voltage of pipe source can be also used for other circuit samplings, include the application circuit for obtain other application circuit Load the voltage of the current information of weight situation.Those skilled in the art can these disclosed technologies according to the present invention Various other various specific variations and combinations for not departing from essence of the invention are made in enlightenment, and these variations and combinations are still in this hair Within bright protection scope.

Claims (5)

1. a kind of adaptive lead-edge-blanking control circuit based on current sample, which is characterized in that including adaptive lead-edge-blanking Circuit and primary current sample conversion circuit, the adaptive lead-edge-blanking circuit are made for generating adaptive lead-edge-blanking signal For the enable signal of the primary current sample conversion circuit, the enabled width of the adaptive lead-edge-blanking signal and application are System is directly proportional in the load current information of previous switch periods;The primary current sample conversion circuit it is described it is adaptive before The sampled voltage that the electric current of switching tube obtains after resistance along the control down-sampling application system of blanking signal, when adaptive Lead-edge-blanking signal samples the sampled voltage when not enabled, stops when adaptive lead-edge-blanking signal is enabled to institute Sampled voltage is stated to be sampled;The output signal of the primary current sample conversion circuit is after impulse modulation and enhancing driving For controlling being switched on and off for switching tube in application system.
2. the adaptive lead-edge-blanking control circuit according to claim 1 based on current sample, which is characterized in that described Adaptive lead-edge-blanking circuit includes the first phase inverter, the second phase inverter, third phase inverter, first switch, first capacitor and the One current source, the grid signal of switching tube, output end connection described the in the input terminal connection application system of the first phase inverter The control terminal of one switch;The input terminal and the first current source of the second phase inverter of one end connection of first switch simultaneously pass through first capacitor After be grounded, the other end ground connection;The current value and application system of first current source are believed in the load current of previous switch periods The inversely proportional relationship of the current value of breath;The input terminal of third phase inverter connects the output end of the second phase inverter, output end output The adaptive lead-edge-blanking signal.
3. the adaptive lead-edge-blanking control circuit according to claim 2 based on current sample, which is characterized in that described First current source is subtracted by a fixed reference current and is converted to the output voltage of the primary current sample conversion circuit Current signal obtain.
4. the adaptive lead-edge-blanking control circuit according to any one of claims 1 to 3 based on current sample, feature It is, the application system is primary side feedback flyback converter, in the switching tube drain electrode connection primary side feedback flyback converter Primary side winding Same Name of Ends, source electrode export the sampled voltage and by being grounded after sampling resistor;
The primary current sample conversion circuit includes that primary side peak point current sampled voltage keeps module, Voltage-current conversion mould Block, sample integration module, dump block and sampled voltage keep module,
It includes second switch and the second capacitor, one end connection of second switch that the primary side peak point current sampled voltage, which keeps module, The sampled voltage, the other end export the primary side peak point current sampled voltage and keep the output voltage of module and by second It is grounded after capacitor, control terminal connects the adaptive lead-edge-blanking signal;
The Voltage-current conversion module is used to keep the output voltage of module to convert the primary side peak point current sampled voltage For current signal and connect the input terminal of the sample integration module;
The sample integration module includes third switch and third capacitor, and one end of third switch connects the sample integration module Input terminal, the other end as the sample integration module output end and by being grounded after third capacitor, control terminal connects Vice-side winding erasing time signal is connect, the vice-side winding erasing time signal is the secondary side of the primary side feedback flyback converter Electric current from maximum value be reduced to zero this period length pulse width signal;
The dump block includes the 4th switch, and one end of the 4th switch connects the output end of the sample integration module and described Sampled voltage keeps the input terminal of module, other end ground connection, and control terminal connects narrow pulse signal;
It includes operational amplifier, the 5th switch and the 4th capacitor that the sampled voltage, which keeps module, and the forward direction of operational amplifier is defeated Enter end and connect the input terminal that the sampled voltage keeps module, negative input connects the one of its output end and the 5th switch End;The other end of 5th switch exports the output signal of the primary current sample conversion circuit and is followed by by the 4th capacitor Ground, control terminal connect the grid signal of the switching tube.
5. the adaptive lead-edge-blanking control circuit according to claim 4 based on current sample, which is characterized in that described The grid signal of switching tube pass through respectively two signals generated after odd number phase inverter and even number of inverters again mutually with obtain The narrow pulse signal.
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