SU905900A1 - Device for control of dc electromagnet - Google Patents

Description

(54) DEVICE FOR CONTROLLING A DC ELECTROMAGNET

The invention relates to electrical engineering and automation and can be used to protect the output stage in the event of a possible break in the power supply circuit in a control device. There are known devices for controlling a direct current electromagnet that contain an output stage from a series-connected electromagnet of a diode-backed diode, electronic switch and feedback element. over the current included in the power supply circuit, the setpoint adjuster and the current stabilizer C 1. The disadvantage of such devices is the lack of askada during loss of power or the voltage in the operational amplifier, present in the input current stabilizer, vrezultate which fully opens the electronic switch of the output stage, which short-circuits the power supply circuit of the electromagnet. The closest in technical essence of the present invention is a direct current electromagnet control device comprising an output stage of serially connected electromagnet shunted by a discharge circuit, an electronic key and a current feedback element connected between the buses of an unstabilized power source, a generator of the field current. connected between the zero and (+) buses of the power supply, a cyclic mode driver connected by inputs to the field current generator and a current feedback loop, an output with an electric switch with a key and connected between the buses (+) and {-) of the power source, a pulsed storage link and an electronic switch L2. However, this device is not sufficiently reliable, since with a negative source of

the power supply opens the electronic key of the output stage and through it a current exceeds the maximum permissible value, which leads to the failure of the electromagnet and the key.

The aim of the invention is to increase the reliability of a direct current electromagnet control device.

The goal is achieved by the fact that in the mouth. A device for controlling a DC electromagnet containing an output stage of a series-connected electronic switch, a current feedback element and diode-shunted terminals for connecting an electromagnet winding between the zero line of the power supply and a terminal for connecting a positive power supply bus , setpoint of the current on-line, includedM) between the zero and polsitelny tires of the power source, and connected between the negative and positive buses of the power source f A cyclic mode equalizer connected by inputs to the exciter current setting and feedback element of the output stage current, and with the output switch electronic key, two dividers, 5 keni on resistors and two transistors, are inserted, and the voltage dividers on the resistors are connected in parallel between the positive and the negative power supply buses, transistors with their collector-emitter circuits are connected in series between the output of the cyclic mode driver and the zero bus source ani, the midpoint of the voltage divider resistors connected to the base terminal of the transistor, and the average - another point on the voltage divider resistors connected to the base terminal of the other transistor,

The drawing is a schematic diagram of the device.

The device contains an exciter current adjuster, made in the form of a switch 1 and resistors 2-4, connected in accordance with a voltage divider circuit, a cyclic mode driver, made in the form of a C-circuit on a resistor 5 and a capacitor 6, an operational amplifier (OA) 7 and a resistor 8 , an electronic protection unit, made in the form of an elec- tron} I1y keys 9 and 10 and voltage dividers on resistors 11-14, terminals for: electromagnet 15, shunted by diode 16, electronic switch 17 and current feedback resistor 18. ОУ 7 is connected (+) by a bus to a current control unit Buses, (-) power supply bus- with feedback resistor

on current 18.

The device works in the following way.

In the absence of a fault in the presence of the input signal U key 1

the cyclic mode driver, made at the OS 7 and the RC circuit from resistor 5 and capacitor 6, is closed and started up. Current pulses from the converter through the

The limiting resistor 8 is fed to the base of the electronic switch 17, which is. ry opens at every pulse that arrives at it.

When a control pulse is generated, the signal UQQ, taken from resistor 18, is fed to the input of op-amp 7, thereby limiting the current in the output stage. When the input signal Ug, key 1 bypasses the input

OU 7 and self-induction EMF are closed through the shunt diode 16.

In the event of a source bus break in the presence of an input signal, the OU 7 is offset by a positive offset and occupies a steady state This voltage is + E

energizes the opener for the electronic switch 17 and the transistors 9 and 10 through the resistors 11 and 13. The transistors 9 and 10 saturate and short the base of the electronic switch 17 by O.

Such a connection of transistors of keys and resistors of voltage dividers increases the reliability of the device in the event of bus failure, - In addition, duplication of electronic switches and voltage dividers also increases the reliability of protection in case of failure of one of the electronic switches or voltage dividers.

The use of the invention improves the reliability and survivability of devices for relay automation and electrical engineering.

Claims (1)

Invention Formula A device for controlling an electromagnet of direct current, soda;