SU1332497A1 - Direct-current electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in systems with subordinate regulation. The aim of the invention is to reduce current and speed overshoots in transient conditions. The drive comprises a second limiting unit 14 connected between the output of the comparator unit 6 and the input of the unit 7 of the current rise rate. The output of the setpoint 7 of the current ramp-up rate is connected with the subtractive input of the comparison unit 6. The proposed electric drive makes it possible to obtain transient processes that are optimal in speed when testing the effects of a load in the mode of stabilizing the speed and when the speed setting changes. 4 il. WITH/)

Description

The equipment, namely, DC electric drives, the control system of which is performed according to the principle of subordinate control, can be used to stabilize and control the speed of machines whose static load varies widely. 10

The purpose of the invention is to reduce overshoot current and speed in transient conditions.

Figure 1 shows the functional velocity,. those. in linear and non-linear zones.

The drive works as follows.

When static load (Fig. 2) is thrown, the speed of the electric motor corresponding to the task), the speed from setpoint 3, begins to decrease, resulting in the output of proportional regulator 4 of the speed, voltage corresponding to the speed deviation from the set state value This causes a cue; Fig. 2 shows transient graphs for determining the voltage at the outputs of the function-processes under the stepwise application of a static load; on fig.Z - that

a national converter 5, a comparison unit 6 and a limitation unit 14. Last Proportional

however, with a stepwise change in the signal converter 5, the comparator unit 6 and the restriction unit 14. Last Proportional

la master of speed; FIG. 4 shows the x-20 derivative of the di / db current and the integration of the input-output function of the speed b converter.

The electric drive (FIG. 1) contains an electric motor 1 connected to a converter 2, the control circuit of which includes series-connected speed controller 3, speed controller 4, functional

It is set by the regulator 7 of the rate of increase of the current. Graph 15 (FIG. 2) changes the output voltage of the setpoint generator -7 of the tempo ij which is the driver 25 for the current control loop

1 formed by a current regulator 9 controlled by a converter

2, a motor chain 1 and

the current sensor 13, with the fast-acting converter 5 and the comparison unit 6 30 In the current control loop, the serially connected master unit coincides with the current flow diagram of the current rise rate with the limiting unit 8 and the current regulator 9, as well as successively connected integrator 10 and adder 11, the second input of which is associated with the output of dat35

th current value i. Graph 16 describes the change in the deviation from the steady-state value of the speed of the electric motor 1 - d and, accordingly, the change in the output voltage of the proportional speed controller 4.

speed 12, and the output is connected to the summing input of the comparison unit 6 and the integrator input 10, the second i

th current value i. Graph 16 thus characterizes the change in the deviation from the steady-state value of the speed of the electric motor 1 - d and the change in the output voltage of the proportional control of the 4 speed, respectively.

At the output of the adder I1 form

the input of which is connected to the output of the date- 40 voltage proportional to

static component i ,. current which unit 6 compares the total with the output voltage of the functional converter 5. As the input of the comparison unit 6 is also supplied with the opposite sign, the output voltage of the setting device 7 tempo n rastroeni current, which is proportional to the task of the total current core

Chika 13 current. The actuator also contains a second limiting unit 14 connected between the output of the comparison unit 6 and the input of the setting device 7 of the current rise rate, the output of which is connected to the subtractive input of the comparison unit 6.

Figure 2 shows the graphs of the 15 current and 1 6 of the dynamic drop in the engine speed L when a static load is thrown. Fig. 3 shows the graphs 17 and 18 of the current and 19 and 20 deviations of the engine speed from the set value i-5 with a step of 45

static component i ,. current, which is compared by unit 6 of comparison with the output voltage of functional converter 5. As the input of comparison unit 6 is also supplied with the opposite sign, the output voltage of unit 7 of the current rise rate, which is proportional to the setting of the total current, cor i

50

output voltage of functional converter 5 at the input of comparison unit 6

ig i - ic O) in proportion to the task of dynamic

change signal setpoint 3 speed gg component of the current.

5-., And, respectively, at the entrance At a constant value of the static controller 4 speeds

(Fig. 2) also characterizes the dynamic component of the current ig; Fig. 4 shows the characteristic input - output of the functional converter 5 at

speeds th those. in linear and non-linear zones.

The drive works as follows.

When a static load is added (Fig. 2), the speed of the electric motor corresponding to the task), the speed from setpoint 3, begins to decrease, resulting in a voltage at the output of the proportional regulator 4, corresponding to the speed deviation from the set value. This causes an increase in voltage at the outputs.

a national converter 5, a comparison unit 6 and a limitation unit 14. Last Proportional

It is set by the regulator 7 of the rate of increase of the current. Graph 15 (FIG. 2) changes the output voltage of the setpoint generator -7 of the tempo ij which is the driver 25 for the current control loop

1 formed by a current regulator 9 controlled by a converter

2, a motor chain 1 and

current sensor 13, with a fast speed of 30 nc, the current control loop is the same as the current

35

th current value i. Graph 16 describes the change in the deviation from the steady-state value of the speed of the electric motor 1 - d and, accordingly, the change in the output voltage of the proportional speed controller 4.

At the output of the adder I1 form a voltage proportional to

static component i ,. current, which is compared by the comparison unit 6 with the output voltage of the functional converter 5. As the input voltage of the comparison unit 6 is also supplied with the opposite sign, the output voltage of the setting device 7 of the current rise rate, which is proportional to the setting of the total current of the core i.

output voltage of functional converter 5 at the input of comparison unit 6

31332497

which, when the input voltage of the generator 7 is temporally in time, i.e. ig et,

Evil et, (2)

 Ug / Ty di / dt is the specified value of the output current;

TC - constant integration of the setter 7 pace.

The change in the speed deviation of the motor 1 corresponds to the inral equation

D T-; igdt

Roe, taking into account the expression (2), so ig "ig,, has the solution

.. th (3)

J

T; - the inertia constant of the drive time (T; j--),

And ,,

J

n n x s

 10 p with g sk

15h to 1

20 not

25 i from whether zs nor

J n

m. driven to the shaft of the motor 1 moment of inertia of the drive;

the nominal value of the angular velocity and the electromagnetic moment of the electric motor I о

Excluding from the expressions (2) and (3) the time parameter t, we obtain the equation

(four)

i3jH2 TjA which is the optimal 1 „1 (1 + 1 /) equation. (6) Expression (6) also determines the output voltage of the tempo setting device 7 at time t, (Fig. 2).

The area of the triangle & 4 was 35

the speed of the phase trajectory. Adjusting the characteristic 22 input - output functional converter 5 (figure 4), respectively

equation (4) (input, output ig,), about em half of the area of the triangle S B, we obtain the maximum speed

testing the deviation of the velocity d-5 elec- S feq, 2, therefore, at the point about the thromotor 1, i.e. the rise of the graph 15, the deviation of the velocity D ka until time t, (FIG. 2), is reduced to a value, i.e. maximum permissible pace and over-. working out by half. If, at the moment t, the current to fall, equation (4) of the characteristic 22 input output of the functional converter 5 is substituted with the value d / 2 ip / 4Т; , obtained with the help of the rising voltage i zadde- jq (5), it can be obtained that the speed 7 of the input 6 of the unit 6 is comparable to the functional voltage

at the same rate up to the value of the static component i .. The time t ;, corresponds to the beginning of the decrease, due to the decrease in the speed deviation D--, the sum

converter 5 or a given value of the dynamic component of the current ig at time t

stress

3j

With this, the voltage at the output of the comparator unit 6 and the output voltage of the limitation unit 14 are reversed, and the rate regulator 7 begins to linearly decrease its output voltage.

Let us prove that at time t, (Fig. 2), the decreasing amount of voltages (ig, -i-ig) at the input of the comparison unit 6 is equalized with the voltage ij of the rate regulator 7, after which the optimal switching of the voltage of the limiting unit 14 occurs and, accordingly, switching the output by 10 spins of 1 l setter 7 of the tempo to decrease. As long as the current is less than the static component (i i, plot O of the graph 15), the speed of the electric motor 1 decreases and the speed deviation uv increases. The highest value of L is the deviation of uv. reaches at the time point corresponding to point S, i.e. to equality. The value of σ is determined from equation (3), substituting the value

t -Je.

d i, / 2T.E. (5) In section S -O-Z of graph 15, current i exceeds the static component 25 i (i ig), and speed deviation is tested, (5). At point b, the current reaches the maximum value of i, the value of which can be determined from the equality of the areas of the triangle CS and Oa & : Wherein

, Ss62 (iM - ip ° - we get the equation

1-25 (1m- ie) /, from where

1 „1 (1 + 1 /). (6) Expression (6) also determines the output voltage of the tempo setting device 7 at time t, (Fig. 2).

The area of the triangle & 4 was 35

about em half the area of the triangle S B,

converter 5 or a given value of the dynamic component of the current ig at time t

55ij - ic / 2. (7)

The sum of the output voltages of the functional converter 5 and adder II at the input of the block 6

il + i, ij- i, .i, (Hl /),

which coincides with the expression (6).

Thus, at the moment of time t, (Fig. 2), the balance is reached, for example, at the inputs of the comparison unit 6, after which this balance is disturbed, since the deviation of the D velocity decreases and, accordingly, decreases

its maximum value and its restriction by block 8 restrictions. In this case, the output voltage of the setting device 7 is switched to a decrease in the current also optimally at the time of the occurrence of the voltage balance at the inputs of the comparison unit 6, since the discharge voltage of the functional

the output voltage of the regulator 4 is the speed of the converter 5, which is determined by the voltage and the functional converter 5. This corresponds to the optimal switching of the current i of the electric motor 1 to a decrease to the speed-optimized test of the speed deviation l.

At point 2 of graph 15, current i decreases to the value of static component i, the dynamic component becomes equal to zero, and the deviation of the velocity E is also worked out to zero. In this case, the output voltage of the speed controller 4 and the functional converter 5 becomes

Zero, at the inputs of block 6 of comparison 25, voltage i (FIG. 3, graph 17),

J

the voltage balance comes, the output voltage of the limiting unit 14 is zeroed, the change in the output voltage of the setpoint regulator 7 stops

and there comes a steady state schedule 19) output voltage of the work.

In order to close the speed control loop of the electric motor 1 near small speed trips, the functional converter 5 switches to the characteristic 21 (FIG. 4), which provides the optimization of the transient function

35

the throttle speed 4 and the function of the converter 5 are reduced and the time of the time t, (fig. 3), the balance of impedance occurs at the inputs of the comparison unit 6, and then the reverse of its output voltage. Since the output voltage of the functional converter 5 is connected with the optimal dependence (4) with the actual speed deflector 4 and the functional converter 5 is reduced and the B time t, (fig. 3), the balance of the inverter occurs; 6 comparisons, and then reverse its output voltage. Since the output voltage of the functional converter 5 is related to the optimal dependence (4) with the actual deviation of the circuit in a small one, for example, according to the modular optimization criterion, when the speed L, the moment t, the re-structure functions in the linear zone. At the same time, since the integral tempo controller 7 is captured through blocks 6 and 14 by a negative feedback, the tempo sender 7 begins to function as a normal inertial link. At the same time, in the closed speed control loop, only one integrating link of the electric motor 1 with the continuous T: integration state remains. The speed contour is stable, and the quality of the speed control is increased.

The specified cycle of testing the deviation of the speed of the motor &) does not change with a static load increase with increasing linearly increasing voltage at the output of the generator 7 the rate of current rise to its own 1332497

its maximum value and its restriction by block 8 restrictions. In this case, the output voltage of the setting device 7 is switched to a decrease in the current also optimally at the time of the occurrence of the voltage balance at the inputs of the comparison unit 6, since the discharge voltage of the functional

The switching moment is due to the optimal dependence (4) with the actual speed deviation (characteristic 22).

With a stepwise change in SOi, the reference signal -J, at the input of the speed controller 4 (FIG. 3), an error signal and is at its output and, accordingly, a voltage J-ai at the output of fuik1 appears, but the transducer 5. If, at the same time, there is no static load, under the action of voltage in and the setpoint generator 7 begins to linearly increase the output

voltage i (FIG. 3, graph 17),

J

which is processed by a circuit of a regulated 1i current and with the opposite sign is brought to block 6 of the comparison, As the error LL decreases) (Fig. 3,

graph 19) output voltage

the throttle 4 speeds and the functional converter 5 is reduced and the B moment of time t, (fig. 3), the balance of imprints occurs at the inputs of the comparison unit 6, and then the reverse of its output voltage. Since the output voltage of the functional converter 5 is related to the optimal dependence (4) with the actual deviation of the speed L, time t, switching the output voltage of the setting voltage 7 to decrease and, accordingly, decrease the current i correspond to the situation when The process of current reduction is the deviation of the speed L-5 y to ten to zero, i.e. An optimal change in speed is developed.

Run cycle 8, no different

from the optimum in the presence of a static load or when a linearly varying voltage is set at the setting device 7, the rate of increase of the current is limited (Fig. 3, graphs L 9 and 20).

Static meter 0

five

current, core i ,,, formed by the integrator 10 and the adder 11, operates in accordance with the integral equation

where t

.if ,; - c) - ic. (eight)

fO

integration integrator constant 10;

K .. 1, P (9)

gain factor of adder 11; the output signal of the adder P; operator. From equation (8) we get

i izElipjL

with рТ „/ К„ -И

Since the excitation flow of the electric motor 1 is constant, the current i is proportional to the moment M of the electric motor, and the static component of the current i is proportional to the moment of the static load M.

If we take the integration constant T, g of the integrator 10 equal to the inertial constant motor T.-,

effects of load in the mode of stabilization of the speed and with changes in the speed reference. At the same time, the order of astatism of the speed loop decreases and the overshoot of the current and speed of the electric motor in transients decreases.

those.

T

H

based on the equation

Claims (1)

(9) it can be seen that the output signal of the adder 11 is proportional to the moment of static load M, since Ti-T d / dt M (in relative units). Choosing a gain factor 10 Formula of Invention An electric current drive containing a motor connected to a converter in a circuit 15 controllers of which are connected in series with a speed controller, a speed controller, a functional converter and a comparison unit, a controller connected in series 20 current ramp up rate with a limiting unit and a current regulator, as well as a sequentially connected integrator and adder, the second input of which is connected to the output of the speed sensor, 25 and the output is connected to the summing input of the comparator unit and to the first input of the integrator, the second input of which is connected to the output of the current sensor, which is K (( Because the adder 1I is sufficiently large to reduce the overshoot current The measurement of the static component of the current is almost zero-inertial. Thus, the proposed DC electric drive allows to obtain optimal speeds in transients, it introduces a second limiting unit, connected between the output of the comparison unit and the input of the current ramp up rate generator, the output of which is related to VIS transient processes when the subtractive input of the comparison unit is used. 13324978 effects of load in the mode of stabilization of the speed and with changes in the speed reference. At the same time, the order of astatism of the speed loop decreases and the overshoot of the current and speed of the electric motor in transients decreases. 10 claims An electric current drive containing a motor connected to a converter in a circuit 15 controllers of which are connected in series with a speed controller, a speed controller, a functional converter and a comparison unit, a controller connected in series 20 current ramp up rate with a limiting unit and a current regulator, as well as a sequentially connected integrator and adder, the second input of which is connected to the output of the speed sensor, 25 and the output is connected to the summing input of the comparison unit and to the first input of the integrator, the second input of which is connected to the output of the current sensor, speed and speed in transient modes; 35 current, the output of which is associated with  subtractive input of the comparison block. tl.t sixteen LU FIG. 2 ( 22 J) five): 7g Fig.Z / IV 4V 2 /  + 22 1g Fy Editor I.Gorn Compiled by V.Kuznetsova Tehred Z.Kadar Proofreader V.Girn to Order 3845/53 Circulation 659 Subscription VNISTI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4