SU1296337A1 - Welding current control - Google Patents

Abstract

The invention relates to the field of welding production, namely to welding current regulators, and is intended for fusion welding. The invention allows improving the quality of welded joints by increasing the stability of the welding process. For this, a voltage inverter is connected in series with the current inverter, which is connected to the welding load through the second transformer and the second rectifier. The current in the voltage inverter is regulated by changing the input resistance of the current inverter. The volt-ampere characteristic in the area of small currents is rigid, and in the area of operating modes it is steeply dipping. A small number of elements, a small value of the operating currents in the thyristors and valves provide a high efficiency of the controller. The device can be executed on standard elements, 2 Il. (L

Description

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The invention relates to the welding industry, namely to welding current regulators, and is intended for fusion welding.

The aim of the invention is to improve the quality of welded joints by ensuring the stability of the welding process.

Fig. 1 shows a structural electrical circuit of the welding controller TOKaJ in Fig. 2 — a circuit diagram of a welding current controller with a DC source made according to a single-phase bridge circuit and with single-phase inverters and rectifiers.

The device contains a DC source 1, the positive terminal of which is connected to the positive DC terminal of the inverter 2 current. The AC outputs of the inverter 2 current are connected to the primary winding of the transformer 3. A rectifier 5 is connected to the secondary winding of the transformer 3 through the reactor 4. The positive terminal of the voltage inverter 6 is connected to the negative terminal of the current inverter 2. The first terminals of the capacitor 7 are connected to the combined terminals of the inverters. The negative terminal of the voltage inverter 6 is connected to the negative terminal of the direct current source 1 and the second terminal of the capacitor 7. There are various variable input resistances. The input resistance of the inverter 2 current has a small value. It is determined by the equation

Ki

x 7k7 + to „

where X is the reactance

switching capacitor current inverter

R is the resistance determined by the losses in the capacitor and transformer; a - coefficient determined by

inverter circuit. Obviously, when Kn - seo the resistance of the current inverter is O, the resistance of the voltage inverter 6 is of great importance. It is determined by

20 high idle loss resistance. Thus, the voltage of the direct current source 1 is almost completely applied to the voltage inverter 6. Voltage

25, the welding load 10 at idle is determined by the transformation ratio of the second transformer 8 and the voltage value of the power supply source 1. With the appearance of load

30 current in the welding load circuit 10 increases the current IJ in the direct current circuit, 6 inverter and inverter 2 current With a decrease in the resistance of the welding load and an increase in current Ij

voltage of the inverter 6 voltage connects- 35 The voltage drop increases by

the input resistance R, the inverter current 2 and the voltage on the transformer 3 and rectifier 5 increase. At the moment of reaching the current in the welding 40 load 10 equal to a critical value, the voltage on the top 5 is equal to the voltage on the rectifier 9. Gates top 5 will start to conduct current. Inverter 2 current goes 45 in the load mode. With an increase in the current in the alternating current circuit 2, the indinny are connected to the primary winding of the second transformer 8, the secondary winding of which is connected to the input terminals of the alternating current of the second rectifier 9. The positive output of the top 5 is connected to the positive output of the second rectifier 9 and connected to the first output of the welding load 10. The control system 11 ensures the operation of the thyristors of the current inverter 2 and the voltage inverter 6.

On the circuit diagram (Fig. 2) of the additionally denoted converter, its input resistance increases. Increases the voltage at the terminals of the direct current

The choke 12 of the current inverter, the commutator of the current 2 and the significant capacitor 13 of the inverter decreases; the voltage of the DC terminals of the inverter 6 is reduced, which leads to a decrease in the voltage

on conclusions above 9. Load

ka, a choke 14 of a voltage inverter and a switching capacitor 15 of a voltage inverter.

The welding current regulator operates on the voltage inverter 6 is reduced as follows. The load value of the current inverter 2 increases. The load current inverter 2 is limited by the idle mode current inverter 2 and voltage inverter 6 have

various input resistances. The input resistance of the inverter 2 current has a small value. It is determined by the equation

Ki

x 7k7 + to „

where X is the reactance

switching capacitor current inverter

R is the resistance determined by the losses in the capacitor and transformer; a - coefficient determined by

inverter circuit. Obviously, when Kn - seo the resistance of the current inverter is O, the resistance of the voltage inverter 6 is of great importance. It is determined by

greater resistance to no-load losses. Thus, the voltage of the direct current source 1 is almost completely applied to the voltage inverter 6. Voltage

The welding load 10 at idle is determined by the transformation ratio of the second transformer 8 and the voltage value of the power supply source 1. With the appearance of load

current in the welding load circuit 10 increases the current IJ in the direct current circuit, 6 inverter and inverter 2 current With a decrease in the resistance of the welding load and an increase in current Ij

by the driver 4. In the operating mode, the power transmitted from the DC circuit by the inverter 2 current and the voltage inverter 6 is close in values. At the same power, the transformers, thyristors and valves of the entire controller are evenly loaded in the operating modes. A capacitor 7 connected to the DC terminals is required d; 1 matching the operating conditions of the current inverter 2 and the voltage inverter 6. The current of the inverter 2 current is continuous.

With a short circuit in the welding load, the load of the current inverter is maximum. The input voltage of the current inverter has a maximum value. The current in the DC circuit of the voltage inverter is limited by the large value of the input resistance of the current inverter. The power consumed from the direct current source is expended on losses in the elements of the device. The current in the welding load has a maximum value. Power in case of a dead short circuit is not released in the load. If during a short circuit the resistance has

If the end value is different from zero, then the power increases and the electrode melts. The arcing of the arc brings the regulator to the operating mode, in which the power from the direct current source is simultaneously transmitted to the welding load through both inverters. “Thus, in modes with a large load resistance, the load characteristic of the controller has a rigid characteristic, and in modes with small values of the resistance of the welding load, the current-voltage characteristic is steeply dipping.

Experimental verification has shown that the use of the proposed controller of welding ITAKa allows to reduce losses by a factor of 2-3 compared with the known one. Regulator allows -

R

fc T use the 380 V, 50 Hz AC mains for welding, which greatly increases its range of application. The use of a reactor regulator to limit the inverter current and regulate the current in the voltage inverter by varying the DC resistance of the current inverter allows providing the necessary current-voltage characteristic with a small number of elements. A distinctive feature of the regulator is the high steepness of the external characteristic, which is natural and does not require devices to form it.

0 EL

- -35

25

40

Claims (1)

Invention Formula The welding current controller contains a direct current source, the positive terminal of which is connected to the positive terminal of an autonomous current inverter, the alternating current terminals of which are connected via a transformer and reactor to the AC input of the first rectifier, in order to improve the quality welded, connections due to the stability of the welding process, a capacitor and a voltage-connected inverter, a second transformer and a second rectifier are introduced into it, the negative output of the latter is connected to the first output of the regulator and to the negative output of the first rectifier, the positive output of which is connected to the second output of the regulator and to the positive output of the second rectifier, the negative terminal of the DC source is connected to the capacitor plate and the negative terminal of the voltage inverter The positive terminal of which is connected to the other plate of the capacitor and the negative terminal of the autonomous current inverter. Editor H, and 1 d.2 Compiled by G. Tchaikovsky Tehred A. Kravchuk. Proofreader L. Patay Order 703/16 Circulation 976 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Proekgna, 4