CN1073128A - DC welder without silicon steel plate iron-core - Google Patents
DC welder without silicon steel plate iron-core Download PDFInfo
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- CN1073128A CN1073128A CN 91111376 CN91111376A CN1073128A CN 1073128 A CN1073128 A CN 1073128A CN 91111376 CN91111376 CN 91111376 CN 91111376 A CN91111376 A CN 91111376A CN 1073128 A CN1073128 A CN 1073128A
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Abstract
DC welder without silicon steel plate iron-core is a kind of electric welding machine of electronization, is suitable for arc welding usefulness, belongs to electric and electronic technical field.Its principle is to be the electric main rectification direct current earlier, is high-frequency ac by the gated transistor inversion then, becomes the direct current of welding usefulness again behind the high frequency transformer step-down rectifier.Be characterized in cancelling the silicon sheet core of traditional welding transformer, that this type electric welding machine of making has is in light weight, noiselessness, friction, advantage such as energy-efficient, particularly economizes iron and economizes copper and reach more than 80%, and economic implications is big.The present invention has solved the serious overcurrent-overvoltage problem of inversion pipe satisfactoryly, makes the Switching Power Supply condenser discharge welder reach practicability.
Description
Arc-welding electric welding machine commonly used now divides two types of AC and DCs.A.C. welder is simple in structure, solid and reliable, but it is actually a permission output instantaneous short-circuit is moved, output current is adjustable transformer, dc welding machine structure more complicated, cost an arm and a leg, but the direct current welding quality is better.Dc welding machine has two kinds of forms now: a kind of is the dc generator formula, a kind of is transformer step-down rectifier formula, commonly used is the dc generator formula, all there are following shortcomings in existing electric welding machine: the one, and weight is big, general every weight is all more than 100 kilograms, the heaviest reaching more than hundreds of kilograms, in work, move very inconvenient, also need expend a large amount of silicon steel sheets and copper cash; The 2nd, power factor is low, and reactive power loss is big; The 3rd, the iron loss copper loss is bigger, and efficient is not high.
Purpose of the present invention is to adopt existing electronic technology, develops the not novel electric welding machine of siliceous steel disc of a kind of main part, thereby makes this electric welding machine reach in light weight, economize the effect that iron is economized copper, efficient, economize on electricity.
The appearance that (is called for short IGBT) because insulated gate bipolar high-voltage high-speed large power semiconductor device, this thoroughly electronic dream of electric welding machine by of the present invention successful and become reality.The present invention adopts the switch inversion principle, is the inversion of three-phase main-frequency ac voltage rectifier high frequency voltage about frequency 15-20KHz, reduces voltage to obtain big electric current by high frequency transformer again, carries out high-frequency rectification then, obtain can be for welding DC current.The present invention has adopted the automatic resist technology of perfect overcurrent-overvoltage; make the inverter electric welding machine reach degree of being practical; this electric welding machine has that volume is little, in light weight, noiselessness, friction, energy-conservation, advantage that efficient is high; economize iron province copper than traditional electrical welding machine and reach more than the 80%-90%, have potential huge social and economic significance.
Two, operation principle
Operation principle block diagram of the present invention is seen accompanying drawing 1,380 volts three-phase alternating-current supply by each commutating phase device respectively rectification become pulsating dc voltage, this DC voltage becomes frequency and reaches high frequency square wave about 15-20 kilohertz sesame through the inversion of IGBT high power transistor, this high frequency voltage is through the high frequency transformer step-down, after becoming the high frequency low voltage of tens of volts, by fast recovery rectifier diode rectification, filtering and become can be for welding DC voltage.
Owing to adopt high-frequency inversion, the volume of transformer, weight and compare with the capacity Industrial Frequency Transformer can be much smaller.The permeability magnetic material of high frequency transformer adopts ferrite, and ferrite is a kind of permeability magnetic material made from the ceramic sintering process similar approach, and the similar pottery of its part physical property is commonly called as magnetic core.The traditional electrical welding machine adopts silicon steel sheet to make permeability magnetic material, is commonly called as iron core.Therefore, this electric welding machine of being made up of high frequency transformer is a kind of electric welding machine that does not have silicon sheet core.
Though operation principle of the present invention is simple, be not easy but implement, this is because electric welding machine is the appliance tool that a kind of work often is in short circuit-load-zero load-short-circuit cycle state, when the welding rod contact workpiece, be equivalent to short circuit, owing to be direct current, welding circuit does not have AC impedance, D.C. resistance is very little, therefore short circuit current is very big, and it is also big to be reflected to the on high-tension side electric current of high frequency transformer, when welding rod transfers the starting the arc (load) state to by short-circuit condition, perhaps electric arc is broken suddenly, because current break can produce strong transient process, at the elementary generation of the high frequency transformer transient voltage more much higher than supply voltage, and the transistor (IGBT) of undertaking the inversion task is a kind of to electric current, the highstrung device of voltage very easily damages because of overcurrent-overvoltage.Therefore, one of main task of the present invention is to properly settle the overcurrent Over-voltage Protection of inverter transistor.
Concrete schematic circuit of the present invention is seen Fig. 2, only shows A facies principle figure among Fig. 2, and figure is mutually identical with A for B, C facies principle, and complete machine is combined by three-phase, the rectification output of each phase+,-hold to be connected in parallel, with the increase output current, and reduce ripple.Under unfiltered situation, the complete machine output voltage is made up of the high frequency square wave, but is modulated by power frequency bridge rectifier pulsating volage, and its waveform (is seen Fig. 4
(d)) identical with common three-phase bridge rectification waveform.
Compositions such as each phase line route single phase industrial frequence rectification circuit of this machine, high-frequency inverter circuit, high-frequency rectification circuit, pulse width modulation (PWM) circuit, overcurrent-overvoltage protecting circuit, anti-jamming circuit.
1, single phase industrial frequence rectification circuit (see figure 2)
Mainly by diode D
101-104Form a bridge rectifier.The 220V alternating voltage is through high frequency choke coil EQ
1, bidirectional triode thyristor SCR, play weldering current-limiting resistance R
101Enter rectifier, C
102Be anti-interference capacitor, when unloaded, C
102Both end voltage equals alternating voltage peak; During load, C
102Filter action is little, mainly plays anti-interference effect, and rectifier output voltage is a pulsating dc voltage, and its average voltage level is less than or equal to 0.9 times of input ac voltage virtual value.R
102Be discharge resistance, its effect is with C when having a power failure
102The lotus of charging is discharged rapidly, in case maintainer's mistake is touched.
2, high-frequency inversion, transformation rectification circuit
By insulated gate bipolar high-voltage high-speed transistor (IGBT) BG
1-2, high frequency transformer B, fast recovery rectifier diode D
107, D
108Form.
IGBT is the novel high-pressure high-speed high-power transistor that occurs in recent years, it has the advantage of excitation of VMOS tube voltage and the low saturation voltage drop of Darlington transistor, also have at a high speed, highly reliable, low shape loss, low pulse stretching electric current, to advantages such as temperature-insensitives, be current very good device for high-power power electronic.
BG
1-2Form push-pull inverter with the primary coil of high frequency transformer B, this inverter circuit is compared with the bridge inverter main circuit that adopts 4 pipes, have the advantage that circuit is simple, few with pipe, excitation is convenient, cost is lower, bear the high shortcoming of voltage but also have pipe.
The operation principle (see figure 2) of push-pull inverter circuit: at BG
1-2Add anti-phase each other rectangle trigger impulse on the grid of two pipes, make BG
1-2In turn conducting with end, when the positive half cycle of pulse, top pipe (BG
1) conducting, following pipe (BG
2) end, this moment, dc source was to elementary last half coil power supply of high frequency transformer B, so at positive square-wave voltage of secondary generation of B; When the pulse negative half period, top pipe (BG
1) end following pipe (BG by the conducting change
2) by by becoming conducting, dc source is to elementary following half coil power supply of B, so at losing side wave voltage of secondary generation of B.Like this, under the effect of continuous trigger pulse, just can obtain ac square wave voltage the secondary of B, the trigger impulse frequency may be selected to be 15-20KHz here, and is more much higher than power frequency 50Hz, therefore can be described as high frequency, and this high-frequency ac voltage is through quick rectifying tube D
107-108After the full-wave rectifying circuit rectification of forming, again through the public capacitor C of three-phase circuit
105And low-frequency choke coil EQ
2After the filtering, just can be used to weld.Capacitor C
105Be used for to high frequency square wave filtering choke coil EQ
2Filtering be 6 times (300Hz) above harmonic wave of power frequency, therefore still adopt silicon sheet core, but because the frequency of elimination is higher, EQ
2Volume can do smallerly.
The secondary both end voltage waveform of high frequency transformer is seen Fig. 4
(a)-(b), Fig. 4 wherein
(a)Be the waveform that observes with the 20KHz synchronizing voltage on oscillograph, this is an ac square wave as seen from the figure.Fig. 4
(b)Be the waveform that observes with the 50Hz synchronizing voltage, by Fig. 4
(b)As seen, this be high frequency square wave by power frequency bridge rectifier pulsafeeder modulated waveform, when 20KHz, each power frequency period includes 400 high frequency square waves.
Waveform after the full-wave rectification of high frequency transformer secondary voltage is seen Fig. 4
(c)-(d), this two figure observes with the 50Hz synchronizing voltage on oscillograph, wherein Fig. 4
(c)It is the single-phase rectifier waveform; Fig. 4
(d)Be the oscillogram behind A, B, the C three phase rectifier voltage superposition, visible identical with common three-phase bridge rectification waveform, wherein except that DC component, comprise that also power frequency is for 6 times main harmonic wave.The high frequency square wave that comprises in these waveforms is by capacitor C
105Filtering; 6 subharmonic are then gripped circle EQ by low frequency
2Carry out filtering.
Two number of primary turns of push-pull transformer equate, end of the same name is forward connected, therefore when a coil electricity, can on another coil, produce the voltage that phase place is identical, this voltage and supply voltage addition equal twice supply voltage forward and are added on the inversion pipe collector that ends, the emitter stage.Under 220V power supply situation, inversion pipe peak forward voltage is 622V, adds peak voltage, generally reach about 800V, so pipe is withstand voltage at least should be more than kilovolt.
3, pulse width modulation circuit:
The effect one of this circuit is to produce the anti-phase each other pulse of two-way, in order to trigger inverter transistor; The 2nd, by regulating the width of trigger impulse, reach the purpose of regulating welding current.So-called pulse width modulation (PWM), control inverter transistor conducting deadline exactly than (dutycycle), when the conducting pulse is wide, big from the dc source absorbed power, when the conducting pulse is narrow, absorbed power is little, therefore pass through to regulate the width of inversion pipe driving pulse, the power output that can regulate high frequency transformer B, power has become, welding current has also just become, and this is the principle that this electromechanics stream is adjusted.
Pulse-width modulator adopts ready-made integrated circuit, and its model is TL494, and domestic like product model is CW494, and this integrated circuit is a desired shapes power supply control integrated circuit, has obtained extensive use, and its inner schematic diagram is seen Fig. 3
(a)
The TL494 operation principle: the major part of this circuit is pulse width comparator (a PWM comparator), and the inverting input and the oscillator of comparator join, and from this end input standard sawtooth waveforms, the frequency of oscillation of oscillator can be from 100Hz to 400KHz.The comparator in-phase input end is connected to the output of error amplifier, and two error amplifier structures are identical, the output diode-isolated, and each amplifier can independently use, and these two amplifiers can be used as overcurrent protector, but this machine is not used temporarily.TL494 is provided with a Dead Time comparator; its inverting input is connected to oscillator; in-phase input end is done to lead to 4 pin behind the 0.12V level deviation; utilize external control voltage except that changing the Dead Time of modulator on a large scale; also can utilize its design soft starting circuit, under-voltage or overvoltage crowbar, Dead Time comparator and PWM comparator pass through or the gate control output stage, and its control ability is extremely strong; control range is extremely wide, and this machine utilizes 4 pin to make the usefulness of electric current adjustment and electric current volitional check.Output stage is divided into two-phase pulse by trigger with pwm pulse, controls two-way transistor (Q respectively
1, Q
2) output stage.Way of output control can make it be operated in single-ended or both-end output dual mode behind the trigger, is both-end output during 13 pin high level, is single-ended output during low level, and during both-end output, output current can reach 200mA.Output stage can be connected into common emitter or common collector mode, and this machine is connected into the common collector mode, so that be output as electronegative potential during no pulse, can prevent that the inversion pipe from misleading.In the sheet+the 5V reference power supply drawn by 14 pin, uses for external circuit.
The C that 5,6 pin of TL494 are connect
204, R
207Adjust element for frequency of oscillation, frequency of oscillation is determined by following formula:
f＝1/（0.817RC+1.42×10
） （Hz）
In this machine, frequency of oscillation can be taken as 15-20KHz.
4 pin of TL494 are the pulse width modulation end, and when 4 pin modulation DC voltage was changed by 0-3V, pulse duty factor was changed by 50%-0%, and adjustment curve is seen Fig. 3
(b)Modulation voltage is by divider resistance R
203-205Obtain potentiometer R
204Be used to adjust pulse width, this potentiometer one has three, one of every phase, and three potentiometers require synchronization action.R
203Effect, be to guarantee pulse duty factor less than 50%, because of dutycycle equals at 50% o'clock, inversion Guan Yin has delay effect and may cause two pipe conductings simultaneously, accident is short-circuited.
9,10 pin of TL494 are pulse output end, and the two-way pulse is anti-phase each other, promptly one the tunnel are output as at 0 o'clock, and another road is output as 1, and vice versa, so just can guarantee inversion pipe BG
1-2Conducting in turn.The two-way pulse is through resistance R
210, R
211Deliver to BG respectively
1-2Grid, grid has metal-oxide-semiconductor character, though not power consumption stream is not crosstalk resistance R
210, R
211, directly connection also can trigger BG
1-2, but BG
1-2The colelctor electrode peak voltage is too big, and is withstand voltage unfavorable to pipe; Facts have proved that the crosstalk resistance of grid institute can not be excessive, otherwise BG
1-2Can burn out BG because of the undesired short circuit of trigger impulse
1-2The grounded-grid resistance R
212, R
213Effect, be to break at grid return, guarantee when grid is unsettled that grid still can ground connection (the rectification output negative pole of this phase), prevent that pipe from misleading and cause short circuit so R
212, R
213Must be from BG
1-2Near more good more.
By Fig. 3
(b)Adjustment curve as can be known, when the 4th pin of TL494 modulation DC voltage was equal to or greater than 3V, dutycycle was zero, the output of 9,10 pin no pulse, this moment BG
1-2Grid potential be that 0, two Guan Jun ends, inverter quits work.
LED
1-2, its brightness is directly proportional with pulse width, is used for summary and shows pulse width.
4, circuit overcurrent protection
The front said that electric welding machine was equivalent to short circuit when playing weldering, all can produce very big electric current the elementary secondary of high frequency transformer B, so current-limiting protection must be set.The way of current limliting has multiple, and this machine adopts the mode in industrial-frequency alternating current source series impedance, and impedance can be adopted emotional resistance, or adopts pure resistance, if adopt emotional resistance, then wants consume silicon steel disc and copper cash, increases cost and weight.Adopt the resistance mode valency the most honest and the cleanest, so this machine adopt this mode.Perhaps think that the resistance current limliting can consume a large amount of electric energy, actually this is not so, at most only needs several seconds because play weldering, after the normal welding of striking success, plaing a part under the weldering current-limiting circuit, and current-limiting resistance withdraws from automatically, so the current-limiting resistance power consumption seldom.
(1), play weldering current-limiting circuit (see figure 2): this part circuit is by the bidirectional triode thyristor SCR, the current-limiting resistance R that are serially connected with on the AC power
101And the weldering testing circuit composition in the frame of broken lines II, playing the weldering testing circuit is that three-phase is public.
Play weldering testing circuit operation principle: this circuit is by three optically-coupled bidirectional triode thyristors (of A, B, the every phase of C) GSCR
1-3, triode BG
3Form Deng element, this circuit be not by detecting electric current but by the size that detects the electric welding machine output end voltage differentiate electric welding machine zero load, load, play three kinds of states of weldering: when the electric welder no-load, its output DC is pressed in about 70-80V, at this moment potentiometer R
114The voltage of swing arm makes voltage-stabiliser tube WD
101So conducting is triode BG
3Also conducting is optocoupler bidirectional triode thyristor GSCR
1-3In control loop (light emitting diode) short circuit, so three optocoupler bidirectional triode thyristors all end, make the bidirectional triode thyristor SCR Triggerless in the ac power supply circuit and disconnect current-limiting resistance R
101Be serially connected with in the ac power supply circuit, what flow through is no-load current, because no-load current minimum (tens of milliamperes), so current-limiting resistance power consumption hardly when zero load.
When beginning to weld, the welding rod core contact workpiece, the output of electric welding machine is equivalent to short circuit, and output voltage drops to 0V suddenly by 80V, optocoupler bidirectional triode thyristor GSCR
1-3Because of no operating voltage continues the remain off state, make current-limiting resistance R
101Still be serially connected with in the ac power supply circuit, though this moment, short circuit current was big, limited by current-limiting resistance, can not exceed the maximum bearing ability of inversion pipe, this moment, the supply voltage major part dropped on the current-limiting resistance.
After electric arc ignites, enter normal welded condition, the electric welding machine output end voltage maintains between the 20-50 volt, R
114The swing arm undertension is so that voltage-stabiliser tube WD
101So conducting is BG
3End, the output voltage of electric welding machine passes through R
112Make optocoupler bidirectional triode thyristor GSCR
1-3Conducting, the bidirectional triode thyristor SCR of electric power loop has the trigger current conducting, current-limiting resistance R because of control utmost point loop
101Out of service by the SCR short circuit, this moment, supply voltage all was added on the single-phase bridge rectifier, and the size of welding current is by the potentiometer R of pulse-width modulation circuit
204Regulate.
In the welding process, overweight as load, electric current is excessive, when causing output voltage to be lower than the 15-20 volt, and Zener diode WD
102End optocoupler controllable silicon GSCR
1-3Also end, SCR is turned off, and is automatically connected into R
101Carry out current limliting.
(2), overcurrent subtracts the pulsewidth circuit automatically: this part circuit is by photoelectrical coupler GB, rectifier D
109-112, resistance R
116-118, voltage-stabiliser tube WD
103Deng composition.
Before address, when playing weldering, by resistance R
101Carry out current limliting.Sometimes it is not smooth to play the weldering striking, and welding rod may cling with workpiece, perhaps output cable short circuit, if the current limliting time is long, and consumed power not only, and make inversion pipe, hf rectifier overheated, employing this moment reduces the way of pulse width automatically and protects.
Operation principle: when overcurrent takes place, R
101On pressure drop be directly proportional with the electric current that it is passed through, by detecting this voltage drop, can know whether overcurrent.Here, resistance R
116-118, voltage-stabiliser tube WD
103, the light emitting diode in the photoelectrical coupler GB constitutes voltage detecting circuit, resistance R
118Be used for operation voltage (electric current) is adjusted.The receiving unit of photoelectrical coupler GB, promptly phototriode is connected into the emitter follower form, and emitter voltage passes through D
205, R
202Be added on the 4th pin of pulse-width modulator TL494, participate in the adjusting of pulse width.
During normal the welding, bidirectional triode thyristor SCR is with R
101Short circuit, R
101Both end voltage is O, and photoelectrical coupler GB does not end R because of there being control voltage
201Both end voltage is O, D
205Oppositely end, pulse width modulator is not had influence.
When unloaded, because no-load current is very little, no-load current is at R
101On voltage drop also very little, circuit condition is identical during with normal welding.
When playing weldering output short circuit or load when overweight, the supply voltage major part drops to current-limiting resistance R
101On, divider resistance R
117On voltage reflected overcurrent condition, this voltage is big, overcurrent is also big.This voltage is through rectifier D
109-112Rectification and C
107After the filtering, make voltage-stabiliser tube WD
103, photoelectrical coupler GB conducting, R
201Last voltage is just being become by O, and this voltage is through D
205, resistance R
202Receive on the 4th pin of pulse-width modulator, with potentiometer R
204The modulation voltage addition of setting up impels the trigger impulse dutycycle to reduce, and pulse narrowing so the output current of electric welding machine reduces, has been played automatic protective effect.
5, overvoltage protection
(1), exterior overvoltage protection: exterior overvoltage is meant the impulse wave far above supply voltage value that imports into from power supply; the precautionary measures are in the welder power point of incoming cables Zinc-oxide piezoresistor BL to be set, to absorb the overvoltage that the lightning induction scurried into from AC power line or other reasons cause.
(2), internal overvoltage protection: the front was said; when electric welding machine is broken electric arc suddenly by short-circuit condition or load condition; because current break; can be on the high frequency transformer primary and secondary very short but the inductance voltage that amplitude is very high of generation time; be called transient voltage; very easily puncture inverter transistor and fast recovery rectifier diode, therefore the internal overvoltage protection must be set.The way that this machine is taked: on inversion pipe collector, emitter stage and meet capacitance-resistance absorber element C
103-104, R
103-104, in order to reduce the spike on the high frequency transformer; Diode D
105-106Be used to eliminate the back-pressure on the inversion pipe; What play an important role mainly is to be connected in parallel on inversion pipe BG
1-2On two-way overvoltage protection diode BD
1-2, the characteristic of overvoltage protection diode is: when its both end voltage was lower than operation voltage, pipe ended, when its both end voltage surpasses operation voltage, and the pipe conducting, and can pass through very big electric current, and on state characteristic is identical with controllable silicon, and above process is reversible, with BD
1-2The resistance of series connection is in order to the conducting electric current of restriction overvoltage protection diode.
For fast recovery rectifier diode D
107-108Protection, mainly be to prevent the too high puncture of back-pressure, way is overvoltage protection diode BD in parallel at the two ends of commutation diode
3-4, when back-pressure raises, the conducting of protection diode elder generation, the back-pressure short circuit on the rectifying tube, rectifying tube just can not punctured by back-pressure.
6, anti-jamming circuit
(1) anti-external interference circuit: current electrical network has many silicon controlled rectifiers, and the use of these equipment can bring pollution to power supply, cause the voltage waveforms distortion, show as sine wave and burr or breach occur, these all threaten to this machine safety, therefore will take interference protection measure.
Facts have proved that pulse-width modulator TL494 modulation voltage input is the influence that the 4th pin very easily is subjected to the bad waveform of power supply.Once took place to use controllable silicon equipment and make the model machine inversion pipe that is connected on the same power line frequently burn out accident, after ascertaining the reason, at capacitor C of 4 pin parallel connection
203Promptly solved problem.
Be connected in parallel on the capacitor C of single phase industrial frequence rectifier output end
102Its effect also mainly is for anti-interference.
(2), prevent to external interference: during the work of this machine inverter, can produce great wide spectrum harmonic wave, as not taking measures, these harmonic waves can be penetrated propagation along the power supply wire spoke, near disturbing apparatus for receiving broadcasting, this task is by the high frequency choke coil EQ that is connected on the power line
1Finish EQ
1The polarity of two coils is pressed Fig. 2 and is connected, and the common-mode voltage that disturbs harmonic wave is played choking effect, and non-common-mode voltage is by capacitor C
101Filtering plays a part to prevent to propagate interference to the external world.EQ
1The connection of two coils, concerning power frequency, the magnetic flux of its generation is cancelled each other, and power frequency impedance is zero, does not produce any pressure drop.
More than be described in detail the operation principle and the function of each several part circuit, now whole working be summarized as follows:
After connecting power supply, the 220V alternating voltage is by high frequency choke coil EQ
1, current-limiting resistance R
101Be added on by D
101-104On the bridge rectifier of forming, the pulsating volage of rectifier output is as the power supply of inverter.Inverter transistor BG
1-2Driving pulse frequency and pulsewidth determine by pulse width modulation circuit.The high frequency voltage that inverter produces is after high frequency transformer B reduces voltage, by fast recovery rectifier diode D
107-108Carry out full-wave rectification, and by capacitor C
105, low-frequency choke coil EQ
2Carry out filtering.Rigidly connect energize, be in Light Condition, this moment, output dc voltage was that this voltage is at potentiometer R about the 70-80 volt
114Dividing potential drop on the swing arm makes voltage-stabiliser tube WD
101So conducting is triode BG
3Also conducting is with optocoupler controllable silicon GSCR
1-3The light-emitting diodes tube short circuit, make it not luminous, the optocoupler controllable silicon ends, cause the bidirectional triode thyristor SCR Triggerless in the major loop and end, this moment current-limiting resistance R
101String prepares to rise at any time weldering in ac main circuit.
When beginning to weld, welding rod touches workpiece, the output positive and negative charge short circuit, and this moment, very big electric current was all passed through in primary and secondary coil, the power frequency loop of high frequency transformer.This moment, optocoupler controllable silicon remain off caused SCR still to end, current-limiting resistance R because output voltage is 0V by the 70-80V bust
101Still be connected in the ac main circuit, limited the rated current that the weldering electric current is no more than the inversion pipe.
Play weldering striking success, change normal welding over to after, output voltage is risen to about 20-50V by 0V, this voltage is at potentiometer R
114Dividing potential drop deficiency on the swing arm is so that WD
101Conducting causes BG
3End, the electric welding machine output voltage passes through resistance R
112, voltage-stabiliser tube WD
102Make optocoupler controllable silicon GSCR
1-3Conducting, then also conducting of bidirectional triode thyristor SCR, the R that has been close to the road
101On voltage drop, make alternating voltage all be used for inversion, strengthened bonding power, and reduced useless power consumption.
If welding rod clings workpiece when playing weldering, the time is long slightly, then current-limiting resistance R
101On pressure drop make photo-coupler GB conducting, resistance R
201On voltage be upgraded to positive voltage by 0V, this voltage and R
204Be added on after the dividing potential drop addition on the swing arm on 4 pin of pulse width modulator TL494, excitation pulse is narrowed down, thereby reduced the output current of electric welding machine automatically, made current-limiting resistance, inversion pipe, rectifying tube not overheated, so even the long period short circuit to this machine also not influence.
Claims (4)
1, a kind of switch power supply type DC welder without silicon steel plate iron-core that is made of the insulated gate bipolar high power transistor is characterized in that comprising circuit overcurrent protection and anti-jamming circuit;
2, circuit overcurrent protection according to claim 1, the resistance value of series connection current limiting element that it is characterized in that the industrial-frequency alternating current resource loop is less than 100 ohm;
3, circuit overcurrent protection according to claim 1 is characterized in that with the size of electric welding machine output voltage as the condition that starts current limiting element;
4, anti-jamming circuit according to claim 1, the capacitance of anti-interference condenser of modulation voltage input that it is characterized in that being connected on pulse-width modulator is greater than 100 micromicrofarads.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91111376 CN1073128A (en) | 1991-12-11 | 1991-12-11 | DC welder without silicon steel plate iron-core |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 91111376 CN1073128A (en) | 1991-12-11 | 1991-12-11 | DC welder without silicon steel plate iron-core |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1073128A true CN1073128A (en) | 1993-06-16 |
Family
ID=4910612
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 91111376 Pending CN1073128A (en) | 1991-12-11 | 1991-12-11 | DC welder without silicon steel plate iron-core |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1073128A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104280592A (en) * | 2014-09-30 | 2015-01-14 | 卧龙电气集团股份有限公司 | Passive lossless high-frequency magnetic isolation type direct voltage detection circuit |
-
1991
- 1991-12-11 CN CN 91111376 patent/CN1073128A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104280592A (en) * | 2014-09-30 | 2015-01-14 | 卧龙电气集团股份有限公司 | Passive lossless high-frequency magnetic isolation type direct voltage detection circuit |
| CN104280592B (en) * | 2014-09-30 | 2017-10-17 | 卧龙电气集团股份有限公司 | A kind of passive and nondestructive high frequency Magnetic isolation type DC voltage detects circuit |
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