SU1119151A1 - D.c.drive - Google Patents

Abstract

A DC ELECTRIC DRIVE containing a motor with a pulse frequency sensor, connected to a power amplifier, connected to the output of a digital frequency regulator equipped with an additional scaling factor switching input, so that in order to expand the range and improve the accuracy of rotational speed control, sequentially connected frequency-code converter, code converter, memory register and code-frequency converter, output are entered into it which is connected to the feedback input of the digital frequency regulator and to the synchronizing lower memory register input, and the frequency input to the output of the pulse frequency rotation sensor connected to the input of the frequency-code converter, and the input of the scale factors of the digital frequency controller connected to memory register output.

Description

The invention relates to electrical engineering, in particular to electric drives with a wide range of control of the rotation frequency of an electric motor.

Known electrically; LB of direct current, containing a series-connected digital controller with reference and feedback inputs for motor speed, power amplifier and motor with frequency sensor in the feedback circuit. In this electric drive, the feedback signal is generated in the form of a pulse frequency period of the frequency sensor. The required value of the rotational speed is specified as a time interval and is entered from the setpoint into the reversible counter in the parallel binary code. In a reversible counter, a deviation is generated as a result of the subtraction of the reference frequency pulses from the reference code during a time interval equal to the pulse period of the frequency sensor. Thus, the regulation error is calculated during each period of the frequency output of the rotational speed sensor, which ensures good characteristics of the electric drive L. .

However, increasing the speed of the engine reduces the control accuracy, which prevents the use of frequency sensors with high resolution and, thereby, limits the range of control of the frequency of rotation.

The closest to the invention according to the technical essence is an electric drive of direct current, containing an electric motor with a pulse frequency sensor, connected to a power amplifier connected to the output of a digital frequency regulator equipped with an additional input of switching of large-scale coefficients. When a long-time electric drive is operated, in the lower part of the tuning range, the feedback input of the digital frequency controller receives pulses with a frequency equal to the output frequency of the pulse frequency rotation sensor. If the electric drive operates in the upper part of the control range, then a signal is generated in it that ensures the switching of the scale factors of the digital frequency controller. With this frequency.

The input to the feedback input of the digital controller is Hi (integer) times less than the output frequency of the IMPulse motor speed sensor, which allows, without reducing accuracy, to widen the frequency control range of rotation 2 times.

However, with high demands on accuracy, this drive cannot provide a wide range of rotational speed control, as within the control range it is required to repeatedly, with a small discrete step, change the scale factors of the digital speed controller.

The purpose of the invention is to expand the range and improve the accuracy of controlling the rotational speed.

The delivered circuit is achieved by the fact that a DC motor connected to the output of a digital frequency regulator equipped with an additional switching input of the coefficients is connected to a direct current drive containing a digital frequency controller equipped with an additional switching input of frequency coefficients. A code converter , the memory register and the code frequency converter, the output of which is connected to the iVi poBoro feedback input of the frequency regulator and to the synchronizing th entry memory register, and input frequencies ny - shlsodu yutulsnogo datg to snip the rotational speed of which is connected to the input transducer chastotakod, wherein the input switching ZOOM coefficients, Sch1frovogo re.gul frequency torus connected to the output of the memory register.

On 4ig. 1 shows the structural scheme of the proposed electric drive; in fig. 2 - input-output characteristic of the code converter in a logarithmic scale; in fig. 3 is a schematic diagram of a code converter, an embodiment; Fig. 4 is a circuit diagram of a code-frequency converter, an embodiment; in fig. 5 - dependence of the output frequency of the converter code - frequency on the output frequency of the pulse frequency of rotation.

The direct current drive comprises an electric motor 1 with a pulse sensor 2 of rotational speed connected to a power amplifier 3 connected to the output of a digital frequency controller 4, equipped with an additional input of switching of scaling factors. Frequency converter 5 - code, code converter 6, memory register 7 and code - frequency converter 8 are connected in series. The output of the code converter 8 is the frequency connected to the feedback input of the digital frequency controller 4 and the clock input of memory register 7, and the frequency input to the output of the rotational frequency sensor 2 connected to the input of the frequency converter 5 code. The switching input of the scale factors of the digital controller 4 frequencies is connected to the output of the register 7 of the memory. The direct current drive operates as follows. The input of the digital frequency controller 4 (Fig. 1) is supplied with a control action corresponding to a predetermined rotation frequency. In this case, the motor 1 rotates, and at the output of the pulse sensor 2 of the rotation frequency, a pulse train is formed with a frequency i |. . These impulses. The transducer enters the frequency converter 5 — a code at the output of which a code N rcc is formed that is proportional to the frequency of rotation of the electric motor 1 and -k- .J -V G) pch-pch 3 where ICfjmj is the transmission coefficient of the converter 5 frequency code; 21 - resolution of the pulse frequency sensor 2 rotation, imp / rev; 52 - 4acTota angular rotation of the electric motor 1. Frequency converter 5 - the code can be performed using the direct conversion method, which consists of counting the number of pulses of the frequency being converted into a reference time interval, or the method of following equilibrium. Frequency-to-frequency converter 5 does not impose high accuracy on conversion j since codeH. Uses directly to form a control error. The code proportional to the frequency of rotation of the electric motor 1, from the output of the converter 5 is frequency - the code is fed to the input of the converter 6 of the code. From figure 2, where the characteristic of the output of the converter of the 6th code is shown on a logarithmic scale, it follows that, 2 with N m pch mm -1 IJ 9 pch-n ifmin with pch picgg, g where i 1.2, ..., - - integer; ten-t ЕО, And the maximum integer satisfying the inequality D / 2H; ent is a fraction fraction; nvKm. - adjustment range fl4fc mm of rotational speed of motor 1 (range of change of the output code of converter 5 frequency - code), mai value of output, code of converter 5 frequency - code corresponding to the upper limit of the range of control of rotation frequency; Нрц min value of the output code of the converter 5 frequency - the code corresponding to the lower limit of the frequency control range. From the expression (1) it follows that if the value of the rotational speed of the engine 1 is less than the value corresponding to the lower limit of the control range, the binary code at the output of the converter 6 of the code corresponds to the number 2, if the value of the frequency of rotation of the engine 1 is greater than the value corresponding to the upper limit of the adjustment range, then the binary code at the output of the converter 6 of the code corresponds to the number 2; With an increase in the rotational speed of engine 1 within the limits of the control range by two times, the code at the output of converter 6 of the code is halved, and when reduced, it is doubled. The advantageous code of the converter 6 of the code (Fig. 1) is fixed by the memory register 7 and is fed to the information inputs of the code-frequency converter 8, to the frequency input of which a pulse sequence is received from output 1 and pulse generator 2 of the rotation frequency. The frequency at the output of the code-frequency converter 8 is determined by the expression pc 4 L-) nKMg- The pulses of the output frequency of the converter 8 code-frequency are fed to the feedback input of the digital controller 4 frequencies and to the clock input of the memory register 7. In this case, in the memory register 7, the output code of the code converter 6 is fixed. It follows from expressions (1) and (2) that when the rotational speed of the engine 1 is changed in the entire adjustment range, the output frequency of the converter 8 the code-frequency changes in the range Ufc TL (3). In FIG. 3 shows the dependence of the output frequency of the code-frequency converter 8 on the output frequency of the pulse sensor 2 rotational frequency, from which it follows that the transmission coefficient of the feedback channel of the electric drive is set depending on the rotation frequency of the electric motor 1 so that the entire frequency control range performs ratio (3). The output code of the code converter 6 (Fig. 1), fixed in memory register 7, is input to the switching input of the scale factors of the digital frequency controller 4, in which the scale factors corresponding to the feedback channel transfer coefficient are set in the function of this code. Since the output code of converter 6 of the code takes the values 2, (-0,1,2, ..., -), the switching of the scaling factors in the digital frequency control 4 can be carried out using shift operations (meaning that it operates in binary code), and when using EV; M (for example, Electronics-60), the change of scale factors can be done. Thus, the converter 6 of the code, depending on the current rotation frequency of the engine 1, controls the output frequency of the converter 8 516 code - a frequency that is proportional to the output frequency of the pulse sensor 2 of the rotation frequency in accordance with the expression (2), and changes the scale factors In the digital controller 4 frequencies. Converter In code - frequency (Fig. 4) contains a pulse counter, formed by the triggers 9, -9 ,, the direct outputs of which are connected respectively to the first inputs of the logic elements I. The second, the input of the logical element And 10, (2,3, ..., g () is connected to the output of the logical element And 10. and the second input of the logical element And 10, is connected to the counting input of the trigger 9, |. The outputs logic elements And Yu, .10; (connected respectively to the first inputs of logic elements And 11 / 2.2 2 (The first input of the logic element 11 llj is connected to the counting input of the pulse counter (to the counting input of the trigger 9). The outputs of the logic elements I 1 1. / connected to the corresponding inputs of the logic element OR 12, - the output of which is connected through the delay element 13 ki (delay time x 0.1 T where T.- „is the minimum value of pF | T) TF of the frequency period fed to the frequency input of the converter 8 code frequency) to the inputs Setting zero triggers 9, (- 9fl. Counting input trigger 9ts By the frequency input of the converter, the 8 code is the frequency, the second inputs of the logic elements AND From 1l2, n + i are the information inputs of the converter 8, the code-frequency, the output of the logic element SchSch 12 is the output of the converter 8, the code-frequency. Converter 8 code-frequency works as follows. The counting input of the pulse counter, formed by triggers connected in series, receives the frequency fj. Triggers are switched on the falling edge of the frequency tg, pulses. At the outputs of logic elements And 10j (-10. Pulse sequences are formed with frequencies, respectively, jriex | a1v | nd,. These pulse sequences. Arrive at the first input, respectively, of logic elements AND ig-} btMiV input logical

.7.

element 11 is received frequency pulses igy.

The information inputs X, ..., X of the code-frequency converter 8 (the second inputs of the logic elements I1 l2.)) Receive a binary code Hgj (. It can take the values 6X 2 (i 0,1,2, ..., p ), (four)

which ensures the uniformity of the output frequency converter 8 code-frequency.

From expression (4) it follows that at any given time the logical unit is present at the second input of only one of the logical elements 11, -11; (pi,).

If) i 2 (0,1, ..., p), then through the logical element 11g (rm) through the loic element OR 12, the output of the converter 8 code - frequency receives a pulse sequence whose frequency is equal to

 I Thus, the value of the output frequency of the converter code 8 - hour. Tota is defined by the expression

c

in

 i

..f 2 "

nv4

where n is the number of flip-flops included in converter 8, the code is the frequency.

In this case, the frequency can take the value

PKCH J. 0 ,,., N)

Frequency pulses of 1 Hz are fed to the inputs Setting zero triggers and set them to zero (initial) state. This ensures synchronization of the beginning of formation of alternate periods of output frequencies of logic elements AND 10; f, -lO.j, with the moment when the formation of the current period of the output frequency of the frequency converter 8 is completed.

The code converter 6 (FIG. 5) is a combinational device that performs logic functions,

x, -Q, "

, - ,;

f-j-Qm vi-iQm-

 1C Q nQm-I Q m-g 7 m- “f + 7“ -1 -and k QroQm-iQm-7 i m-Kfa trv-n + i j.

1518.

where is x ... , X | - binary code values at the corresponding outputs of the code converter 6; , - m binary code values at the outputs of the k bits of the frequency converter — code 5 (FIG. 1) k m- (j vi) —number of the bits of the frequency converter 5; code — connected to the corresponding inputs of the code converter 6; m "i er t 6d lNn J (nh lpJ number of bits of the frequency converter 5 - code;

Y is an integer, which is defined by the following expressions mn if yi. „,„ - 2 ° eHHpchkp,; g, 1,

L5 $ 0, then 5} 1 + ent eo tHn4mir, l;

 ecliNnchx irt-2® 1,5fO, To.:i eviit -ug, Vln4Km; nT wheredep is intact

part of the fraction; D is the frequency control range;

MCPC mih is the output code of the frequency-5 converter, which corresponds to the lower limit of the frequency control range.

Converter 6 code (Fig. 5) works as follows.

G-direct outputs k high-order bits of the frequency converter 5 - the code signals are received to the corresponding inputs of the converter 6 of the code

Qm- (k-0 t the rotational speed of an electric motor does not exceed the level corresponding to its doubled

value. At the lower limit of the control range, then all 1 inputs of converter 6 of the code have a logical zero signal. If the engine speed 1 is in accordance with .t. the upper limit of the control range, then a logic signal is present at the input of the converter of the 6th code connected to the upper section of the converter of the 5th frequency code

units.

From the expression (5) it follows that the signal of a logical unit at a time can be present at the output of only one logical element AND

(only on one of the outputs of the converter of the 6th code), and this logical element is the one whose input is connected to the output: the most senior of the bits of the 5 frequency converter is the code whose state is different from zero. If the logic zero signal is present at all inputs of the converter of code 6, then a logical unit signal is present at its (k + 1) -M output. If at the output of the higher bit there is a level of a logical unit, then the first output of the converter of the 6th code contains a signal of a logical unit. Thus, the code converter 6 has an input-output characteristic, similar to that shown in FIG. 2. In the proposed electric drive, the duration of the periods of the frequency signal input to the feedback input of the digital frequency controller varies within

laggNm 1 f- Of. Qt 4fcmi CHAP 1 At THIS, the last relation is fulfilled in the whole range of rotational speed control (Fig. 3), which ensures high accuracy of adjustment. Thus, the introduction; In a wide-frequency drive, a frequency converter — a code, a code converter, a memory recorder, and a code – frequency converter provides for the expansion and increase of the speed control function.

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Claims (1)

A DC electric drive, comprising an electric motor with a pulse speed sensor, connected to a power amplifier, an input connected to the output of a digital frequency regulator, equipped with an additional input for switching scale factors, which is different in order to expanding the range and increasing the accuracy of speed control, a frequency-to-code converter, a code converter, a memory register, and a code-frequency converter, the output of which are sequentially connected connected to the feedback input of the digital frequency controller and to the synchronizing input of the memory register, and the frequency input of the pulse speed sensor connected to the input of the frequency-to-code converter, and the input of switching the scale factors of the digital frequency controller is connected to the output of the memory register. to the exit