SU1700612A1 - Device for demagnetization - Google Patents

Abstract

The invention relates to electrical engineering and can be used for demagnetization of parts of a large mass or a group of parts of equivalent mass. The purpose of the invention is to reduce the size and weight of the device, as well as improving the quality of demagnetization. The demagnetization device includes the main current source - the winding 1 of the transformer 2, the limiting resistor 3, the main charge key - the thyristor 4 and the main capacitor battery 5. The winding 6 of the transformer 2 is an additional current source from which 7.8; additional capacitor banks 9, 10 are charged; thyristors 11. are bit switches providing the discharge of the main and additional capacitor batteries to the magnetic system 13. 3 sludge. cl

Description

H controllers of thyristor cells, 7, c. It, t

No

FIG.

The invention relates to electrical engineering and can be used for demagnetization of parts of a large mass or a group of parts of equivalent mass.

The aim of the invention is to reduce the size and weight of the device, as well as improving the quality of demagnetization.

Figure 1 is a diagram of a device for demagnetization; figure 2 - the timing diagram of the device; FIG. 3 is a functional block diagram of the control.

The device contains the main - / current source - the winding 1 of the transformer 2, the limiting resistor 3, the main charging key – thyristor 4 m of the main capacitor battery 5. The winding 6 of the transformer 2 is an additional current source from which keys 7 and 8 charge additional capacitor banks 9 and 10. Thyristors 11 and 12 are bit switches providing the discharge of the main and additional capacitor batteries to the magnetic system 13.

A possible variant of the control unit 14 comprises a series-connected one-shot 15 with an inverse output, the input of which is connected to the Start input, and the output with control electrodes of the thyristors 4, 7 and 8. Delay element 16, generator 17, the output of which is connected to the control electrode of the thyristor 11 and the inverter 18, the output of which is connected to the control electrode 12, the magnitude of the shutter speed At is selected for a greater range of oscillations of the supply network (15-20 ms). The oscillation period of the generator is chosen large by 20-25% of the oscillation period of the circuit. The pulse duration of the one-shot 15 is selected by 30-40% longer than the duration of the oscillatory process.

Figure 2 shows: Ug is the voltage of capacitor 9, Uio is the voltage of capacitor 10, IMC is the voltage on the magnetic system, | Mc is the current through the magnetic system),

The device works as follows.

Initially, all three capacitors 5, 9, and 10 are charged, thyristors 4.7 and 8 are open, and thyristors 11 and 12 are closed. 8 at time ti, the thyristors 4, 7, and 8 are closed until the end of the oscillatory process, thyristor 12 is opened with a slight delay, and the total voltage of the capacitor batteries 5 and 10 (UMc) is applied to the magnetic system 13. The capacitor discharge starts. The capacitance of the capacitor 5 is significant (at least ten

times) is less than the capacitance of capacitors 9 and 10. Therefore, the discharge of capacitor 10 is significantly less. At time ta, the capacitor 5 is discharged polynomially. At this moment, the current of the magnetic system (1ms) reaches its maximum. Subsequently, the inductance of the magnets of the system of 13 m recharge of the capacitor 5 is discharged. At the time point ta the current of the magnetic system (ms) reaches zero, the thyristor 12 closes, then the thyristor 11 opens and the total voltage of the capacitors 5 and 9 is applied to the magnetic system 13 The process is repeated with the opposite sign until the thyristor 11 is closed, after which the thyristor 12 is opened again and the process is repeated. The control unit operates as follows.

When the Start signal arrives, the mono-oscillator 15 closes thyristors 4, 7 m 8 with its output for the duration of the oscillatory process. After a time equal to the shutter speed At (which is necessary for the complete closure of the charging keys), the generator 17 starts working, alternately opening the thyristors 12, 11 and 12, etc., thus providing oscillations in the circuit. When the single-oscillator 15 returns to the initial state, the circuit returns to the initial state and the charge of the capacitors begins.

In the process of oscillation, the energy loss in the circuit is compensated by the addition of additional capacitors in turn. The parameters of the circuit (frequency, current through the magnetic system) are determined mainly by the parameters of the main capacitor battery 5 and the magnetic system 13, However, the amount of energy stored in capacitors 9 and 10 can exceed many times the amount of energy in the capacitor the expense of which the duration of the oscillatory process increases significantly. The damping form of the oscillatory process depends on the ratio of the initial charge of the capacitor banks 9, 10 m 5. If the initial charge of the capacitors 9 and 10 is small, the oscillatory process quickly decays first. With a larger charge, the attenuation proceeds according to a law close to linear. With an even greater charge of capacitors 9 and 10, the beginning of the oscillatory process is accompanied by an increase in the amplitude of oscillations.

The device for demagnetization was experimentally tested with the following parameters. The capacitor battery 5 with a capacity of 1000 µF was charged to 320 V. The capacitor batteries 9 and 10 with a capacity of 20,000 µF were charged to 70 V. The magnetic system 13 consisted of two paraple

connected coils wound with a wire with a diameter of 2 mm on frames with a diameter of 250 mm, three hundred turns each. The oscillation frequency is 25 Hz, the duration of the oscillatory process is about 1.3 s.

The device favorably differs from the known ones with smaller dimensions and mass, since it lacks additional chokes, transformers-magnetic conductors.

In addition, the quality of degaussing in the device is higher. The quality of demagnetization depends on the number of cycles of the oscillatory process during demagnetization, i.e. at a fixed frequency, depending on the duration of the oscillatory process. The duration of the oscillatory process is determined by the quality factor of the oscillating circuit, which at low frequencies is determined mainly by the active resistance of the contour elements. With the introduction of additional elements in the circuit (in the known device - energy storage devices), the resistance increases. New connections between cells, namely the inclusion of capacitor batteries directly into the circuit, reduce the resistance of the circuit.

In the device, the quality factor is determined only by the magnetic system. However, the initially stored energy is easily increased by adding additional capacitor batteries without changing the parameters of the circuit and, in particular, its quality factor.

Additional advantages of the device include the ability to adjust the shape of the device.

Claims (1)

oscillatory process by changing the charge ratio of the main and additional capacitor batteries, which allows to choose the optimal shape. Invention Formula A demagnetizing device, including a main current source connected in series, a limiting resistor, a main charge-thyristor, a main capacitor battery, and a magnetic system, a key control unit, characterized in that, in order to reduce the size and weight of the device, as well as to increase the quality of demagnetization, the device additionally introduced two charge switches, thyristors, two bit switches, thyristors, additional capacitors, made in the form of two series-connected capacitor banks, the first one being connected to the cathode of the first additional charge switch and the anode of the first bit switch, and the second pin connected to the anode of the second additional charge switch and cathode of the second bit switch, and the common point of the additional capacitors current and common point of the main current source and the main capacitor bank, the second output of the additional current source is connected to the anode of the first and the cathode of the second additional charge switches, the cathode of the first and the anode of the second bit switches connected to the output of the magnetic system, the second terminal of which is connected to the common point of the main capacitor battery and the main charge switch. To thyristors 4,7,8 To thyristor 11K thyristor f2 15 1617 Rig.Z 18