CN1215171A - Auxiliary induction method transformer magnetic bias test method and apparatus thereof - Google Patents
Auxiliary induction method transformer magnetic bias test method and apparatus thereof Download PDFInfo
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- CN1215171A CN1215171A CN 98118974 CN98118974A CN1215171A CN 1215171 A CN1215171 A CN 1215171A CN 98118974 CN98118974 CN 98118974 CN 98118974 A CN98118974 A CN 98118974A CN 1215171 A CN1215171 A CN 1215171A
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Abstract
The present invention relates to a bias current detection method for monitoring bias magnet of transformer in switching power supply and its equipment. It adopts an auxiliary inductor which is made up according to a limited condition and can be directed to work under the correspondent limited conditon, and makes its produced field current use high-speed sampling switching-over circuit to detect the current representing the bias magnet and overexcitation of the monitored transformer, and convert the current into voltage signal and switching value signal. Said voltage signal and switching value signal are small in time delay, so that they can be used as ideal control signal for pulse-width regulation circuit and switch-off protective circuit in the switching power supply.
Description
The present invention is the bias current detection method and the device of transformer bias in the monitoring Switching Power Supply, relates to Switching Power Supply, the over-current detection technology of power switch pipe especially wherein.
Transformer is as the intermediate conveyor load in the Switching Power Supply, and one when entering magnetic saturation by magnetic biasing, causes the power switch pipe output short-circuit immediately.Power switch pipe damages because of output short-circuit, is a mortal wound of Switching Power Supply, and of common occurrence.Especially as the Switching Power Supply of inverter arc welding power source, big and load variations is frequent because of its power output, by being that the transformer magnetic saturation phenomenon that causes is more common.
Magnetic biasing is magnetically saturated tendency, if can carry out fast detecting and adjusting to it, just can prevent that transformer from entering the magnetic saturation state.
During magnetic bias, exciting current increases rapidly, therefore can realize the detection to magnetic bias with the method for detection exciting current.But in the positive activation type Switching Power Supply, the electric current in the primary of flowing through loop is made up of two kinds of current components, and except that exciting current, also having a kind of is the transmission current that is sent to transformer secondary output.Therefore, can't realize detection with the method for independent detection of primary loop current to exciting current.In the prior art, what be used for detecting exciting current is a kind of differential technique.This method has two basic links: one, respectively primary and secondary loop are carried out current detecting with two groups of current sensing meanss, obtain two current values; Two, two current values are carried out the difference computing with computing circuit.This difference is the exciting current value.Operational pattern is:
In the formula: n is a primary and secondary winding turns ratio.The secondary loop electric current divided by turn ratio n after, obtain the elementary secondary transmission current that is sent to.After from primary return, deducting this component, asked for excitation current component.Because the influence of afterflow inertance element in influence, the especially secondary loop of inertance element in core loss and the circuit, and the influence of arithmetic eror, the exciting current value of operation result gained and actual value often differ very fortune.As reaching request for utilization, must increase many adjunct circuits.But the deadly defect of this method is through the signal of computing output bigger time delay is arranged, and can't be used for magnetic bias and regulate and realize quick turn-off protection.So still few people use so far.
Purpose of the present invention provides and a kind ofly need not pass through computing, can carry out method and device that bias current detects fast, makes the signal that detects gained can satisfy magnetic bias and regulates and the requirement of protection fast.
Realization the objective of the invention is following a kind of method.This method has two links: one, adopt an auxiliary induction, make its with monitored Switching Power Supply in primary equate or approximately equal, synchronous or near-synchronous and work under the constant or approximate constant voltage conditions of the ratio of amplitude under same or approximate same voltage conditions or respectively two pulsewidths, make its generation and transformer bias, the corresponding exciting current of overexcitation; Two, from auxiliary induction, detect exciting current with a circuit with sampling and function switching signal; wherein representing monitored transformer bias to become voltage signal or switching value signal with overexcited current conversion, to be used for the input control signal of Switching Power Supply bias set circuit and Switching Power Supply cut-off protection circuit.
Realizing the key of this method, also is that main feature is the employing and the coiling of auxiliary induction.At the auxiliary induction of under same or approximate same voltage conditions, working with monitored primary, or equate or approximately equal, synchronously or another auxiliary induction of working under the constant or approximate constant voltage conditions of near-synchronous and amplitude that in pulsewidth the time rate of change curve of their relative magnetic flux density should be similar with the time rate of change curve of the relative magnetic flux density of tested primary with monitored primary.Next is that the circuit with sampling and function switching signal also should have enough little time-delay for exciting current sampling in the auxiliary induction and conversion of signals output, and magnetic bias is regulated and the turn-off protection requirement of response fast to satisfy.The device (being named as " bias current pick-up unit ") that designs according to the inventive method, this auxiliary induction design main points and method for making is provided, basic structure and this device embodiment of the testing circuit (being named as " sampling switching circuit ") with sampling and function switching signal is provided.
Fig. 1 is the electrical schematic diagram according to the bias current pick-up unit of the inventive method design
Fig. 2 is with the enforcement illustration of sub-push-pull type Switching Power Supply in the bias current pick-up unit
Fig. 3 implements illustration for sampling switching circuit with switching value output in the bias current pick-up unit
Fig. 4 implements illustration for sampling switching circuit with detection magnetic bias direction function in the bias current pick-up unit
Fig. 5 is sampling switching circuit enforcement illustration that is used to detect pulsating direct current formula exciting current in the bias current pick-up unit
Fig. 6 in the bias current pick-up unit one can be used for direct-coupled sampling switching circuit and implement illustration
Fig. 7 is enforcement illustration that is used to improve the sampling switching circuit noiseproof feature in the bias current pick-up unit
Fig. 8 is enforcement illustration of working in the bias current pick-up unit under different voltage conditions
Fig. 9 in the bias current pick-up unit one with photoelectric coupled device and connect the enforcement illustration of use
Figure 10 is enforcement illustration that uses with the pulse transformer merging in the bias current pick-up unit
The identical components and parts of all signs have identical effect among the figure, do not make repeated description.
Bias current checkout gear (hereinafter to be referred as device) is by auxiliary induction L1 and sampling switching circuit A1 is in series, if must provide self overcurrent protection to this device, again adjunction current limliting is protected Protect resistance R 1, be in series again with above-mentioned series circuit. This device is connected across monitored switch electricity On source transformer B1 and the elementary N1N2 two input lines, with primary and connect use, or With monitored transformer respectively two pulsewidths equate or approximately equal, synchronously or near-synchronous, And work under the constant or approximate constant voltage conditions of the ratio of amplitude. Signal from this device output Transport to the control circuit in the Switching Power Supply, be used for control circuit and realize magnetic bias control or Switching Power Supply The control signal of turn-off protection or magnetic bias control and Switching Power Supply turn-off protection. Auxiliary induction L1 A1 connects with sampling switching circuit, or connects with current-limiting protection resistance R 1 again, the two or three's The mutual alignment can be any. Also sampling switching circuit A1 can be connected on the centre of auxiliary induction L1.
When under high voltage condition, working, the device current-limiting protection resistance R 1 of should connecting, resistance resistance Value is according to magnetic bias exciting current value (i.e. maximum normally excitation electricity the most very much not among 5～20 times of auxiliary induction L1 Determine that flow valuve) resistor power is 1～10W or complies with actual use value and decide. Current-limiting protection resistance R 1 Also can be divided into two, or some, concentrate or disperse and be connected in the device.
Auxiliary induction L1 forms with insulated conductor coiling on magnetic core. With monitored transformation Device is compared, and their core material is identical or not identical, geometry be similar or Dissimilar. When auxiliary induction L1 be use with monitored transformer and the condition that connects under, adopt The magnetic core coiling identical with material, that geometry is similar is conducive to improve the stability of monitoring.
The magnetic flux density usage factor is the key technical indexes of coiling auxiliary induction L1.So-called usage factor is meant the peakflux density (hereinafter to be referred as maximum magnetic flux close) of magnetic core under magnetic bias condition of work not and the ratio of the saturation magnetic flux density of this magnetic core.This coefficient value size should be with reference to the magnetic flux density usage factor of transformer, can identical, also can be close.If, can make the former relative change in magnetic flux density rate curve be ahead of the latter with the magnetic flux density usage factor value of auxiliary induction L1 usage factor greater than transformer.This can not only improve bias current and detect degree of stability, can also reduce the defer time of magnetic biasing rectification and turn-off protection.
Sampling switching circuit A1 is made up of sample circuit A1-1, filtering circuit A1-2 and signaling conversion circuit A1-3.Include at least one sampling device among the sample circuit A1-1, this device is D.C mutual-inductor B2, direct current transducer, sample resistance device R2 or isolated amplifier etc.; Filtering circuit A1-2 is RC or LRC formula or RC and electronic switch type or LRC and electronic switch type; Signaling conversion circuit A1-3 has two kinds, and what wherein a kind of circuit was exported is the varying level voltage signal of representing the magnetic bias direction, and two groups of storage circuitry are arranged in this circuit, and storage circuitry is formed with storage capacitor C 2 by electronic switch K1 respectively; What another kind of circuit was exported is the overexcited switching signal of representative, includes one or two devices with threshold values identification function in this circuit, and this device is triode V3 and V4, voltage comparator ic 1, IC2 or controllable silicon etc.1. with 2. two input ends of sample circuit A1-1 are serially connected in input circuit in the device loop, after converting voltage signal to, the current signal that sampling is got is sent among the filtering circuit A1-2, this voltage signal is after filtering circuit A1-2 filtering undesired signal wherein, transport to signaling conversion circuit A1-3, signaling conversion circuit to varying level voltage signal or the switching value signal of converting, and exports the control circuit in the Switching Power Supply to.
This device adopts the method in parallel with monitored primary to implement.Whole device and monitored primary are worked under same voltage, thereby are synchronous, same pulsewidths.
This inverter arc welding rectifier that is to say a kind of full-bridge type Switching Power Supply.Use as Arc Welding Power, very easily produce magnetic biasing, therefore more must install the bias current pick-up unit additional, protected.During enforcement, to carry out the technology of auxiliary induction L1 earlier and make design, be undertaken by following six main points.During the narration main points, simultaneously the auxiliary induction L1 in the present embodiment is designed.
One, ask for transformer relevant technologies data, mainly contain:
(1) magnetic core of transformer material: R2KB, saturation magnetic flux density Bb=4000 Gauss, initial magnetic permeability mu o=2000.
(2) magnetic core of transformer geometric configuration: 4 E65 magnetic cores dock in twos.
(3) magnetic flux density usage factor Ko:Ko=0.6
(4) primary operating voltage amplitude Uo:
(5) primary maximum functional pulsewidth t:t=15 * 10
-6S
Two, auxiliary induction experimental technology data setting mainly contains:
(1) core material: R2KB, magnetoconductivity value μ: μ=0.75 * μ o=1500 (because of the magnetic gap influence).
(2) magnetic flux density usage factor K:K=0.7
The close Bm=0.7Bb=0.7 of maximum magnetic flux * 4000=2800 Gauss
(3) magnetic bias exciting current I value the most very much not: I=40mA=40 * 10
-3Peace
(4) protection cut-off current is in 20 times: Im=20 * 40 * 10
-3=0.8 peace
(5) current-limiting protection resistance R 1 resistance: R
1=Uo/Im=387 Ω, get 400 Ω and be divided into two.
(6) auxiliary induction L1 terminal voltage U:U=(Uo * 2-R
1* I)/2=302.2V.
Three, number of turn n, inductance value L and magnetic core At (A: magnetic core sectional area, unit [cm]
2T: the length of magnetic path, the cm of unit) long-pending calculating.
(1) number of turn n formula value: n=Ut * 10
-6* 10
8/ BmA=1.62 * 10
2/ A (circle)
(2) inductance value L:L=Ut/I=1.13 * 10
-1Prosperous
(3) ask the At value: with above-mentioned numerical value substitution following formula
L=4 π n
2A μ * 10
-9/ t puts in order
At=4.377cm
3
Four, determine magnetic core, magnetic core adopts standard component, and E128 magnetic core At value is 4.11cm
3, its A value is 0.85.Magnetic core geometries is closely similar to magnetic core of transformer, select for use.
Five, calculate umber of turn n:n=1.62 * 10
2/ A=190 circle.
Six, selected diameter of wire φ: φ=0.1～0.18mm.
According to above-mentioned design, can carry out auxiliary induction and make.During coiling, draw two taps, be used for sampling switching circuit A1 and put in series from the centre.Winding and magnetic core should be fixed on the skeleton.
It is switching value that control circuit in this inverter arc welding rectifier requires to provide magnetic bias to regulate with protecting the control signal of turn-offing fast, can select the sampling switching circuit of Fig. 3 example design for use.Among Fig. 3, sample circuit A1-1 is made up of with the pull-up resistor R2-1 and the R2-2 that are connected in series mutually by two bridge rectifier circuit that diode D1-1, D1-2, D1-3 and D1-4 form D.C mutual-inductor B2.Filtering circuit A1-2 is two groups, all is RC formulas, is made up of resistance R 3 and capacitor C 1.Signaling conversion circuit also is two groups, is made up of triode V3, V4 with threshold values identification function and output load resistance R4, R5, and one the tunnel is V3 and R4, and another road is V4 and R5.Sampled signal after the bridge rectifier circuit rectification, adds to pull-up resistor R2-1 and R2-2 by B2 level output of D.C mutual-inductor, converts the magnitude of current to voltage on resistance, after R3C1 filtering, is sent to signaling conversion circuit A1-3.The threshold voltage of triode is 0.65V, when resistance R 2-1 goes up voltage u
1When rising to about 0.65V, triode V3 is from by transferring conducting to, and by 3. switching signal of end output, this signal is that magnetic bias is regulated control signal.Voltage u on resistance R 2-2
2When rising to about 0.65V subsequently, triode V4 conducting is used for the switching signal of turn-off protection by 4. end output.Resistance R 2-1 and R2-2 should set according to minimum overexcitation current value, about respectively 2.7～47 Ω, and in debugging, revised.During the choosing value, determine the ratio of resistance R 2-1 and resistance R 2-2 earlier, this ratio is with voltage u
2Than voltage u
1Hysteresis and set, this hysteresis is switching signal sum time delay that response time and sampling switching circuit A1 are corrected in magnetic biasing.The physical significance of above-mentioned setting is through lagging behind, to fail to realize voltage u if magnetic bias is regulated
2Along with rising to 0.65V, make triode V4 output cut-off signals, the stopcock power work.Resistance R 3 and capacitor C 1 are according to the time constant value, and this time constant is decided according to the undesired signal width.Resistance R 4 is about 4.7K with the R5 value.
If the controlled quentity controlled variable that the magnetic bias in the Switching Power Supply is regulated the control circuit requirement to be provided is the magnetic bias direction signal, can select the design of Fig. 4 example for use.Compare with Fig. 3 example, pull-up resistor is a R2, filtering circuit is one group, what main difference was that signaling conversion circuit (A1-3) adopts is two groups of storage circuitry and voltage comparator ics 1 that structure is identical, storage circuitry is formed with storage capacitor C 2 by electronic switch K1, and the output terminal of two storage circuitry is connected with 1 liang of input end of voltage comparator ic respectively.Owing to be added on the control signal of electronic switch (K1) control utmost point G and be synchronizing signal or standard (hysteresis) synchronizing signal with leading from Switching Power Supply power switch pipe switching signal, therefore, the exciting current amount that voltage in two capacitor C 2 of son is represented two magnetic directions respectively is sent to and stores in two electronic switches (K1) timesharing under the alternation switch signal controlling, under their unequal conditions, voltage comparator is just exported the voltage of representing the magnetic bias direction, its voltage high level is corresponding one by one with two kinds of magnetic bias directions respectively with low level, is regulated in the control circuit by the magnetic bias that 5. voltage comparator ic 1 output terminal is sent in the Switching Power Supply.Resistance R 4 is pull-up resistors of voltage comparator ic 1.Since interior group of electronic switch K1 with store capacitor C 2 and have the RC filter function simultaneously, therefore, resistance R 3 can be by them for it with capacitor C 1.
Fig. 4 example can and connect use with the design of Fig. 3 example, and contact two resistance (R2-1 and the R2-2) two ends of connecting in Fig. 3 example.Pull-up resistor R2 in Fig. 4 example of back in parallel can, also can do and connect and adjust resistance and use.
Since the afterflow characteristic of inductive current, the exciting current in first cycle can last till this semiperiod and with the work of other undesired signal stack, disturbed sampling change-over circuit A1.Can be filter capacitor C1 two ends also, and connect an electronic switch K2 (see figure 7) with strengthening RC or LRC time constant in the filtering circuit, make its conducting during above-mentioned interference, short circuit undesired signal at the output terminal of filtering circuit A1-2.Electronic switch K2 can select triode or field effect transistor for use.The control signal u of electronic switch conducting
3The forward position of available driving pulse is triggered monostable circuit or is formed through delay circuit.This control signal u
3Pulsewidth decide by the undesired signal width.After installing electronic switch K2 additional, RC among the filtering circuit A1-2 or LRC time constant can reduce, to improve the sampling slewing rate.
Embodiment 2, are used for the bias current pick-up unit of push-pull type Switching Power Supply, with reference to Fig. 2.
This device also adopts the method in parallel with monitored primary to implement.
In the push-pull type Switching Power Supply, primary has two windings (N1N0 and N0N2), is wound on the same group of magnetic core.Therefore, device also should have two groups, and two windings of its two auxiliary inductions (L1-1 and L1-2) also should be wound on the same group of magnetic core.For avoiding sampling switching circuit A1 to cause the detection error because of parameter differs, two groups of devices should a shared sampling switching circuit A1.Their electrical connection is: each end of two auxiliary inductions (L1-1 and L1-2) is connected (also promptly being connected with primary one input end) with the output terminal line of power switch pipe (V1 or V2) respectively.Their each other end is connected to a common port, and sampling switching circuit A1 is serially connected on this common port and the power supply line.After doing to change like this, the cascaded structure of sampling switching circuit A1 and auxiliary induction L1 does not change.Two power switch pipes of push-pull type Switching Power Supply also are alternations, V1 turn-offs when pipe, pipe V2 is when opening, and the auxiliary induction L1-1 that is connected with pipe V1 closes because of pipe V1, so via the electric current of sampling switching circuit A1, flow into auxiliary induction N1-2, like this, L1-1 does not work at auxiliary induction, and auxiliary induction L1-2 when work, the latter and sampling switching circuit A1 are in series, and are in parallel with primary N0N2.Otherwise sampling switching circuit A1 and auxiliary induction L1-1 are in series, and N1N0 is in parallel with primary.The design of auxiliary induction L1-1 and L1-2 is with reference to embodiment 1.Because exciting current is a kind of pulsating direct current, sampling switching circuit should select for use Fig. 5 to design.This design also is made up of three parts.Sample circuit A1-1 is composed in series by sample resistance R2 and pull-up resistor R2-1, and filtering circuit A1-2 is made up of resistance R 3 and capacitor C 1, if be subjected to first cycle exciting current afterflow interference, at the C1 two ends and meet electronic switch K, as example 1.Signaling conversion circuit A1-3 is made up of threshold values discriminating triode V3 and output load, and output load is photoelectric coupled device HD1.Resistance R 6, capacitor C 3 and three diode D2-1, D2-2 and D2-3 form stabilized voltage supply, voltage stabilizing value 2.1V, and the diode decision by three serial connections is used for the power supply to photoelectric coupled device HD1, and resistance R 7 is used for current limliting.About 100 Ω of resistance R 6 values, about 47 Ω of R7 value, the about 6800p of capacitor C 3 values.Resistance R 2-1 is about 2.5 to 0.65 with the ratio of resistance R 2.When the voltage U on the sample resistance R2 2 rose to 0.65V, resistance R 2-1 went up terminal voltage and rises to about 3.1V.Resistance R 2 resistances are selected according to initial overexcitation current value.Served as exciting current by 1. with 2. when input end, triode V3 conducting drives photoelectric coupled device HD1 work, by 7. with 8. hold output switching signal.
Photoelectric coupled device in this sampling switching circuit can be with pulse transformer B3 for it.During replacement, pulse transforming is elementary to be inserted at " x " point, and elementary and connect one and absorb circuit, this circuit is connected in series with stabilivolt D4 by diode D3 and forms, voltage stabilizing value 5～10V.Threshold values differentiates that device V3 also can use voltage comparator instead.Using pulse transformer instead, especially behind the voltage comparator, must kind power supply.The change method is: resistance R 2-1 is increased, the voltage on the R2-1 is brought up to about 7V.Use three serial connection diodes instead the 5V stabilivolt, capacitor C 3 is used 0.1 μ f instead, and is connected in series a release blocking-up diode with resistance R 6.Power to voltage comparator by the 5V stabilized voltage supply.Or add a power supply and power to it.
If must be in this device adjunction current-limiting protection resistance, this resistance can be serially connected in the auxiliary induction two ends, or with a common resistance, is serially connected between the common port and sampling switching circuit A1 that two auxiliary inductions (L1-1 and L1-2) are connected.
Embodiment 3, the magnetic bias pick-up unit of working under different voltage conditions with monitored transformer.
With different with monitored transformer and the service condition that connects, the auxiliary induction L1 in this magnetic bias pick-up unit should add another operating voltage it is implemented excitation.This driving voltage if with the voltage that is added on monitored transformer be synchronously or near-synchronous, constant or approximate constant with the ratio of the amplitude that is added on monitored transformer with pulsewidth or approximate same pulsewidth, its voltage magnitude, can realize that equally magnetic bias detects.This driving voltage can provide with bridge-type (containing half-bridge and push-pull type) circuit, also can provide with the double push-pull circuit.When providing with the double push-pull circuit, its rate of change of ratio that is added on the voltage on voltage and the monitored transformer on the auxiliary induction L1 also can be realized the magnetic bias monitoring up to ± 30% o'clock.This is because the double push-pull circuit can provide a high Q afterflow passage for auxiliary induction L1 at the excitation tempus intercalare, makes auxiliary induction L1 have good magnetic memory characteristic, thereby has improved the magnetic bias detection sensitivity.Push-pull circuit can be used complementary type, also can be with totem pole type or other.Among Fig. 8, complementary triode V5 and V6 form one group of complementary type push-pull circuit, complementary triode V7 and V8 form another group complementary type push-pull circuit.Diode D6 and D7 are in order to link up the afterflow passage.When the drive signal that is added on push-pull circuit was positive polarity, diode D6 and D7 be respectively with underarm three utmost point V6, V8 and connect, if during negative polarity, diode D6 and D7 are then respectively with upper arm triode V5, D7 and connect.Auxiliary induction L1 is connected across on the two push-pull circuit output terminals.The drive signal that is added on the double push-pull circuit input end and the voltage that is added on monitored transformer is from same signal source, thus be synchronously or near-synchronous, with pulsewidth or approximate same pulsewidth.This device is if adopt the words of the low-tension supply power supply that is used for main control circuit in the Switching Power Supply; the then output of the access of drive signal and magnetic bias correcting signal and turn-off protection signal; all can realize directly coupling, help improving the application performance of magnetic bias pick-up unit with main control circuit.Sampling switching circuit A1 is serially connected between the points of common connection and ground of double push-pull circuit underarm triode V6 and V8.It and auxiliary induction L1 also are series relationship.When positive polarity drive signal u4 was added on the left side push-pull circuit, electric current was through V5, auxiliary induction L1 and V8, injection sampling switching circuit A1; And when positive polarity drive signal u5 was added on the right side push-pull circuit, electric current was through V7, auxiliary induction L1 and V6, notes people sampling switching circuit A1.It is the dynamic series connection between a kind of full detection period.The magnetic core of auxiliary induction L1 can be selected bead for use, and size is all suitable, as 10mm (external diameter) * 6mm (internal diameter) * 4mm (thick).The method that the number of turn provides according to example 1 is calculated and is determined.Sampling switching circuit A1 can select for use Fig. 6 to design.Sampling device is a resistance R 2.Signaling conversion circuit A1-3 is made up of with the resistance R 8, R9, R4 and the C4 that are used to set sampled threshold voltage voltage comparator ic 2.Since undesired signal a little less than, R3 in the filtering circuit and C1 can get very little value.
In the main control circuit of Switching Power Supply, all be provided with driving signal output circuit, in order to the coupled apparatus of direct driving power switching tube or driving switch signal, as photoelectric coupled device and pulse transformer etc.This output circuit also can provide driving voltage for auxiliary induction L1.Perhaps adopt one can be shared output circuit.
Fig. 9 is auxiliary induction L1 and photoelectric coupled device in the magnetic bias pick-up unit and the electric principle design figure that connects use.The photoelectric device HD2 that is used to transmit semibridge system or push-pull type drive signal and the input end of HD3 separately with current-limiting resistance R10 or R11, diode D9 or D10 oppositely is connected in series, again each other oppositely and connect the back, with auxiliary induction L1 again and connect, be connected across the double push-pull circuit output end.Sampling switching circuit A1 also is connected between the points of common connection and ground of two underarm triodes of double push-pull circuit V6, V8.Here, the sampling input end of sampling switching circuit A1 is connected with above-mentioned parallelled circuit, and the sampling device of therefore flowing through is not only exciting current, also has the drive current of photoelectric coupled device.But this does not influence and detects sampling.Because drive current is a fixed value, the pressure drop that produces on sample resistance R2 also is a fixed value, therefore, the threshold value setting voltage among the change-over circuit A1-3 is improved a fixed value get final product.A1 also selects for use Fig. 6 to design.If increase by two photoelectric coupled device circuit, promptly transmit the full-bridge drive signal.
Figure 10 is auxiliary induction L1 and the elementary shared electric principle design figure of pulse transformer in the magnetic bias pick-up unit.This pulse transformer that is used to transmit drive signal is different with monitored transformer, and the former load is changeless.Therefore, its elementary in non-excitability electric current be fixedly changing value of a fixed value or.Therefore, equally with Fig. 9 example design also solved with the respective fixation value of threshold value setting voltage among the raising change-over circuit A1-3.The elementary output terminal that is connected across the double push-pull circuit of pulse transformer B4, secondary is two windings, in order to transmission semibridge system or push-pull type drive signal.If increase by two groups, promptly transmit the full-bridge type drive signal.Sampling switching circuit A1 also is connected in the double push-pull circuit between the points of common connection and ground of two underarm pipe V6 and V8.Also select for use Fig. 6 to design.
Above-mentioned so-called fixedly changing value is that the capacity load of dimension level causes, as the input capacitance of MOSFET pipe with the IGBT pipe.Therefore in switching pulse signal output moment a bigger transmission current can appear, about about 1 μ S of time.Can be eliminated with increasing RC among the filtering circuit A1-2 or LRC time constant or adjunction electronic switch K2.
Transformer produces magnetic bias and magnetic saturation has multiple reason.It mainly is the feedback amplifier in the main control circuit and error amplifier is disturbed or job insecurity and the drive signal imbalance that causes cause.Therefore, use the magnetic bias pick-up unit of embodiment 3, can eliminate the magnetic bias that causes by above-mentioned reason.Cause magnetic bias and magnetically saturated other reason to also have: a certain road drive signal coupled circuit lost efficacy, and it is inconsistent that each organizes the driving circuit performance, transmission line open circuit or short circuit, a certain power switch pipe damaged etc.Adopt the magnetic bias pick-up unit of embodiment 1 and 2, can eliminate magnetic bias and magnetic saturation former because of all thereby that cause.Because it is mounted on the final detection position.
Find out that from above-mentioned several embodiment the present invention is to the magnetic bias and the magnetically saturated detection of transformer, though be from auxiliary induction L1, to obtain, but still the tool substantivity need not be carried out indirect computing.Thereby working stability, quick, have novelty and practicality clearly.
Claims (10)
1, a kind of monitoring method that is used for the switching mode power supply transformer magnetic bias, it is characterized in that this method has following two links: one, adopt an auxiliary induction, make it equate or approximately equal, synchronous or near-synchronous and work under the constant or approximate constant voltage conditions of the ratio of amplitude under same or approximate same voltage conditions or respectively, make its generation and transformer bias, the corresponding exciting current of overexcitation two pulsewidths with monitored Switching Power Supply primary; Two, from auxiliary induction, detect exciting current with a circuit with sampling and function switching signal; wherein representing monitored transformer bias to become voltage signal or switching value signal with overexcited current conversion, to be used for the input control signal of Switching Power Supply bias set circuit and Switching Power Supply cut-off protection circuit.
2, a kind of bias current pick-up unit, this device characteristic that is used for monitoring the Switching Power Supply transformer bias is:
2.1 this device is in series by auxiliary induction (L1) and sampling switching circuit (A1), or is in series with current-limiting protection resistance (R1) again;
2.2 this device is connected across on the two input end lines of the transformer (B1) elementary (N1N2) in the monitored Switching Power Supply, with transformer (B1) elementary (N1N2) and connect use, or equates or approximately equal, synchronous or near-synchronous and work under the constant or approximate constant voltage conditions of the ratio of amplitude two pulsewidths respectively with monitored primary;
2.3 transport to control circuit in the Switching Power Supply, be used for that control circuit realizes that magnetic bias is regulated or the turn-off protection of Switching Power Supply or magnetic bias are regulated control signal with the Switching Power Supply turn-off protection by the signal of this device output.
3, bias current pick-up unit according to claim 2, it is characterized in that: auxiliary induction (L1) forms with insulated conductor coiling on magnetic core.
4, bias current pick-up unit according to claim 2, it is characterized in that: when this device is employing and primary and the method that connects when monitoring transformer bias in the push-pull type Switching Power Supply, two groups of shared sampling switching circuits of bias current pick-up unit (A1).
5, according to the auxiliary induction (L1) in claim 2 and the 3 described bias current pick-up units, it is characterized in that: when this device is employing and primary and the method that connects when monitoring transformer bias in the push-pull type Switching Power Supply, the shared one group of magnetic core of two auxiliary inductions (L1-1 and L1-2) in its two groups.
6, bias current pick-up unit according to claim 2, it is characterized in that: sampling switching circuit (A1) is by sample circuit (A1-1), filtering circuit (A1-2) is formed with signaling conversion circuit (A1-3), sample circuit (A1-1) is connected in series sampling from the exciting current loop of auxiliary induction (L1), current signal is converted to voltage signal, after being sent to filtering circuit (A1-2) filtering undesired signal wherein, transport to signaling conversion circuit (A1-3) again, signaling conversion circuit (A1-3) to the monitored transformer bias of representative and the overexcited voltage signal or the switching value signal of converting.
7, according to the sampling switching circuit (A1) in claim 2 and the 6 described bias current pick-up units, it is characterized in that: include at least one sampling device in the sample circuit in this sampling switching circuit (A1-1), this device is D.C mutual-inductor, direct current transducer, sample resistance or isolated amplifier etc.
8, according to the sampling switching circuit (A1) in claim 2 and the 6 described bias current pick-up units, it is characterized in that: include one or two devices with threshold values identification function in the signaling conversion circuit in this sampling switching circuit (A1-3), this device is triode, voltage comparator or controllable silicon etc.
9, bias current pick-up unit according to claim 2, it is characterized in that: when with the double push-pull circuit auxiliary induction (L1) being implemented excitation, sampling switching circuit (A1) is serially connected between the points of common connection and ground of two underarm triodes (V6 and V8) of double push-pull circuit.
10, bias current pick-up unit according to claim 2, it is characterized in that: elementary during as auxiliary induction (L1) when the pulse transformer that utilizes the transmission drive signal, its sampling switching circuit is serially connected between the points of common connection and ground of two underarm triodes (V6 and V8) of double push-pull circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 98118974 CN1215171A (en) | 1997-10-16 | 1998-09-26 | Auxiliary induction method transformer magnetic bias test method and apparatus thereof |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN97118163.2 | 1997-10-16 | ||
| CN97118163 | 1997-10-16 | ||
| CN 98118974 CN1215171A (en) | 1997-10-16 | 1998-09-26 | Auxiliary induction method transformer magnetic bias test method and apparatus thereof |
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| Publication Number | Publication Date |
|---|---|
| CN1215171A true CN1215171A (en) | 1999-04-28 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 98118974 Pending CN1215171A (en) | 1997-10-16 | 1998-09-26 | Auxiliary induction method transformer magnetic bias test method and apparatus thereof |
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| CN (1) | CN1215171A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100395950C (en) * | 2002-06-05 | 2008-06-18 | 欧姆龙株式会社 | Transforming device of push-pull circuit type |
| CN102645602A (en) * | 2012-05-17 | 2012-08-22 | 东华大学 | Online detection method of magnetic biasing of transformer based on attached coil |
-
1998
- 1998-09-26 CN CN 98118974 patent/CN1215171A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100395950C (en) * | 2002-06-05 | 2008-06-18 | 欧姆龙株式会社 | Transforming device of push-pull circuit type |
| CN102645602A (en) * | 2012-05-17 | 2012-08-22 | 东华大学 | Online detection method of magnetic biasing of transformer based on attached coil |
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