SU1198726A1 - Electric drive with flexible coupling between electric motor and mechanism - Google Patents

Description

The invention allows to increase the reliability of work, as well as the accuracy and performance of an electric drive with an elastic coupling between an electric motor and a mechanism by eliminating fluctuations in the elastic coupling and reducing the time of transients. This is achieved due to the fact that the specified drive

consists of an electric motor connected to the output of the torque control loop with a controlled converter, the input of which is connected to the output of the adder, the summing input of which is connected to the output of the maximum dynamic moment unit, where the input of the dynamic torque setting unit (BFZDM) is also connected, the output of which is connected to the subtractive input adder, while BFZDM implements the dependence

four? ,

—— behr

natural oscillation period in ELECTRIC COMMUNICATION)

- maximum dynamic moment)

- elastic stiffness rigidity)

- current time)

- moments of inertia, respectively, of the motor and mechanism.

WITH

00

m

Yu

>

* 1198726 *

The invention relates to electrical engineering, in particular to electric drives with a non-rigid connection between the driving electric motor and mechanism, and can be used in electric drives of industrial manipulators and robots, mining and lifting transport vehicles, rolling

; mills and paper machines,

£ de the presence of an elastic bond can ·

: Ylvat fluctuations and significant additional load in the mechanism.

The purpose of the invention is to improve the reliability, accuracy and performance of the electric drive due to the exclusion of oscillations in the elastic connection and reducing the time of transients,

FIGS. 1 and 2 depict a functional diagram of an electric drive with various embodiments of the dynamic torque setting unit} in FIG. 3 - graphs of changes in the components of the signal set of the dynamic moment of the electric motor during a transient mode and the corresponding graph of the change in the moment of load in an elastic connection.

The actuator (Fig. 1) contains an electric motor 1, a block 2 for setting a maximum dynamic moment, the output of which is connected to a dynamic torque setting unit 3, and a torque control circuit 4 with a controlled converter, to the output of which an electric motor 1 is connected. dynamic moment assignment implements dependency

'pz \ PU)

- I 3 3

where T _pu = 2yt1-t ^ - ~ is the period of the own 1 ^s (/ a ⁺ Ll) oscillations in the elastic bond ·,

M - maximum diaA1C1KS

namic moment; c is the elastic stiffness; ί - pulling time)

, Z _m - moments of inertia of the electric motor and mechanism, respectively>,

the output of the block 3 of the formation of the moment is connected to the subtractive input

ten

15

20

25

thirty

35

control circuit 4 of the moment (in the drawing, the control circuit of the moment is shown with an adder 5 at the input), to the summing input of which the unit 2 is set to specify the maximum dynamic moment. The electric motor 1 is connected to the mechanism 6 by means of elastic coupling 7.

The dynamic moment setting unit 3 in FIG. 1 embodiment is implemented on an operational amplifier 8, at the input of which a capacitor 9 and a resistor 10 are connected in series, and in the feedback circuits, capacitor Ί and resistor 12 are connected in parallel.

This ensures the implementation of dependency (1) when selecting block parameters in accordance with the expressions

• OK

'9 ^ν ιο' - • and 11 277

ten

In the embodiment shown in FIG. 2 embodiment of the invention, the block of forming the dynamic moment setting is performed on the operational amplifier 8, capacitors 13 and 14 and resistors 15 and 16. The implementation of the dependence (1) is provided by selecting the parameters of the elements included in the block 3 in accordance with the expressions

'14

^ zs

13

(h)

Block 3 formation tasks

dynamic moment can be

made and based on a micro-computer.

Plot I7 in FIG. I characterize

The constant value setting of the maximum dynamic torque of the electric motor during the transient mode, graph 18, changes the component of the motor torque reference signal from block 3, and graph 19, changes the load torque in elastic coupling using the invention.

The drive works as follows.

In the transient mode (for example, in acceleration mode) a signal appears at the output of block 2 for setting the maximum motor torque,

55 equal (proportional) to the maximum dynamic moment,

permissible for this drive motor and provide 1 198726

topic is the minimum transition time. This signal is fed to the input of the control circuit 4 torque motor and determines the first component of the reference signal of this moment

^M E1 ^{= LA} "" KS ^{= C0} " ⁵ * ·

(four'

At the same time, the output signal of the block 2 is fed to the input of the block 3 forming a dynamic torque setting of the electric motor, which provides a change in the signal at its output in time according to the dependence

lou

where = 27

2 And ^t p

period of natural oscillations in elastic coupling;

elastic bond stiffness; current time, moments of inertia of the electric motor and mechanism.

In this case, the motor torque reference signal (graph 18 in Fig. 3) in a time shorter than the natural oscillation period by 2 times, i.e. I = _ТЛ / / 2л, smoothly increases from zero to a value equal to 2 / e of the maximum dynamic moment, i.e. M ^ _r = - | -M _max , and then until the end of the time period of the period of natural oscillations smoothly decreases to zero.

The output signal of the block 3, 'defined by the expression (1), is fed to the input of the electric motor torque control circuit 4 with the sign opposite to the sign of the maximum dynamic torque setting signal. In this case, in the case of a sufficiently small inertia of the electric motor torque control circuit 4 as compared with the period of natural oscillations in the elastic coupling, which is the case for electric drives of many of the above-mentioned machines, the nature of the moment variation. load in the elastic bond is determined by the expression

y "ks \ lu / \ ny

(L

ΑΛ

^g d ^f

natural frequency of the motor.

Expression (5) follows from the solution of the differential equation \ 2

ten

15

20

25

£ ²

^ω Α ^τ ™

2

si

se)

describing the time variation of the load in an elastic connection, taking into account the nature of the change in input actions M _{} 1} and M ^, defined by expressions (1) and С4).

The embodiments shown in the drawings relate to a DC motor driven by an armature circuit of an electric motor. However, similarly, the invention can be implemented in an adjustable AC drive (for example, an asynchronous drive with a thyristor voltage regulator or a thyristor frequency converter) or for a DC drive controlled by an excitation circuit of an electric motor.

thirty

35

40

45

50

55

As follows from expression (5) and the corresponding graph 19 in FIG. 3, when using the invention, the monotonous nature of the load moment variation in the elastic coupling during transients is provided, the magnitude of this torque does not exceed the maximum value determined by the required acceleration rate of the mechanism, oscillation and overshoot are absent, which eliminates additional loads in the elastic gear, mechanism and working equipment Thus, the reliability of electrical equipment and machinery is increased. At the same time, reducing the amplitude of oscillations of the mechanism relative to the motor shaft to zero ensures that the mechanism can be accurately stopped in the desired position, that is, it increases the control accuracy. The considered electric drive with elastic coupling between the electric motor and the mechanism allows simultaneously reducing the duration of transients and thereby increasing the productivity of machines with

1198726

such a character control drives. It provides the minimum transient time for all possible continuous functions characterizing the nature of changes in the motor torque command signals, when restrictions are imposed, requiring complete exclusion of oscillations (zero amplitude of oscillations), and from this point of view is' optimal.

Claims (1)

Claim An electric drive with an elastic coupling between the motor and the mechanism containing the motor, a block for setting the maximum dynamic moment, the output of which is connected to the block for generating the task of the dynamic moment, and a control loop for the moment with a controlled converter, the output of which is connected to the motor reliability, accuracy and performance by eliminating fluctuations in elastic bonding and reducing the time of transient processes ₅ moment realizes dependence poo 6 exp ten where is t "Y = 27 ^ natural period in elastic ¹⁵ communication · Mdedks ^- maximum dynamic moment; c is the rigidity of the elastic bond *, B is the current time Rear, 7 "" respectively, the moments of inertia of the electric motor ²⁵ la and mechanism, its output is connected to the subtractive input of the control circuit of the moment, to the summing input of which is connected the block for setting the maximum dynamic torque. 7 9 II 4ΞΞΗ 12 1 3 1198726