RU2189655C1 - Electromagnet incorporating field-forcing provision - Google Patents

Abstract

FIELD: electrical engineering; automatic-control systems for oil production, power, and other industries. SUBSTANCE: electromagnet used for forced energizing of actuating electromagnetic devices such as actuators of electromagnetic valves has two input terminals for connecting ac supply mains, electromagnet coil, first and second capacitors, first and second rectifiers, voltage regulator diode, first resistor, and optoelectronic ac switch; first and second rectifiers are connected to output leads through first and second capacitors, respectively; output leads of optoelectronic switch are connected in parallel with second capacitor; voltage regulator diode is connected to output leads of first rectifier and its anode is connected through first resistor to first input of optoelectronic switch; novelty is introduction of second resistor and third capacitor and using full-wave circuit arrangement for first and second rectifiers and bidirectional thyristors for optoelectronic ac switch; second input of the latter is connected to second resistor and to third capacitor; cathode of voltage regulator diode and second lead of first power supply are connected to second resistor and to third capacitor; outputs of second rectifier are connected to electromagnet coil leads. EFFECT: enhanced operating efficiency of electromagnet; ability of forcing-pulse length control. 1 dwg

Description

 The invention relates to electrical equipment and can be used to force the inclusion of actuating electromagnetic devices of automation systems in the oil, energy and other industries, in particular, in actuators of electromagnetic valves.

 It is known "Device for forcing an electromagnet" (AS USSR 612290, H 01 F 7/18, published 06/25/78, Bulletin 23). The device provides forced inclusion of an electromagnet when powered by AC power. The device comprises a transformer with high and low voltage windings, a starting thyristor, a control circuit of the starting thyristor.

The disadvantages of the device are:
- high complexity of the forcing scheme;
- the need to use a special transformer and a switching contact in the power circuit of the electromagnet, limiting the scope of use of such forcing devices.

 It is known "Device for forcing an electromagnet" (AS USSR 838764, H 01 F 7/18, published 06/15/81, Bulletin 22). The device is designed to control electromagnetic drives in AC circuits. The device contains a controlled key - a mechanically activated contactor, two diodes, a main and an additional capacitor. The boost mode in the device is achieved due to the energy stored in the main capacitor, which is supplied to the electromagnet when the contactor is closed.

 The advantage of the device is the simplicity of its circuit.

The disadvantages of the device include:
- the need to use an inclusive contact, limiting the scope of use of the boost device;
- the large dimensions of the device, due to the need to use a main capacitor of large capacity with high operating voltage;
- the need to use an additional capacitor of increased capacity due to the fact that the power of the electromagnet in steady state is carried out by a half-wave voltage.

 It is known "Device for controlling an electromagnet" (AS USSR 845183, H 01 F 7/18, published 07.07.81, bulletin 25). The device is designed to force the inclusion of electromagnets in automation systems. The electromagnet is powered from the AC mains by the voltage of a half-wave rectifier: either through an open thyristor (in boost mode) or through an additional capacitor (in steady state).

 The well-known "Device for controlling an electromagnet" (AS USSR 926730, H 01 F 7/18, published 07.05.82, Bulletin 17), "Electromagnet with force" (AS USSR 1141456, H 01 F 7/18 published on 02/23/85, bulletin 7).

 Devices are intended for forced switching on electromagnetic devices of automation systems.

 The electromagnet is supplied with AC power in these devices by the voltage of a half-wave rectifier: either through a fully open thyristor (in boost mode), or through the same, but partially open thyristor (in steady state). The partial opening mode of the thyristor is set by changing the phase of the alternating voltage at its control electrode.

 The advantages of the devices include the simplicity of the circuit and the absence of switching elements.

 A disadvantage of the devices is the low efficiency of using electromagnets both in the boost mode and in the steady state due to the supply of the electromagnet with the voltage of a half-wave rectifier. This circumstance limits the possibility of using forcing devices when controlling powerful electromagnets.

 Closest to the claimed is the "Electromagnet with force" (RF patent 2037219, H 01 F 7/18, published 09.06.95, bulletin 16).

 The device is designed to control the electromagnetic drives of automation systems. The device contains a capacitor connected in series with the winding of the electromagnet, an optoelectronic switch of alternating current, made on the basis of a thyristor optocoupler installed parallel to the capacitor, a resistor optocoupler acting as a delay circuit and connected in series with the input circuit of the thyristor optocoupler, a thyristor installed parallel to the resistor optocoupler and the input circuit thyristor optocoupler, power supply elements: input circuit of a thyristor optocoupler, resistor optocoupler, thyristor.

 At the moment of forced switching on of the electromagnetic drive, the thyristor optocoupler shunts the capacitor, thereby providing a high boost current. After a time determined by the delay circuit, the thyristor shunts the input of the opto-thyristor, as a result of which the latter is turned off and the device goes into steady state, in which the electromagnetic drive is kept in operation due to the current flowing through the capacitor.

 The advantages of the device include the simplicity of the circuit and the absence of switching elements in it.

The disadvantages of the device are:
1. The power supply of the electromagnetic drive voltage of a half-wave rectifier both in boost mode and in steady state, which reduces the efficiency of the boost device, limits the possibility of using the device to control powerful electromagnets.

 2. There is no possibility to control the duration of the boost pulse, since it is determined by the characteristics of the resistor optocoupler and cannot be adjusted. When controlling electromagnets with different switching times, this feature is desirable, because allows you to choose the best control mode of the electromagnetic drive.

The objectives of the claimed device are:
1. Improving the efficiency of the electromagnet with force.

 2. Providing the ability to control the duration of the boost pulse.

 Fulfillment of the tasks is achieved by the fact that the proposed electromagnet with boost contains two input terminals for connecting to an alternating current network, an electromagnet winding, first and second capacitors, first and second rectifiers, a zener diode, a first resistor, an optoelectronic switch of alternating current, and the first and second the rectifiers are connected to the input terminals through the first and second capacitors, respectively, the output terminals of the ac optoelectronic switch are connected in parallel with the second capacitor, bilitron connected to the output terminals of the first rectifier and the anode of the zener diode is connected via a first resistor to the first input of the optoelectronic AC key, characterized in that a part of the electromagnet with boost administered a second resistor and a third capacitor; the first and second rectifiers are made according to the scheme of half-wave rectification, and the optoelectronic switch of alternating current is made using symmetric thyristors; the second input of the optoelectronic switch is connected to the second resistor and the third capacitor, the zener diode cathode and the second output of the first power source are connected to the second resistor and the third capacitor, the outputs of the second rectifier are connected to the terminals of the electromagnet winding.

Wherein:
1) improving the efficiency of the claimed device is achieved through the use of:
- optoelectronic switch with symmetric thyristors;
- half-wave rectifiers for powering the electromagnet and the input circuit of the optoelectronic switch, which together provide a half-wave power supply of the electromagnet both in boost mode and in steady state;
2) the ability to control the duration of the boost pulse is achieved by using a third capacitor and a second resistor.

 It is known that when using the voltage of a half-wave rectifier, current pulses with a duration of not more than 0.01 s flow through an electromagnet, while the response time of most electromagnets lies in the range 0.05-0.25 s and more (see, for example, A. G. Slivskaya, "Electromagnets and Permanent Magnets", M., "Energy", 1972, p.218). Accordingly, the boost time for reliable operation of the electromagnetic drive must be at least 0.25 s. In this case, the power of the electromagnet in the boost mode by current pulses reduces the traction force of the electromagnet and its speed. In order to compensate for the decrease in traction, it is necessary to increase the amplitude of the current pulses, which, in turn, requires an increase in the diameter of the wire of the electromagnet coil. The result will be an increase in mass, size, cost and, accordingly, a decrease in the efficiency of the electromagnet with boost.

 Power supply of the electromagnet in steady state with current pulses of a half-wave rectifier, as well as d mode of forcing, reduces the pulling force of the electromagnet, is the reason for additional heating of the magnetic circuit due to the appearance of high-frequency harmonics.

 Accordingly, the use of the claimed device circuits of half-wave power supply of the electromagnet in the steady state and the boost mode increases the efficiency of boost with an electromagnet.

 In this case, an optoelectronic switch with symmetrical thyristors, the first and second rectifiers, made according to the half-wave rectification scheme, provide a half-wave power supply of the electromagnet with boost in the inventive device.

 Adjusting the duration of the boost pulse is provided by the selection of the nominal value of the third capacitor. In the inventive device, the charge of this capacitor is used to form a current pulse in the input circuit of the optoelectronic switch of alternating current. By changing the value of the capacitor, you can change the time of its charge, the duration of the current pulse in the input circuit of the optoelectronic switch and, accordingly, the duration of the boost mode.

 The second resistor is used to discharge the third capacitor and, accordingly, bring the forcing device to its original state after disconnecting the mains voltage at the input of the device.

Thus, the use of the claimed solution:
- an optoelectronic switch with symmetric thyristors, half-wave rectifiers for powering the electromagnet and the input circuit of the optoelectronic switch, in total, provides power to the electromagnet according to the two-half-wave circuit both in the boost mode and in the steady state and, accordingly, increases the efficiency of the electromagnet with boost;
- the third capacitor and the second resistor provides the ability to control the duration of the boost pulse.

 The drawing shows a diagram of an electromagnet with force.

 The forced electromagnet contains two input terminals for connecting to an alternating current network 1, 2; electromagnet winding 3; the first 4 and second 5 capacitors; first 6 and second 7 rectifiers; Zener diode 8; first resistor 9; optoelectronic switch of alternating current 10 with symmetric thyristors at the output; a second resistor 11 and a third capacitor 12.

 The device operates as follows.

 In the initial state, in the absence of voltage at the input terminals 1,2, the optoelectronic switch is closed, the third capacitor is discharged.

When applying an alternating voltage to the input terminals 1.2 of the electromagnet with force, it simultaneously arrives at:
- connected in series to the first capacitor 4 and the first rectifier 6;
- serially connected to the second capacitor 5 and the second rectifier 7.

 In this case, the first 4 and second 5 capacitors limit the alternating current in the circuit of the first 6 and second 7 rectifiers.

 Under the action of the voltage at the output of the first power supply 6, limited by the zener diode 8, through the first resistor 9, the input circuit of the optoelectronic switch 10 starts to flow the charge current of the third capacitor 12. As a result, the optoelectronic switch 10 opens, the output circuit of the optoelectronic switch, in which symmetric thyristors are used, the second capacitor 5 is shunted. The current in the circuit of the second rectifier 7 and, accordingly, in the electromagnet circuit increases sharply, thereby ensuring forced radiation of an electromagnetic drive. The current flow time of the forced switching on of the electromagnet is determined by the charge time of the third capacitor 12. As it is charged, the current in the input circuit of the optoelectronic switch decreases to the level at which the latter closes, the shunt action of the symmetric thyristors ceases, and the boost mode ceases. In the steady state, the current through the electromagnet decreases sharply to a value determined by the capacity of the second capacitor 5.

 When the supply voltage at the input terminals 1,2 is turned off, the capacitor 12 is discharged through the resistor 11, as a result of which the electromagnet with force returns to its original state. The device is ready for a new inclusion of the electromagnet.

The inventive device was used to control a gas shutoff valve with the following main characteristics:
- pressure of the working medium - 0.3 MPa;
- anchor stroke - 6 mm;
- bore diameter - 25 mm;
- the power supplied to the valve at the moment of switching on is 135W; the power consumed by the valve in steady state is less than 1 W.

The forced electromagnet was made using the following components:
1) the electromagnet 3 is made with a PEV-1 wire with a diameter of 0.16 mm, the number of turns is 6300, the resistance of the winding is 360 Ohms;
2) capacitors 4, 5 - K73-17-630V-022 uF;
3) a half-wave rectifier 6 - diode bridge RB157;
4) a half-wave rectifier 7 - diode bridge RS205;
5) Zener diode 8 - Zener diode KS 156A;
6) resistor 9 - resistor C2-33-0.25-100-100 ± 5%;
7) optoelectronic switch 10 consisting of:
- optoelectronic triac 13-AOU160A,
- resistor 14 C2-33-0.25-510 ± 5%,
- resistor 15 C2-33-0.25-1kom. ± 5%,
- symmetric thyristor-triac TS 106-10;
8) resistor 11 C2-33-0.25-30 com. ± 5%,
9) capacitor K50-35-16V-100.0 μF.

The inventive device allows through the use of a half-wave power supply of an electromagnet:
- reduce current in boost mode compared with the prototype by at least 50%;
- reduce the holding voltage and, accordingly, the power consumed by the electromagnet in steady state by at least 70%;
provides the ability to change the boost time from 0.1 to 10 s.

Claims (1)

 A forced electromagnet containing two input terminals for connecting to an alternating current network, an electromagnet winding, first and second capacitors, first and second rectifiers, a zener diode, a first resistor, an optoelectronic alternating current switch, the first and second rectifiers being connected to the input terminals through respectively the first and the second capacitors, the output terminals of the optoelectronic switch are connected in parallel with the second capacitor, the zener diode is connected to the output terminals of the first rectifier, and the anode of the zener diode connected through the first resistor to the first input of the optoelectronic switch, characterized in that a second resistor and a third capacitor are introduced into the electromagnet with forcing, while the first and second rectifiers are made according to a half-wave rectification circuit, and the optoelectronic AC switch is made using symmetric thyristors, the second the input of the optoelectronic switch is connected to the second resistor and the third capacitor, the zener diode cathode and the second output of the first rectifier are connected to the second resistor and the third capacitor, outputs a second rectifier connected to the terminals of the electromagnet winding.