SU838985A1 - Device for recuperative-dynamic braking of motor in asynchronous-power diode cascade - Google Patents

Description

The invention relates to electrical engineering, namely to a controlled electric drive, made according to the scheme of an asynchronous-valve cascade, and can be used for regenerative-dynamic braking without an external excitation current source.

A device is known. Asynchronous valve stage comprising a rectifier and inverter system with pulse-phase control, a switching element supplemented to include ¹ obmo- motor stator current in the rotor circuit of the rectified current and excitation current source in the form of a transformer and rectifier [1].

The disadvantage of this device is the presence of an additional source of field current. '

The closest in technical essence and the achieved result to the invention is a device for regenerative dynamic braking in an asynchronous-valve cascade containing an uncontrolled rectifier, an inverter with a pulse-phase control system, a switching element2 connected in series between the inputs between the rectifier and the inverter, and the outputs to two phases of the stator, regulator and sensor of the rectified current of the rotor [2].

The disadvantage of this asynchronous-valve cascade is the increase in the magnetizing current during braking, which causes a substantial (up to 40-50%) increase in the EMF and rotor compared to the nominal one, which reduces the reliability of the inverter switching and can cause it to tip over at high speed.

The purpose of the invention is to increase the reliability of braking by eliminating the overturning of the inverter as a result of an unacceptable increase in the EMF of the rotor at a high engine speed.

This goal is achieved by the fact that a setter, a regulator and an engine speed sensor and an additional engine speed regulator are introduced into the device, with one of its inputs connected to an engine speed setter, and its other input connected to a rectified rotor current sensor, the output of an additional regulator engine speed is connected to the input of the engine speed controller, the engine speed sensor is connected to the speed controller, the output of which is connected to the input ohm current regulator ..

The drawing shows a block diagram of the proposed device.

A device for regenerative dynamic braking of an induction motor 1 consists of a rectifier 2, an inverter 3, a switching device 4, which turns on the stator of the motor in the rectified current circuit of the rotor during braking,. a rectified current sensor 5, a pulse-phase control system 6 of a current regulator 7, a rotational speed controller 8, a rotational speed sensor 9, an additional regulator 10 with a saturation level variable as a function of the rectified rotor current and a rotational speed setting apparatus 11. When the rectified circuit current increases above the value that determines the EMF of the motor rotor, which is the limit according to the reliability of switching the inverter, the saturation level of the additional controller 10 decreases, therefore, the maximum allowable speed decreases.

The device operates as follows. From the apparatus 11 for setting the speed to the input of the additional controller 10, a signal corresponding to a given speed is supplied. In the absence of a rectified circuit current, this signal is fed without limitation to the input of the speed controller 8, the output of which is connected to the input of the current controller 7. When the motor accelerates to a predetermined speed under the action of an external moment, the error signal at the input of the speed controller becomes positive, and a current reference signal appears at the input of the current controller 7. The further braking process is carried out in the system of subordinate regulation of the rectified mismatch current between the actual and the set rotation frequency. When the external moment and, therefore, the current of the rectified circuit increases to a value that determines the permissible rotor EMF at maximum speed under the action of a signal proportional to the rectified current, the saturation level of the additional controller starts to decrease and limits the signal at the input of the speed controller 8, which causes reduction in engine speed.

The use of this device for regenerative dynamic braking allows to ensure the reliability of the circuit without an external source of excitation current of the motor and to increase productivity by increasing the permissible speed during braking with a lower external torque.

Claims (2)

(54) DEVICE FOR RECOVERATIVE DYNAMIC DRIVE OF THE ENGINE IN THE ASINHYUN-VENTILE CASCADE 3 of the rotor current, the output of the additional regulator of the engine speed control is connected to the set input of the speed controller, and the size of the rotational speed of the engine, the area of the rotor, the size of the rotor, the size of the rotor, is applied to the motor speed of the motor, the output of the additional engine speed control is assigned to the output of the speed control, the composition of the rotor speed, the composition of the engine speed, the main part of the engine, the heading of the engine speed, the main part of the engine speed, and the same speed. connected to the input of the current regulator h The drawing shows the block diagram of the proposed device. The device for recuperative-dynamic braking of the asynchronous motor 1 consists of rectifier 2, inverter 3, switching device 4, turning on the stator of the motor in the straightened rotor current during the braking period, sensor 5 of the alternating current, system 6 phase control of the 7th current controller, the rotational speed controller 8, the rotational speed sensor 9, the additional controller 10 with the saturation level as a function of the rectified rotor current and the frequency setting device II. When increasing the current of the higher circuit above the value causing the motor rotor EMF, limiting in terms of the reliability of the inverter commutation, the saturation level of the additional regulator 10 decreases, therefore the maximum permissible rotation frequency decreases. The device works as follows. From the apparatus 11, setting the rotational speed to the INPUT of the additional regulator 10 is supplied with a signal corresponding to the predetermined rotational speed. In the absence of a rectified circuit current, this signal is unlimitedly applied to the input of the speed controller 8, the output of which is connected to the input of the current regulator 7. When the motor accelerates to a predetermined rotational speed under the action of an external torque, the error signal at the input of the speed regulator becomes positive, and a signal is applied to the current at the input of current regulator 7. The subsequent deceleration process is carried out in the system of slave regulation of the up-to-date mismatch current between the actual and the set rotational frequencies. With an increase in the external torque and, consequently, the current of the disconnected circuit to a value that determines the allowable EMF of the rotor at maximum speed under the action of a signal proportional to the rectified voltage, the level of the secondary controller starts decreasing and limits the signal at the input of frequency regulator 8 rotation, 1PGO causes a reduction in the frequency of the engine rotation. The use of this device for regenerative-dynamic braking makes it possible to ensure the reliability of the circuit without an external source of the wiggler excitation current and to improve performance by increasing the allowable rotation frequency during the braking process with a lower external torque. The invention is a device for regenerative-dynamic braking of an engine in an asynchronous-fan cascade, containing an uncontrolled driver, an inverter with a pulse-phase control system, a switching element connected in series with the inputs between the sweeper and the inverter, and the outputs to the two phases of the stator, the controller and A rotor rectified current sensor, characterized in that, in order to increase the braking reliability by preventing the inverter from tipping over due to an unacceptable increase in the rotor EMF, in It has a master frequency controller, a regulator and an engine speed sensor and an additional motor speed regulator. p, one of its inputs is connected to a motor frequency regulator, and its other input is connected to a sensor, rectified rotor current, output of an additional frequency regulator motor rotation is connected to the driver input of the engine speed regulator, the engine speed sensor is connected to the engine speed regulator, the output of which is connected to the current regulator input. Sources of information taken into account in the examination of 1 Meistel AM. Dynamic braking of drives with asynchronous motors. M. Energie 1967. 2. USSR author's certificate in application N 2157996, cl. H 02 R 3/24 17.06.75.