RU1786622C - Method of control over source of welding current - Google Patents

Abstract

SUMMARY OF THE INVENTION: The method is based on the control of the presence and magnitude of the welding current and voltage of the welding circuit and voltage to the input circuit of the inverter / delay time and data. ...: - v. ; / - Л ;; / - transformations at the moment of arc initiation and ripn first and second stages on the input circuits and multiple: b ptimization and by-pass process 1 of changing the welding current and voltage of the contact network after they are restored; - In order to increase the reliability of the welding of 1x converters and the safety of their maintenance, the welding current of the primary circuit of the transformer is normalized; , set the value of their disagreement nor, at the moment of inconsistency progression, a control signal is generated above its set value, it is fed to the inverter and the nodes of artificial switching (6t pre-conversion. W.,...:: .. ..:. tA WITH

Description

:.; The invention relates to an electric furnace and is intended to control the welding process when supplying an arc

gap through a transformer current source bt of a single-phase invert and a mine contact network of a postb nogb current, including a network with a Tsiklichky interruption Circuit load 5y31y: - -; . . -. :., -

; The purpose of the invention is to increase reliability. : ../ .: v - .., -. v; v: ;;;.;.; v-y; -:; /.;: Fig. 1 shows the trans-block block diagram.

 format source svarbinogr tb ka; figure 2 is a diagram of the current transformer and voltage of the source; figure 3 is a real oscillogram of the voltage levels of the rudder contact network .; ; : - ;:.-v. ;

The block diagram contains a single-phase inverter 1 with pulse control methods and artificial switching

main thyristors, loaded with welding transformer 2, in the primary and secondary circuits of which current sensors are connected - 3 and 4, respectively. At the input of inverter 1, filter 5 is included, which contains capacitor b and solenoid 7. The latter. restricts the value of the 4th day of the DnBUo tb to kbndensatbr 6 and the development of emergency currents in the elements of inverter 1. In addition, part of the solenoid 7 is covered by kbndensatdrbm 8, which makes it possible to give filter 5 cutoff properties at the coupling frequencies. EXECUTE-. Available by contact. The latter excludes the following: mechanical action of the invert 1, during its operation, on the means of high-frequency communication. From the contact network, the inverter is divided by valve 9, voltage control in the supply (contact) network, to the ondencator 6 and at the output of the transformer VJ

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a 2 is monitored by sensors, respectively, 10, 11 and 12. At the same time, the sensor 10 responds to interruptions, especially in the contact network / for example, breaking through the minus circuit - in the rail path due to faulty contacts at the joints of the relay s, as well as those mentioned; cyclic interruptions. The duration of these breaks is from 2-3 ms to 1-5 s. Sensor 11 monitors for undervoltage. on the. Te capacitor at the mentioned breaks ;; The control of the 1-button on the element 6 of the entry. after a decrease in the voltage level to a level

at which the operation k oft & epfopa 1. is unstable.. Л -; -: - / - ./ ...-:. .-. : y - Sensor 12 monitors the voltage in the welding circuit in the absence of

CURRENT a load. .; .:.; ;; -. l,; .., .-.:.:. ........ .. ..; .. the output circuits of the TO and 11 sensors are connected to the input of the OR element 13, the output of which through the time delay element .14 the input of the control system 15 is turned on. Inverter 1. In turn, the system 15 contains a control unit 16 k. control channels 17 and 18 Responsible for switching and. main thyristors of the inverter 1 .-;.: -,:, .. j ...:. ,;. :;: The output circuits of sensors 3 and 4 are turned on; bj is at the input of the comparison element 19, the output is, at whose circuit is included; on the;

control circuits of the control channels 17 and 18. In addition, the output circuits of the sensors 4 and 12 are connected to the input of the driver 16 of the control system 15, and its output circuit is respectively connected to the inputs of the channels 17 and 18., V l; : ;;.,.;. .: -:;

In turn, inverter 1 contains the main 20-23 and switching 24-27 thyristors, capacitors 28, 29, and solenoids 30, 31 of artificial switching nodes, return valves 32-35, switched on side-by-side; l. Lel; but mainly to the main thyristors . All thyristors of the inverter are covered by RC circuits: 36-37.38-39, 40-41, 42-43, 444ё, 46-47, and 50-51. ;;;,, {;.: - ..-. ; .; -. The diagram (figure 2) presents: Ui

- control signals of switching thyristors; UK- voltage of the contact network; U2-voltage at the output of a single-phase inverter; - current through the primary winding of transformer 2; 2p - the same, taking into account the saturation of the magnetic system of the transformer during power supply with a high voltage level without the action of a signal

from element 19; 12f - the same, upon the action of a signal from element 19; Uz and Od - antiphase signals of sensors 3 and 4; Igg

- signal of the comparison element 19; t is the time parameter. ......., ...,.

The waveform (fg.Z) shows a fragment of the waveform of the voltage level of the UK contact network.

In addition to the indicated elements, the executive circuit has connecting contacts that connect the product to the contact wire and the rail: path, circuit breaker, contactor, operating voltage source

for power supply of inverter thyristor controls - (the positions in the. block diagram are not reflected). . .

A method for controlling a transformer source of welding current is carried out

in the following way. -.

, When applying voltage to the contact network and. operational voltages on the elements of the flowchart of the charging circuit of the capacitor 6 to the voltage level of the network; condensate drums 36, 38, 40, 42, 44, 46, 48, 50 - up to the level

about the indicated voltage and the appearance of a single signal at the output of the sensor 10; ; after the charge time

capacitor 6 to a predetermined value of

the voltage at the output of the sensor 11 is a single signal. The signals of the sensors 10 and 11 are fed to the input of the OR element 13, while the signals of the voltage sensor 10 in time are primary. The last signal, which is transmitted to the input of element 13 and then to the input of time delay element 14, does not produce a logical effect on elements 1 and 15. This is limited by the time setting of element 14, the value of which

exceeds the full charge time of the capacitor 6 of the input filter 5.

In turn, the response of the voltage sensor 11 is determined by the value of the minimum voltage on the elements of the inverter 11 at which the conservation of its consumer properties is achieved. . ;; .., „;.:.

The following modes are possible,

WE WORKS. y:;.: -. v;.;:. ; - ,, -; ..,:. . ;.

Idle when welding

the chain is broken. From the output of sensor 4 to the input

system 15 receives a zero signal channel 18

control of the main thyristors of the inverter 1 is disabled. In this case, a limited voltage U2x is generated at the output of the inverter 1. The value of the latter for mine welding conditions is limited to 12V with an amplitude of not more than 25 V. When the limited voltage is turned off in the direction of increasing from the permissible level and there is no current in the welding circuit, a single signal from the sensor 12 gives a command to carry out protective shutdown.

The voltage U2x is obtained by briefly opening the switching thyristors with signals Uiy coming from channel 17 in accordance with the control action of the driver unit 16 and the flow of charging currents of the capacitors of the RC circuits and artificial switching units.

For example, when the UVM control signal arrives at the switching thyristor 24 in Circuit x: + - 9-7-30-24-29-2-3-39-38. and. + - 9-7-30-24-47-46-31, charging currents flow. As a result, k; a transient voltage pulse is applied to the primary winding of transformer 2, and a limited voltage is generated at its secondary winding

U2X-1. -; .. /; ;:,:: .- .- :; .--:; -:; / g .:. When the control pulse U-I7-2 arrives in the same half of the period on the thyristor 26, the following chains are formed in the same way:. + - 9-7-30-26-28-3-2-43-42-1 - + - 9- 7-30-26-51-50-31 - - and voltage U2x-2 is formed. . :. ..-V .U; ,,: .-

When changing half of the period, i.e. By changing the sign of the generated limited voltage, the control signals Ui7-3 and U17-1 are alternately fed to the thyristors 25 and 27 - similar circuits are formed and the voltage U2x-3 and U2x-4 are generated at the output of transformer 2. . - ... .. At the next change in sign of the generated voltage at the output of the inverter 1 corresponding to the idle mode, the processes associated with the signals Ui7-i, Uiy-2 are repeated .. .. - ,. //.

 Load mode of the welding current source. The specified mode occurs after the welding circuit is closed.

In this case, it is also necessary to distinguish two submodes, the first - when there is a cyclic or random interruption of the supply voltage; the second is when the value of the supply voltage changes stepwise in the direction of exceeding the nominal level. . : .-.

After closing the welding circuit to the arc gap, the current sensor 4 at the moment of formation, for example, of a voltage pulse U2x-i, will generate a single signal. The latter will go to block 16 and at a time close to 90 ° electric, releases channel 18 for controlling the main thyristors of inverter T. At its output voltage U2 will be generated, and current 2 will flow in the welding circuit. In this case, the signal from sensor 4 will block the signal from sensor 12 - the latter occurs in the driver unit 16. The indicated voltage (U2) is generated as follows. Upon receipt of pulses Ui8-i. U18-2, U.18-3. to governing

the electrodes of the main thyristors 20, 23 (or 22.21, respectively) voltage 0 at the output of the inverter 1 (on the primary winding of the transformer 2) is formed by the following circuit + - 9-7-20-3-2-23 - - (or 5 9-7-22-3-21). : ...: -. :: ..,: Vv:,

The capacitor 28 is charged through the following circuit. + - 9-7-20-28-27-31 - -, respectively 29 through the circuit. + - 9-730-24-29-23 - -. ;; .. „. ; . Ya .l

0 Closing of thyristors 20, 23 is carried out according to the following Knturemg (20) 28-32-30-26-28 and (23) 29-35-31-25-29. and . thyristors 21 and 22 along the contours (21) 28-27- .31-33-28 and (22) 29-34-30-24-24-29. .

5 If the welding current exceeds the current set by the task, a signal of phase change is automatically generated in the driver unit 16 at the sign of the switching thyristor control signals

0 and the value of the welding current is set equal to the set by the latitudinal regulation of the output voltage of the inverter 1.

Moreover, for charging the switching capacitors to the level of the voltage of the direct contact DC network, ke al 17, switching and main thyristors are used. The process of charging capacitors 28, 29 coincides with the phase of the forms and - voltage U2 (in the drawing

0 indicated signals are not shown). :,:

If there is a load current and the power supply is equal to, blue or;

close to nominal, signals

3 and 4, respectively, Uz and UA are not in Yzvan Yanet

5, the state changes of the element 19 are equal to i. because these signals are equal in value and opposite to the rio sign. If in. In this mode, the load momentarily. The mains voltage disappears, - the sensor

0 10 gives a zero signal. However, the energy conversion process will continue due to the energy accumulated by the elements 6 and 7. The valve 9 thus excludes. Condenser Energy Consumption b

0 filter 5 to other consumers, joins. Connected to the contact network. If the value of the pause in the power supply turns out to be: - those times of the accumulated energy consumption to a predetermined level;, when the network voltage is restored, the conversion process

5. will continue. ,: .. -: i; - ::; ;: /

 If the value of the mentioned pause turns out to be longer than the energy consumption time of the filter 5 and the charge voltage of the capacitor 6 decreases below the setpoint of the sensor 11, then the latter blocks the energy conversion process by inverter 1. Using its zero signal (through elements 11-13-14-15) happen at the beginning

channel 18, and then with a pause - channel 17; - -.... : V

If the pause is long - in practice, more than 5-7 s, a general disconnection of the welding current source will occur (general disconnection circuits are not shown in the drawing). -. V.; ; - VVv 4 v. ...-...

Upon restoration of the voltage of the contact network (before general shutdown), a single signal 6 will be output by the sensor 10, a capacitor 6 will be charged and a single signal will be output by the sensor 11, the time will be counted by the element Informing signals by the system 15 and, when the arc gap is closed, the voltage U2 will be formed. including an intermediate phase of 90 degrees, and the continuation of the process

 welding. ;: / :. ;:;:; ,. .about. ; - ;; -. :., -. :. . When the voltage of the mine contact network increases and the current source operates in the load mode, the magnetization current of the welding transformer will increase. As a result of the latter, its magnetic system will become saturated. Moreover, as practice has shown, an unsatisfactory magnetic state in TD type transformers, TDM occurs at a 10% excess of the supply voltage over the rated voltage. The aforementioned leads to a decrease in the inductance of the transformer, as well as to a violation, to the magnetic transfer of energy to the welding circuit. And this, in turn, leads to an increase in the current increase in the primary circuit of the transformer 2 over the current increase in the welding circuit. Moreover, when the signal Pz of the current sensor 2p of the primary circuit of the transformer 2 is exceeded

. over the signal 1M of the welding circuit current sensor 4 (point a of the current diagram 12, Fig. 2) at the output of the comparison element .19 a signal Uig is received. The indicated um pulse, arriving at channel 18, blocks the further formirovaniyu. Ny ё control signals / geni main thyristors 20, 23 or 22, 21 and generates,

entering channel 17, additional switching signals of switching thyristors 26, 25 or 24, 27. This achieves the suspension of the output half-period

the inverter voltage of the energy conversion process, and the current value 12 instead of reaching the level 12p is equal to the value 12f. In this case, the magnetic state of the welding transformer, despite the excess voltage of the supply network above its nominal level, retains its nominal parameters. As a result, energy conversion sustainability and consumer conservation are achieved.

properties of the welding current source.

: Form and sample

Method for controlling a welding current source with power supply from a mine

DC contact network made in the form of a single-phase thyristor inverter with artificial switching, the output of which is connected to the primary winding of the transformer, the secondary winding

which is connected to the welding circuit, which consists in controlling the voltage at the input circuits of the inverter and the current of the welding circuit, in the absence of which and with a decrease in the voltage at the input

the inverter circuits below a predetermined level block the conversion process in the inverter, when voltage is restored at the input circuits of the inverter and when current appears in the welding circuit,

the conversion process in the inverter with a delay for a predetermined time, characterized in that, in order to increase reliability, control the current of the primary winding of the transformer, normalize it,

compare with the normalized current value of the welding circuit, set the mismatch value and, if the mismatch exceeds the set value, block the conversion process in the inverter; ;:

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