RU2523066C1 - Plasmatron power supply source - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: plasmatron power source includes three-phase bridge rectifier based on controlled transistors, filter capacitor, current regulator, control system, where each output of the rectifier is connected to respective phase windings of external power transformer A, B, C, output terminals of the rectifier are connected to filter capacitor and regulator input, output terminals of the regulator are connected to plasmatron input, control system is connected to actuator units of the regulator, and includes additional second three-phase bridge rectifier based on controlled thyristors, and regulating switch consisting of six thyristors, where input terminals of the first rectifier A1, B1, C1 are connected to delta group of phase windings of external transformer, input terminals of the second rectifier A2, B2, C2 are connected to star group of phase windings of external transformer, positive output terminal of the first rectifier is connected to positive output terminal of the second rectifier, to positive terminal of filter capacitor and to positive input of regulator, negative output terminal of the first rectifier is connected to negative output terminal of the second rectifier, to negative output terminal of filter capacitor and to negative input of regulator, cathode of first switch thyristor is connected to input A1 of the first rectifier, cathode of second switch thyristor is connected to input B1 of the first rectifier, cathode of third switch thyristor is connected to input C1 of the first rectifier, anode of fourth switch thyristor is connected to input A2 of the second rectifier, anode of fifth switch thyristor is connected to input B2 of the second rectifier, anode of sixth switch thyristor is connected to input C2 of the second rectifier, anodes of first, second, third switch thirystors are combined with cathodes of fourth, fifth, sixth switch thyristors in a single point.

EFFECT: reduced set power of plasmatron power source.

2 dwg

Description

Technical field

The invention relates to the field of electrical engineering, in particular to the conversion of electrical energy into thermal energy using a plasma torch, and can be used, in particular, in waste gasification plants.

State of the art

Known power sources for plasmatrons. So, for power supply of welding installations based on air-plasma technology, a power source is used (Patent US 5237153, 08/17/1993), containing an input three-phase transformer, a three-phase rectifier with an LC filter and output current regulators based on step-down converters, and to the input current regulators are connected in parallel.

A power source (US Pat. No. 5,991,169, 11/23/1999) is used to power an air-plasma welding machine. It contains an input single-phase rectifier, an intermediate voltage inverter, a pulse transformer with an output rectifier, and an output current regulator based on a step-down converter.

For power supply of the air-plasma installation, a power source is also used (Patent US 6600134, 07.29.2003), containing an input three-phase transformer, a three-phase rectifier and an output current regulator. The main disadvantage of the known technical solutions is that with large operating ranges of the output currents of the source, in order to ensure maximum output power of the device, they have to use electrical components (transformer, rectifiers) with increased installed power.

The closest technical solution is the power source of the plasma torch (Patent UA 84654, Bull. No. 21. 2008). This device (Fig. 1) contains a three-phase rectifier 1 connected to a three-phase AC voltage network, a current regulator (RT) 2, with its input connected to the rectifier output, and connected to a plasmatron with an output, a control system (SU) 3 connected to a current regulator to control the regulator, a filter capacitor 4 connected to the output of the rectifier.

In this device, to ensure a given range of output power, converter units with excess installed power and, as a result, with high material consumption are used, which significantly increases the cost of the plasma torch power supply.

Disclosure of invention

The task to which the claimed invention is directed is to reduce the installed power of the plasma torch power supply units.

When solving this problem, a technical result is achieved, consisting in reducing the material consumption of the plasma torch power source.

The specified technical result is achieved due to the fact that the power source of the plasma torch includes a three-phase bridge rectifier based on controlled thyristors, each of the inputs of which is connected to the corresponding phase windings of the external power transformer A, B, C, filter capacitor, current regulator, control system, while the rectifier output terminals are connected to the filter capacitor and the regulator input, the regulator output terminals are connected to the plasma torch input, the control system is connected to the executive m controller nodes, while the plasma torch power supply additionally includes a second three-phase bridge rectifier based on controlled thyristors and a control switch consisting of six thyristors, the input terminals of the first rectifier A1, B1, C1 connected to a group of phase windings of an external transformer connected in a triangle, the input terminals of the second rectifier A2, B2, C2 are connected to the group of phase windings of the external transformer connected to the star, the positive output terminal of the first rectifier is connected and with the positive output terminal of the second rectifier, the positive terminal of the filter capacitor and the positive input of the regulator, the negative output terminal of the first rectifier is connected to the negative output terminal of the second rectifier, the negative terminal of the filter capacitor and negative input of the regulator, the cathode of the first thyristor of the switch is connected to the input A1 of the first rectifier, the cathode of the second thyristor of the switch is connected to the input B1 of the first rectifier, the cathode of the third thyristor of the switch is connected to ode C1 of the first rectifier, the anode of the fourth thyristor of the switch is connected to input A2 of the second rectifier, the anode of the fifth thyristor of the switch is connected to input B2 of the second rectifier, the anode of the sixth thyristor of the switch is connected to input C2 of the second rectifier, the anodes of the first, second, third thyristors of the switch are combined with the cathodes of the fourth , fifth, sixth thyristors of the switch in one point.

The technical result is achieved due to the introduction of switched rectifiers, which allow the rectifiers to be connected in series or in parallel using control signals, and a control switch that implements the connection data. When the rectifiers are connected in series, the voltage at the input of the regulator doubles, which corresponds to the operation mode of the power source at low output currents on the load current-voltage characteristic of the device. When the rectifiers are connected in parallel, the current doubles, which the regulator can take from the input network with a lower voltage at its input. As a result of this solution, it is possible to almost halve the installed capacity of the transformer. By reducing the power of the transformer, the cost and material consumption of the power source are reduced, relative to the option without switching rectifiers.

The presence of a second three-phase bridge rectifier and a regulating switch in the plasma torch power supply allows, upon command of the control system, the formation of voltage rectification circuits in such a way that, in one switch state, a rectifier output connection is formed, with a different switch state, a rectifier parallel output is formed. This makes it possible to form an increased (doubled) voltage at the input of small currents consumed by the regulator (equal to about half of the maximum) due to the series connection of rectifiers, and to allow reduced voltage (at the voltage level at one rectifier) due to the parallel connection of the rectifiers, which makes it possible to reduce the installed power of the external power transformer and rectifier elements by half and possibly the ability to reduce the material consumption of an external power transformer and rectifier elements.

Brief Description of the Drawings

The invention is illustrated by drawings, where:

figure 1 shows the structural diagram of the power source of the plasma torch according to patent UA 846546 selected as the closest analogue;

figure 2 shows a structural diagram of the claimed technical solution.

An embodiment of the invention

The proposed device (figure 2) includes two controlled rectifiers (1), (2), the outputs of which are connected in parallel, and the inputs are connected to an external power transformer: inputs (A1), (B1), (C1) are connected to the transformer windings group, connected in a triangle, inputs (A2), (B2), (C2) are connected to a group of transformer windings connected to a star. The device contains a control switch (3) connected between the inputs of the rectifiers. A filter capacitor (4) and a current regulator (5) are connected to the output of the rectifiers. The device also contains a control system (6), connected by control channels to the current regulator, rectifiers and switch. The controlled rectifiers and the regulating switch contain controlled thyristors (7), (8), (9-24).

The device operates as follows.

In the mode of low currents consumed by the current regulator (5), the control system (6) generates control signals that keep the thyristors (13), (14), (15) in the rectifier (1) open, all thyristors (7), (8), (9-12) of the regulating switch (3) and thyristors (22), (23), (24) of the rectifier (2). Thyristors (16), (17), (18) and (19), (20), (21) are in a permanently locked state. Thus, a rectification circuit is formed with two rectifiers connected in series to the output. This is a rectifier based on thyristors (13), (14), (15) and (7), (8), (9), as well as a rectifier based on thyristors (10), (11), (12) and (22) , (23), (24). The output voltage, equal to twice the voltage at each rectifier, is supplied to the current regulator (5). From the output of the current regulator, voltage is supplied to the plasma torch.

In the mode of maximum currents consumed by the current regulator (5), the control system (6) generates control signals that keep all thyristors (13), (14), (15), (16), (17), (18) open ) in the rectifier (1), all thyristors (19), (20), (21), (22), (23), (24) in the rectifier (2). All thyristors (7), (8), (9), (10), (11), (12) of the control switch (3) are in a permanently locked state. The output voltage equal to the voltage across the rectifier (1) and (2) is supplied to the current regulator (5). From the output of the current regulator, voltage is supplied to the plasma torch.

Thus, in this circuit, unlike the prototype, the regulating switch allows the rectifiers to be connected in series or parallel to the output using control signals. When the rectifiers are connected in series at the stage of low consumption currents, the power supply voltage of the current regulator doubles, and when the rectifiers are connected in parallel, the current that is fed to the current regulator input with half the supply voltage is doubled. This allows you to halve the installed power of the transformer and rectifier elements, and also reduces the material consumption of the transformer and rectifier elements. Due to this effect, the cost and material consumption of the plasma torch power source are reduced.

Claims (1)

The plasma torch power supply, including a three-phase bridge rectifier based on controlled thyristors, a filter capacitor, a current regulator, a control system, each of the rectifier inputs is connected to the corresponding phase windings of an external power transformer A, B, C, the rectifier output terminals are connected to the filter capacitor and the input of the regulator, the output terminals of the regulator are connected to the input of the plasma torch, the control system is connected to the Executive nodes of the regulator, characterized in that it additionally turns on the second three-phase bridge rectifier based on controlled thyristors and a control switch consisting of six thyristors, the input terminals of the first rectifier A1, B1, C1 connected to a group of phase windings of an external transformer connected in a triangle, the input terminals of the second rectifier A2, B2, C2 connected to the group of phase windings of an external transformer connected to a star, the positive output terminal of the first rectifier is connected to the positive output terminal of the second rectifier, the positive terminal to the filter capacitor and the positive input of the regulator, the negative output terminal of the first rectifier is connected to the negative output terminal of the second rectifier, the negative terminal of the filter capacitor and the negative input of the regulator, the cathode of the first thyristor of the switch is connected to input A1 of the first rectifier, the cathode of the second thyristor of the switch is connected to input B1 of the first rectifier , the cathode of the third thyristor of the switch is connected to the input C1 of the first rectifier, the anode of the fourth thyristor of the switch is connected to ode A2 of the second rectifier, a thyristor switch fifth anode coupled to the input B2 of the second rectifier and the anode of the sixth thyristor switch connected to an input of the second rectifier C2, the anodes of the first, second, third thyristor switch combined with the cathodes of the fourth, fifth, sixth thyristor switch at one point.

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