SU1220097A1 - D.c.drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in systems for automatically controlling the rotational speed of a direct current drive. The purpose of the invention is to improve the accuracy of stabilization of the speed when the load torque changes. The electric drive contains an electric motor (ED) 1, a generator of reference frequency 2, a frequency divider (PM) 3, a matching element 4 with a selsyn (C) 5 connected in series. In addition, the drive contains DC 6, connected via phase discriminator 7 and power switch 8 to the core winding ED I, correction unit 9, speed setting blocks 10.11, interface block 12, driver (F) 13. Introduction of dividers 14 and 15 the decoder 16 and the trigger 17 permits the passage of pulses with F 13 through the elements OR 19, and 20. This changes the phase of the signal by an amount proportional to the deviation of the rotational speed, increasing the stability of the electric drive. When the load moment changes, when the impulse with С 5 clones from its steady state, the electric drive provides an increase in the average voltage value, which leads to smaller errors in the stabilization of the speed of ED 1. j 2 ill. C & (Lu kae i-l with figure 1

Description

t

The invention relates to electrical engineering and can be used in systems for automatically controlling the rotational speed of electric drives and direct current, in particular, in systems containing a phase discriminator. a minator in the control channel and a selsyn as the speed sensor of the actuator shaft.

The purpose of the invention is to increase the accuracy of stabilization of the speed when the load torque changes.

Fig. I is a direct current electromotive circuit; figure 2 - timing charts of his work.

The DC motor (Fig. 1) contains an electric motor 1, a generator 2 of a reference frequency, the output of which is connected through series-connected frequency divider 3 and matching element 4 to the selsyn 5 mounted on the motor shaft 1, frequency divider 6, the input of which is connected to the generator 2 of the reference frequency, and the output through the phase discriminator and the power switch 8 to the core winding of the electric motor 1, the correction unit 9, the output of which is connected to the second input of the phase discriminator 7, speed setting blocks 10.11 speed which, through the interface block I2, are connected to a frequency divider 3, the output of the speed reference unit 10 is connected to the input of frequency divider 6, a driver 13, an input connected to the measuring winding of selsyn 5, serially connected frequency dividers 14, decoder 16, trigger 17, element AND 18 element OR I9, as well as element AND 20. The output element OR 19 is connected to the input of the correction unit 9. The output of the decoder 16 through the element AND 20 is connected to the second input of the element OR 19. The second input of the element AND 18 is connected to the first input of the frequency divider 15 , the second entrance to orogo shaper connected to the output 13, and no element inputs 20 and frequency divider 14, the other input connected to the output kotorogo- setting unit 10.

The device works as follows.

Pulses of frequency f, obtained by dividing by K times the frequency of the generator

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2 by divider 6 (where K is the coefficient set by the speed setting unit 10), is fed to the input of the phase discriminator 7. With the arrival of every 5 pulse fj, the phase discriminator 7 connects the electric motor 1 to the network via the power switch B. The rotation of the motor shaft 1, mechanically connected to the shaft of the resolver 5, and 10 leads to the appearance on the measuring winding of the resolver 5 pulses with a frequency f (J, which in the steady state is N times smaller than f and is determined by the formula

 - % eleven.

where f is the frequency of the signal supplied to the excitation winding of agriculture 5 through matching element 4 and divider 3 from the generator 2 of the reference frequency;

g is the rotation speed of the electric motor 1; P is the number of poles of the selsyn 5. Short frequency pulses f c, formed by shaper 13, arrive at the second inputs of dividers 14 and 13. At the same time, high potentials are set at the first output of decoder 16 and trigger 17. This permits the passage of a pulse from the imaging unit 13 through the element AND 20 and the element OR 19 to the input of the correction unit 9, which changes the phase of the signal f by an amount proportional to the deviation of the rotational speed I, increasing the stability of the device. The impulse from the correction unit 9 is fed to the second input of the phase discriminator 7. In this case, the signal for decelerating the electric motor 1 is given. The average voltage value to the electric motor 1 is determined by the phase error,; At the pulses f, and f. After the arrival of the pulse fj, the divider I4 starts counting from the zero state. The frequency of the signal at its output is f and is N times greater. frequency f (taken from the measuring winding of the selsyn 5 in the steady-state mode. Since there is a high potential at the output of the trigger 17, the pulses from the divider 14 pass through the AND 18 element and the OR 19 element and the correction unit 9 to the phase discriminator 7 input this frequency

the signals arriving at the inputs of the phase discriminator 7 are equal, since the conversion factors of dividers 6 and 14 are the same, and the pulses are shifted in phase by the value c. Thus, after the arrival of the pulse f | the inputs of the phase discriminator 7 alternate impulses of reference and feedback, and a voltage is applied to the motor 1, the average value of which

becomes the value of NCf .j-, measured by st

Noah at the moment of arrival of the pulse fg, where and is the voltage amplitude on the electric motor; cf (- - phase mismatch between the pulses of the generator 2 of the reference frequency and feedback.

Divider 15 counts the number of pulses arriving from divider 14. After the arrival of (N-1) pulses, a high potential appears at the second output of the decoder 16, which triggers trigger 17 and causes a low potential at its output, which prohibits the passage of pulses 14 through the element and 18.

In the steady state operation at the input of the correction unit 9 through the elements AND 20 and OR 19 comes a pulse from the selsyn 5. The timing diagrams of the device in the steady state (dl) are presented in figure 2, section T.

When the load moment changes, when the pulse from the selsyn 5 deviates from its steady state by Acf (figure 2, section I), the device operates in the same way, only all N-1 pulses from divider 15 are shifted by the same amount. In this case, the average voltage on the engine increases by the value of & U, defined as

whether

A f.N.Ujj -

The DC drive provides a N-fold increase in the average voltage supplied to the motor when the impulse from the selsyn 5 deviates from a position corresponding to the steady state operation. This provides less error stabilization speeds.

ti electric motor 5 when the load torque changes. In the case of a linear change in the moment of load, the error in stabilizing the speed of the speed D 57 5 of the electric motor is determined by the formula

- - f.

where M is the moment variation rate;

Mjj is the torque developed by the engine at zero speed and total voltage on the core winding and is N times less than in known devices.

Thus, the electric drive provides an increase in the accuracy of stabilization with a change in the load torque.

Claims (1)

Claims. A DC motor that contains an electric motor, a reference frequency generator, the output of which is connected through a first frequency divider and a matching element to a choke mounted on an electric motor shaft, a second frequency divider whose input is connected to a reference frequency generator, and an output through a phase discriminator and power key - to the motor winding, the correction unit, the output of which is connected to the second input of the phase discriminator, the first and second speed reference blocks, the outputs of which through the interface unit connected to the first frequency divider, the output of the first speed reference unit is connected. not connected to the input of the second frequency divider, driver, input connected to the measuring winding of the selsyn, characterized in that, in order to improve the accuracy of stabilizing the speed when changing the load moment, it is entered the third and fourth frequency dividers connected in series, a decoder, a trigger, the first AND element, an OR element, and a second AND element, the output of the OR element is connected to the input of the correction unit, the output of the decoder is connected through the second AND element to the second input of the OR element, the second first entrance 512200976 element And is connected to the first input element And and the third divider of the often-partial frequency divider, the second one, the friend of which the input is connected to the input of which is connected to the output of the first block of the task driver, and second-rate inputs. Compiled by Y.Vorobyov Editor N. -Gunko Tehred N. Bonkalo Proofreader G. Reshetnik     - - - --11 - - “-fc -“ - -.-. -.- i. | l "MM ... Order 1330/59 Circulation 631 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Branch of PSh Patent, Uzhgorod, Proektna St., 4