SU1233817A3 - Device for controlling direct current electromagnet - Google Patents

Abstract

A circuit arrangement for enabling the magnetization and demagnetization of electromagnets operated by direct current utilising the self induction current produced in the coil of the electromagnet has two polarized capacitors (C1, C2) connected in parallel with the coil (L) of an electromagnet (M), the capacitors being series connected such that their like poles are connected to each other and a reverse direction diode (D1, D2) is connected in parallel with each capacitor (C1, C2). The magnetizing voltage charges one of the capacitors (C1) through diode (D1) so that it will not be damaged by the self induction voltage produced in the coil (L) of the electromagnet (M) after the magnetizing current has been cut off, the voltage being opposite to the polarity of the capacitor (C1). The electrical energy produced by self induction in the coil (L) of the electromagnet (M) after the magnetizing current has been cut off will become charged and levelled out into the capacitors (C1, C2), producing a low resistance to the self-induction voltage and thus causing strong demagnetizing current in the coil (L) of the electromagnet (M). In alternative circuits only one diode is used (Figs. 2, 3, not shown), and one or both of the capacitors may be a non-polarised capacitor. <IMAGE>

Description

one

The invention relates to electrical engineering, more specifically to devices for controlling a direct current electromagnet.

The aim of the invention is to reduce the size and power consumption.

FIG. 1 shows a schematic and electrical diagram of the device and electromagnet 5 in FIG. 2–4 are graphs of voltage dependences, respectively, on the coil of the electromagnet Uj and on the capacitors U, U, on time.

The device (Fig. 1) consists of a bridge rectifier 1, connected through switch 2 to the coil of electromagnet 3. Two polarized capacitors 4 and 5 are interconnected end-to-end, two diodes 6 and 7 are also connected in an opposite way, the capacitors and the diodes are connected in parallel to each other and to the coil of the electromagnet so that the negative poles of the capacitors are connected to the anodes of the diodes, and the positive to the cathodes.

The device works as follows.

When the switch 2 is closed, the voltage U is applied to the winding 3 (Fig. 2,), the capacitor 4 is charged through the diode 7 to the voltage U (Fig. 3,), which is higher than the voltage U, and the capacitor 5 charges Under the influence of direct current pulsation through diode 6 to voltage Uj (Fig. 4, which is lower than voltage U.) When opening switch 2, capacitor 4 is discharged, the electromagnetic field creates a self-induction voltage Uj in winding 3

2338172

(Fig. 2), which reduces the voltage and (Fig. 3,) in the capacitor 4, increases the voltage U (Fig. 4, T -T) in the capacitor 5, soz5 gives the winding J of the electromagnet a reverse magnetizing current - demagnetizing current. During the demagnetization of the electromagnet, the charges in the capacitors are not discharged.

Thus, energy is saved that would otherwise be required for magnetization to charge a non-polarized capacitor connected in parallel with the winding of an electromagnet. Polarized capacitors, as electrolytic, are small in size, which allows to reduce the size of the device. In some cases, instead of

20 polarized capacitors can be used unpolarized.

Invention Form

25 A device for controlling a direct current electromagnet, containing a source of direct voltage, connected through a switch to the output terminals to which

Connection 30: 1 capacitor, characterized in that, in order to reduce overall dimensions and power consumption, it is equipped with an additional capacitor and two diodes, while both capacitors are polarized, connected in series and connected in parallel with the output terminals, two diodes are connected in opposite -consistently

.- and connected in parallel to the output terminals, we accept the negative poles of the capacitors connected to the anodes of the diodes, and the positive - to the cathodes.

35

fig.Z

Ti

Editor N. Egorova

Compiled by A. Lukin.

Tehred L.Oleynik Proofreader I - Kolb

Order 2790/60 Circulation 643

VNRSHPI State Committee of the USSR

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

-TjT

FIG. four

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Claims (1)

Claim 25 A device for controlling a DC electromagnet containing a DC voltage source connected via a switch to output terminals to which 30, a capacitor is connected, characterized in that, in order to reduce the dimensions and power consumption, it is equipped with an additional 'capacitor' and two diodes, while both capacitors are polarized, connected in series and connected in parallel to the output terminals, two diodes are connected in series and connected parallel to the 4U output terminals, the negative poles of the capacitors connected to the anodes of the diodes, and the positive to the cathodes.