SU361027A1 - AUTOMATIC CONTROLLER OF PARALLEL OPERATION OF MULTI-POST WELDING CONVERTERS - Google Patents

Description

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This invention relates to the field of automating welding production processes.

Known automatic parallel controllers of multi-station welding converters, consisting of control and control units, are uneconomical in operation.

The proposed controller differs from the known ones in that the control unit has sensors for switching-on current levels connected to the input of an adder, including magnetic amplifiers, acting on the control objects.

FIG. 1 shows a block diagram of a regulator; in fig. 2 is a schematic diagram of the summation block; on fng. 3 is a schematic diagram of an inverter control unit.

The scheme includes the regulation objects /, the summation block 2 and the converter control blocks 3.

The summation unit consists of inputs 4 and 5 connected to transformers for measuring the current of each converter, rectifiers 6, load resistors 7, filter capacitors 8, control resistors 9, bias setting resistor 10, input And bias winding of magnetic amplifier 12 (MU), elements 13 and M of the flexible feedback circuit, operating winding 15 MU, diodes 16, elements 17 and 18 of controlling the parameters of the output 19.

The control unit contains a common input 21, a resistor 22 for setting the cut-off threshold of the first converter, a sensor 23 and an inverter 24, an adjustable delay element 25, memory circuit elements 26 and 27, an amplifier 28, a relay 29, a relay winding terminal 30, contacts 31 and 32 of the relay .

The regulator operates in three modes.

“Avtomat-1 - Remote start from welding stations and automatic shutdown of the first converter.

"Avtomat-2 - start and shutdown of the first

converter from board} of the board; “Manual control - independent operation of converters.

Switching on and off of the second and subsequent converters in the modes of Avtomat-1 and Avtomat-2 is performed automatically as a function of the current of the welding network.

For operation of the device in the mode “Automatic-1 switches / I in the control unit by the first converter and the switch,

mounted in the converter circuit /, set to the closed position.

In the initial state of the automatic controller, the potential of the order of 12 V is supplied from the automatic control unit.

through the open relay contact IP to the welding rail. There are no signals on the inclusive inputs of the memory cells of the element 27. At the disconnecting inputs of the element 26, there is no signal due to the presence in this circuit of the closing contact of the relay IP.

When the welder tries to induce an arc between the electrode AND the piece to be welded, there is no voltage on the welding tires, a negative potential 12 V is fed to the input of the amplifier 28, the output signal of which disappears, a signal appears on the output of the element 26 input element 27 and, thus, the memory cell is turned on and remembers the signal. The signal from the cell output of element 26, amplified by amplifier 28, turns on an IP relay, the opening contacts of which break a circuit, supplying voltage 12 in to memory element 26. The closing contact of the IP relay, outputs 31 and 32, turns on the fan of the first unit and includes a welding converter in the sequence stipulated by the VKSM-1000 scheme. The memory cell is not disconnected at the moment of switching on the unit due to the presence of the time element 25 in the control circuit.

A constant voltage appears on the welding rails. The current consumed by the converter is measured by a CT current transformer (Fig. 2), the voltage from which is supplied to the charging winding of the OU-3 magnetic amplifier 12. The amplifier is loaded on the element 17, therefore the output voltage is proportional to the current of the welding network.

An increase in the welding current up to 50 a and more results in the activation of the zero-load sensor 23 - a relay element. In this case, the voltage at the output of the inverter 24 disappears, which prevents the appearance of a tripping signal at the “Memory.

The maximum current of the welding converter is taken to be its nominal current of 1000 A, a reduced pa of the value of the standard deviation of the oscillations, which is about 150 A. The minimum current is taken to be the current at which each welding transducer has

 / „(Fe-1) 0.95

tt - K

where K is the number of simultaneously working

converters,

/ n - the rated current of the converter. The factor 0.95 is chosen from the possibility of obtaining various settings of the maximum and minimum current sensors needed to eliminate self-oscillations in the system. Increasing the welding current to 475 a triggers the minimum 25 sensor, the output of which, being fed to the input of element 24, removes the signal from the disconnect input of the “Memory 251, T-g.y” cell by allowing the second converter to turn on.

When the current increases up to 850 a, the maximum 25 sensor triggers, the signal from which is fed to the input of the delay block 25. When the unit is loaded continuously for a certain time, the voltage at the output of element 25 causes the memory element to operate. which, amplified by the amplifier 28, triggers the 2P relay, including the second converter, and the load is distributed evenly between the first and second converters. The signals from current transformers are summed by a magnetic amplifier 12, at the output 19 of which a signal is obtained proportional to the total current of loading of two units.

When the welding current reaches the minimum value for the three rectifiers, the minimum sensor is triggered, issuing

signal "Permission to enable the third converter.

Increasing the load beyond 1850 a triggers sensor 25 and with a time delay, the inclusion of the third converter. The operation of the control unit circuit

three and subsequent converters

similar to the second control unit

converter ,.

With four working converters, a decrease in the current to 2850 a leads to the disappearance of the output signal of the elements 23У and 25, but the signal from the output of the memory elements 33 and 34 does not disappear. Reducing the welding current to 2700 a leads to the disappearance

the signal from the 25Vi sensor output, the appearance of the signal on the output element “NOT and the output of the delay element. If the current does not increase during the exposure time of the element, the element will operate and turn off the memory cell of element 34, as a result of which the fourth unit will be disconnected from the welding network. A further decrease in the current to 1760 and in the same way disconnects the third unit, and at a current less than 810 a, the second.

A reduction in the welding current to zero results in the appearance at the output 19 of a magnetic current idler. The zero load sensor 23 is disconnected at the element output.

A NOT 24 clock signal cuts off the time delayed cell space 26 and 27, the IP relay turns off the first converter, and the circuit returns to its original state.

The start of the first unit is carried out by pressing the button 1KU. The turn-on signal is fed to the input of the cell of the memory blocks 26 and 27 and through the amplifier 25 turns on the relay IP, which activates the first unit. Included

and subsequent units are turned off in the same way as in the mode “Automatic-1.

The first unit is turned off using button 2 / SU, the signal from which is input to the prohibition of memory elements 26 and 27, causing the IP relay to turn off.

Subject invention

An automatic controller for parallel operation of multi-station welding converters containing summation and control units, characterized in that, in order to increase the controller operation reliability, the control unit contains transducer switching current level sensors connected to the output of the summation unit including magnetic amplifiers acting on objects of regulation.

: h-17Gs: SG 4. nwk -i

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