SU1564590A1 - Apparatus for controlling rotational speed of d.c. electric motor - Google Patents

Abstract

In order to improve control accuracy, a master oscillator, a reversible counter, a control unit, two comparators, a setting block, a modulo two, a low-pass filter, an emitter follower and a digital-analog converter are entered into the device. The control unit contains the first and second pulse splitters, the inputs of which are the first and second inputs of the block, a pulse distributor, two pulse-pulse shapers, an RS flip-flop, two keys, an OR element, an OR element — NOT, and a short pulse shaper.

Description

the OR element, the OR-NOT element and the short pulse shaper, whose output is the first output of the block, and the input is connected to the output of the OR element, the first and second pulse splitters are connected to the first inputs of the first and second pulse shapers, respectively. pulse, the second inputs of which are connected to the first and second inputs of the pulse distributor, respectively, whose input is connected to the input of the first pulse splitter, the output of the first pulse-pulse generator is connected to the R-input of the short-circuit and the first the input of the OR element, the output of the second pulse-pulse generator is connected to the S-input of the short-circuit trigger and to the second input of the OR element, the third input of which is connected to the output of the OR element, whose first and second EHO are connected to the outputs of the first and second keys, respectively The first inputs of which are the third and fourth inputs of the block, respectively, the direct output of the trigger is connected to the second input of the first key, and the inverse output is connected to the second input of the second key and is the second output of the block.

The invention relates to electrical engineering and can be used in automated systems that are subject to the requirements of high accuracy of speed.

The aim of the invention is to improve the accuracy of control.

FIG. Figure 1 shows a block diagram of a device for controlling the speed of rotation of an electric motor; in FIG. 2 is a block diagram of the control unit; in fig. 3 is a schematic diagram of a pulse-pulse shaper; on fng, 4 - schematic diagram of a short pulse shaper.

The device contains an executive unit 1 with an electric motor LJ and a power amplifier C, an operational amplifier 2 with resistors 2-f-2j, a discriminator 3, a speed sensor 4, an attenuator 5, a power supply 6, a setting block 7, a master oscillator 8, a control block 9, a reversible counter 10, a digital-analog converter 11, a first 4 12 and a second 13 comparators, an adder 14 modulo two, a low-frequency filter 15 and an emitter follower 16,

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Control unit 9 has inputs 17-

20, outputs 21 and 22, and contains the first 23 and second 24 pulse splitters, the distributor 25 pulses, the first 26 and second 27 formers of the pulse-pulse, the RS flip-flop 28, the first 29 and the second 30 keys, the element OR 31, the element OR- NOT 32, shaper 33 short pulse.

Each of the pulse-pulse formers 26 and 27 contains two D-flip-flops 34 and 35 and the element OR-NO 36,

The shaper 33 short pulse contains three logical inverters 37-39 and the element AND NOT 40,

Shapers 26 and 27 (1) pulse-pulse, as well as short pulse shaper 33 (2, 3), are known elements of the pulse technique.

The speed sensor 4 and frequency discriminator 3 close the main circuit of the automatic rotation speed control of the motor C, speed sensor 4, master oscillator 8, control unit 9, reversible counter 10 and digital-analog converter 1 form a correction circuit, and speed sensor 4, master oscillator 8, adder 14 modulo two, low-pass filter 15 and emitter follower 16 — second feedback feedback loop. In addition, the first feedback loop has local feedback through comparators 12 and 13, to the inputs which are supplied with constant voltage from block 7 of settings.

The device works as follows

When the power supply 6 is turned on, the output voltage of the operational amplifier 2 sets the maximum voltage and accelerates the electric motor H, since a constant voltage from the attenuator 5 is applied to the non-inverting input of the operational amplifier 2 and a low pulse frequency at the inverting input speed sensor 4 and the corresponding action of feedback feedback loops,

In the main control loop, at the output of the frequency discriminator 3 from each rectangular pulse of the speed sensor 4, a pulse is formed with exponentially growing and falling edges, comparing these voltage pulses fed through the resistor 2P to the inverting input of the operational amplifier 2, with the voltage supplied from the output of the attenuator 5 to the non-inverting input of the operational amplifier 2, the latter produces a voltage to control the electric motor 1, in which the acceleration phase takes place (when electric ktrodvigatel 1, 6 connected to the power source) and the phase dinamkuderzhivaets low voltage level given by the setting unit 7.

When the synchronous rotational speed is reached and its frequency is exceeded, the speed sensor 4 pulses become larger than the frequency of the master oscillator 8, 3 as a result, the control unit 9 generates pulses in the direction of summation for the reversible counter 10, and the code state of the latter increases and the voltage increases accordingly output digital-to-analog converter 11,

15 which through the resistor 2 / acts on the inverting input of the operational amplifier 2, with increasing voltage on the inverting input of the operational amplifier 2 in the output signal

20 of the latter, the acceleration phase decreases and the dynamic braking phase of the motor C increases. As a result, when overshoot the braking effect of braking begins to increase (when the electric motor on the motor 1 1, When the power C is disconnected from the power source 6), the content overshoot re - Such a pulse-width control of the inverse counter 10 is growing rapidly,

accordingly, the output voltage of the digital-analogue transformer increases, which makes it possible to control the motor 1, more dynamically and efficiently.

ZS l 11, At some voltage level set by the setting unit 7, the top level comparator 3 is triggered and in the control unit 9 the formation of pulses in the nVB of the first correction loop is prohibited the control unit 9 compares the pulse frequency of the speed sensor 4 with the pulse frequency of the master oscillator 8 and shaping, summing, Thus, the counting pulses for reversing the output voltage of the digital-analog

the counter 10 and the signal of the direction of the inverter 11 is limited to that. The pulses of the master oscillator 8 some voltage (upper) level reduce the contents of the reversing counter 10, and the pulses of the speed sensor 4 increase.

This double-sided limitation of the operation of the digital-to-analog converter 11 together with the reversible counter 10 eliminates the possible overflow of the reversible counter 10 in both the forward and reverse of the motor 1, the pulse frequency of the speed sensor 4 is less than the frequency of the master oscillator 8, therefore an arbitrary number , and, consequently, the one written to the reversible counter 10 at the time of power-up, decreases and, accordingly, the voltage at the output of the digital-analogue voltage decreases.

the formation of an abrupt jump in the correction voltage, which would lead to a deterioration of the transient process. As a result, the damping of the converter 11 is increased to the level specified by the 50 transition process and shortened by the unit 7 settings with the help of a computer

rarator of the lower level, when triggered-Thus, the first correction of which in block 9 of the control is prohibited the formation of subtractive, im55

pulses and the formation of only summing pulses for the reversible counter 10 is allowed. As a result, the counting stops at the output of the digital-to-analog converter 11

The overclocking circuit also contributes to the acceleration of the electric motor 1, but to a much lesser extent

one

compared to the main control loop,

I The main control loop outputs. 1D electric motor to subsynchronous

1564590.

a low voltage level maintained by the setpoint block 7 is maintained.

When the synchronous rotational speed is reached and its frequency is exceeded, the speed sensor 4 pulses become larger than the frequency of the master oscillator 8, 3 as a result, the control unit 9 generates pulses in the summation direction for the reversible counter 10, and the code state of the latter increases and the voltage increases accordingly output digital-to-analog converter 11,

5 which, through a resistor 2 /, acts on the inverting input of the operational amplifier 2, with increasing voltage on the inverting input of the operational amplifier 2 in the output signal

0 of the latter, the acceleration phase decreases and the dynamic braking phase of the motor C increases. As a result, the deceleration effect starts to increase during overshooting. 11 At some voltage level set by the setting unit 7, the top level comparator 3 is activated and in the control unit 9 the formation of pulses in the voltage is inhibited

Such a two-way limitation of the operation of the digital-analog converter 11 together with the reversible counter 10 eliminates the possible overflow of the reversible counter 10 in both the forward and reverse circuits at the acceleration stage also contributes to the acceleration of the electric motor 1, but to a much lesser extent

one

compared to the main control loop,

I The main control loop outputs. 1D electric motor to subsynchronous

speed and further due to the action of the first correction circuit, the motor 11 is in synchronism. In this case, the reversible counter 10 through the control unit 9 integrates the frequency difference of the pulses from the master oscillator 8 and the speed sensor 4 and, via a digital-to-analog converter 11 and a resistor 2, outputs a correction voltage to the inverting input of the operational amplifier 2,

When establishing the synchronous speed of the pulse frequency of the sensor 4, the speed of the master oscillator 8 is equal, the contents of the reversible counter 0 oscillates by a unit of the least significant bit, and thus the output of the digital-to-analog converter I1 maintains almost the same voltage

In the second correction control loop, during acceleration, the output of the emitter follower 16 establishes a certain average voltage, since the pulse frequency from the master oscillator 8 is greater than that from the speed sensor 4, and the phase shift between them continuously changes,

When a synchronous speed is reached, a constant phase difference between the pulses of the speed sensor 4 and the master oscillator 8 is established, and the corresponding voltage value at the output of the emitter follower 16, which is corrective and through the resistor 2, acts on the inverting input of the operational amplifier 2,

When the specified phase difference changes, the duty ratio of the pulses at the output of the adder changes accordingly.

14 modulo two and further through the filter

At a low frequency, the average voltage at the output of the emitter follower is 16. If in synchronous mode the phase difference of the frequency sequences under consideration is zero (the pulses coincide in phase), then at the output of the emitter follower 16 we obtain the minimum correction voltage. If the phase difference of the frequency sequences under consideration is equal to T (the pulses are opposite in phase), then we obtain the maximum correction voltage. The nominal phase difference is 1G / 2, and a decrease in this phase difference causes accelerating corrective action, and an increase, respectively, retarding effect on the electric motor 1,. Thus, the second correction circuit processes the phase difference of the compared pulse sequences and thereby stabilizes the instantaneous rotational speed. electric motor 1.

The described processes in the corrective circuits flow simultaneously, providing a quick acceleration of the electric motor 1 and its synchronization input. The voltage value at the noninverting input of the operational amplifier 2 determines the initial conditions of the automatic tuning system, the magnitude of this voltage set by the attenuator 5, it is necessary to choose so that, by means of the main control loop, the rotational speed of the electric motor 1 is close to synchronous. This is due to the fact that the transfer coefficients (gains) of the main control loop and the correction circuits are sharply different, and therefore, when forcibly controlling the rotational speed of the motor Q, it is necessary to synchronously change both the output voltage of the attenuator 5 and the frequency of the master oscillator 8 that is not entirely convenient. Therefore, it is more expedient to use the proposed device to stabilize the rotation speed of a direct current electric motor.

But the end of acceleration of the motor lj when rotating at a synchronous speed using the main control loop provides control in which a pulse control signal is also generated for each pulse of the speed sensor 4, which includes a dynamic deceleration phase, which improves the control dynamics, since as a result of the drift of the elements of the main control loop arising during operation, the speed of rotation of the electric motor 1 slowly moves away.

Using the first feedback feedback loop, the difference between the frequencies of the master oscillator 8 and the speed sensor 4 is monitored and eliminated. This ensures that the average synchronous speed is attained and constant, and as a result

the influence of the drift of the elements of the main control loop,

Using the second feedback feedback loop, the instantaneous rotational speed is ensured by the fact that the modulo-two adder 14 modulates the low-frequency filter 15 and the emitter follower 16 opposes a change in the phase shift between the pulses of the master oscillator 8 and the speed sensor 4, keeping this shift constant.

The control unit 9 operates as follows.

The 25 pulse distributor produces two sequences of non-coincident pulses, each of which

applied to the second inputs a shaping signal) for the element OR 31 such

Leu pulse-pulse 26 and 37, the first inputs of which are pulses from the outputs of the dividers 23 and 24 pulses. Thus, the pulses of a constant frequency of the master oscillator 8, which are fed to the input 17 of the block, after their passage through the divider 23 pulses and the shaper 26 never coincide with the pulses changing during acceleration of the motor 1 of the speed sensor 4 after their passage through the input 18 block through a divider 24 pulses and a driver 27, which eliminates the uncertainty of the state of the hS-flip-flop 28 when the compared pulses may coincide in time.

At synchronous speed, RS-flip-flop 28 synchronously switches to single and zero states, opening one and closing another of keys 29 and 30 with permissive levels at their first inputs connected via inputs 19 and 20 of the block to the output device has more advanced technical features and can be used

The comparators 12 and 13. In this case, the resolution level is understood in various areas of the technology, where a high level of stabilization of the voltage is required for a single logical level. As a result, the inverse state of the inputs is provided as OR-NOT 32 and at the third input of the element OR 31 of the instantaneous rotational speed, for example, in instrument making in digital angle meters, in radio engineering at sounding rotational speed, for example, in instrument making in digital angular meters, in radio engineering in sound

is the resolving level (zero 5Q recordings, sound reproduction, etc.

five

logical signal), the first and second, swarm inputs of which are pulses from drivers 26 and 27. These pulses pass through the OR circuit 3 and are transformed into pulses arriving at the counting input of a reversible counter 10 through the output of the 22 block. In this case, the counting direction is specified by a logical signal from the inverse output of the R-flip-flop 28 via the output 21 of the block.

During acceleration of the electric motor 1, when one of the comparators 12 and 13 produces a prohibiting voltage level (zero logic signal); the element OR NOT 32 also produces a inhibitory signal (a single logical 5

Thus, with the signal of the comparator 12 of the lower level, the forward counting pulses pass into the reversible counter 10, and with the signal of the comparator 13 of the upper level, respectively, the counting pulses

The proposed device for controlling the rotational speed of a direct current motor has a high accuracy of stabilization of the instantaneous rotational speed, a wide capture band and a short transient time. In the device, due to the action of correction circuits in which the correction voltage is generated digitally, it compensates.

the resulting drift of elements along the main analog control loop. In the prototype, the rotational speed of the electric motor for this reason slowly goes away.

The proposed device has improved technical characteristics and can be used

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5 in various areas of technology where high stabilization accuracy is required.

in various areas of technology where stabilization accuracy is high

instantaneous speed of rotation, for example, in instrument making in digital angle gauges, in radio engineering in sound recording, sound reproduction, etc.

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Claims (2)

1. DEVICE FOR CONTROL OF SPEED OF ROTATION OF ELECTRIC MOTOR. DC containing the source. a power supply connected to the input of the executive unit connected to a speed sensor, the output of which is connected to the input of the frequency discriminator, an operational amplifier with three resistors, the output of the operational amplifier is connected to the control input of the executive unit, the attenuator is connected to a power source, the output of the frequency discriminator is through the first the resistor is connected to the inverting input of the operational amplifier, with the exception of the fact that, in order to increase the accuracy of control, a master gene is introduced an inverter, a reversing counter, a control unit, two comparsors, a setting block, an adder modulo two, a low-pass filter, an emitter follower and a digital-to-analog converter, the output of which is connected to the first inputs of the comparators _ and through the second resistor to the inverting input of the operational amplifier, the master oscillator is connected to the first input of the control unit and the first input of the adder modulo two, the second inputs of the control unit and the adder modulo two are interconnected and with the output of the speed sensor, the first and second The odes of the control unit are connected to the first and second inputs of the reverse counter, the output of which is connected to the input of the digital-analog converter, the input of the settings block is connected to the output of the power supply, the outputs of the settings block are connected to the second inputs of the first and second comparators, respectively, the outputs of which are connected respectively to the third and the fourth inputs of the control unit, the output of the adder modulo two through a series-connected low-pass filter, an emitter follower and a third resistor connected to the inverter by the input of the operational amplifier, the output of the attenuator is connected to the non-inverting input of the operational amplifier, 2. The device according to claim 1, with the proviso that the control unit comprises first and second pulse dividers, the inputs of which are the first and second inputs of the block, a pulse distributor, two pulse-pulse shapers , RS-trigger, two keys, OR element, OR-HE element and a short pulse shaper, the output of which is the first output of the block, and the input is connected to the output of the OR element, the outputs of the first and second pulse dividers are connected to the first inputs accordingly, the first and second shapers pulse - pulse, second the inputs of which are connected to the first and second inputs of the pulse distributor, respectively, whose input is connected to the input of the first pulse divider, the output of the first driver, pulse-pulse 15 is connected to the R-input of the RS-trigger and the first input of the OR element, the output of the second driver pulse-pulse is connected to the S-input of the RS-trigger and to the second input of the OR element, the third input of which is connected to the output of the OR element, the first and second inputs of which are connected to the outputs of the first and second keys, respectively, the first inputs of which are yayutsya third and fourth inputs of the block, respectively, a direct output latch coupled to a second input of the first key and inverse output is connected to the second input of the second switch and a second output.