DE1231803B - Circuit arrangement for generating pulses from an alternating current source, in particular for welding equipment - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl .:

H 02 j

German KL: 21 d2 - 42/02

Number: 1231 803

File number: R 28770 VIII b / 21 d2

Filing date: September 20, 1960

Opened on: January 5, 1967

The invention relates to a circuit arrangement for generating sharp energy pulses with controllable Distance from a power source with continuously reversing polarity, where the voltage the pulse has a much greater height than that of the source at the time of the pulse delivery supplied voltage, in particular for the delivery of short energy pulses from an alternating current network to a load, e.g. B. a welding transformer for carrying out welding work.

Although the circuit arrangement according to the invention for a wide range of different applications is usable, it is primarily designed for resistance welding purposes and commercial use is primarily in the area of resistance welding. For this reason, the invention is specifically explained using the example of resistance welding, it however, it is clear that the choice of circuitry and terminology in this field is only have been made to facilitate the explanations and do not represent a limitation of the invention.

Since the equivalent circuit of an executed circuit in which the invention is implemented, Resistance, inductance and capacitance components are included as a load in one chosen a component that brings the desired result.

However, since there is usually a resistance where energy is drawn the load will be at least partially ohmic. The load in resistance welding therefore usually consists of both resistive and inductive components.

It has already been found useful in welding technology to transmit a large number of short energy pulses to give a welding transformer to the welding heat generated thereby within the joint focus on the welding zone. By using short, interrupted and spaced out Given energy impulses, the heat of the welding zone can be supplied quickly without affecting the surrounding Material is excessively heated. This type of weld used to be used for various purposes used where it was necessary to limit the heat close to the welding zone, for example at the welding of aluminum and the welding of relatively thin sheets with inclusion of Aluminum sheet or the welding of plastic-coated metal, such as. B. with vinyl coated steel sheets.

Circuit arrangement for generating pulses
from an AC power source, especially for
Welding equipment

Applicant:

Robotron Corporation, Detroit, Mich. (V. St. A.)

Representative:

Dr.-Ing. E. Liebau, patent attorney,

Göggingen near Augsburg, v.-Eichendorff-Str. 10

Named as inventor:
Stuart C. Rockafellow,
Plymouth, Me. (V. St. A.)

Claimed priority:

V. St. v. America September 25, 1959

(842 451),

of April 18, 1960 (22 822) -

So far, however, the generation of short pulses of this type has required either a substantial one Effort, or the impulses did not arise quickly enough to make the weld with an economical to be able to carry out an acceptable speed. Often there were welding machines with capacitor discharge used to realize a type of welding quite similar to the above, however were these due to the required capacitor charging between the pulses on a relative slow pace of work limited.

In previous experimental work with this type of power supply, especially for welding purposes, The efforts have largely been focused on delivering the required performance with high levels of efficiency Amperage at normal mains voltage or mostly directed at double the mains voltage. the Feeding the power to the primary winding of the welding transformer required processing this power through switching devices, but economically working switching devices such as Current tubes, not available and even now are not available that provide the necessary Process currents under these conditions and the desired performance of the welding zone in can supply short periods of the required length of time. For example, is a "B" ignitron

609 750/187

3 4

Not suitable for use with over 1200 Am- led and controlled by the switching device pere instantaneous current, with the supplied mains power for the most part as a voltage to the peak voltage 750 volts, while adding can be made, so the ampere reversal can the present invention with a network number can be reduced accordingly. Because of this A peak voltage of 750 volts and a current of more than 5 procedure make it possible to carry out the required switching reren thousand amperes can be drawn. to be carried out by current gate circuits in which As a result - the previous attempts in common components can be used by the this direction either relatively long the circuits economically from a cost standpoint Heating periods result, such as. B. in the USA. Then through delivery Patent Specification 2,440,309, or they have many in proportion to this performance over very short periods of time moderately slow work performed, such. B. with previously unattainable and unexpected advantages than the usual capacitor discharge welding. Result of the present invention achieved. That

In addition, the usual welding scarf- that is, by the present invention are not required For capacitor discharge, a switch in the previously sought, but commercial up-discharge circuit of the capacitor, and the presence of unobtainable advantages due to its being such a switch limits the amperage, turning short impulses has been realized, sondie can be processed. Since such condensate also many advantages have been achieved that completely generators were usually only charged to mains voltage unexpectedly.

limits this switching of the current that the circuit arrangement according to the invention

can be carried out automatically, the overall 20 consequently delivers extremely short energy pulses in

energy, which in a given time interval of a desired load, but within the framework

can be fed to the welding zone. an economically feasible switchgear

It is also a control circuit for anti-parallel direction. The circuit arrangement accordingly exists switched discharge paths of gas or steam for the above-mentioned purpose essentially off Discharge vessels controlled by ignition electrodes, an ohmic resistor, a capacitive one as well as troden, which are connected to the main inductive energy storage element, among each other electrodes are excited, became known when connected in series and with the alternating current source using shut-off valves, a Vcrwo- are connected via a switch that is at the point of connection is created in the other than the permissible relationship to the polarity reversal of the changes the ignition electrodes a third line min- 3 ° current source closed and, shortly after the det, over which the current flowing through has reached its minimum with constant direction, Control pulses for both ignition electrodes that are opened. The circuit according to the invention is branch point to flow towards. The gas discharge paths are characterized by their sizes are connected in parallel in opposite directions. the formula

Furthermore, a circuit arrangement for 35 » y ~ c

Control of a consumer from an alternating χ ₌ \ 4. _e ~ T " ^R \ T
electrical power supplied to the power source

periodic interruption of the power supply are determined with, where K is a constant of one

adjustable ratio of on to off time size between 1 and 2, e the base of the natural

using transistors whose diameter is 40 logarithm, R is equal to the total ohmic resistance

Let stretch with the consumer and the change of the circuit including the resistance

power source are in series, known. The known of the memory elements and the switch, C the same

The arrangement is intended to include a known control system including the total capacitance of the circuit

principle at very low voltage of the feeding capacity of the capacitive storage element and

Enable AC power source. 45 L equal to the total inductance of the circuit

In welding technology, finally, the inductance of the inductive storage arrangement, which is the element of the current flow, has finally become known. The value of the constant K can advantageously be between 1.33 and 1.8 during the switch-on period of the welding current.
Control discharge routes. When the circuit arrangement was used, these discharge paths were partly connected in anti-parallel and a grid-controlled hot cathode tube was ignited over 50 according to the invention for welding purposes. With ordinary alternating current from a heavy current of one embodiment, the grid circle of the source of e.g. B. 460 volts, periodically a self-hot cathode tube a phase-shiftable quenching circuit fed to the primary winding sinusoidal control voltage which contains in series a welding transformer, and that the connected to a negative bias voltage 55 self-extinguishing circuit is designed so that it is one whose terminal voltage can be regulated in the sense of a certain current flow only for very short periods of time. from Z. B. one millisecond. By considerable-. It has also already been proposed to reinforce the correct circuit arrangements supplied to the primary winding by means of an ohmic voltage, e.g. B. to three to five times the supply resistors, capacitive and inductive elements, 60 voltage is the voltage supplied by the supply source, which are connected to the alternating current source via switches, voltage to the primary winding of the welding, within certain time intervals transformer in high-voltage pulses of short to achieve a current influence. Focused for a long time. These impulses occur every second

In the invention of previous investigations därkreis as corresponding short pulses of very

it was now assumed that the power, 65 high instantaneous amperage of z. B. 50,000

d. H. in the case of welding the heat up a product up to 100,000 amps.

is made up of voltage and amperage. If thus the this process then results in the welding

the primary winding of the welding transformer - a subdivision of a specific welding point

5 6

supplied electrical energy in extremely short electrodes can not overcome, and for

Increments while at the same time the amperage part because

the same is increased so much that the necessary _{b) the effectively supplied energy is somewhat smaller;} Amount of heat applied within a total _{welding penode as sfe bd usual} welding current

of the same or shorter duration than previously known 5 _w j _{r (} j
is fed. The delivery of a very high

Amperage into the interrupted, d. H. too sweat- Another previously unexpected benefit arises

ßende zone in extremely short periods of time concentrated through the essentially complete deactivation the heat of welding triggers in this discontinuous zone the problems that usually arise from reactance strong that this results in the immediate adjoining effect in the gripper of the welding machine, area very quickly to welding temperature when using a 240 volt 60 Hz mains voltage is heated without in most cases the um- at the primary winding of the welding transformer giving metal to heat significantly. it was previously necessary to

Among the previously unattainable advantages is in the welding transformer's winding in proportion First and foremost, the very essential 15 to the strength, location and length of the lines between Reduction in the amount of energy for a given one of the secondary winding of the welding transformer The welding and the resulting load and welding electrodes must be calculated very carefully on the power line to a nen, especially if these lines the gripper to carry out the given welding work. This is that of a welding machine make up. Because the reactance result the extremely high concentration of the 20 effect is a geometric function of the length of the Welding heat exactly at the welding point, which is again the gripper, was found to be when feeding a supply of energy, d. H. Heat to weld - sufficient tension to a weld at extremely high speed compared to a machine with a 30 cm long gripper the speed with which this heat increases the gripper to 45 cm without any excess the adjacent, the welding zone surrounding 25 speaking change of the transformer output Spreading material. This means that the chip part will be much larger in common types of welding and often the heat developed during a work between the electrodes in such a ganges are welded, and as a result a trap will sink so much that a usable amount of welding will be achieved larger part of which is impossible to discharge in the operation. In the case of the apparatus according to the used energy to raise the temperature of the work- 30 present invention are, however, although the Piece effective on the melting temperature and the same inductance in the gripper of the welding machine thus a much higher efficiency when welding occurs, the other electrical properties of the Process achieved. Device in such a way that they compensate for themselves

Another advantage of the present invention and a change in the gripper inductance by consists in reducing the size of the required change in length of the gripper or by inserting it similar welding transformer. If, for example, other workpieces are in the gripper or from another for a certain aluminum weld with storage causes no noticeable effect on the strength Solution from an ordinary alternating current network with the welding current between the welding electrical impulses of 60 Hz and 240 volts so far has a 200 KVA.

Transformer was required, so the same may be 40 Another completely unexpected property of the He-welding work according to the invention when feeding from the invention is that only one resistance is required same network by means of a transformer load on the power line comes into effect be carried out in the same way in normal operation as when a DC voltage is applied z. B. from a 60 Hz AC network as 20 KVA- the lines to the welding electrodes are applied Transformer would be to look at. This reduction would 45. It thus becomes the significant phase shift Size of the welding transformer results in an exercise of conventional welding equipment avoided, and it is significant cost reduction of the welding equipment, no correction of the power factor required, which is necessary for a given purpose. This has further been found that due to the

furthermore results in a simplification of the handling by the welding process with the circuit of the Apparatus, especially if such an arrangement according to the invention is produced Transformer in a hand welding apparatus metallurgical effect turns a much finer grain will. structure is achieved than was previously possible

Another previously unmatched benefit of this was held. It was many years ago The type of welding consists in the fact that it is possible to recognize a welding zone with a fine grain Welding with only a relatively large structure is highly desirable. It's from earlier light pressure on the welding electrodes by ordinary welds known that the respectively. This results from the fact that somewhat prolonged exposure to heat is a rapid Gröder Electrode pressure is primarily required to determine the grain structure of the weld zone to push away the electrodes by the immediately surrounding metal, and to prevent jolting electrical forces that cause the area to become brittle, caused by the application of the welding current. so that this often breaks even if the weld In the case of the apparatus according to the invention, self-connected remains. Although this has been the case since but no repulsive forces of this magnitude had been recognized for a long time, no way has been found so far Electrodes as in commonly fed welding around this recognized desirable grain structure devices, partly for the reason that 65 can be reached. Tests carried out have shown

that in the welds produced according to the invention

a) the power is supplied in such short periods of time, the grain structure remains fine and as a result, that they have the mechanical inertia of the process according to the invention

executed welds are of much greater strength and much less brittleness than this has so far been accepted as inevitable. In circumstances where, due to the nature of the used metal or for other reasons the grain size is not a serious problem, is the The weld achieved with the circuit arrangement according to the invention is still at least the same Strength as in previous processes, and in many cases the weld shows an improved one Resistance to welds using previous methods.

Furthermore, there are numerous possible uses for energy pulses generated at a distance except for the welding area where the method and circuits of the present invention are applicable. For example, the use of such pulses in induction heating has already been established recognized as desirable to increase the efficiency of the induction circuit and the overall consumption to reduce the electrical power required for a specific purpose.

The circuit arrangement according to the invention is therefore intended to provide the following tasks and ideas can be shown or solved:

1. To provide a method for use in conjunction with conventional AC power sources to generate very short pulses with a voltage equal to several times the maximum Have supply voltage.

2. The creation of a process for energy extraction • would be taken from an ordinary alternating current source, the energy being stored and delivered in short bursts of high peak power Load is delivered using conventional switching devices to control the Energy.

3. The creation of a method of delivering pulses from a common AC power source in such a low amperage that the current produced by technically available Switching devices, e.g. B. Stromtorröhren, can be processed, but with such Voltage that a large amount of energy in very short periods of time, e.g. B. 1 to 2 ms a desired load can be delivered.

4. The creation of a welding process that makes the production of welds equally great or better strength than with previously known welds.

5. The creation of a method for generating pulses for electrical welding purposes, which is equally suitable for single-phase and multi-phase operation.

6. The creation of a method for generating pulses, especially for electrical welding purposes, in the reactance changes in the secondary winding of the welding transformer automatically compensate, so that this previously known current compensation devices become superfluous.

7. The creation of a method of generating pulses in which both stored Energy used in a capacitor as well as stored energy in an inductor which both act in series and have a much higher voltage than the voltage of the connected power line, creating a burst of energy of high peak power arises that can be delivered to a resistance load.

8. The creation of a resistance welding process suitable for both ferrous and non-ferrous metals is effective, the latter in particular aluminum, magnesium and copper alloys lock in.

ίο 9. The creation of procedures and devices of the aforementioned type, in which the pulse width with an extremely high degree of accuracy can be regulated.

10. The creation of a pulse generating circuit for the aforesaid purpose, which is paramount Simplicity and still high functionality is.

11. The creation of a pulse generating circuit for the aforementioned purpose in which the voltage of the impulses supplied in a part thereof are considerably higher than those of the supply source maximum voltage supplied is.

12. The creation of an energy converting circuit that has a suitable switch and a Includes control for the switch that closes the switch, if desired, and the Switch opens when the current flowing through it

. becomes essentially zero, and capacitive and inductive energy storage devices and one Resistance in which energy is destroyed, taking all elements out of an ordinary AC power source are fed and are arranged so that the resistor Power is delivered in short bursts of high peak power.

13. The creation of a pulse generation circuit of the aforementioned type that works as well on a Multi-phase source as can be used on a single-phase source.

14. The creation of a pulse generation circuit of the aforementioned type that is sufficiently fast works so that a large number of pulses during each half cycle of an ordinary, either single-phase or multi-phase AC power source can be generated.

15. The creation of a pulse generating circuit of the aforementioned type which is economical to manufacture and requires little maintenance.

16. The creation of a pulse generation circuit of the aforementioned type which is used to power a A large number of different loads can be used, including both ohmic as well as inductive loads.

17. The creation of a pulse generating circuit of the aforesaid type which is suitable for a large number various uses including resistance welding is applicable.

The invention is explained in more detail in some exemplary embodiments with reference to drawings, and although shows

F i g. 1 is a schematic representation of a circuit according to the invention, which is for use on is suitable for a single-phase supply source,

F i g. 2 shows a representation of a current-time diagram to explain the flow over the tubes Current to charge the capacitor,

this current flow being generated at a point lying before the peak value of the sinusoidal oscillation will,

F i g. 3 a is a representation of the current-time diagram, which shows a pulse that in the peak value the sinusoidal oscillation supplied by the supply source occurs,

F i g. 3 b a representation of the current-time diagram, in which the impulse occurs at a point behind the peak value of the sinusoidal oscillation,

F i g. 3 c a representation of the current-time diagram in which the pulse before the peak value the sinusoidal oscillation occurs,

F i g. 4 is an illustration of oscillograms showing the voltage across the transformer primary winding, the current in the transformer primary winding and the voltage across the capacitor in one show given characteristic embodiment of the invention,

F i g. 5 is a circuit diagram representation of a modification of the invention which can be used for single-phase power is and allows the achievement of multiple output pulses during each input half-wave,

F i g. 6 shows a circuit arrangement according to the invention, which is for use in a triangle switched multi-phase supply source is suitable,

F i g. 7 shows a circuit according to the invention for connection to a star-connected multiphase supply source,

F i g. 8 is a diagram of the pulses generated in the circuit of FIG. 6 can be obtained from each input phase, with the pulses line by line shown together with the energy pulses occurring at the output of the circuit are,

F i g. 9 shows an illustration of the circuit with the circuit according to FIG. 7 multiple pulses generated from each phase, whereby the pulses line by line together with those arising at the output of the circuit Energy pulses are shown,

F i g. 10 shows part of a circuit for modifying the circuit of FIG. 6 that allow the use of multiple Transformers in normal design enables

F i g. 11 a modification to achieve unidirectional output pulses,

F i g. Figure 12 is a diagrammatic representation of the pulses resulting from a state of no previous charge develop on the condenser and the way of its enlargement to the steady state demonstrate,

F i g. 13 shows an equivalent circuit diagram to explain the invention, which is used subsequently Components and symbols shows

F i g. 14 a simplified equivalent circuit diagram in which all values are combined in individual elements,

F i g. 15 is a characteristic set of curves showing the operation of the device according to the invention during the time in which the switch is conductive, and under circumstances show under which the later explained Factor »ÜT« is equal to 1.5,

F i g. 16 is an equivalent circuit diagram of a typical transformer with a load similar to that specified in the later specified The symbols used in equations,

F i g. 17 shows a similar illustration as in FIG. 16 with the equivalent circuit diagram of a typical transformer, that is the magnetization inductance, the equivalent resistance and the leakage inductance shows and

F i g. 18 is an equivalent circuit diagram for the circuit of FIG. 16 with further symbols that are in the specified Equations are used.

General

In general terms, the invention consists in initially carrying power from a power source periodically reversing voltage, e.g. B. from a conventional AC network to storage devices is given that then this power is removed in short pulses of such a low amperage becomes that it can be processed by ordinary switching devices, but with sufficient high voltage, usually a multiple of the voltage of the power supply that each Impuls delivers considerable peak power. These power pulses are then in the desired manner used. In welding technology, they are converted into corresponding pulses of lower voltage and higher amperage transformed and fed to the welding zone. The invention therefore sees the Energy supply to the welding zone in very short energy increments of 1 to 2 ms duration, this energy having an extremely high peak power, so the temperature in the welding zone rises at such a rapid rate that relatively little of this energy and the heat caused by it has time to be appreciably in during this heating period penetrate the material surrounding the welding zone. Thus, the heating of the metal becomes predominant limited to the area in the immediate vicinity of the welding zone, which is presumably not a monomolecular one Layer, but certainly represents a fairly similar layer, and the amalgamation of the Metal takes place before significant heat enters the metal behind the immediate weld zone and can also penetrate. This gives a number of advantages, the most obvious of which is and the most immediate is the reduction in the power required to perform a flawless weld and reducing the harmful effects of excessive heating of the metal outside the Zone that is directly involved in the fusion of the parts to be connected.

In terms of circuit technology, the invention generally provides a circuit for carrying out the method which is operated from a conventional high-voltage network and connects the voltage source to the load in such a way that short pulses with a power of high instantaneous value are generated in the load. Basically, this is achieved with the help of a suitable switch, the term switch being used here in the most general sense, and a suitable i? - £ -C circuit. The RLC circuit is one in which all three elements play an essential role, so that if one of them is neglected, the circuit does not bring the desired result. One embodiment of this proposal leads to an equivalent circuit with a series connection of resistance, inductance, capacitance, a switch and the power source. In order to achieve the required pulse power in the load, the various circuit components must be selected in a suitable manner, as will be explained in detail below, but with an important one

609 750/187

i 231 803

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Relationship expressed by the equation can work, whereas the current tubes can work for

is: processing a corresponding amount of energy not

_ ^ ] A [£ _ are able if this in the form of high

K = 1 + e ~ ² " ^L amperage occurs.

5 The one occurring in this way in the inductance

where the size of .ST is between 1 and 2, preferably high voltage pulse is inductive into a pulse

is between about 1.33 and 1.8. of high amperage and relatively low

Since the values of R, L and C in the above equation transforms voltage and then the welding

the sizes of the elements in the equivalent circuit diagram are supplied to darzone.

result in the circuit shown in the io by sufficient spacing between the pulses

generally other values, which can, however, be influenced by the operating frequency of the

Formation of the equivalent circuit in the executed circuit used device kept within acceptable limits

can be determined. will. In fact, as far as the sweat trans-

The person skilled in the art will recognize that a formator is concerned, possible to use a much smaller substantial number of executable circuits from the transformer than was required in the case of the simplified equivalent circuit arrangements explained below, as can be deduced elsewhere, with which the purpose of the present is stated in more detail.
Invention can be achieved. Due to this supply of a large electricity

An embodiment of a device according to the strength of z. B. 50,000 amps becomes the welding zone Invention provides a circuit in which one side 20 is affected by this sudden and sharp concentration of current Capacitor with one of the main electrodes of tration, if only for a short period of time, in two reversed interconnected, gas-filled the interruption point of the welding zone one extreme Tubes are connected, said main- rapid heating of the material on the welding electrodes are of opposite polarity. The stand causes. However, it is by limiting the The other main electrodes of the gas-filled tubes ensure that this energy supply to the welding zone lasts 25 times connected to one end of the load, e.g. B. made that damage to the workpiece verPrimärwickung a welding transformer. One is avoided. Furthermore, the zone becomes the first side of this kind A power source is in with the other side of the heating in a relatively small area Capacitor and the other side of the source with the immediate vicinity of the separation point between the connected to the other side of the burden. Suitable 30 two parts to be welded concentrated, and Circuits, such as rotating phase circles, are between the metal that surrounds this zone and the cathode and control electrode each of the gas-filled moderately cool. As a result, after the Im-bellowing has stopped switched to the part of the pulse concerned the heat tending to move quickly from the To determine the half-wave of an alternating voltage and to spread the welding zone into the surrounding metal, to regulate, during which the relevant tubes 35 so that a rapid cooling of the weld are permeable. results. Even if the

This effect occurs

Detailed description of what is proven by the fact that the workpiece rarely heated to over 40 or 50 ° C and

The invention, although it can be varied in many ways, after such a weld has been completed dene loads is applicable, can best be touched by hand, but increases within one for purposes of explanation assumed half a few seconds after the end of the welding load be made understandable. You will therefore ßung the temperature of the workpiece up to one In the terminology of the application, the point at which it is no longer touched by hand Welding technique described, however, this 45 can be done.

only for the sake of simplicity and better determination - in the case of metallurgical investigation of this process is the name of the description. With this clarification it can be seen that an extremely rapid heating and It can be said that the invention is primarily a full one in cooling the welded material Conversion of the weld supplied by a power source causes it to become noticeable ten energy exists and in a delivery of the same 5 ° grain enlargement can form in the material, with several times higher voltage than the supply chip The welded parts become effective as a result voltage to the primary winding of the welding transformer and firmly welded, but with a ratio in pulses of extremely short duration of z. B. results in a moderately small grain size in the material, 1 ms. Expressed more specifically, the invention consists in which the weld seam immediately surrounds. In the Applying the voltage of an ordinary power line, for example, when welding steel, the heat becomes the power line to a switching and voltage type quickly supplied to the welding point that the metal multiplier during successive in such short periods of time, e.g. B. in the above time periods. These periods are in each case no longer mentioned 100 to 4000 μβ from the ferritic state in than a quarter period of the supply voltage, preferential the austenitic state passes over, that the the wise, however, of much shorter duration, e.g. B. in the 60 welding point immediately surrounding metal main size from 100 to 4000 ^ s. Which actually remains in the ferritic state. The heat measurements Supply via the voltage multiplier is then stopped and the temperature drops A skillful flow of current generates an inductance so quickly that only a very small one Stress of several times the height of the supplied grain growth occurs. Even with ongoing and Tension. By generating a very high voltage, 65 repeated application of the high-voltage impulse generation the application of rapid temperature rise and fall without follows on this inductance Current torches in the switchgear possible because of this high, noticeable grain size increase. Furthermore it results Tensions of e.g. B. apparently several thousand volts, although this has not yet been done experimentally

13 14

it is clearly stated that the alternating energy source and the circuit of F i g. 1 that their

casting supply and removal the tendency arises, the use a good prediction of the effectiveness of the

Interrupt grain growth as soon as it occurs. real switching. In Fig. 13 is the

With reference to the figures, the supply source according to the invention is intended to be provided by an equivalent circuit generator

Circuit arrangement shown using the example of some embodiments 5 V sin st , with a series inductance L ₁ and

Shapes and schematic diagrams explained a series resistor R ₁ . In different cases

will. the source can be viewed as capacitive, or

In Fig. 1, an AC power source is shown, which can have a negligible reactive component

have an alternating voltage on two lines 1 and 2, however, none of these cases will do the analysis and

supplies. It should be mentioned that the high current source io noticeably influence the result, nor will it be

has an internal resistance that takes into account any difficulties when R _{1 approaches zero.}

it must, although it is negligible in various cases. On the other hand, the equivalent impedance

can be released. In general, the current of the source cannot become too high, otherwise the

source replaced by a suitable backup circuit.

so that the AC voltage that can be assumed here is 15.

In Fig. 13, the power pulse circuit consists of which the alternating voltage in the equivalent circuit diagram is to be added to the equivalent circuit from an idealized switch S in. This makes it possible to refer to a series with a resistor N ² Rt, an inductive AC voltage that is dependent on the load N ² Lt and a capacitance C all independent of that on power lines 1 and 2. 20 Series equivalent circuit of the power source connected in series. Line 1 is connected to a terminal of a condenser. Rt is connected to the total resistance of the transformer 5 of a suitable size, and the other and the load, transformed to the secondary terminal of the capacitor, is connected to a connection of the transformer, Lt is the total inductance of point 3 connected. The connection point 3 is transformer and the load, transformed to one side of a suitable switch connected to 25 the secondary side of the transformer (with the exception of this case the cathode of a first gas discharge of the magnetizing inductance), and JV is the Winröhre, z. B. a current tube with the commercial service ratio of the transformer. Is at Transformiezeichnung thyratron or Ignitron, the designated with 4 tion of the total resistance and the Gesamtinduknet, and the anode of a second corresponding tivity to the primary side of the transformer give gas discharge tube 6. The other side of the switch 30 for these, the sizes of N ² Rt and N ² Lt. Since here the anode of the tube 4 and the cathode of the capacitance of the transformer and the load on the tube 6, is connected to a connection point 7, circuit according to FIG. 1 can be neglected, and this connection point is connected by a line and has the capacitance C in FIG. 13 in reality the device 8 with one end of an inductance in connection with the value of the capacitor 5 in FIG. 1. For the purposes of this, which also represents the load here, and the equations below, it is assumed that the primary winding 9 of a welding transformer forms the idealized switch in the closed state, the mator 11. The total load includes resistance zero and in the open state, of course, the inductive and ohmic components also have infinite resistance and can be opened and closed in every genenten of the transformer primary winding as well as the desired time instantly and without time-related components of the transformer 4 ° delay. Secondary circuit. The other end of the winding 9 is in operation, such a switch is connected in parallel with the line 2. for the ideal mode of operation of the above-mentioned electricity

To actuate the switch between the mentioned gates at a desired time close and

th points 3 rnd 7 a switch control is required- then remain closed until the current that comes with the

loaned to flow the circuit across the switch in the manner desired to close the switch

To bring work. Since gas discharge tubes begin to try to change its direction, d. h., the

in particular, the above-mentioned power tubes when the switch opens when the

are used, are useful usual phase current through the switch when changing from one

rotary switches used for switch control. This direction goes through zero in the other. It doesn't play

for a suitable phase rotation circle 12 of any 50 role, in which direction the current flows first through the

usual design from the lines 1 and 2 ge switch begins to flow, but it can be without

feeds, and its output terminals will not reverse the opening of the switch, and the intermediate

The cathode and the control electrode of the tube 4 are connected between the closing of the switch and

closed. Another phase rotation circuit 13 is made from the opening is completely dependent on the circuit

the lines 1 and 2 and fed to the cathode and 55 outside the switch.

Control electrode of the tube 6 connected. For further investigation, the circuit is an essential part of the invention in the quantitative FIG. 13 is further simplified, so that the relationship between the various R, L and F i g. 14 finally simplified equivalent circuit C components of the circuit, as shown briefly above. Here all resistances are mentioned in a counter under the general explanations, 60 stood R summarized, all inductances in one and this quantitative ratio best on hand inductance L and all capacities in a capacitive equivalent circuit diagram of an executed circuit did C. Furthermore, the alternating current source is through one can be made understandable, the attention direct current source with the voltage V, which each total is now directed to such an equivalent circuit diagram and the desired polarity according to a selected one of the associated mathematical relationships. 65 half-wave of the alternating current source.

F i g. 13 shows the equivalent circuit diagram of the heavy current The reason that the real sinusoidal current source for

source and the circuit of FIG. 1. The circuit investigation by a constant source

contains such an extensive representation of the current alternating polarity can be replaced, exists

in that the idealized switch 5 ¹ in the simplified equivalent circuit is closed only for a very small fraction of a period of the sinusoidal current source and consequently, for practical purposes, the sinusoidal source in the simplified equivalent circuit is almost constant in height for the time the switch S closes can be accepted.

When examining the simplified circuit diagram, the following symbols are used:

The instantaneous voltage across resistor R is written as

V ₁₂ or V ₂₁ ,

where V _{12 is} positive when point 1 is more positive than point 2, and V _{21 is} positive when point 2 is more positive than point 1, and V ₁₂ = - V ₂₁ . The same goes for the other voltages. The current is positive when it flows in the direction indicated by an arrow. Furthermore, the rule is applied that the current is positive when it flows out of the positive terminal of a power source.

The different voltages are designated as follows:

v _{12 is} the instantaneous voltage drop across the
Resistance R

V _{23 is} the instantaneous voltage drop across the
Inductance L

V _{34 is} the instantaneous voltage drop across the
Capacity C

v _{41 is} the instantaneous voltage drop across the
Source F.

The reference character g is used to denote the current charge on the capacitance C.

The equations that outline the operation of the circuit are:

(D (2)

a =

Yl

- damping factor,

R ²

lc

Usually will

4 pounds ²

neglected in β so that

- y lc

In other words, a sufficiently small resistor is normally used that neglect from

4L *

gives good results.

The above equations and the following equations are only valid for

or

LC

> l.

This is the same as when it is said that only the underdamped case is examined in the equivalent circuit diagram. In fact, this is the only operational case of interest.

The opens in the simplified equivalent circuit diagram

Switch S in the first current zero, which follows the closing. It can thus be seen from equation (2) that the magnitude of T for which the switch opens is when

ß ■
Thus is the time domain for all equations

Now the various instantaneous voltages can be expressed as

V ₁₂ =

Let

Re - ** sin β t

(10)

Therein mean:
β = w = 2 π /

/ = Resonance frequency of the if-LC circuit
i = instantaneous current in the loop
v ₁₄ = supply voltage

F ₃₄ = initial voltage on the capacitance before the switch is closed, e.g. B. if

F ₃₄ = Vc = size of the initial voltage on the capacitance, (3)

V ₂₃ = (v ₁₄ - F ₃₄ ) e- * \ wsst - ä-sinusst \ (11)

v ₃₄ = ^ ₃₄ + (v ₁₄ - F ₃₄ ) fl - e- * (cos t + j sin / 8rJl.

(12)

These equations tell what is going on in time while the switch is closed. When the switch is open, no current flows, so the voltage drop across the resistor is zero, and since there is also no current change in the inductance, the voltage drop across it is also zero. Only the capacitance generally retains its charge, so that a voltage drop remains on it. The power pulse circuit operates in such a way that the voltage source is reversed for each actuation of the switch. Therefore, if V ₁₄ is positive for closure 1 of the switch, then V _{34 is} positive when the switch opens. For switch closure 2, F ₃₄ is equal to V ₃₄ at the point in time when the switch opens after closure 1. For closure 2, the source voltage V _{14 is} negative, so that the two voltages v _I4 and F ₃₄ add up. Thus, in equation (12), the quantity (V ₁₄ - F ₃₄ ) has the value (-F- V _n ), where V _n

17 18

the magnitude of the initial voltage on the capacitance in load is usually an equivalent circuit with a time t = 0 for closure 2, accordingly, as we know, resistance is the only way to get to the other equations. This process continues converting the supplied energy into heat or continues with every further switch actuation. Work consists in making the load an adverse

It should be noted that he has ^at an important component 5 Stand.

Is a factor in all equations. In some use cases, the existing

Processes in the pulse circuit in the usual way load can be purely ohmic, but the rewriting can Being able to stand on this exponential is not the right size to be in optimal Relationship based factor useful. He will work in way in the circuit and it can be a derived from the following explanation. At the time io transformer used to increase the size of the when the switch is turned off, the resistance component reaches to change. Furthermore, the Electricity its first zero. From equation (2), light load is ohmic and capacitive or ohmic and it can be seen that this can be inductive, or all three components

make up the burden. Again, the impedance can

t - J ⁷ L. 15 not be suitable for the circuit and a trans-

ß formator may be required. For this reason

entry. a short treatise on transforming

To find what voltage at that time on mator, the equivalent circuit and the transformation of the capacitance is present, is based on equation (12) of the load resistance for an understanding of the invention To refer to which the capacitor voltage 20 is important, the following is done: indicates and a sine and a cosine expression in FIG. 16 is the circuit of a transformer

contains. The time when the switch opens is shown with a characteristic load, whereby it can be seen that only the cosine term is not zero, the load is ohmic (R £), capacitive (Ci) and, in fact, it is -1. Therefore it has an inductive (L £) component. The shown multiplier factor 25 transformer is not an ideal transformer and

__ _a 7E is therefore both ohmic and capacitive

~ * ~ ^e ~~ ß ~ '. '^ and inductive components in its replacement circuit

picture on.

This can be expressed using the expressions R, L, C However, are for purposes of the following discussion

30 are the transformers specified in the equivalent circuit diagram

effects are limited to the ohmic and inductive components. This is possible as in most

K— 1 + e V ^c * (14) cases the capacitive effect is small and the advance

determination equally good without taking into account the

and approximated as (in most cases of interest) 35 capacitive components. A characteristic one

, - and suitable equivalent current run of a usual transit— 1 1 q ~ ^ ^r \ / ~ jr (15) transformer, in which the total leakage inductance and

the transformer resistance to the secondary

Since K is merely a function of the constants R, page transformed, is shown in FIG. 17, and L, C is, it is also constant for a given device, although it is an ideal transformer. Nevertheless, it is a parameter which is set with a series resistance R _s and a series in such a way that the desired effect is achieved in an inductance component L _s , which is the given scatter case. For a given size represents inductance.

from K can now the voltage on the capacitance Another inductive component, which in many

At the end of a current pulse, what matters in 45 circuits is the magnetization den Print out the supply voltage and the initial inductance (Fig. 17), which are here on the secondary side voltage on the capacitance at the beginning of the current- transformed and parallel to the secondary winding of the impulse at the time the switch closes. It's transformer is shown.

In the equivalent circuit diagram used here is

V ₃₄ (at t = -) = F ₃₄ + (v ₁₄ - F ₃₄ ) K (16) 5 ° magnetizing inductance neglected because it is a

\ ß I has a negligible effect, while the scatter

_Y \ f_ \ γ _ y \ ν (γη inductance and the series resistance are the main

^{34 3i} most effective effect in the secondary winding.

The plus and minus are determined by the respective switch closing period. Due to the 55 that has no losses and voltages with N, currents peculiarity of the pulse circuit is always found 1 " _r .,, ,,. ,, ... " _TO .

that the signs are such that those with ^, resistances and inductances with N \ and

The size of F and the size of F ₃₄ in the brackets, _capacitances transformed by 1, can add the real one from equation (17). N ²

At this point it appears to be desirable to draw the transformer and its load for the purpose of the equivalent circuit diagram with the real circuit under investigation replaced by an equivalent current run. For this purpose the first thing is to be one that does not contain a transformer. The substitute definition of what is to be understood by load is the circuit diagram for the circuit of FIG. 16 is in FIG. 18 namely one or more elements (R, L or C) are shown. This equivalent circuit diagram shows a glimpse into or at which the desired output value appears on the two terminals on the primary side and exits. Generally speaking, it is the aim of the invention based on the assumptions made above, namely to find to convert the energy from an energy source into one that the transformer capacitance effect and the load. Furthermore, the magnetizing inductance is neglected. That

corresponding equivalent circuit diagram of the circuit according to FIG. 17 is the same, except that the resistor is of size N ² R _S and the inductance is of size N ² L ₈ . For example, the circuit in FIG. 1 a load that is formed by a welding transformer with resistance and inductance on the secondary side. This results in an equivalent circuit that only consists of a resistor and an inductance. When deriving an equivalent circuit diagram for the circuit of FIG. 1 the in F i g. 16 and 17 are used for a load and a transformer equivalent circuits to arrive at the circuit shown in Fig. 13, where Rt is equal to the sum of Rl and Rs - and Lt is equal to the sum of Ll and Ls.

After returning to the discussion of the load and the equivalent circuit diagram in comparison to the real one In the case of a welding circuit, the current flow must be determined that the actual load (the point in the energy is converted into heat) a fraction of the resistance load on the transformer secondary side represents. This load resistance is part of the resistance in the equivalent circuit. When calculating the real load energy or power, only the equivalent resistor may be used which corresponds to the real load resistance.

In the above explanations about the equivalent circuit diagram, the voltages for the various elements were calculated. These relate to the total resistance, the total inductance and the total capacitance. In the real circuit these elements may be distributed and some may be in the power source and some in the load, etc. As a result, one cannot immediately say that, for example, v ₁₂ + V _{23 is} the voltage across the primary winding of the welding transformer, since In some equivalent circuit diagrams, the inductance and the resistance can be combined with the current source. The actual transformer primary voltage can therefore sometimes be slightly less than v ₁₂ + V ₂₃ . However, since in most applications the impedance of the current source is small compared to the load, it will be found that the voltages calculated in the above equations can be used as good approximations of the voltages of the actual circuits without any division of the voltages.

The current calculated as above is of course a series current and flows through each component of the simplified equivalent circuit and is therefore the same in each.

In continuation of the quantitative investigation of the circuit, a few more equations result, which can be derived with suitable assumptions and provide information about which Effect every component in the circuit has on the performance of the circuit. On one A caveat must be noted, however, namely that these equations, although they are closer approximation result, with a certain choice of parameters, no completely exact numerical solutions deliver, while if the parameters are chosen differently, the numerical solutions represent good results. Even so, in all cases the equations give a good indication of the changes in performance occur when the various parameters are changed and are therefore still useful. The conclusions that these equations allow are important for the realization of the experimental Development of the invention.

Assumptions: When using the equivalent circuit of FIG. 14 it is assumed that a continuous initial voltage has been achieved:

β so ._. jL._.

^P ~ fTc

hs primary peak = peak current in the transformer primary winding under continuous initial voltage conditions

Si V

sinh

(23)

the magnitude of the initial voltage on the capacitance under steady state conditions. This is the capacitor peak voltage.

V

tanh

(24)

Assuming that there is a transformer, the mode of operation can be in the expressions the secondary inductance and the secondary resistance (which simulates a welding process) with the following additional assumptions:

That all ohmic and inductive effects associated with the transformer are proportional to JV ² when looking at the primary side of the transformer, where JV is the turns ratio.

That some resistance and inductance quantities are combined in the circuit with the current source and are therefore independent of the transformer turns ratio.
That all capacitance effects are on the primary side and are independent of the transformer turns ratio.

Eat primary tip

1 / c

Iss secondary peak = V · N \ - —775-7— · (^ 6)

\ l L ₁ + N * Lt

sinh

v _Css m ν

tanh

(27)

where means:

R ₁ Resistance of the power source
L ₁ inductance of the current source
N- transformer turns ratio

Rt total resistance of transformer and load translated to the secondary side

Lt total inductance of transformer and load, transformed to the secondary side, with the exception of the magnetizing inductance, which is neglected in this case.

The following further assumptions are now made, namely:

That the resistance and the inductance of the supply source can be neglected.
In addition, that sinh χ and tanh χ can be replaced by x. This gives a good approximation when χ is small (less than 0.1) and not so good for larger x. For example, for K = 1.5 and a switch closing time of 1 ms, χ is approximately 0.15.

4th
Eat primary tip Si F

Tl

Tl Jy

rs ⁴

* ss secondary peak = "

π Ν Rt

° ^ss ~ π NRt VL _t

(28)

(29)

(30)

Next, a formula is determined that gives the numerical value of C for a given load inductance, pulse duration, and turns ratio entered.

Further assumptions: The duration of the current pulse T = a constant.

where L = L ₁ + N ² L _T.

(31)

where the size of the supply source inductance L ₁ is neglected as above.

(31a)

Substituting equation (31a) into equation (30) gives

Eat primary peak SF —-——, (32)

Tt JS Kt
4 1

^ SS secondary peak = F τ- ^ ζ , (33)

Tt JS Rt

Coo -

Rt

(34)

For many applications, Rt and Lt are determined by the real load one has to work with. If so, then the choice of C is based on the pulse width that one desires. This C is also influenced by the transformer turns ratio for a given T. This relationship is expressed in equation (31 a).

The peak voltage on the capacitor (also the peak voltage on the inductor, is approximately the transformer primary voltage)

i "only a function with first approximation of F, Rt, Lt and T, of course C will influence it, but not for a constant T. This relationship is expressed in equations (31 a) and (34) he himself from equation

(33) is a function of N, Fund Rt. It is independent of L and C to a first approximation. As a result, the welding is not significantly affected by inserting a sheet of iron into the gripper of the welding device. In other words, the pulse circuit according to the present invention is a constant device

Peak current with respect to changes in L or C within the limits of the assumptions made.

While the circuit parameters change according to the equations given above, to certain To meet requirements, in a preferred embodiment of the invention, which is described elsewhere is described herein and has a pulse duration of one millisecond, the rate of pulse rise and decay are chosen to be equal to a wave having a frequency of 500 Hz.

The circuit and the transformer are therefore included chosen according to this embodiment.

Because of these pulses of short duration (relatively high frequency of the circuit compared to usual Welding Circuits) is the size of the capacitor, which in this case is the element that the Pulse duration determined, small compared to the capacitors used in previous welding circuits, in which the capacitor is not used to determine the pulse duration, but only to correct the Power factor is used. For common pulse welding applications, the invention is at a mains voltage of 230 volts capacitor sizes in the order of 100 to 1000 μΡ are used, and the voltage level on it will be at least 2000VoIt. However, these numerical values are merely to further explain a specific exemplary embodiment of the invention and are not to be construed in a limiting sense.

In general, one of the problems is large inductance compared to resistance and the required pulse duration and in relation to the maximum voltage that the switch must withstand, and the maximum voltage that the capacitor must withstand. As a result, it is usually desirable have a transformer with minimal leakage inductance. This requires a little clarification because of the presence of a variable turns ratio in the transformer. That's why the transformer requirements are to be formulated as follows:

A leakage inductance of the transformer must be provided, that on the secondary side the inductance compared to the load inductance is as small as is possible.

It is usually desirable to keep the resistance losses in the transformer to a minimum

23 24

hold to reduce the cooling problem. the same to the opposite polarity. In this

However, if there is too much time in a given case, the charge on the condenser

Capacitor voltage, one can add an external sator, albeit not arithmetically, to that of the

Insert the resistor at a point where it easily adds to the potential supplied to the current source, and the at

is cool. This of course reduces the overall impulse delivered by the load

efficiency. generates a voltage that is significantly greater than

The secondary winding of the transformer becomes the voltage of the source at the point of the sine wave,

In terms of magnitude, it cannot be measured differently by which the relevant impulse arises. Directing the

than with previously used welding transformers. Tube 6 is terminated in the same way as above

The parameter K is important because the fixed anio was explained on the basis of tube 4,
indicates the initial peak voltage that occurs across the capacitor and there should now be another characteristic of the effective inductance of the equivalent circuit. For all to be treated wisely. A feature of this circuit values of K between 1 and 2 is the voltage am is that at an initial voltage of zero on the capacitor is greater than V and the peak voltage of the capacitor when the result of the switch on the inductance is greater than 2 V. This applies to the 15 closings is set in motion, the initial equivalent circuit. In most of the executed welding voltage in the following closings in the circuits where the line impedance is small, height increases. Eventually it will remain to a certain extent that it will be found that these values approximate the state of the initial voltage, which corresponds to the values on the capacitor and on the maximum transformer voltage which correspond to the capacitor primary winding. At K up to 1.5 the 20 sator occurs. The time it takes for this capacitor peak voltage to reach approximately 3 V and the state is a function of the magnitude of the peak voltage across the inductor is approximately 4 V. That of LRC. The initial voltage remaining on the preferred range for K is currently around capacitor can be calculated on the basis of between 1.33 and 1.8. The fact that this condition occurs when the

The effective voltage between the welding electrodes 25 initial voltage on the capacitor at the beginning

trode is a function of the transformer peaks - the same as a switch closing period, but of the opposite

voltage, the transformer turns ratio and set polarity such as the voltage that is on the

the distribution of resistance and inductance capacitor at the end of the switch closing period

between transformer and load. It must prevail. Using equation (17),

Suitable values can be chosen to keep the capacitor peak voltage V _e p (permanent

To maintain voltages on the electrodes. State of the initial voltage) and arrives

Experimental results have shown that with the following result:
high values of K, e.g. B. of 1.8 or 1.9, straight

more impressive and desirable results - V _c = V ₀ + (- V - V _c ) K , (18)

were achieved with regard to the 35 ρ ρ highlighted above

Advantages, as they can be used with smaller values of K, 2 V _Cp = KV + KV _Cp , (19)
z. B. 1.4 or 1.5, were achieved for the purpose

of safe operation have been applied. Next- (2 - K) V _Cp = KV, (20)

such experiments have also shown that with K g

equal to 1.5 circuit parameters can be achieved at 40 Vc _p = - ^ ^ - V. (21)

which the stated advantages of the present ~
Enter circuit technology with a high degree of satisfaction, without the operator being exposed to the peak voltage on the inductor, which, if at all, precedes the source voltage plus the capacitor peaks, is greater than the practical voltage. This can also become more common in terms of K approved electrical welding equipment as indicated below:

Cling to execution. _Tr ". ..,,. . ,

Vl _p = peak voltage over the (entire)

Mode of operation inductance,

In the circuit according to FIG. 1 becomes different 50 y _L = v _c + V,

which times during each half period of the current ^vv

source, namely these times are represented by the phases - _ 2, ".

rotating circles determined, one or the other gas discharge ~ 2 - K '
charge tube, e.g. B. the tube 4, conductive and effected

the charge of the capacitor 5, and this 55 A characteristic family of curves that

conductive state lasts until the capacitor 5 show a, which occurs during the time in which the

such a voltage that the current flow switch is conductive are shown in Fig. 15,

tries to reverse in the gas-filled tube, so that equation (21) can also be written:
the tube ceases to be conductive. At this point

the voltage 60 _ t \, ^π R applied across the tube 4 is canceled
and the opposite occurring at the capacitor 5 ^c p ~~ * »4
set voltage and the tube stops
conduct. This occurs even if the pulse is on. It can be seen from this that the effect of an ascending branch of the sinusoid arises, as in the change from R to V _{Cp is} greater than the effect of FIG from L or C. This polarity is given to the tubes, so the result is because the resistance of the primary tube 6 is conductive and first causes a discharge of the winding of the transformer, capacitor 5 is kept very low and then a charge.

25 26

It can be seen that by appropriate adjustment by correct balancing of the phase rotation circles of the phase rotation elements the tubes 4 or 6 at each can be achieved that the pulses either in the desired position of the half-waves opposite or behind the peak value of the sine polarity supplied to the current source in known Wise conductive wave or occur before the peak value. Which can be turned on. However, to the extent that an associated voltages resulting from the load, a certain phase shift is necessary for the correct one. They are shown in FIGS. 3a, 3b and 3c.
Work of the present circuit required than it was previously determined that the size of the voltage across the capacitor 5 and the primary of the impulses occurring at the load winding 9 immediately when the tubes 4 become conductive greater than the voltage supplied to the arrangement and 6 available have to be. This continues to be io. This is because the voltage on the condenser is shown in FIG. 2 and the associated description is added to the supplied voltage if in the following paragraph. also not necessarily arithmetically. Example

In FIG. 2, the line 14 shows the voltage that is partly supplied by the power source when the load is formed, and the lines 16, the primary winding of a welding transformer, 17 and 18 show the current flowing through the corresponding Wrong measurements at the output of the transformer in the tubes 4 and 6 flows. The line 16 shows, by way of example, many examples of a voltage at the primary winding that the voltage through one of the tubes, shown for the purpose of being many times greater than the source of the explanation, is also assumed to be the tube 4; For example, with a supply current at a point approximately 60 ° behind the voltage of 240 volts, assuming a half-wave beginning with the beginning of the part 14 "of the line 14 20 arrangement with K - 1.5 voltages of 1000 volts, indicated half-wave continues up to 1400 volts or much higher. Corresponding the charge on the capacitor 5 is such that measurements on the capacitor showed charges on itself as the current in the tube 4 tries to reverse. this capacitor, which was considerably larger than that of the voltages supplied to the supply source, stops the current flowing through the tube at this point. So on, even if the voltage of the source continued to result, e.g. B. in the above case, when increases, due to the disappearance of the supply voltage was 240 volts and K = 1.5 of the voltage difference between the Hauptelek- was, voltages on the capacitor from 900 to troden. 1200 volts.

If, however, the voltage is reversed and the length of the phase rotation circuit 13 of the circuit according to the invention makes the tube 6 conductive, whereby 30 pulses supplied can be assumed according to the requirements of the assumption that this tube 6 is also 60 ° respective load within a limited range behind the beginning the half-wave is conductive, so ches can be changed. Thus, the pulses, the voltage on the capacitor 5 becomes the voltage supplied to the tube 6 when working with extremely short pulses from the source is impracticable, can be easily lengthened by the amount of energy required, and the current through the welding transformer 35 the workpiece is therefore a function of the sum of the voltages, but approximately a quarter of the periods of the capacitor and the source appear, as is the maximum pulse duration, line 19 in FIG. 3 c is indicated. When that is the most effective. The preferred pulse duration for capacitor 5 discharges through the tube 6 and a voltage of the opposite sense builds up the present use for welding purposes, the 40 falls about 1 ms, but pulses of even shorter current through the welding transformer very suddenly have duration than 1 ms, e.g. B. from 100 \>. S, a few more and reaches zero essentially immediately. Thus, the current through the welding transformer achieves advantageous properties for at least some, areas of application compared to the pulses of as indicated by line I in FIG. 4 is shown to be 1 ms in duration. As a result, although the maximum number of pulses can be changed very quickly after the circuit 45 becomes conductive, tube 6 and drops very quickly thereon, so that the pulse lengths within a range of approximately immediately thereafter become zero. This corresponds to 100 \ ls up to about 4 ms, which is an advantage, however, where the capacitor 5 is completely charged in the opposite sense, at least for the welding application areas, and the further current flow has a duration in the order of magnitude of about 1 ms through the tube 6 interrupts in the same way as 50 own,
this is explained above with reference to the tube 4. _se U ₌ ^ _amch

Through the following inversions of the polarity of the ^b \ t J

AC power source is generating sharper the ratio of inductance to capacitance. the

Continued power impulses, each of which is essential- the following equation indicates this:

borrowed beyond the height determined by the voltage 55 γ ~ _λ , ^ r

the source alone could be generated, and where /? = 1 ''

each pulse has an extremely short duration. The γ LC 4L ²

^{m following} If R is very small, - ^ can be neglected,

Although the phase rotation circles 12 and 13 in the broader 60 so that the following relationship can be applied as a practical form, the scope of the invention can not necessarily be set so:
must be that they have the same phase shift -. r ~ -r

generate, and therefore the pulses are not the same β g

Size in the relevant opposite directions- ^
Since the magnitude of the use of the device provided by the arrangement, preferably the same pulses, is partly a function of the capacitor phase shift in circuits 12 and 13 and charge at the time of the start of the pulse, is therefore slightly the same Impulses applied. can be seen that a progressive increase in the

27 28

Output pulses of the arrangement can be achieved, influenced in a pulse duration and not the sizes of the

Way that an increasing sweat control achieved impulses, which in each case alone by the supplied

in at least two ways: voltage and by location on the sinusoid

that the impulse arises can be determined.

a) For the first, it is assumed that the value of 5 Die on the basis of Fig. 6 to 9 explained circuit "K" is relatively high, z. B. 1.7 or higher. examples are suitable for multiphase power sources. Thus, the capacitor voltage adds up in the circuit in FIG. 1 described first. 6 over several pulses to the supply voltage, and 'is a three-phase input with three feeds, the peak voltages increase as a result, lines 31, 32 and 33 are provided. For ongoing purposes. This process is illustrated in the description below in FIG. 12, where it is shown how the peaks of 31 and 32 phase A, between lines 32 pulses progressively increase until they reach one and 33 phase B and between the lines 31 reach the permanent state that they no longer and 33 the phase C. A welding transformer 34 falls below. However, this normally has a secondary winding 36 which is in some way only more of an initial state when the usual manner with the electrode welding device indicated at 37 is switched on again as a pre-connected. The transformer also has primary windings 38, 39 and 41 of the usual shape, which are used for regulating purposes. could. By partially discharging the capacitor, the upper end (in the drawing view) of the sators between operations and changing primary winding 38 is connected to one side of a power of the rate at which the charge build-up 20 is connected to capacitor 42, the other side of which is allowed to be on the capacitor, can be connected to a connection point 43. However, this function, as indicated, for the discharge tube 44 filled with gas, for which a position is expediently used. Thyratron or an ignitron is used with theirs

b) The more immediate and simpler method of the anode to the connection point 43, with its cathode Regulation that is used both for increasing the pulse rate and 25 via a line 46 to a connection point 47 can also be used for lowering, and with its control electrode through a line 48 however, there is phase control. Since the at the output of a phase turning circle 49-output pulse at least partially a radio control. This phase turning circle has a common one tion of the mains voltage at the time of the pulse shape, so that details of the circuit do not arise can be given by regulating the phase 30. Another gas shift a rising or a falling discharge tube 51, for which also expedient Pulse waveform can be generated. For a steep a thyratron or an ignitron is used The time of the impulse with its anode at the connection point 47 is the same as the curve generation from a point near the zero of its cathode via a line 52 to the passage the sinusoidal supply voltage, but 35 tie point 43, and with its control electrode not directly in this, up to the peak value through a line 53 to the other starting point pushed. A falling gear is connected by ent of the phase turning circle 49. The entrance opposite shift reached. This of the phase rotation circle 49 is available through a line 54 Way is a precise pulse control with only one input, z. B. the supply line 31, made possible by the phase-locked loops without 4 ° in connection, and the other line 56 of the phase, other quantities of the device are changed. turning circle 49 is with the other supply line,

z. B. the line 32 connected. The lower end

F i g. 5 shows a modified embodiment, the primary winding 38 is connected to a line 57

which is used to generate a plurality of pulses from being closed to the supply line 32

a single sinusoidal supply voltage is suitable. Here 45 suitable place, z. B. at junction 58, in

is a plurality of circles, each of which is connected.

a pair of oppositely connected gases. The second primary winding 39 is in a corresponding manner

Charge tubes in series, each with a capacitor, in the same way as the winding 38 with gas discharge tubes

exists, interconnected in parallel with each other and with the load in and a phase rotation circle. That

Switched in series. The with the circuit in F i g. 1 5 ° upper end of the primary winding 39 is with one side

Matching parts are shown in FIG. 5 connected to that of a capacitor 59, the other

the same reference numerals. In the newly added side is connected to a connection point 61.

The circles inside are the reference numerals of the discharge tube 62 is with its anode on the

speaking parts with the indices "α" and "Z>" connection point 61, with their cathode to the

Mistake. Each of these separate capacitor 55 connection point 58 and with its control electrode

Tube circles work independently of the others, at a starting point of the phase shift element 64

and each creates a pulse in the load connected to it, which is of some known origin

a point in time that can be guided by the phase setting. A gas discharge tube 63 is

the control electrodes of the one used in the circles with their anode to the connection point 58, with

Tube pair is determined. In this way, 60 of its cathode can be connected to the connection point 61 and with

by suitably setting the phase rotation circles of your control electrode at the other starting point

be achieved that several pulses, here three, connected by the phase shift member 64. The entrance

each of which lines 65 and 66 of the phase shifter 64 through a condenser tube circuit

is supplied, occur at the load, this corresponding to the feed lines 32 and 33

Impulses are expediently extremely close together. 65 connected. The gas discharge tubes 62 and 63 are

It can be seen that the number of such parallel appropriately corresponding tubes such as tubes 44

tube circles and the sizes of these circles and 51 and can also be called Tyratron or

provided capacitances and inductances only the ignitron tubes can be formed. The other end of the

29 30

Primary winding 39 is connected to feed line 33. This mode of operation continues as long as foil

bunc en. AC pulses at the phase A terminals

The third primary winding 41 has a lead.

stungskondensator 67 connected to a connection point 68 by the appearance of alternating current pulses. A gas discharge tube 69 is in phase B with its 5, ie between the feed lines 32

At the junction 68, with its cathode and 33, the capacitor 59 becomes in a corresponding manner

to a connection point 71 and with their control mode in alternating directions under control

electrode charged to a starting point of a usual through the phase rotation circuit 64, and it

Phase rotating member 72 connected. Another gas- impulses of alternating direction are created by this The anode of the discharge tube 73 is connected to the verio in the primary winding 39. Each of these has pulses

connection point 71, with its cathode at the association a significantly larger amplitude than the maximum

tie point 68 and with its control electrode on voltage in phase B, it being assumed that

the other starting point of the phase rotation element 72 of the phase rotation circle 64 is also set so that

connected. The connection point 71 is connected by the tubes 62 and 63 approximately 90 ° on the one line 74 to the feed line 33. 15 start of impulse in phase B and the duration of the

The input line 76 of the phase shifter is also pulsed through the capacitance of the condenser

the feed line 33 and the input line 77 with sators 59 is adjustable.

connected to connection point 78. The other farther are similarly by impulses

The end of the primary winding 41 is connected by a line 79 in the phase C pulses of alternating direction and to the connection point 78, which has a significantly greater amplitude than the pulses in the over 20

another line 81 is generated with the feed line 31 in phase C in the primary winding 41, wherein

Connection. again it is assumed that by corresponding

Assume that a positive phase adjustment pulse on phase rotator 72 causes the tubes

the feed line 31 occurs and that the phase rotation 69 and 73 is set approximately 90 ° after the start of the pulse in circle 49 so that a positive pulse 25 phase C ignites.

at the control electrode of the tube 51 at a point in FIG. 8 are the position and size of the impulses in the

90 ° after the start of the positive pulse on the feed phases A, B and C shown, both the

line 31 is created. In this case the tube 51 pulses to each other as well as to the sinus

conductive at the mentioned 90 ° point, and the pulse voltages in the individual phases,
flows through the tube 51 and through the condenser 42 3 ° in the lower part of FIG. 8 are all impulses

and then across the first primary winding 38 to the shown together in a single line to the

other side of phase A to feed line 32. As soon as mutual time interval of the different

the capacitor 42 to point to the maximum voltage of the pulses.

Phase A is charged, the current stops flowing. With the in F i g. Pulses shown in FIGS. 2 and 3 If the parameters of the circuit are chosen so that there are no overlaps of the pulses, and that this occurs very quickly, it can be seen that there is no possibility that a single conductive pulse in the first Primary winding condition occurs in a phase where the pulses generated in a 38 arises and then the current flowing in it in another phase is extinguished or ceases to flow. When an inverted voltage occurs, it can be influenced in some other way. As described in the phased circuit, the current flows in the reverse 4 ° circuit as a result of which delivers individual pulses, at direction, this time via the tube 44, which, as shown, every pulse from all the others as soon as the current flows through The pulses on the control electrode are separated and in which each output of the tube 44 acting phase rotation circle 49 is released pulse approximately twice the amplitude of the feed. If it is assumed that this phase source is set at the moment the pulse arises so that a positive pulse has 45, and no moving parts of the last-mentioned control electrode are required in the circuit.

90 ° after the start of the reverse impulse arises, _. _Cj _,. "^, ._. ".
so it can be seen that this pulse is essentially common tapped star-connected)
starts at the maximum voltage of phase A , and bfeiseschaltung
also that it adds to the voltage on the capacitor 50 although the circuits noted above. Consequently, one gets work satisfactorily and satisfy 31 and 32 changes substantially higher voltage, the Anforleitungen provided between the table salt, they have the disadvantage that it remains as the maximum voltage of the phase A. a welding transformer having a plurality of primary At the end of the pulse, the capacitor 42 windings require the effort and costs caused by opposite polarity compared to that caused by 55, the greatest possible reduction of which is desired without the last-mentioned impulse between the feeds. Impairment of the mode of operation. lines 31 and 32 generated polarity, so the following modified circuit has therefore been developed so that when the next pulse occurs in the first, in order to be able to use a single primary winding tapped in the middle, the charge on the capacitor, again the Voltage between the feed lines 60 with which likewise all in connection with FIGS. 31 and 32 increases at the moment in which the requirements set out in the invention are met, the gas discharge tube begins to become conductive. As long as a star-connected four-wire generator is available at the point at which the power source becomes conductive, or in the known tube 51 remains at about 90 °, the impulse is again essentially created by transformer conversion through the first primary winding 38 can be.

borrowed greater than the size of the maximum stress in In F i g. 7 are four feed lines 101, 102, 103

of phase A, and it again has a very short and 104 shown. Line 104 is the common

Duration. same neutral wire, and lines 101, 102 and 103

31 32

the phase conductors of phases A, B, C are provided opposite 131 and 132 , which in a corresponding manner to line 104. A welding transformer 105 , like the parts in question in FIG. 1 work,
a secondary winding 106, which is connected in the usual manner to the welding electrodes indicated at 107. The phase rotating elements 116, 117 and 118 are expediently set in such a way that a pulse is bound to one. The welding transformer has a 5 specific point of the sinusoidal voltage of the feed single primary winding 108, which has a source in the middle, e.g. B. arises at 90 °, and the phase rotation tap 109 has, through which it is divided into two halves members 116 a, 117 ″ and 118 a are set in such a way. The end of one half, in the drawing that pulses at a different point in the sine of the upper half, is parallel to one voltage, e.g. B. uater 130 °, are generated. The sides of the capacitor pairs 111, lilac, 112, 112a, io phase rotating elements 129, 131 and 132 are connected for the purpose 113 and 113a . The other sides of the moderately adjusted so that the capacitors capacitors are each connected to two oppositely connected gas discharge tubes 121, 122 and 123 picked up pulses. In this way the capacitor 111 with the 111, purple, 112,112a, 113,113a occurs, e.g. at 110 °. Tubes 114 and 115 connected and of these with 15 in F i g. 9, the axes denoted by the phases A, B and C of the line 101 and the capacitor lilac represent the impulses arising on the various correspondence with the tubes 114 a and 115 a and from the capacitors. The pulse 141 occurring here with the line 101. The other side of the 90 ° cone emanates from the capacitor 111 , the capacitor 112 is correspondingly via two tubes, the pulse 142 arising at 130 ° from the cone line 102 and the other side of the condenser - 20 capacitor purple and the pulse 143 going from capacitor 123 to 113 via two tubes with line 103 occurs at 110 °. The impulses connected. The other side of capacitor 112a 141a, 142a, 143a move from the capacitors 111, is connected via two tubes with the line 102 and the purple and 123 during the opposite half other side of capacitor 113 a over two tubes wave of the phase A from.

with the line 103 in connection. In the same way, the pulse 144 comes from the condensation of the gas discharge tube pairs are each with a capacitor 112, the pulse 145 from the capacitor 112a the starting points of the associated phase rotation and the pulse 146 from the capacitor 122 , which subdivide 116, 116 a, 117, 117 a, 118 and 118 a are all connected to phase B , while the connected. inverted pulses 144a, 145a, 146a are similar

The principle of operation is basically the same, capacitors through the opposite half-wave as shown in FIG. 1 is explained. When the feeding phase B is generated,
occur of pulses in the corresponding phases A, In addition, correspondingly the pulse 147 from B and C is a voltage to the associated capacitor 113, the pulse 148 from the capacitor capacitors 111, purple, 112, 112a, 113, 113a, 113a and the pulse 149 from the capacitor 121 . placed, and consequently arise in the same way, The reverse pulses 147 a, 148 a, 149 a arise as on the basis of FIG. 1 explains, impulses from the same capacitors due to the opposite significantly larger amplitude than the maximum set half-wave of phase C.
amplitude of the supply source in the upper half of the The lowest axis in F i g. 9 shows the output primary winding 108. pulses that arise in the secondary winding 106.

The center tap of the primary winding 108 is 4 °. From this it can be seen that the one from the condensers is connected to the line 104 . Up to this point is the generator 123, 122, 121 outgoing pulses 143, 146, description of the circuit in FIG. 7 can be reversed to the winding 108 connected to 149 by the action of the lower half of the primary upper half of the transformer 105 , so that at the circuit part which is completely sufficient, output of the transformer as shown, a use of unidirectional pulses is desired. 45 multiplication of the alternating impulses results. With the arrangement shown here, however, multiple pulses in alternating directions can be demanded at 50 Hz, especially if such pulses are delivered on the output side with 1080 pulses per second higher frequency for welding purposes.

this can be done by adding more.

Capacitors 121, 122 and 123 can be achieved. 5 ° phase input with three lines according to Fig. 10

Such a reversal of the impulses is often made from. Here are three separate ones

desirable for various reasons, e.g. B. to use a transformer instead of a single transformer

To prevent saturation of the transformer. These mators with three primary windings as in FIG. 6th

Capacitors are used with two gas discharges each. The primary windings 38 a, 39 a and 41 a

Tubes connected to 126, 127 and 128 are 55 in the same way as windings 38, 39 and 41

are drawn. The capacitors and the gas in FIG. 6 switched. The secondary windings are

Discharge tubes are connected to the feed lines 101, as in FIG. 6, with a load 107a, for example two

102 and 103 connected in the same way as welding electrodes, connected and in parallel

connected above in detail for the capacitors 111, 112 , so that regardless of which

and 113 and the associated tubes illustrated 60 primary winding energized at a given moment

became. As a result, the capacitors 121, will always be fed to the load by a

122 and 123 in the same way as with reference to FIG. 1 secondary winding is supplied. This makes the

explained that the use of normal transformers on lines 101, 102 and 103 is possible,

supplied pulses are charged, so that another which is possibly more economical than the one in

Sequence of pulses to the lower half of the primary 65 F i g. 6 special transformer shown.

winding of the welding transformer is supplied. If only unidirectional impulses are required

To control the ignition point of the tubes, it is completely sufficient if the secondary pairs 126, 127 and 128 are phase rotors 129, winding the circuits described above

is connected to a rectifier arrangement and this to the output terminals. In FIG. 11, the secondary winding S, which is the secondary winding of one of the transformers in FIGS. 1, 5, 6 or 7, or the output lines of which can be formed by lines 138 and 139 in FIG. B. the shown rectifier bridge R connected to the output lines 151 and 152 . This embodiment of the invention can find application in many cases, e.g. In plating, which requires unidirectional pulses of high frequency and considerable power.

In all of the circuit embodiments discussed, it can be observed that the greatest heat then achieved if it is ensured that the pulses are in the peak value of those supplied by the supply source Sinus voltage arise. Thus, unlike the usual heat control by phase control, the Greatest heat at 90 ° phase shift between the time when the current tubes became conductive and the beginning of the sinusoidal supply voltage, and the heat is reduced by the phase shift in both directions from the peak value of the supply voltages.

In addition to the advantages of the method and the devices according to the invention already explained these have many other advantages, the mention of which provides a full understanding of the invention will continue to support:

Copper alloy metals have been welded to one another and to both aluminum and steel. Existing welding arrangements of previous designs that are only for steel and iron welding are suitable can easily be welded to aluminum by a converter arrangement according to the present invention, including one for relatively thin aluminum sheets.

By changing the position or the size of a workpiece in the gripper of a welding machine the current flow between the electrodes does not change. A current compensation is as a result not mandatory.

The present arrangement primarily represents an ohmic load on the power line and furthermore reduces equalization processes that otherwise have the tendency to have an effect on the power line.

By reducing the total heat required, resulting from the precise concentration of the Consumers result, the welding of relatively sensitive parts is safe for this possible, e.g. B. of transistor parts.

Due to this concentration of the welding heat at the point of use, it becomes ohmic together with the Characteristic of the welding circuit made it possible to weld successfully from power lines of lower power capacity than was previously possible. The circuits are suitable for the use of an insulating transfer crater between the power line and the welding circuit, through which the probability of grounding the welding circuit and the dangers that often arise for the user as a result are avoided.

The invention is of course not limited to the specified specific exemplary embodiments, but rather can be modified within the scope of the inventive concept and implemented in a different form.

Claims (11)

Patent claims: 1. Circuit arrangement for generating pulses from an alternating current source for the supply a load, especially for welding equipment with an ohmic resistance, a capacitive and inductive energy storage element connected in series and are connected to the AC power source through a switch which is in certain Relation to the polarity reversal of the alternating current source closed and shortly after the one flowing through it Current has reached its minimum, is opened, characterized that the sizes of the circuit by the formula where K is a constant between 1 and 2, e is the base of the natural logarithm, J? is equal to the total ohmic resistance of the circuit including the resistance of the storage elements and the switch, C is equal to the total capacitance of the circuit including the capacitance of the capacitive storage element and L is equal to the total inductance of the circuit including the inductance of the inductive storage element. 2. Circuit arrangement according to claim 1, characterized in that K has a value between 1.33 and 1.8. 3. Circuit arrangement according to claim Ioder2, characterized in that the primary winding of a transformer is used as the inductive energy storage element, the secondary winding of which is connected to the load, the size of R in the formula being the resistance of the secondary circuit of the transformer, and the size of L in the formula includes the leakage inductance of the transformer. 4. Circuit arrangement according to one of the preceding claims, characterized in that that the switch consists of two alternately conductive electrical tubes (4, 6), the main electrodes of which oppositely connected to one another and between the alternating current source and the capacitive storage element (5) in such a way are switched on so that the respective conductive tube becomes non-conductive when the capacitive storage element during each half-wave the supply current source is charged. 5. Circuit arrangement according to claim 4, characterized in that the tubes (4, 6) are gas discharge tubes, for. B. Ignitrons or Thyratrons are used, and phase rotators (12, 13) are connected to the control electrodes of the tubes, so that the point in time at which the tubes are made conductive with respect to the voltage curve of the AC source can be set. 6. Circuit arrangement according to one of the preceding claims, characterized in that a plurality of secondary circuits is provided, each of which has a switching device (4, 6, 4 α, 6β, 4b, 6b) and a capacitive element (5, 5a, 5b ) contains, and that these secondary circuits are connected in parallel between the AC power source and the inductive element (11), so 609 750/187 that during each half cycle of the power source the inductive element (11) a plurality of Pulses is supplied, the sizes of each secondary circle determined according to the formula given are (Fig. 5). 7. Circuit arrangement according to one of claims 1 to 5, characterized in that one delta-connected polyphase alternating current source is provided and circles with a Ohmic resistance and a capacitive and an inductive energy storage element so arranged are that they receive power from each phase of the AC power source, where a Energy pulse is delivered during each half cycle of each phase of the AC power source, and where the sizes of each of these circles are determined according to the formula given. 8. Circuit arrangement according to one of claims 1 to 5, characterized in that a single, tapped in the center inductive storage element (108) is provided and a star-connected AC power source and a secondary circuit which contains a switch and a capacitive element and is connected in this way is that it receives energy from each phase of the alternating current source and supplies it to the inductive element, the sizes of each of these circles and the parts of the inductive elements connected to them being determined according to the formula given (FIG. 7). 9. Circuit arrangement according to claim 8, characterized in that two secondary circuits so are connected to receive energy from each phase of the power source, so that during each Half-wave two pulses are delivered in each phase. 10. Circuit arrangement according to claim 8 ίο or 9, characterized in that a further secondary circuit is connected so that it receives energy from each phase of the power source, and is connected to the inductive element (108) that it has one during each half-wave Impulse of opposite polarity supplies. 11. Circuit arrangement according to one of the preceding claims, characterized in that that two welding electrodes are provided as a load. Considered publications:
German Patent No. 894 582;
German interpretative document No. 1 058 615;
German patent application A12370 VIIId / 21h (published on 3.18.1954); U.S. Patent No. 2,440,309;
Electrical Engng. (1934), p. 1366 ff. In addition 3 sheets of drawings 609 750/187 12.66 © Bundesdruckerei Berlin