SU1399875A1 - Method of controlling d.c. motor speed - Google Patents

Abstract

The invention relates to electrical engineering and can be used for electric drives that do not have RPS sensors, speed feedback. The purpose of the invention is to improve the accuracy of the adjustment. According to this. The method is measured by block 23 and, in block 24, the instantaneous to the bulk values of the AC mains voltage is recorded. The real angle of control of the thyristor converter 4 is measured and the instantaneous values of the electromotive force of the converter are calculated. Subtracting from the last voltage drop in the active resistance of the crustal circuit, the motor emf is determined. 2 Il. 9 $ (L s 9; about x x h: n CPue.l

Description

The invention relates to an electrical sensor, in particular to automated electric drives, and can be used for automatic control systems for high-speed thyristor drives with small control errors that do not have speed feedback sensors.

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

Fig, 1 shows a diagram of the electric drive that implements the proposed method; in fig. 2 - diagrams that show the operation of the drive.

The drive contains series-connected regulators 1 and 2 of the EMF and current, respectively, connected at the input of the system 3 of the thyristor converter 4. To the output of the thyristor converter 4, the serially connected bark of the motor 5 and the current shunt 6 are connected. Parallel to the current shunt 6, the maximum current sensor 7 is connected to conduction interval of the converter, the output of which is connected to the first input of the first multiplication unit 8, the first input of the control unit 9 and the feedback input of the current regulator 2. The first output of the control system 3 is connected to the input of the first memory block 10, the first input of the first subtracting unit 11, the input of the function converter 12 and the first input of the second subtracting unit 13. The output of the functional converter 12 is connected via the second memory block 14 to the second input of the second subtracting unit 13, and the output of the first memory block 10 is connected to the second input of the first reading unit 11. The output of the subtracting unit 11 is connected to the first input of the adding unit 15, the output of which is connected to the third input of the second subtracting unit 13 via the second multiplication unit 16. The output of the multiplication unit 16 is also connected via a third memory block 17 to a second input of the second multiplication unit 16. The output of the second subtracting unit 13 through the sine function enumming unit 18 and the third multiplying unit 19 are connected to the first input of the third subtracting unit 20, to the second input of which the first multiplication unit I is connected. The output rpeTTievo of the subtraction unit 20 is connected to the feedback input of the regulator 1 of the EMF of the engine 5, the setpoint input of which through the fourth multiplication unit 21 is connected to the speed setting unit 22. The maximum voltage measuring unit 23 with its inputs is connected to the network supplying the thyristor converter, and its output is connected to the fourth memory unit 24. The output of the latter is connected to the second input of the third multiplication unit 19. Block 25 of constant memory first, second and third

the outputs are connected to the second inputs of the first 8, second 16 and fourth 21 multiplicators, respectively, and the fourth output of the block 25 is connected to the fourth input of the second block 13

subtraction.

The second output of the control system 3 of the thyristor converter 4 is connected to the second input of the control unit 9. The outputs of the control block 9 are connected to the control inputs of the regulators 1 and 2, the add block 15, the blocks 11, 13 and 20 of the subtraction, the blocks 10, 14, 17, 24 and 25 of the memory, the blocks 8, 16, 19 and 21 multiply, the sensor 7, block

23 measuring the maximum value of the voltage, the functional converter 12, the sine function calculation unit 18, the task unit 22.

The drive works as follows.

In the initial position, at the output of current regulator 2, the code for the thyristor control angle (n) is set, which is fed to the input of the pulse-phase control unit 3, where time intervals start, starting from the natural switching times of the corresponding thyristors AND ending with the pulses controls on these thyristors. The magnitude of these time intervals, corresponding to real control angles, is measured in control system 3. The next thyristor is opened immediately after the end of the calculation by the regulator 2 of the control angle current, if the latter is greater than the current actual angle, and when the measured and specified control angles are equal, if the current angle at the end of the calculations in regulator 2 is less than the calculated one.

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The code of the measured real steering angle, with which the opening of the next thyristor occurred in the considered period, is fed to the inputs of the subtraction unit 11 and the functional converter 12, and is also stored for one period of operation of the converter 4 in the memory unit 10.

FIG. Figure 2 shows the dependences of the steady state phase shift component Vij f (ei) when the control angle varies in the range from 20 to 160. Dependence A defines the steady state phase shift component,. as a function of the steering angle oi dp, the magnitude of the time constant of the root chain T is 0.1 s, and the dependence of B corresponds to the magnitude of the time constant T, 0.002 s. Functional converter 12 converts the value of the control modulus code oL into the value of the fixed phase shift component in accordance with the relationship (Yc (n-1) (n-1)) entered into the converter.

In block 11, the code obtained from the control angle code et (n) of the next thyristor is subtracted from the code received from memory block 10, which corresponds to the control angle of the motor EMF, after the result of the subtraction operation to block 13, the code, proportional to the voltage of the thyristor converter, the case of powering the last network with a constant voltage, for the point in time at which the current reaches its maximum value at the current conduction interval. the multiplication unit 19 takes place on the squared obtained at the output of the unit 18 in accordance with the measured unit 23 and stored in the unit 24 the maximum value of the supply network voltage, which determines the current in the current conduction interval of the inverter. The output code from the output of block 19, corresponding to the real voltage of the non-emf of the thyristor converter at the moment of maximum current at the current conduction interval, goes to the input of block 20, where it is subtracted from the code proportional to the voltage drop in the core circuit obtained 25 in block 8 by multiplying the resistances of the korna circuit and the current maximum at the current interval. At the output of block 20, a feedback signal code is established,

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nor oi (n-l) of the previous conduction interval. In addition, in block 15, the calculated difference with the code coming from memory block 17, and then multiplying the sum obtained by block 16 by a constant factor determined by the dynamic parameters of the electric drive and coming from the fixed value memory block 25, phase shift 9 (p) at the current cycle of the device. The code of the phase transition transient component (n) is stored in memory block 17 for calculating the next clock cycle and is fed to block 13 of the subtraction. In the latter, the angle b is 180 for single-phase circuits, 150 ° for a three-phase zero circuit, and 120 ° for a three-phase converter bridge circuit, the control angle rb (n) and the phase transition component f „(n) for the current interval are subtracted the thyristor conductivity and the settled phase shift component Vu (nl) for the previous conduction interval.

In block 18, calculating the sine function from the angle obtained

The motor's EMF, resulting from the subtraction operation in block 13, contains a code proportional to the ELS of the thyristor converter, if the latter is supplied from the mains with a constant voltage, for the point in time at which the current reaches its maximum value at the current conductivity interval. In multiplication unit 19, the value obtained at the output of unit 18 is corrected in accordance with the maximum supply voltage value measured in unit 23 and stored in unit 24, which determines the current in the current transducer conductivity interval. The output code from the output of block 19, corresponding to the actual value of the non-emf of a thyristor converter at the time of maximum current at the current conduction interval, is fed to the input of block 20, where it is subtracted from a code proportional to the voltage drop in the core circuit obtained in block 8 by multiplying the values of the resistance of the root chain and the maximum at the current current interval. At the output of block 20, a feedback signal code is established, proportional to

five

0

five

0

five

finging on the inverse input (feedback input) of the regulator 1 of the EMF of the engine 5. The task from block 22 to the speed of the engine 5 multiplied in block 21 to a constant proportionality factor between the speed and the EMF of the engine, characterizing the design parameters of the engine, is supplied to the direct input (input vadan) of the motor EMF regulator. The latter calculates the value of the task for the current. Current regulator 2 calculates the angle of control (n + 1) of the thyristors for the next operation cycle of the converter, based on the mismatch of the reference signals for the current supplied from. the output of the regulator 1 is the motor EMF, and the feedback signal from the output of sensor 7 is the maximum current value for the current device operation cycle at the conduction interval. The operation of the device is controlled by signals from control unit 9. In turn, the synchronization of unit 9 operation is controlled by i-tM control bullets themselves, coming from unit 3 of the pulse-phase control and the maximum current sensor 7.

The use of the proposed method allows, by increasing the range of regulation, to expand the use of electric drives with feedback on the EMF of the engine instead of speed feedback, for the realization of which it is necessary to install a tachogenerator on the engine shaft.

Claims (1)

Invention Formula The method of controlling the speed of a direct current motor connected to a thyristor converter in continuous current mode, at which time the current reaches the maximum value in the conduction interval of the thyristor converter, is determined, the maximum current value is determined, the value of the voltage drop on the active the resistance of the root circuit, algebraically summarize the result obtained with the magnitude of the instantaneous value of the emf of the thyristor converter, The motor's electromotive force (EMF) and change the current of the horse circuit in accordance with the magnitude and mismatch sign of the actual and set values of the motor speed affect the value of the converter thyristor control angle, characterized in that, in order to improve the control accuracy for each conduction interval, and memorize the instantaneous amplitude values of the AC mains voltage to which the thyristor converter is connected, measure and memorize the value of the actual control angle about alternating thyristor of the converter, the component of the phase shift between the beginning of the conduction interval and the moment the current reaches the maximum value in the interval, determines the difference between the real angles of control of the thyristors at the previous and current intervals, add it to the transient component of the phase shift, obtained in the previous interval, multiply the sum by the attenuation coefficient; component .fazovogo shift at the current interval and. g using the memorized magnitude of the amplitude value of the mains voltage corresponding to the flow of current in the current conduction interval, calculate the instantaneous value of the EMF of the inverter e j (n) and .. 8 (n) -VyCn-1) (n) |, 0 where e 1 (p) poppy 0 15 20 25 30 oi (n) 35 40 45 50 55 - "(n) the instantaneous value of the EMF of the converter in the current nth interval, calculated for the point in time at which the main circuit current reaches its maximum value; the measured amplitude value of the voltage of the alternating current source to which the thyristor converter is connected (phase for zero circuits, linear for converter bridge circuits) corresponding to the nth conductivity interval, an angle of 180 for single-phase circuits, 150 for a three-phase zero circuit, and 120 ° for a three-phase converter bridge circuit; real angle of thyristor control of the converter on the current nth interval ej f ,, (p-1) Gw (p-1) - having established a phase shift component between the beginning of the conduction interval and the point in time at which the core circuit current reaches a maximum value in the previous conduction interval - a function of the real angle of control (x in the previous (n-1) -th interval ; V (p) K (p-1) + (n-Di.  .ts transient component of the phase shift in the nth interval U greg 36 J 32 thirty 28262 2220 O 20 0 60 80 SOO G20 fffo a.grad Phi 2 9 Compiled by M.Kr Khtuyova Editor E. Kopcha Tehred M. Khodanych Corrector N. Korol Order 2676/55 Circulation 583 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., d. A / 5