SU1309228A1 - Device for automatic starting of capacitor electric motor - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives of general industrial mechanisms. The purpose of the invention is to increase functional reliability. The device contains a switching node consisting of diode and thyristor 5, working and starting capacitors 2 and 3, control unit 9, synchronization unit 10. In this device, the starting capacitor 3 is connected in parallel with the working capacitor 2 when the motor is started or overloaded when the voltages are equal to them, which allows to eliminate current surges through the thyristor 5. 1 Il. i (L so about so go HCHE 00

Description

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The invention relates to electrical engineering and can be used in electronics waters of general stray mechanisms.

The purpose of the invention is to increase functional reliability.

In the drawing, the circuit diagram of the device is represented in principle.

The device for automatic start-up of the motor 1 comprises working 2 and starting 3 capacitors, diode 4, thyristor 5, two resistors 6 and 7, current transformer 8, control unit 9, the output of which is connected to the control electrode of the thyristor 5 and one output of the first resistor 6, the other output of which is connected to one output of the primary winding of the current transformer 8, to the anode of diode 4, to the cathode of the thyristor 5, to one output of the working capacitor 2 and is intended to connect the beginning and the end, respectively, of the nerve and the second phase x the capacitor motor windings, the cathode of diode 4 is connected to the anode of the thyristor 5, to one output of the starting capacitor 3 and through the second resistor 7 to the other outputs of the starting 3 and working 2 capacitors, designed for the sub. Located at the beginning and end, respectively, of the second and third phase windings of a capacitor motor 1, the second output of the primary winding of a current transformer 8 is for one wire of a single-phase power network, the other wire of which is designed to connect the beginning and end of the third and first phase windings of a capacitor motor I, unit 10 synchronization, single-phase bridge solver 11, variable resistor 12, filter or capacitor 13, the input of the asynchronous unit 10 is connected to the cathode of diode 4, the output is connected to the input of the unit 9 controls

The synchronization unit 10 is composed of a pnp transistor 14, a diode 15, a resistor 16 and a capacitor 17, the control unit 9 is composed of a pnp transistor 18, a zener diode 19, three resistors 20-22. The single-phase bridge rectifier 11 input is connected to the secondary winding of the current transformer 8 and is shunted by a temporary resistor 12, the output is ground by a filter with a capacitor 13, put; 1 output of the single-phase bridge rectifier 11 is connected to the emitter of the transistor 18 and to one output of the first - zstor 20 of the control unit 9, the collector of this transistor 18 is connected to one output of the second resistor 21 of the control unit 9, the other output of which forms the output of the control unit 9, another output of the first resistor 20 of the control unit 9 By connecting the transistor 18 and the base through

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the third resistor of the same block - to the cathode of the Zener diode 19, the anode of which forms the input of the control block 9, the emitter of the transistor 14 of the synchronization block 10

5 is connected to the thyristor cathode 5, the collector forms the output of the synchronization unit 10, the base of the transistor 14 of the unit 10 through the resistor 16 of this unit is connected to one output of the capacitor 17, the other you .JQ of water which forms the input of the synchronization unit 10, the control transition of the transistor 14 is backed by a diode 15 of the synchronization unit, the negative terminal of the single-phase bridge rectifier 11 is connected to the cathode of the thyristor 5.

15 The device operates as follows.

When the supply voltage is applied, the working capacitor 2 is charged, and an increase in starting current flows through the main and auxiliary windings of the electric motor. In the positive half-period of the voltage of the papapi through diode 4, the starting capacitor 3 is charged. Such inclusion of diode 4 and lycKOBoro capacitor 3 makes it possible to use electrolytic capacitors with automatic current molding as starting capacitors. In the secondary winding of the current transformer 8, an emf arises, the value of which is necessary for the operation of the heating, heating 9 and synchronization 10 to be set by the resistor 12. The voltage from the secondary winding of the current transformer 8 through the rectifier 11 with the capacitor 13 connected to its output. transistors 14 and 18 b; 1okov 9 and 10. Functional purpose b. Yuka 9 control consists in applying voltage to the control electrode of the thyristor 5 along the circuit: positive) 1st output terminal.

thirty

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11, the transition emitter-collector of the transistor 18, resistor 21, control. 1 kltsyy electrode thyristor 5.

When applying thyristor control voltage, two

45 conditions: the current in the windings of the electric motor 1 should increase so that it becomes necessary to connect in parallel to the working capacitor 2 of the starting capacitor 3 (when the motor is started and overloaded); connection

50 of the start-up capacitor 3 must be grown at the moment of time, the most favorable q and r of the switching of the thyristor 5, i.e. when the voltage on it is low to zero, and this is possible at the time of equality of the voltages on the working 2 and starting 3 capacitors.

The first condition is achieved by adjusting the resistor 12. The second is the presence of the synchronization unit 10.

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If these two conditions are met at the moment of starting the electric motor 1 at the beginning of the half-period of the voltage on the thyristor 5, which is conductive for it, the transistor 14 of the synchronous unit 10 P is switched on by charging the capacitor 17 through the resistor 16 and the base-emitter transition of the transistor 14 when In the case of a positive voltage on the anode of the thyristor 5. The output current of the opening of the transistor 18 of the control unit 9 through the zener diode 19, resistor 22, and the base-emitter junction of the transistor 18 is created through the output of the 10-cHiixonization unit.

The latter also opens and, through its transition, the emitter-collector resistor 21, the supply voltage from the rectifier 11 is fed to the control electrode of the thyristor 5. The thyristor 5, turn on, connects the starting capacitor 3 in parallel to the worker. After switching on the thyristor 5, the capacitor 17 is discharged by uein-i: diode 15, resistor 16, the anode-to-cathode transition of thyristor 5. When the polarity of the capacitors 2 and 3 is changed, the connection of the starting synchronizer 3 is connected in parallel with the operating diode. It is provided with diode 4. In Further, in the case of zero voltages, capacitors 2 and 3, the operation of the circuit proceeds in a similar way.

By measuring the electric motor I i, the starting current in its windings of the siizhegs also decreases the EMF in the secondary winding of the current transformer, and consequently, the voltage at the output of the rectifier 11 n of the synchronization blocks 10 and control 9 connected to it. At a certain level of voltage reduction, the breakdown of the zener diode 19 of the control unit 9 becomes impossible, and, consequently, the transistor 18, and then the thyristor 5 also turns off. Starting capacitor 3 is also disconnected from parallel operation with working capacitor 2. When increasing ki on the motor shaft during operation, an automatic connection of the starting capacitor is also provided in the same way.

Thus, due to the automatic switching on of the starting capacitor in parallel to the working one, at the moment of equal voltage there are no sharp current surges through the thyristor, which allows using the thyristors of the installed power and increasing the reliability of the device as a whole.

Claims (1)

Invention Formula Device d; 1 automatic start cond, sensory electric motor, containing niee working and starting capacitors, thyrisgori, diode, two resistors. trans (| n) rm. current circuit, the control unit, the output of which is connected to the control of the thyristor electrode and to one output of the first resistor, the other output of which is connected to one output of the primary winding of the current transformer, to the diode anode, to the thyristor cathode, to one output of the working capacitor and to - assigned to connect the beginning and end of the first and second phase windings of a capacitor electric motor. The diode diode is connected to the rii anode |) iiCTOpn. 1 to one conclusion of the starting con5 of the capacitor n through the second resistor - to the conclusions; capacitor and operating capacitor, designed to connect the beginning and Koiuia second and third, respectively, e1 of the condenser motor windings, the second output of the primary: current transformer winding is designed for connecting one wire one: C (power supply network, roii is intended for a TCV-KC connection of the beginning and end of the cooTBeTCTiiCHHO third n iiepBoii phase b windings of a capacitor electric motor .h, characterized in that, with the aim of novpei and .1 ;;) , a block of snapshot entered into it with one g, input and one output, single-phase mine- TOBoii rectifier m1ge. 1b, are variable; resistor (capacitor, capacitor input, input to the cathode of the diode, output of the inverter iodine key to the input of the control unit, transistor cocTais icH synchronization unit, transistor, diode, resistor, capacitor, Hiisi control unit, transistor Zener diode, three resistors, a single-phase bridge input is connected to the secondary winding of the current transformer and wired T1 {non-resistive resistor, Bb: xo; i occupied ч1T; single-phase conclusion 1 on the bridge bridge } The key to the emitter of the transistor and odiomu 5 of the first TipaB ezistor. ie- and. the collector of the transistor of the control unit 1P1 is connected to one output of the second res1: the stopper of this block, the other output of which forms the output of the control unit, the other BbHKX i to the cathode of the Zener diode of the control unit, the anode of which is the image} of the input of the control unit, the emitter granzisto | kkha sync From the notes.: 1yuchen. to the thyristor city, the transistor co-collector is 1g-; it calls the output of the synchronization unit, the transistor base of the synchronization unit through the resistor of this unit is key to one terminal of the synchronization capacitor, shunted by the diode of the synchronization block, another terminal of the synchronization, negative terminal It forms the input of the synchronization unit, a single-phase bridge rectifier, a subcontrol transition of the block transistor connected to the thyristor cathode.