SU1686676A1 - Device for dynamic braking of three-phase induction motor - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives of general industrial mechanisms. The aim of the invention is to increase the braking efficiency. The dynamic braking current flowing through the circuit: third phase - photothyristor 17 - third and second phase of the stator winding of the electric motor 1 - photothyristor 16 - second phase, is summed with the discharge current of the capacitor 7 with a voltage greater than the instantaneous value of linear voltage across the circuit: third phase — third and first phase of stator motor winding 1 — diode 9 — resistor 8 — capacitor 7 — photo-thyristor 16 — second phase. This increases braking efficiency. 1 il.

Description

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The invention relates to electrical engineering and can be used in electric drives of general industrial mechanisms.

The aim of the invention is to increase the braking efficiency

The drawing shows a diagram of the device.

The device for dynamic braking of a three-phase asynchronous motor 1 contains a contactor with three power contacts 2-4 for connecting the phases of the stator winding to the power source and the disconnecting contact 5, one terminals of adjustable resistor b, capacitor 7 and resistor 8 are combined, another terminal of resistor 8 is connected to the cathode the first diode 9, the anode of which is intended to be connected to the first phase of the stator winding, another terminal of the capacitor 7 and the anode of the second diode 10 are intended to be connected to the second phase of the stator winding, one output of the opening contact 5 is designed to connect to the third phase of the stator winding, another output of contact 5 is connected to the cathode of the third diode 11, the other output of the adjustable resistor 6 is connected to the anode of the setodiode 12 of the first optocoupler 13, the cathode of which is connected to the anode of the LED 14 of the second optocoupler 15, the cathode of which is connected to the anode of diode 11, the photo thyristor 16 is switched on oppositely to the LED 12 and connected in parallel to pin 3, the photo thyristor 17 is switched on according to the LED 14 and is connected in parallel to pin 4.

The device works as follows.

When the power contactor is turned on, its opening contacts 2-4 connect the electric motor to the network. On the circuit: the first phase-diode 9 - the resistor 8 - the capacitor 7 The second phase is the charge of the capacitor 7.

When the motor is switched to dynamic braking mode, the closing contacts 2-4 open, and the opening contact 5 closes. According to the circuit: (+) capacitor 7 - adjustable resistor 6 - diodes 12; 14 - diode 11 - opening contact 5 - second and third phases of the stator winding of electric motor 1 (-) of capacitor 7; capacitor 7 is discharged. LEDs 12 and 14 turn on photo thyristors 16 and 17. Circuit: third phase thyristor 17 - third and second phase the stator winding of the electric motor 1 — photo-thyristor 16 — the second phase begins to flow a rectified current, producing a deceleration of the rotor.

Turn diode 10 - opening contact 5 - the second and third phases of the stator

ki of the electric motor 1 creates a short-circuited circuit through which the current continues to flow due to the action of electromagnetic induction.

During the flow of the positive half-wave of the linear voltage UCB, when the voltage on the capacitor becomes less than the instantaneous value of the linear voltage, the discharge circuit of the capacitor closes and the capacitor starts to charge in the circuit: the third phase - the third and the first phase of the stator winding of the electric motor 1 - diode 9 - resistor 8 - capacitor 7 - photo-thyristor 16 - second phase. In this connection, the capacitor 7 is discharged not at once, in parts by pulses. Thus, with a significantly lower capacity, the most effective braking process is obtained.

The capacitor discharge duration is adjusted by the adjustable resistor 9.

Thus, by summing the dynamic braking current and the discharge current of the capacitor, when the voltage is higher than the instantaneous value of the linear voltage, the braking efficiency is increased.

Claims (1)

Apparatus of the Invention A device for dynamic braking of a three-phase asynchronous electric motor, comprising a contactor with three power closing contacts for connecting the phases of the stator winding to the power supply and the opening contact, two optothyristors, one terminals of an adjustable resistor, a capacitor and a resistor are combined, another resistor lead is connected to the cathode of the first diode whose anode is intended to be connected to the first phase of the stator winding, the anode of the second diode is intended to be connected to the second phase stator winding, one output of the contact contact of the contactor is designed to connect to the third phase of the stator winding, the cathode of the LED of the first optocoupler is connected to the anode of the LED of the second optocoupler, the photothyristor of the first optocoupler is connected opposite to its LED and connected in parallel with the force closing contact of the contactor to connect the second phase of the stator to the source power supply, the photothyristor of the second optocoupler is turned on according to its LED and is connected in parallel to the closing contact of the contactor for connecting The third phase of the stator winding to the power source, characterized in that, in order to increase the efficiency of the torus; A third diode is inserted into it, the anodode OTHER the output of the capacitor is pre-connected to the cathode of the light emitting diode to be connected to the second phase of the optocoupler, the cathode of the third diode of the electro-winding, the other output The keys to the other output of the normally open resistor are connected to the contactor's anokontakt and to the cathode of the second di-5 of the first optocoupler LED.