SU1577040A1 - Dc electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in mechanisms that require automatic stopping of an electric motor when it is disconnected from the power source. The aim of the invention is to increase reliability and efficiency. The device contains an electric motor connected by winding the core 7 via key 8 to power supply 2, transistor 3, switching circuit of excitation winding 1, as well as dynamic braking circuit composed of brake resistor 5 and thyristor 6. When opening key 8, thyristor 6 automatically turns on the transistor 3 is kept open by the back electromotive force of the core until the end of the braking of the motor. 1 il.

Description

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The invention relates to electrical engineering and can be used in mechanisms that require automatic shutdown of an electric motor when it is disconnected from a power source.

The aim of the invention is to increase reliability and efficiency.

The drawing shows a diagram of the device.

The DC motor contains an electric motor with a winding 1 of independent excitation connected to the power source 2 through a collector-emitter junction of transistor 3 and a reverse diode 4 shunted. a power supply 2 via a switch 8. In parallel to the winding 7 of the core, a circuit is also connected in series between the limiting resistor 9 of the first diode 10 and the first resistor 11, and th point of the last base of the transistor 3 is connected.

Parallel to thyristor C, there are i connected in series a second diode 12, a capacitor 13 and a third diode 14. Partially, a second resistor 15 is connected to the second diode 12 and a common point of the capacitor 13 and the second diode 1 is connected to the thyristor control electrode 6

The drive works as follows.

When the key 8 is closed, the voltage of the power source 2 to the winding 7 of the core and to the chain consisting of the limiting resistor 9, the first diode 10, the first resistor 11 is applied, as a result of which the transistor 3 goes into saturation mode. Start and operation of the engine occurs.

When opening the key 8 in the winding of the core arises EMF of self-induction EL (direction shown in the drawing). Since the resistances of the diodes 12 and 14 (in the forward direction) and the resistor 5 are small, and the capacitor 13 is thus discharged, almost all the energy stored in the core winding will be spent mainly on charging the capacitor 13. At the same time, the current capacitor charge will flow through the circuit: winding 7 core, - second diode 12 - capacitor 13 - third diode 14 - brake resistor 5 - winding 7 core. At the end of the charge, the capacitor 13 is discharged through a control electrode - thyristor cathode b and a resistor lb. In this case, the thyristor b will be opened and under the action of the back emf in a closed loop the winding 7 core - brake resistor 5 - thyristor

b a current will flow that will cause a dual braking dvmngg.

Under the influence of proteoEMF: ok, it will flow through resistor 9, diode 10, resistor 11. At the same time, transistor 3 will be kept open due to the presence of a drop in voltage (on the resistor 11 and excitation winding 1 will flow current.) will become zero, the voltage drop

on the resistor 11 will be zero, the emitter and the base of the transistor will have the same potential and the transistor 3 will close, the waiting winding B03f will be de-energized. In this case, the electric motor and the device in C ° scrap will not

consume energy.

The device has no power-consuming elements in the electric motor core circuit, no overvoltages on the elements, and for switching on (the braking deformer uses the energy of the EMF of the core winding.

Claims (1)

DETAILED DESCRIPTION OF THE INVENTION An electric current drive comprising an electric motor with an independent excitation winding connected to the power supply via a collector-emitter transistor and a shunt-inverse -1 diode, a dynamic braking circuit composed of a controlled element and braking resistor connected in parallel to the winding of the core connected to the power supply jack Cheyoz key, a limiting resistor, characterized in that, in order to increase reliability and efficiency, s it has two resistors, three diodes and a capacitor, and a controllable element is made on a thyristor, while parallel to the core winding there is a circuit of a series-connected limiting resistor, the first diode and the first resistor, to the junction point of the first diode - the base of the transistor is connected with a stator, parallel to the thyristor is a circuit of the second diode, the capacitor and the third diode are connected in series, these diodes are connected in the opposite direction of the thyristor, parallel to the capacitor and the second diode, connect the second resistor, and the common point of the capacitor and the second diode is connected to the control electrode of the thyristor.