SU1348105A1 - Power supply unit for welding - Google Patents

Abstract

The invention relates to welding production, in particular, to devices for current welding at a higher frequency optical fiber. The aim of the invention is to improve the quality of the welded joint by improving the arc ignition reliability and the accuracy of maintaining the arc current. The goal is achieved in that a device containing an inverter 1, a high-frequency transformer 3, a current sensor 5, a comparison node 8, a source of reference voltage 9 and a controlled divider 10, additionally introduced two diodes 11 and 12, a switch 15 and a pulse-width module torus 16. During operation of the device when the key 15 is turned on, energy is stored in the high-frequency transformer 3. When the voltage at the output of inverter 1 disappears at the moment when the secondary winding of the high-frequency transformer 3 starts, a self-induced EMF occurs, which is sufficient for breakdown of the interelectrode gap 7. At the output of the current sensor 5 there is a voltage leading to a change in the pulse width at the output of the pulse-width pulse. modulator 16 so as to provide at the output of the device a predetermined current value. 2 Il. (L // & 0 4 eo SP Phie. /

Description

one

The invention relates to welding production, in particular, to devices for current welding at a higher frequency optical fiber.

The purpose of the invention is to improve the quality of the welded joint by increasing the reliability of ignition of the arc and increase the accuracy of maintaining the arc current.

Figure 1 shows the diagram of the device; Fig. 2 shows diagrams for his work.

The device contains an inverter 1, an input 2 connected to a source of electrical energy, a high-frequency transformer 3, the secondary winding 4 of which through the current sensor 5 and the limiting resistance 6 is connected to the electrodes 7 of the device, the node 8 comparing with one input connected to the source 9 of the reference voltage, and the second through the control divider 10 - with the output of the sensor 5 to134

ka, two diodes 11 and 12, by anodizing the voltage at the inverter output (at the moment the pause begins), self-induction EMF occurs on the winding of the high-frequency transformer 3, the value of which is directly proportional to the magnetizing current flowing through the primary half-winding of the transformer 3 and back proportional to the sum of the limiting resistance and the resistance of the interelectrode gap. At the moment of switching on, the resistance between the connected with the beginning and the end of the output winding 13 of the transformer 14 of the inverter 1, the cathodes with the beginning and the end of the input winding of the high-frequency transformer 3, and the middle points of these windings are interconnected via a switch 15, the control input of which is connected to the output width -pulse modulator 16, the control input 17 of which is connected to the output of the comparison node 8, and the synchronization input 18 - with the additional winding 19 of the transformer 14, For reliable ignition of the arc when it is turned on use an inverter 1 with a fixed pause at zero or limit the duration of the output pulses of the pulse-width modulator 16 (Fig, 1).

The device works as follows.

Consider the case where an inverter is used, providing a pause at zero. When turned on, input 2 of inverter 1 is energized. Inverter 1, running on, provides on the windings 13 and 19 of transformer 14 a rectangular voltage with a pause at zero (FIG. 2). The duration of the pause is chosen equal to or slightly longer than the development time of the arc discharge in

air, 1

Since the arc between the electrodes 7 does not burn at the first moment, then for example 30

35

electrode gap is large, which causes a high value of the EMF of self-induction, sufficient for the breakdown of the interelectrode gap. After switching inverter 1 high frequency

 transformer 3 through diode 12 and switch 15 is connected to inverter 1. The current from winding 4 of high-frequency transformer 3 is limited by the resistance of the arc between the electrodes 7 and

 b limiting resistance 6. At the output of current sensor 5, a voltage appears that leads to a change in the duration of the positive pulses by

output of the pulse-width modulator 50 so as to provide at the output a predetermined current value. The arc burning process reaches a steady state. At small values of the current in the arc, the process of starting the arc takes place every half-period, and the duration of the pulses at the output of the pulse-width modulator 16 is set so that between the electrodes 7 to provide the required amount of current.

1052

The voltage taken from current sensor 5 is zero. The reference voltage is present. From the output of the comparison node 8, the control input 17 of the pulse-width modulator 16 receives a signal that provides at the output of the last the maximum duration pulses of positive polarity

10 providing the open state of the key 15, the voltage from the winding 13 of the transformer 14 is applied through the diode 11 and the open key 15 to the input winding of the high frequency transformer 3, On the winding 4 of the high frequency transformer 3, a voltage can occur in most cases insufficient to ignite the arc. High frequency

20, the transformer 3 is made on a core with a gap or with a large saturation intensity value, therefore, when the key 15 is turned on, considerable energy is stored in it. When the voltage at the inverter output (at the moment of the pause) on the winding of the high-frequency transformer 3 disappears, self-induction EMF occurs, the value of which is directly proportional to the magnetization current flowing through the primary half-winding of the transformer 3 and inversely proportional to the sum of the limiting resistance and the resistance of the interelectrode gap. At the moment of turning on the resistance between

electrode gap is large, which causes a high value of the EMF of self-induction, sufficient for the breakdown of the interelectrode gap. After switching inverter 1 high frequency

transformer 3 through diode 12 and switch 15 is connected to inverter 1. The current from winding 4 of high-frequency transformer 3 is limited by the resistance of the arc between the electrodes 7 and

the limiting resistance 6. At the output of the current sensor 5, a voltage appears that leads to a change in the duration of the positive pulses by

output of the pulse-width modulator so as to provide at the output a predetermined current value. The arc burning process reaches a steady state. At low values of the current in the arc, the process of ignition of the arc is pro. each half-period occurs, and the pulse duration at the output of the pulse-width modulator 16 is set such that between the electrodes 7 provide the required current value.

31

Thus, the proposed welding power unit allows, in comparison with the known one, to ensure reliable ignition of the arc. the appearance of a high-voltage pulse high-voltage transformer on the high-voltage secondary winding, which ensures reliable breakdown of the gap between the electrodes, and since the energy stored in the high-frequency transformer depends on the required

the current between the electrodes, the current is maintained, including at very low levels, due to the fact that the voltage on the electrodes is established by self-induction EMF, which is necessary and sufficient to provide a given current, regardless of the voltage the input of the inverter and the magnitude of the gap between the electrodes.

Claims (1)

Invention Formula A welding power supply device containing an inverter, an input connected to a source of electrical energy, a high-frequency transformer, the secondary winding of which is via dates / w /, / "l V / tri / unifpiipat ff (j ,, ffffuf VNIIPI I and 2 Order 5149/12 TierYa7 969 Random polygons pr-tie, Uzhgorod, st. Project, 4 The current tick and limiting resistance is connected to the electrodes of the device, the comparison node, one input connected to the source of the reference voltage, and the other via a controlled divider to the current sensor output, which differs in that. that, in order to improve the quality of the welded joint by improving the arc ignition reliability and the accuracy of maintaining the specified arc current, a key, two diodes and a pulse-width modulator are entered into it, the inverter transformer being made with additional and output windings, and the latter is made with an average point, with the first and second diodes anodes connected to the beginning and end of the output winding of the inverter transformer, cathodes - to the beginning and end of the input winding of the high-frequency transformer, and the middle points of the AC associated coils interconnected through a switch, whose control input connected to the output pulse-width modulator, a control input coupled to an output of the comparator, and sinhroniziruh diy input - with the additional winding of the inverter transformer. Settled Subscription