RU16837U1 - POWER SUPPLY FOR ARC WELDING - Google Patents

Abstract

1. A power source for arc welding, consisting of a single-phase transformer with a primary and two secondary windings and a rectifier electrically connected to the secondary windings, characterized in that the two secondary windings of the transformer are connected in series and have three leads: the first output from the first secondary winding the second terminal from the first secondary winding and the second secondary winding connected together, the third terminal from the second secondary winding, the terminals of the secondary windings connected to the rectifier, made a three-phase bridge circuit vypryamleniya.2. The source according to claim 1, characterized in that the primary winding is placed on one core of the magnetic circuit, the first secondary winding is made of two sections, one of which is located on the same core of the magnetic circuit as the primary winding, the second section of the first secondary winding is placed on the second rod the magnetic circuit, the end of the first section is attached to the end of the second section, the second secondary winding is also located on the second core of the magnetic circuit, its end is attached to the beginning of the second section of the first secondary winding, forming a common output ary windings.

Description

POWER SUPPLY FOR ARC WELDING

The technical solution relates to electric welding of metals and can be used in arc welding installations.

Known single-phase rectifiers for arc welding containing a transformer, one uncontrolled rectifier and a smoothing inductor 1. They are simple and reliable in operation, however, they have an increased mass of copper and electrical steel due to the inductor, since its dimensions are comparable to the dimensions of the power transformer. To reduce these indicators in welding plants, pulse arc stabilizers or device drills are sometimes used, which provide increased voltage during arc ignition.

The disadvantage of these sources is their low reliability due to the use of sophisticated electronic devices for their handling.

As a prototype, a power source for arc welding 2 was selected, containing a single-phase transformer with a primary and two secondary windings, two rectifiers connected in parallel with the arc gap and two chokes included in the circuit of each secondary winding. One of the rectifiers serves to confidently ignite the arc, and the second - to create a working welding current. The phase shift between the two currents of the main and auxiliary rectifier ensures that the arc current does not drop to zero. The disadvantages of this solution are: the increased complexity of manufacturing a choke with magnetically connected windings and its high metal consumption, as well as an increased level of welding current ripple, which negatively affects the quality

The technical solution is based on the task of creating, on the basis of uncontrolled rectifiers, a single-phase power source for arc welding with reduced mass and size indicators, providing high welding and technological properties.

The problem is solved in that in a power source for arc welding, containing a single-phase transformer with a primary and two secondary windings and a rectifier that is electrically connected to the secondary windings, two secondary windings are connected in series and have three leads: the first output from the first secondary winding, the second the output from the first secondary winding and the second secondary winding connected together, the third output from the second secondary winding, the outputs of the secondary windings are connected to the rectifier, made according to the scheme t ehfaznogo bridge rectification.

The use of two series-connected secondary windings with three leads allows you to get three voltage at the output of the transformer. This is the voltage taken from the first secondary winding, the voltage taken from the second secondary winding and the total voltage from the series-connected windings. After rectification, each of these voltages creates its own component of the load current in the arc gap and, due to the different phase shift of these currents, the ripple of the load current is smoothed out without a choke, the DC component of the rectified current increases and it drops to zero.

The efficiency of this solution increases with increasing load current.

In the claimed solution, the phase shift of the currents in the secondary circuit of the transformer and the required type of external characteristics of the source are obtained due to the transformer with increased scattering.

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Ha figure 1 presents the electrical circuit of the inventive power source; figure 2 is a voltage diagram at the input of the rectifier; Fig. 3 diagram of the rectifier currents.

The inventive power source (figure 1) contains a transformer 1 with a primary winding 2 located on one rod of a two-core magnetic circuit, the first 3 and second 4 secondary windings. The first secondary winding is made up of two sections, one of which is located on the same side of the magnetic circuit as the primary winding, the second section of the first secondary winding is placed on the second core of the magnetic circuit. The second secondary winding is located on the second core of the magnetic circuit. The end of the second secondary winding is connected to the beginning of the second section of the first secondary winding, forming a common output of the secondary windings. Pin 6 is the beginning of the first section of the first secondary winding, pin 7 is the beginning of the second secondary winding. Terminal 6 of the transformer is connected to the anode of valve 8 and the cathode of valve 9, terminal 5 to the anode of valve 10 and the cathode of valve 11, terminal 7 to the anode of valve 12 and the cathode of valve 13. The cathodes of valves 8, 10, 12 are connected together and form a positive terminal source 14, the anodes of the valves 9, And, 13 are connected together and form a negative output of the source 15.

The power source operates as follows. When the primary winding 2 is connected to an alternating voltage network, the voltages from the terminals of the secondary windings 5, 6, 7 are fed to the input of the rectifier and, when an arc discharge is applied to the terminals 14 and 15, a rectified arc current is generated in the arc gap.

Three voltages are obtained at the terminals of the secondary windings: voltage U between terminals 6 and 7, voltage U2 between terminals 5 and 6, and voltage Us between terminals 5 and 7.

there is more scattering than winding 3, because the majority (first section) of winding 3 is open circuit on the same shaft as the primary winding. As a result, the voltage Is lagging in phase from the voltage U2. The voltage Ui is composed of the component voltages U2 and Us and has an intermediate phase shift.

A smaller part of the first secondary winding (second winding section 3) is located on the second core of the magnetic circuit, this allows you to limit the short circuit current of the source.

The three-phase two-half-wave rectification circuit allows a current at the output of the rectifier, the form of which is shown in Fig.Z. During the period of time ti, the load current i is created by the voltage Ui, while two valves 12 and 9 are open; in the time interval t2, the load current is generated by the voltage Us, while the valves 12 and 11 are open; in the time interval ts, the load current is created by the voltage Ua, while the valves 10 and 9 are open. In the second half of the period, the pairs of valves 8 and 13.10 and 13.8 and 11 are opened alternately. As a result, the voltage across the arc remains constant, and the arc current does not drop to zero, and with an increase in the arc current due to the lower inductive resistance of the scattering of the winding 3, the smoothing effect of the rectified current increases, since the amplitude of the current component 12 grows faster than the amplitudes of the components ii and is, which contributes to stable arc burning.

Tests of the prototype of the claimed source showed the following advantages compared with the prototype:

-consecutive connection of the secondary windings allows you to get the necessary open circuit voltage with much less

the total number of turns of the secondary windings, and, consequently, the consumption of copper is reduced;

-4- / W // f O

 S without throttle. Moreover, the smoothing efficiency increases with increasing load current. The efficiency of the inductor decreases with increasing load current.

Due to the presence of three components of the rectified current, the average value of the rectified current increases with a slight decrease in the current consumed from the network.

Compared with the prototype, the number of required valves has been reduced (six instead of eight).

Thus, the inventive source provides a reduction in overall dimensions of the installation, high welding and technological properties at a low level of power consumed from the network.

Sources of information taken into account when compiling the application:

1.Paton B.E., Lebedev V.K. Electric equipment for arc and slag welding. - M. Machine-building, 1966. - 360 p.

2. Patent No. 2035275, IPC V23K9 / 06, application No. 5066586/08 published

05/20/95, Bull. No. 14 (prototype).

Vice Rector for Science, OmGA

V.P. Rusakov

Authors: V.V. Zilbernagel

A.V. Zilbernagel

Claims (2)

1. A power source for arc welding, consisting of a single-phase transformer with a primary and two secondary windings and a rectifier electrically connected to the secondary windings, characterized in that the two secondary windings of the transformer are connected in series and have three leads: the first output from the first secondary winding the second terminal from the first secondary winding and the second secondary winding connected together, the third terminal from the second secondary winding, the terminals of the secondary windings connected to the rectifier, made a three-phase bridge rectification circuit. 2. The source according to claim 1, characterized in that the primary winding is placed on one core of the magnetic circuit, the first secondary winding is made of two sections, one of which is located on the same core of the magnetic circuit as the primary winding, the second section of the first secondary winding is placed on the second core of the magnetic circuit, the end of the first section is attached to the end of the second section, the second secondary winding is also located on the second core of the magnetic circuit, its end is attached to the beginning of the second section of the first secondary winding, forming a common terminal original windings.