SU1515306A1 - Device for starting a.c. motor - Google Patents

Abstract

The invention relates to electrical engineering and can be used for smooth starting of various AC motors. The purpose of the invention is to increase the smoothness of the start-up by limiting the power supply voltage surges. The device contains a rectifying bridge 1, a transistor 2, capacitors 3-5, resistors 6-9, Zener diode 10, emitter follower 11, transistor 12 and diodes 13,14. The device provides a smooth start of the electric motor due to the gradual unlocking of the transistor 2 up to its saturation, which leads to a smooth linear increase in the alternating voltage on the motor winding. 1 il.

Description

SP

SP

with about

O5

The invention relates to electrical engineering and can be used for smooth start-up of various AC motors.

The aim of the invention is to increase the smoothness of the start-up by limiting the power supply voltage surges.

 / 2 and,,

where Ug, is the actual value of the voltage at the power supply terminals.

Since the capacitor 5 is discharged, the transistor 2 is locked, the output voltage on the motor winding

The drawing shows the principle Q is zero. If we assume that the fall on the circuit device.

The device contains a rectifier bridge 1, the first transistor 2 is connected to the diagonal of the direct current, the first AC terminal (5 rectifier bridge 1 is equipped with a terminal for connection to the mains supply, and the second AC terminal with a terminal for connecting - not from

the motor winding water, the other 20 P is chosen so that the voltage to the output of which is provided with a clamp for the Zener diode 10 remains unchanged connection to the supply mains, three kon- when changing the potential difference of the capacitor 3, 4 and 5, four resistors between the Zeneriode cathode 10 and emitter voltage When the diode of the rectifier bridge, when the current flows through them in the forward direction, is small, then for different polarities of the input voltage the power of the emitter follower 11 changes, i.e. the potential of the emitter of transistor 2 relative to the cathode of the diode 14 varies in the range V2 u

before

sVzii

in

However, the resistor of transistor 2 is in the specified range, as a result of which the collector current of transistor 12 remains constant. Thus, over time, the capacitor 5 is charged across the circuit of the voltage doubler output (cathode of the Zener diode 10) - resistor 7 - transistor 12 - capacitor 5 - resistor 9 - emitter of transistor 2, as a result of which the voltage on the capacitor 5 varies linearly time i

6-9, Zener diode 10, emitter follower 11, second transistor 12, two diodes 13 and 14, the base of the first transistor 2 through the first resistor 6 is connected to the output of the emitter follower 11, the first AC output of the rectifying bridge 1 is connected through the first capacitor 3 with the cathode of the first 13 and the anode of the second 14 diodes, another motor winding lead is connected to the anode of the first diode 13 and through the second capacitor 4 to the cathode of the second diode 14, the cathode of the Zener diode 10, the first lead of the second resistor 7 and the first power lead of the emitter Secondary terminal 11, the second output of the second resistor 7 is connected to the emitter of the second transistor 12, the base of which is connected to the anode of the Zener diode 10 and the first output of the third resistor 8, the collector of the second transistor 12 is connected to the input of the emitter follower and through the series-connected third capacitor 5 and the fourth resistor 9 with the second output of the zmitter repeater 11, with the emitter of the first transistor 2 and the second output of the third resistor 8.

The device works as follows.

When the device is turned on, the capacitor 5 is discharged, and a voltage is formed on the cathode of the diode 14 relative to the anode of the diode 13

equals zero. If we assume that the fall

not from

P is chosen so that the voltage on the Zener diode 10 remains unchanged when the potential difference between the Zener diode 10 cathode and the emitter voltage on the diodes of the rectifier bridge, when the current flows through them in the forward direction, is small, then at different input voltage the power of the emitter follower 11 changes, i.e. the potential of the emitter of transistor 2 relative to the cathode of the diode 14 varies in the range V2 u

before

sVzii

in

However, the resis P is chosen so that the voltage on the Zener diode 10 remains unchanged when the potential difference between the cathode of the Zener diode 10 and emit5 changes.

5 0 0 h 0

five

transistor 2 in the specified range, as a result of which the collector current of transistor 12 remains constant. Thus, over time, the capacitor 5 is charged across the circuit of the voltage doubler output (cathode of the Zener diode 10) - resistor 7 - transistor 12 - capacitor 5 - resistor 9 - emitter of transistor 2, as a result of which the voltage on the capacitor 5 varies linearly time i

The resistor 9 is chosen so that the current flowing through it creates a voltage across it that at the moment of turning on the transistor 2 does not start at the linear portion of its input characteristic (the base current depends on the base-emitter voltage), therefore when applied to the alternating voltage device transistor 2 is outputted to the beginning of the linear portion of the input current-voltage characteristic, since a voltage drop is generated at the input of the emitter follower 1I

Uo Io R9.

where DO is the voltage at the input of the zmitter follower 1I relative to the emitter of the transistor 2 when applied to the alternating voltage device; 1 (5 collector current of transistor 12;

51515306

Rg is the resistance of the resistor 9, then the voltage at the input of the emitter follower 1I is varied

t

I can see it at the same time as the third stratum of the third stratum before picking up the second half of the second half of the second half of the second half

and

+ j tdt Uo + k-1,

k

t

where U is the current value of the input voltage of the emitter follower 1 1;

- constant coefficient;

-the current value of time. Thus, the base current of transistor 2 increases linearly with time, which causes gradual unlocking of transistor 2 to its saturation, and since transistor 2 is included in the diagonal of the rectifying bridge 1, this leads to a gradual increase in the alternating voltage on the motor winding nominal value V, and 5 ". Resistor 6 is required to protect the base-emitter transistor 2 from breakdown.

Thus, the proposed device provides a smooth terrestrial state control system due to a linear increase (in amplitude.

Fore

V l

1 acquaintance

The device starts the AC motor, which contains a rectifying bridge, the diagonal of which Yuka has the first connection, the first pin on the re 0

five

0

alternating current: the rectifying bridge is provided with a first clamp for connecting / charging to the mains supply, and the second step of the alternating current of the alternating bridge is equipped with a clamp for connecting to a single motor winding terminal, in order to increase the starting smoothness due to limiting the power supply voltage surges, three capacitors, four resistors, a zener diode, an emitter follower, a second transistor and two diodes are inserted into it, the nepfeoro base of the transistor is connected to the emitter output through the first resistor l, the first AC output of the rectifying bridge through the first capacitor is connected to the cathode of the first and the anode of the second diode; and the first power output of the emitter follower, the second output of the second resistor is connected to the emitter of the second transistor, the base of which is connected to the anode of the Zener diode and the first output of the third resistor, The second transistor collector is connected to the emitter follower input and, via a successively connected third capacitor ti, a quadruple resistor with a second emitter repeater, with the emitter of the first transistor and the second output of the third resistor.

five

0

Claims (1)

Claim The device for starting electric motors; a gate for an alternating current containing a rectifier bridge, in the diagonal of a constant current of which the first transistor is connected, the first terminal for alternating current of the rectifier bridge is equipped with a first terminal for connection to the mains, and the second terminal for alternating current of the rectifier bridge is equipped with a terminal for connecting to one conclusion of the motor winding, characterized in that, in order to increase the smoothness of the start due to the limitation of power surges, three capacitors, four resistors, a zener diode are introduced into it, an emitter follower, a second transistor and two diodes, the base of the first transistor is connected through the first resistor to the output of the emitter follower, the first alternating current output of the rectifier bridge through the first capacitor is connected to the cathode of the first and the anode of the second diodes, the anode of the first diode is equipped with a second clamp for connecting to the power supply network and through the second capacitor is connected to the cathode of the second diode, the zener diode cathode, the first output of the second resistor and the first power output of the emitter follower, the second output of the second the resistor is connected to the emitter of the second transistor, the base of which is connected to the anode of the zener diode and the first output of the third resistor, the collector of the second transistor is connected to the input of the emitter follower and through the third capacitor and the fourth resistor connected in series with the second output terminal of the emitter follower, with the emitter of the first transistor and the second the output of the third resistor.