SU970614A1 - Dc electric drive control method - Google Patents

Description

This invention relates to electrical engineering and can be used in direct current drives.

Methods are known for controlling the braking of DC electric drives using a converter motor system by transferring them to regenerative mode 1 and 2.

Closest to the proposed method of controlling a direct current drive, which sets the speed of rotation of the drive, measure the speed of rotation of the drive, compare the set and actual speed of the drive, determine the sign of their mismatch, and when the actual speed of the set value is exceeded, the braking command is given .

In this case, with the appearance of a negative difference between the actual and set rotational speeds, a command is generated in the control system and the electric drive goes into regenerative deceleration mode. GZ.

The disadvantage of these methods is that the electric drive can go into deceleration mode at a constant value of the speed reference, for example, in the case of a slight overshoot of the speed after the acceleration process. In addition, this mode, which reduces the reliability of operation, is undesirable or completely unacceptable for a number of production mechanisms, in particular, with large flywheel masses and a small moment of static load, operating cyclically with parts of steady 10 speed and very frequent alternation of acceleration and deceleration modes.

The purpose of the invention is to increase the reliability of the drive.

The goal is achieved by

15 that, according to the direct current drive control method, the derivative of the speed reference is additionally measured, its sign is determined and braking is performed only if the negative sign of the derivative coincides with the negative mismatch sign of the specified and actual speeds of the electric drive.

The drawing shows a structural

25 scheme of the electric drive that implements the proposed method.

Claims (2)

The electric drive contains an electric motor 1, serially connected unit 2 of the rotational speed of electric motor 0 of engine 1, unit 3 of intensive network with a built-in discriminator of the sign of the derivative of the master signal unit 4 of the control with the braking control element, the root converter 5, the output of which is connected to the main winding of the electric motor 1 , the reversing transducer is the exciter 6, the input of which is connected to the control unit 4 and the output to the excitation winding of the electric motor 1, is connected to the motor shaft 1 ogenerator 7, which is connected to the control unit 4 and Th Res comparing unit 8 to the logic unit 9 and the input of the set point 3 the intensity, the second input logic unit 9 is connected to the intensity setting unit 3, and the output - to the control unit 4. . The device works as follows. Speed controller 2 sets the speed setpoint of the electric motor 1, and tachogenerator 7 measures the actual speed of rotation of the electric motor 1. When the setting device 2 switches to a position less (or equal to zero), the speed set taken from the output of the discriminator built into the intensity 3 generator is negative the signal of the first derivative of the master signal is fed to the input of logic block 9 with memory. The presence of an atoro signal and a speed error control signal (a negative signal with a speed greater than the driver) causes a signal to appear at the output of block 9. From the output of logic block 9, the signal goes to the second input of control block 4 and to its control element during braking, as a result of which there is a change in drive control through the control channels of the output voltage of converter 5 and converter-exciter 6. Polarity of output voltage of converter - the driver 6 and the sign of the magnetic flux and the emf of the electric motor 1 are reversed. The voltage of converter 5, which changes its polarity also to reverse, becomes directional. a counter EMF and a current of the electric motor, which corresponds to the inverter mode of the converter 5 and regenerative: braking of the electric drive. At the end of the deceleration mode, the memory from logic unit 9 is removed by a speed error signal (close to zero) received from the comparison unit 8. When the speed value corresponding to the specified setpoint is less (or equal to zero), the speed mismatch becomes zero or close to it, the polarity of the converter of the exciter 6 and the magnetic flux of the electric motor 1 are restored to the previous sign, the inverter mode of the converter 5 and the deceleration of the electric motor 1 stop . The electric drive stops or rotates at a steady speed in accordance with a predetermined speed setpoint, after which it is again ready to perform braking. Thus, the proposed control method ensures reliable operation of the electric drive, since it eliminates the possibility of the electric drive switching to a braking mode in case of a random overshoot in speed. Claims The method of controlling an electric drive with direct current, which determines the setpoint speed of rotation of the drive, measures the speed of rotation of the drive, comparing the set one. and the actual speeds of the electric drive, determine the sign of their mismatch, and when the actual speed exceeds a predetermined value, they give a command to braking, which means that, in order to increase reliability, the derivative of the speed reference is additionally measured its sign and braking are performed only if the negative sign of the derivative coincides with the negative mismatch sign of the given and actual speeds of the electric drive. Sources of information taken into account in the examination 1. The author's certificate of the USSR 375743, cl. H 02 R 5/06, 1973. 2. Authors certificate of the USSR 379034, cl. H 02 R 5/26, 1973.