RU2133075C1 - Control unit for metal-cutting tool drive - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: control unit has induction motor, voltage regulator built around transformers, three-phase rectifier bridge, and variable resistor; main and auxiliary transformers are connected in series with supply mains phase leads through their primary windings; secondary windings of main transformers are connected to motor stator winding; control windings of auxiliary transformers are connected through rectifier bridge to variable resistor. Newly introduced in control unit is pulse-width modulated thyristor whose anode is connected to cathode output of rectifier bridge and to first lead of variable resistor; thyristor cathode is connected to anode lead of rectifier bridge and to second lead as well as to center tap of variable resistor; additional resistors are connected in parallel with respective primary windings of main and auxiliary transformers. EFFECT: improved reliability and enlarged drive speed control range. 1 dwg

Description

 The invention relates to electrical engineering and can be used in installations requiring smooth and automatic speed control of mechanisms.

 A device for controlling the rotational speed of a three-phase asynchronous squirrel-cage motor, comprising an asynchronous electric motor, a voltage regulator made on transformers, a three-phase rectifier bridge and an adjustable resistor, main and auxiliary transformers are connected to the network phases by primary windings in series, the secondary windings of the main transformers are connected to the stator winding of the electric motor , and the control windings of auxiliary transformers are connected through rectifier solid bridge with adjustable resistor.

 The disadvantages of this device are low reliability and a relatively small range of drive speed control.

 The purpose of the invention is to increase reliability and expand the range of regulation of drive speed.

 This goal is achieved by the fact that in the device for controlling the electric drive of the machine containing an asynchronous electric motor with a squirrel-cage rotor, a voltage regulator made on transformers, a three-phase rectifier bridge and an adjustable resistor, the main and auxiliary transformers are connected to the network phases by primary windings in series, secondary windings of the main transformers connected to the stator winding of the electric motor, and the control windings of the auxiliary transformers are connected through you a bridge bridge with an adjustable resistor, additional thyristor with TIR and six resistors are introduced, the thyristor anode is connected to the cathode output of the rectifier bridge and the first output of the adjustable resistor, and the thyristor cathode is connected to the anode output of the rectifier bridge and the second and middle terminals of the adjustable resistor, additional resistors are connected in parallel the first windings of the main and auxiliary transformers.

 The drawing shows a diagram of a device. A device for controlling the drive of a metal cutting machine contains an induction motor (1), a voltage regulator made on transformers (2, 3, 4, 5, 6, 7), main transformers (2, 4, 6) and auxiliary transformers (3, 5, 7) connected to the network phases by primary windings in series, and according to the "triangle" scheme - transformers (2 and 3) are connected by windings (8 and 9), transformers (4 and 5) are connected by windings (10 and 11), transformers (6 and 7 ) are connected by windings (12 and 13), the secondary windings (14, 16, 18) of the main transformers (2, 4, 6) are connected according to the star pattern ", and the stator windings of the motor (1) are connected to their output terminals, the control windings (15, 17, 19) of the auxiliary transformers (3, 5, 7) are connected according to the star circuit, their output ends are connected through a three-phase rectifier bridge (20 ) to an adjustable resistor (21) and a thyristor (22), additional resistors (23, 24, 25, 26, 27, 28) are connected in parallel to the primary windings (8, 10, 12, 9, 11, 13) of the main (2, 4 , 6) and auxiliary (3, 5, 7) transformers like (23 - 8), (25 - 10), (27 - 12), (24 - 9), (26 - 11), (28 - 13).

 The device operates as follows.

 When the mains voltage is turned on, the thyristor (22) opens. (The thyristor control system is not shown in the drawing). Pulse-width regulation (WID) is carried out, according to which the rectifier (20) outputs are shorted and opened by the thyristor (22).

 As a result, voltage appears on the secondary windings of the main transformers for motor operation. The engine speed can be changed within wide limits by changing the shape of the thyristor control pulses, as well as by changing the value of the resistor (21) within the specified limits. When the mains voltage is disconnected, the motor is effectively braked. Thanks to the introduction of additional elements into the circuit, the range of regulation of the engine speed and the speed of regulation are improved. Reduces losses in email. drive and increases reliability.

Claims (1)

 A device for controlling an electric drive of a metal cutting machine, comprising a squirrel-cage induction motor, a voltage regulator, a three-phase rectifier bridge, an adjustable resistor, a thyristor and a thyristor control system, the thyristor anode is connected to the cathode output terminal of the rectifier bridge and the first output of the adjustable resistor, and the cathode is connected to the anode the output terminal of the rectifier bridge and the second and middle terminals of the adjustable resistor, characterized in that the regulator is voltage I was made on six transformers, the three main and three auxiliary transformers with the primary windings connected in series in a triangle and connected to the phases of the network, the secondary windings of the main transformers are connected in a star circuit, and the output terminals are connected respectively to the stator winding of the motor, the control windings of the auxiliary transformers are connected according to the star scheme, the output ends of which through a three-phase rectifier bridge are connected to an adjustable resistor, additional resistors connected in parallel to the primary windings of the main and additional transformers, and the thyristor control system provides pulse-width regulation.