SU1376202A1 - D.c. electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in pulsed static DC electric drives with increased demands on the accuracy of maintaining the rotation frequency. The purpose of the invention is to improve the quality of regulation. The electric drive contains an electric motor, the main winding of which receives a control signal generated by the comparison logic device and modulated by pulses, the duty cycle of which depends on the average current flowing through the electric motor and corresponding to its load. This allows for a wide range of loads and rotational speeds to stabilize the duty cycle of current pulses and use a rotation speed sensor of low accuracy class of about 1 slug. Q

Description

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The invention relates to electrical engineering and can be used in pulsed astatic electrically-driven -: - dc dc current with increased demands on the accuracy of maintaining the rotational speed. The purpose of the invention is to improve the quality of regulation by stabilizing

As the load moment increases, the phase sequence of the pulses generated by the rotational speed sensor 2 lags, which leads to an increase in the ratio of the control pulse duration to the period of the pulse train at a given frequency and, accordingly,

pulse rate, forming an increase in the average current flowing by the logic device

The drawing shows the functional diagram of the drive.

The DC electric drive contains an electric motor 1 with a rotating speed pulse sensor 2 installed on its shaft, the output of which is connected to the input of the logical device 3 Comparison. The second input of the latter is connected to the output of the master frequency generator 4. The armature winding of the electric motor 1 is connected to the output of the power switch 5. In addition, the electric drive contains the sensor 6 of the current of the electric motor circuit 1, output through a series-connected block 7 of forming the average current and generator 8 of pulses with an adjustable duty cycle connected to the first input of the logical element 9 o

The second input of the latter is connected to the output of the logical unit 3 of the comparison, and the output to the input of the power switch 5.

A filter may be used as the average current value generating unit 7. The variable-duty cycle pulse generator 8 may consist of a series-connected multivibrator and one; vibrator with adjustable pulse duration.

The drive works as follows.

The master frequency generator 4 generates a sequence of pulses arriving at the first input of the comparison logic device 3, the second input of which receives a sequence of pulses from the sensor 2 speed of rotation of the motor 1 o In the phase control mode, each pulse of the generator 4 forms a leading edge of the control pulse at the output logic device 3 comparison, and the pulse from the sensor 2 speed of rotation forms the trailing edge of the control pulse.

measles electric motor 1, compensating for the increased load torque.

This current is detected by the sensor.

6 current root chain. The current signal is averaged by the average current value generating unit 7.

The generated average current value determines the magnitude of the control signal at the input of the generator 8 pulses with an adjustable duty cycle. The increase in the average current leads to an increase in the duty cycle of the pulses at the second input of the logic element 9 AND

and, accordingly, to an increase in the time of opening of the power switch 5 in the following period through the first input of the logic element 9 AND of the control pulse from the logical device 3 of the comparison.

An increase in the opening time of the power switch 5 leads to an increase in the current in the motor bark and a decrease in the phase shift by comparing the following sequences of pulses

The stability of control is determined by the choice of the dynamic characteristics of the drive units.

The feedback described at the moment of switching on the electric drive blocks the power switch 5, since in the absence of current through the bark of the electric motor 1, the control input of the generator 8 pulses With a variable duty cycle, a zero signal arrives. In connection with this, a necessary operating condition is the presence of pulses at the output of the generator of 8 pulses with a zero signal at its input. In this case, the pulse duty cycle must be sufficient to form the initial current on the electric motor bark 1 o

Thus, the DC electric drive provides a stabilization of the current pulse rate in a wide range of loads and rotational speed, which allows the use of a rotational speed sensor low

class of accuracy and good controllability of the electric drive

Claims (1)

Invention Formula A DC motor that contains an electric motor with a rotary speed pulse sensor mounted on its shaft, the output of which is connected to the input of a comparison logic device, a second input connected to the output of the frequency setting generator, and a power switch whose output is connected to the motor winding, TL and - with the aim that improving the quality of regulation, the current sensor of the electric motor's root circuit, the average current value generating unit, the pulse generator with an adjustable duty cycle and the logic element And, the output of the current root sensor through the serial connected average current value generating unit and the pulse duty variable generator are connected to the first input of the logic element And, the second input of which is connected to the output of the logical comparator, the output of the logic element And is connected to the input power key. /