SU1399876A1 - Digital electric drive - Google Patents

Abstract

The invention relates to electrical engineering and m. Used in automated DC motors. The purpose of the invention is to increase the accuracy of the rotation frequency control of the electric drive. The electric drive comprises an electric motor 1 with a rotational speed sensor 3. The signals from sensor 3 are fed to the input of the distributor 4 pulses, to-ry alternately starts each of 2 n one-shot block 5 units, at the outputs to which ода a sequence of pulses of a given duration is formed. The decoder 9 converts the status code of the outputs of block 5 to the binary code of the system state. At code 01, the electric motor 1, controlled via the integrating converter 8 and the power amplifier -2, is accelerated, at code 10 it is decelerated. The duration of the adjustment pulses depends on the magnitude of the mismatch between the actual and specified time intervals. With code 00, i.e. in the intervals between the control pulses, by turning off the integrator input, the influence of the parasitic component of the input current of the integrating converter is eliminated. 2 Il. i (L

Description

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The invention relates to electrical engineering and can be used in automated DC motors,

The aim of the invention is to improve the accuracy of controlling the frequency of rotation of the drive.

Fig, 1 shows a functional diagram of a digital electric drive; Fig. 2 illustrates a signal conversion circuit from the output of a digital one-shot unit.

The digital electric drive contains a DC electric motor 1, the root winding of which is connected to the output of power amplifier 2, a motor speed sensor 3, the output of which is connected to the input of the distributor 4 pulses, and a block of 5 digital one-shot with restarting. The first inputs of the block 5 are connected to the corresponding outputs of the distributor 4 pulses. In addition, the digital electric drive contains a control 6 control signals, the first and second information outputs of which are connected to the second, third and information inputs of the digital one-oscillators of block 5, the adder 7 with 2p inputs, the output of which is connected to one of the inputs of the integrated. a transducer 8, a decoder 9 with 2p inputs and a switch 10 connected to the input of the integrating converter 8, the output of the decoder 9 is connected to the input of switch 10, and its 2p inputs are connected to the corresponding outputs of the block 5 digital single-oscillators. The output of the integrating converter 8 is connected to the input of the power amplifier 2.

The drive works as follows.

The decoder 9 is designed to convert the code of the state of the outputs of digital one-shot to the binary code of the state of the control system. The latter can be in 3 states: 1, Regulation in the direction of increasing the speed, 2, Regulation in the direction of decreasing the speed, 3, Waiting (no regulation),

The system status information is contained in the states of the digital single vibrator outputs. If on the 2. outputs of one-shot signals dominate, s.otpetstvuyuyshe level logs

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5 o 5 o Q

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If the system is in the 1st state. If 1 is dominated by the single-vibrator output, the system is in the 2nd state, with the same number of zeros and ones, the system is in the 3rd state.

The decoder 9 (FIG. 2) consists of two major elements 11 and 12, each of which has (2-fl) input, 2p inputs of each majority element are connected to 2n outputs of block 5 digital one-shot one-shot. The () th inputs of elements 11 and 12 are supplied with levels O and 1, respectively.

The switch 10 is designed to convert the binary code of the control system state into negative pulses (for the 1st state) or positive (for the 2nd state) polarity, as well as for disconnecting the integrator's input in the idle mode (3rd state ). Switch 10 consists of two keys 13 and 14, the control of which inputs are connected respectively to the forward output of the major element 11 and to the inverting output of the major element 12, the information input of the key 13 is connected to the level 1 signal, and the information input of the key 14 - with the level signal O, the outputs of the keys 13 and 14 are interconnected, and the common point of their outputs is the output of the switch 10, the keys 13 and 14 are opened when a signal, level 1, is applied to their control inputs and closed when fed to their control inputs are sig ala the level of O

Adjustment pulses (positive or negative polarity) are generated relative to the midpoint formed by a voltage divider consisting of two resistors 15 and 16 of the integrating converter. The middle point of the voltage divider is connected to the non-inverting input of opamp 17,

A capacitor 18 is connected to the feedback loop of the operational amplifier 17. A variable resistor 19 is connected between the inverting input of the amplifier 17 and the switch output. The integrator is equipped with a correction circuit consisting of a series connection of a variable resistor 20 and a capacitor 21 connected between the output of the adder 7 and the inverting input. operational amplifier 17.

At the initial time (when turned on), the outputs of block 5 of digital single-oscillators form zero-level signals. At the output of the majority element 11 of the decoder 9 a signal of level O is formed, and at the inverting output of the majority element 12 a signal of level 1, i.e. The code 01 appears at the outputs of the decoder 9, corresponding to the location of the control system in the 1st state. The key 14, since the signal at its control input has a level 1, is opened, and the key 13 is closed (at its control input there is a zero signal). Thus, a negative polarity signal appears at the output of switch 10 relative to the input of integrating converter 8. At the same time, the voltage at the output of integrating converter 8 supplied through power amplifier 2 to electric motor 1 increases, the motor shaft begins to rotate, and the signals from the sensor 3 rotational speeds with a frequency proportional to the rotational speed, are fed to the input of the distributor 4 pulses. The distributor 4 pulses alternately starts each of the 2n single-vibrators of block 5, at the outputs of which a sequence of pulses of a given duration T is formed. The decoder 9 converts the state code of the outputs of the digital single-shot into the binary code of the state of the control system (code 01 corresponds to the 1st state, code 10 to the 2nd state, code 00 to the 3rd state). If the inputs of the switch have a code 01 or 10, control pulses are generated at the output, respectively, of negative or positive polarity relative to the common point of the integrating converter 8, formed by resistors 15 and 16. The pitch of the control pulses depends on the magnitude of the error between the actual and the specified time intervals. With the input code 00, the keys 13 and 14 are closed, the output of resistor 19 connected to the output of switch 10 has an infinitely large impedance relative to the common point, which is equivalent to disconnecting this (main) input of the integrating converter 8. The voltage from the output of the integrating converter 8 through the amplifier 2 power arrives

to the electric motor 1 and changes the frequency of rotation of the electric motor shaft in the direction of decreasing the difference between the actual and the specified time interval.

A circuit consisting of an adder 7, a variable resistor 20 and a capacitor 21 serves to improve the quality of the regulation. When operating, the input of the adder 7 receives a sequence of pulses from the outputs of the digital one-vibrators of the block 5. The adder 7 selects pulses, taking into account the sign, the duration and amplitudes of which depend on the magnitude of the error between the actual and the specified time intervals. Higher, the impulse arrives at the input of the correction circuit 20 and 21 and is converted by the integrating converter 8.

Upon arrival at the Stop input of the control signal block 5 from the sensor 6, the signals of the one-vibrator signals are generated at level G. At the output of the decoder 9, code 10 is generated, which causes the output of switch 10 to produce a positive polarity signal relative to the input of the integrating converter 8 In this case, the voltage at the output of the integrating converter decreases and the motor 1 stops.

Adjustment accuracy is enhanced by eliminating parasitic effects.

component of the input current of the integrating operational amplifier in the intervals between the control pulses. In the steady state of operation of the motor, the duration of the control pulses is dramatically reduced compared with the Start and Stop modes.

Claims (1)

Invention Formula A digital electric drive that contains a DC motor, the root winding of which is connected to the power amplifier voltage, a motor speed sensor, an output connected to the input of the pulse distributor, a unit consisting of 2p digital single-oscillators with a restart, the perch terminals of which are connected to the corresponding outputs are distributed. 1p.p. pulses, signal setter: control governing, first the second and information p1 outputs of which are connected respectively to the second, third and Information inputs of the digital one-shot block, an adder with 2-pin inputs connected to the corresponding outputs of the digital one-shot block connected by an output to the input of the preamplifier-integrated power amplifier, characterized in control accuracy, a descrambler with 2p inputs connected to the corresponding outputs of the digital one-shot block and a switch whose input is connected to the output encoder, and the output - with the diverter, the output of the integrating converter connected to the th input. by (par.2