SU1436254A1 - Electric drive with resilient mechanical link - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electric drives of cranes, draglines. The aim of the invention is to simplify the design and adjustment of the electric drive and increase the efficiency of vibration damping of the elastic coupling in the conditions of instability of the natural frequency of these oscillations. The device contains an integrator 9, the input of which is connected to the output of the current sensor 7, and the output to the second input of the adder 8. The output of the adder 8 is connected to the input of the speed regulator 4 and to the input of the current regulator 5, This device provides for the suppression of oscillations the instability of the natural frequency of oscillations, since the damping signal at the output of the parallel correction node is formed as a function of the speed and current of the electric motor in accordance with the actual value of this frequency, 2 sludge. s

Description

14;

O9

Od

uh

9U2.1

The selection relates to electrical engineering, namely, electric motors with elastic coupling between the motor and the mechanism, and can be used in electric drives of draglines, cranes, hoists, test benches and papermaking machines.

The purpose of the invention is to simplify the schemes and commissioning of the electric drive and increase the efficiency of vibration damping in elastic coupling with the instability of the natural frequency of these vibrations.

FIG. 1 shows a functional diagram of the drive; in fig. 2 graphs of the transition process during acceleration of the electric drive, which show its work.

An electric drive (Fig. 1) with an elastic mechanical coupling 1 containing a direct current electric motor 2 is connected to the U1F in the transducer 3, and the reference circuit includes sequential adjustments | Speed 4 and current 5, for kykgchёishyy to the inputs of the corresponding regulators sensors skrrort 6 and current 7, 8 also an adder 8, connected by one of its input with the output of the sensor b speed, and vyosod - with the second input of the current regulator 5, and an inverter 9, its input connected to the output of current sensor 7, and the output to second input of adder 8, the output of which is also connected to the input of speed controller 4, while the time constant of integrator 9 T is chosen equal to

 m

A

T. il4-J: M.K "jL

"KmKd.s

where, K. - transfer coefficients of the speed and current sensors; 1 - moments of inertia

electric motor and mechanism;

 K - coefficient is proportional to the network by the current and torque of the electric motor. FIG. 2 shows two modes of acceleration of the electric drive of the graph of the change in the moment M h) in the elastic coupling (graph 10), the speed of the UE electric motor (graph 11) and the velocity WM of the mechanism (graph 12), as well as for comparison (graph 13) changes in the speed of the electric motor and mechanism absolute connection between.

The drive works as follows.

The time constant of the integrator 9 is chosen equal to the mechanical time constant.

m

.- m1BA1.

(one)

d.s.

numerically equal to the acceleration time of the electric drive with an absolutely rigid connection between the electric motor and the mechanism to the rated speed with the nominal torque.

where k

TO.

Lc f

BUT

- gear ratios of speed sensors 7 and current 8, | one . - moments of inertia

electric motor and mechanism;

Sd F is the proportionality factor between the current and the motor moment. When selecting coe1 |) of the amplifiers of the adder 8 equal to one, its output voltage is determined by both inputs

and.

TO

4.T

1 "; 5; -Kl.si ;,. (2)

40

35 where

H motor current; p is the Laplace operator. Considering that the relationship between the current I g and the speed l of an electric motor is determined by the dependence

Ka

Yt

AG - P.liL aJlElIk: .. (3)

U2 vTvP + T pY

where t

C v

G 1d1 / "

m 1 dt - 7-g constant

V 1С (Ц + 1л,) L time of elastic connection; elastic stiffness; the relative attenuation coefficient of the oscillations in the elastic coupling;

 1 + - ratio to mass

From the simulations (2) and (3), it is assumed that the output voltage of the adder 8 is determined by the following transfer function with respect to the speed of the SD motor:

.Ubk. piTi (i3l).

.c

.1 + 1ТТ, rh-T, | р

The output signal of the adder 8 is fed to the input of the current regulator 5 with the coefficient K and to the input of the controller 4 of the speed with the coefficient K, which are to be selected.

When a signal A is applied to the input of the regulator A and the speed is set, its output signal U p almost abruptly increases to the maximum value determined by the limitation of its output voltage, and remains constant. Taking into account that the motion parameters of the electric drive, depending on the input signal of the current regulator 5 Uex.pT Irs-1 pk K, are determined by the transfer functions (with a small inertia of the current control loop as compared to the constant elastic time)

Cm

Hgg

G-1

 f

one

,

  1 1 f m 1 +2 ,, p + T§p l

 - 1 1 + 2

BX.F kGs pT «T p + if;

taking into account the effect on the speed controller of the output signal determined by the transfer function (4), it can be established that in the indicated mode of change of motion parameters of the electric drive is characterized by transfer functions

MV

7 with “F7k ;;

til

and

one

c

Di (p) .i 4 1. Il2b TvElTvlti

PC / CAS rtl, D; (P)

hi l. PC

Wow. / Cds

rTd, D (p)

where D, (p)

Y -

Tv (-l)

g

K, p (11)

As follows from expression (11), to provide the required relative attenuation coefficient J

(for example, (2/2) coefficient

Oss To1436254

feedback, characterizing the effect of the output signal of the adder 8 on the current regulator 5, should be selected from

(four)

2 (t, t

-5u) hm

vTrfT

(12)

ten

At the same time, My, in elastic coupling, smoothly with overshoot less than 5% increases to a steady-state value (Fig. 2, graph 10), and engine speed ui (graph 11) IS and mechanism s, (graph 12) also smoothly transition to progressive graphics (to equally accelerated motion),

When the speed of the electric drive approaches the steady-state value, the speed controller 4 goes to the linear sections of its characteristics, and the change in the motion parameters of the electric drive, taking into account the effect of the output signal of the adder 8 on the input of the speed controller 4, is characterized by transfer functions

20

25

Mji

thirty

dt

21-1

g

Tm

)

(13)

i777k

U) A li2 5 y T iTvXE A. S

Odr)

(14)

  Ii2JijLTitE

% s / CDR where Do (p)

V / g (p)

1 2 iVi ;:: (15)

T “-rs

40

  ij: (rO (K, -K, p

(sixteen)

, & BE1.

Kpc

45 Changing the structure of the electric drive at this stage of movement also requires a different approach to choosing its parameters, which can be vibran, for example, given the values of the Vyshnegradsky coefficients, which it is advisable to choose equal to 2.2-2.4. expression (16) of the coefficients of the characteristic equation of the system, we are determined by the dependencies

 , BUT

K}. (17)

2

t

y (

AT

+ IlS

V

f1ts

l pc

From the expression (18) it is possible to determine the limiting value of the gain factor of the speed regulator, at which the required character is achieved, a transient process with small overshoots, and with a small value relative to the attenuation coefficient S ;, oscillations in elastic coupling, one can use addiction

V. ± L

l ot:;

pc

which gives a slightly underestimated value of the limiting value of the coefficient Kpc t, and the margin on the value of this coefficient will be thereby greater, the greater the relative attenuation coefficient 1, and the greater the inertia of the current control loop. From expression (17), one can determine the required value of the coefficient K (i.e., the force coefficient of the speed controller 4 through the output signal of the adder 8) to ensure the required character of the transition process with some ratios of the drive parameters, the value of this coefficient can be close to zero, which equivalent to the connection between the output of the adder 8 and the input of the speed controller 4.

k, .r i (rl) (20)

14362546

speed for an absolutely rigid system, the presence of elasticity leads to (18) the speed lag of only 1.3 T0, while ensuring effective damping of oscillations.

The proposed device allows to simplify the electric drive due to the fact that the parallel correction unit is complete on two elements and the number of connections between the elements is reduced. Adjustment of the electric drive is also simplified by reducing the number of adjustable parameters of the parallel correction node to one (the integrator time constant).

At the same time, the efficiency of quenching is increased: d under conditions (19) of instability of the natural frequency

20 oscillations (for example, when changing the height of the suspension of cranes and excavator, changing the length of the hoist rope and elevator, etc.), since the damping signal at the output of the parallel correction node is formed as a function of the motor current speed in accordance with the actual value of this frequency.

thirty

Claims (1)

Invention Formula 35 40 AClAir M -Av- j Kpt; j. With this choice of the coefficients Crs and 4, a smooth decrease in the elastic coupling moment and a smooth transition of the motor speed and mechanism to the steady-state value (4 and 2 g) are provided, where the graphs are plotted for the following values of drive parameters: - 0.05; 1 1.2; T „/ TU 10; CRS "0.3 Tm / T ,,. As follows from the comparison of graphs 11 and 12 of the change in speed of the electric motor 2 and the mechanism in the proposed system with schedule 13 of change An elastic mechanical coupling actuator containing a direct current electric motor connected to a control converter, the control circuit of which includes serially connected speed and current controllers connected to the inputs of the corresponding regulators of speed and current sensors, as well as an adder connected by one an input with an output of the speed sensor, and an output with a second input of the current controller, characterized in that, in order to simplify the circuitry and commissioning of the electric drive and increase the efficiency of damping in elastic coupling with the instability of the natural frequency of these oscillations, an integrator is introduced into it,  input connected to the output of the current sensor, and output to the second input of the adder, the output of which is also connected to the input of the speed regulator, while the time constant is the integrator T 55 is chosen equal to 45 t and (Ia) KM- K A. c thirty Invention Formula An elastic mechanical coupling actuator containing a direct current electric motor connected to a control converter, the control circuit of which includes serially connected speed and current controllers connected to the inputs of the corresponding regulators of speed and current sensors, as well as an adder connected by one an input with an output of the speed sensor, and an output with a second input of the current controller, characterized in that, in order to simplify the circuitry and commissioning of the electric drive and increase the efficiency of damping in elastic coupling with the instability of the natural frequency of these oscillations, an integrator is introduced into it, input connected to the output of the current sensor, and output to the second input of the adder, the output of which is also connected to the input of the speed regulator, while the time constant is the integrator T is chosen equal to (Ia) KM- K A. c  , K.g transfer coefficients of speed and current sensors; dm moments of inertia electric motor and Hyk dm mechanism; - coefficient of proportionality meddu current and torque of the motor eight 12 iSI 9ig.2 24