SU1319215A1 - A.c.electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used to drive crane mechanisms, mine lifting installations, ventilation and compressor installations. The purpose of the invention is to increase reliability, efficiency and reduce dynamic performance. The electric drive contains an asynchronous motor 1 with a phase rotor, a three-phase bridge semi-controlled rectifier 2, an additional resistor 3, a controller 4, a contactor with contact 12, a switching element 11. The target is achieved by combining the current in the rotor circuit of the engine. 1 il. (C (L gll

Description

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The invention relates to electrical engineering and can be used to drive mechanisms for cranes, mine hoists, ventilation and compressor units,

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The purpose of the invention is to increase the reliability, efficiency and improved dynamic performance.

The drawing shows an electrical circuit diagram of an electric drive.

The AC drive contains an asynchronous motor 1 with a phase rotor, a three-phase bridge semi-controlled rectifier 2, an additional resistor 3 with four taps, a controller 4 with four make contacts 5-8, a control unit 9 whose outputs are connected to the control electrodes of the three-phase bridge thyristors a semi-controlled rectifier 2, the alternating current outputs of which are connected to the rotor winding pins of the asynchronous motor 1, the stator winding pins of which through the closing contacts of the linear contact and 10 are intended for connecting the supply mains phases, the switching element 11, an additional contactor with closing contact 12, the first tap of the additional resistor 3 is connected to the first terminal of the rotor winding of the asynchronous motor 1 and one terminal of the third closing contact 7 of the controller 4, the other end of which is connected to the second the output of the rotor winding of the induction motor 1 to the third tap of the additional resistor 3, the second tap of which through the second closing contact 6 of the controller 4 is connected to the same terminals of the first and the fourth make contacts -5 and 8 of the controller 4 and both terminals of the additional resistor 3 and the third output of the rotor winding of the induction motor, 1, a quarter of the add-on of the resistor 3 connected to another output of the first contact 5 of the controller 4, another output of the fourth contact 8 of the controller 4 is connected to the second terminal of the rotor winding of the asynchronous motor 1, the connection point of the cathodes of the thyristors of the three-phase semi-controlled rectifier 2 is connected to one terminal of the stator winding asynchronously th engine, Drew

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The second terminal of which is connected through the switching element 11 to the connection point of the anodes of the diodes of the three-phase bridge semi-controlled rectifier 2, the output of which is shunted by the closing contact 12 of the additional contactor.

The control unit 9 contains a rotational speed sensor 13, a sensor 14

current, control pulse driver 15, amplifier 16, two comparison elements 17 and 18, and inverter 19j of the KOTopoi o input are connected to the output of the rotational speed sensor 13, the output to one input of the first comparison element 17, to the other input of which the master signal arrives 18 comparisons are connected to the outputs of the first element 17.

comparison and sensor 14 of the winding current of the rotor of the engine 1, the output of the second element 18 of the comparison through the amplifier 16 is connected to the input of the driver 15 of the control pulses, the outputs of which form the output of the control unit 9. The switching element can be performed on the thyristor.

The drive works as follows.

When starting engine 1 in the circuit of the rotor circuit, a fully inserted additional resistor 3 to those is found. then, while the starting current measured by the current sensor 14 is not reached.

tygnet values (1, 4-1.5) 1.,. Upon reaching the specified current values, a command is generated to close contact 12 of the auxiliary contactor and the control unit 9 will begin a gradual decrease in the ignition delay angles of the thyristor group of the upper - cylinder 2. The decrease in the ignition delay angles of the thyristors causes a change in the duty cycle, which represents

is the ratio of the time of the nonconductive state of the semi-ellviruated rectifier 2- to the period of arrival of control pulses.

The magnitude of the equivalent additional resistance R-, introduced into the rotor winding circuit, is equal to

RSI H

where R is the resistance of the pre-base

resistor.

As the engine rotor accelerates 1 thyristor delay angle

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The system is also insensitive to changes in the driving force V, and at low angles. In order to restore the optimum sensitivity level, the additional resistor 3 is shunted by means of the controller 14 in four steps by contacts 5-m. After closing the last contact 8, the input of the semi-controlled rectifier 2, and hence the exit of the rotor winding, is shorted by contacts 7 and 8, which ends the output of the engine 1 to its natural mechanical characteristic.

The drive goes into dynamic braking mode with self-excitation - by shunting the input of the semi-controlled rectifier 2 and opening the contact 12 of the additional contactor, after which the motor 1 is disconnected from the mains, the switching element is switched on; element 11 and the rotor winding energy is used for dynamic braking or obtaining ultralow steady speeds of movement of the electric drive. The described operating mode of the electric drive also makes it possible to stabilize its angular velocity in the range of load aoKj determined by the artificial characteristic with the full value of the resistance of the additional resistor and the natural characteristic.

When switching thyristors, the rotor winding circuit does not break, as a result, no additional torque pulsations occur and the electric drive dynamics improves.

In the event of a failure of the control unit 9, the electric drive can operate in the manual control mode, in which the engine 1 is started using the controller 4 by sequential output of four additional resistor 3 stages. Similarly, the engine start control is performed during the breakdown of the thyristors, in these cases it is blocked the additional contactor 7 is closed and the controller 4 is controlled, and the dynamic deceleration mode with self-excitation turns out to be possible.

Thus, due to the introduction of an additional single-pole contactor and a switching element and a change in the power circuit of the electric drive

Yes, the reliability and efficiency of the electric drive is improved and its dynamic characteristics are improved.

Claims (1)

An AC drive containing an asynchronous motor with a phase-rotor, a three-phase bridge semi-control driver, an additional four-tap resistor controller with four make contacts, a control unit with three-phase bridge semi-controlled rectifier, and one of the drawers, which draws, draws, draws, three-phase bridge pull-outs, control signals, control signals, three-phase bridge contacts, three-phase bridge control switches, and one of the drawers, and three-phase bridge switches, which draw the number of drawers, control signals, three-phase bridge control signals, and the number of drawers that draw the number of switches. control unit, the AC outputs of the three-phase semi-controlled rectifier are connected to the rotor windings of the induction motor, The stator windings, through the closing contacts of the linear contactor, are designed to connect the phases of the mains supply, characterized in that, in order to increase reliability, efficiency and improve the dynamic characteristics, a switching element and an additional contactor with a closing contact are introduced into it, the first step of the additional resistor connected to the first output of the rotor winding of the induction motor and to one output of the third closing contact of the controller, the other output of which is connected to the second output windings of the rotor of the induction motor and to the third tap of the additional resistor, the second tap of which is connected via the second closing contact of the controller to one terminal of the first and fourth closing contacts of the controller, to both terminals of the additional resistor and to the third terminal of the rotor winding of the induction motor, a fourth of the additional resistance of the resistor is connected to another input of the first closing contact of the controller, another output of the fourth closing contact of the controller is connected to the second winding contact the rotor of an induction motor, the connection point of the cathodes of the thyristors of a three-phase bridge semi-controlled rectifier is connected to one terminal of the stator winding of the induction motor, the other output of which is connected to the connection point of the anodes of my three-phase diodes 5113192156 This is a semi-controlled semi-controlled top, with an additional contact on the end of which is shunted by a closure-tactorp. Compiled by V. Aleshechkin Editor A. Sabo Tehred V. Kadar Corrector T. Kolb Order 2526/53. Circulation 660 Subscription VNIIPI USSR State Committee on affairs of inventions and otkrysht 113035, Moscow, Zh-35, Raushsk nab ,, d. 4/5 Production and printing company, Uzhgorod, cv Project, 4