JPH0341021B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for controlling a drive mechanism that imparts horizontal movement to a driven unit via an elastic reaction support or elastic connection.

By way of non-limiting example, some horizontal movements of this kind may be enumerated as follows.

(a) Horizontal movement of lifting equipment (crane, overhead crane, etc.).

(b) In the case of tower cranes of the "down-swing" type, the fixed strut supports a mechanism at the top for swinging the jib around the vertical axis, and the inertia of the entire rotating part is extremely large. As far as the horizontal pivot mechanism is concerned, this column forms an elastic reaction support which operates under compressive, bending and torsional stresses. Dynamic deformation of the strut during horizontal swing of the jib tends to cause jerks and inappropriate reactions of the crane.

The elastic reaction support or elastic coupling part is the source of various complex dynamic phenomena that have an unfavorable effect on the operability, precision, configuration, service life and dimensions of the parts, etc. of the horizontal movement part. .

One method known in the art for reducing these dynamic effects is to control the drive by a suitable device so that the mechanical torque required for the horizontal movement is gradually applied.

However, this method has the following drawbacks.

- It takes a considerable amount of time to increase the torque. Therefore, deformation of the elastic reaction support or the elastic coupling part due to the action of torque is unavoidable, and there is an added disadvantage that the movable part of the driven unit cannot be started quickly.

- Due to the overlap of the gradual deformation of the elastic support and the gradual start-up of the moving parts, energy and vibrational stresses are transferred to the elastic support, which is dangerous.

- Cannot deal with increases and decreases in torque due to external factors such as wind.

- There is a dead time before starting the moving part, and the operation does not go smoothly.

-The speed of moving parts cannot be controlled.

An alternative approach is to control the drive torque by means of a speed control loop connected to a speed sensing transducer in conjunction with an elastic reaction support or elastic coupling; It captures every vibration of the velocity (control) loop and therefore also the torque (control)
At the level of the loop, the phenomenon of "alternating fluctuations" occurs.

The object of the invention is to eliminate the above-mentioned disadvantages by controlling a drive for horizontal movement via an electrical device characterized by a combination of at least the following four basic circuits: The purpose is to remove the

A Torque loop constituted by the components necessary to control the electromechanical torque provided by the drive device with reference to a predetermined target torque in each operating period.

B. A loop for controlling the absolute ground speed of the moving parts of the driven unit, which controls the torque loop by providing a target torque value for achieving and maintaining the speed manually commanded by the operator.

C. When the speed difference between the absolute ground speed of the movable part and the speed of the drive device exceeds a predetermined threshold value, the target torque is corrected to create a sudden operation (dynamic shock) caused by the kinetic energy accumulated in the rotor. Velocity difference loop to reduce.

D. Drive speed differentiator circuit for stabilizing the overall dynamic behavior by introducing a derivative of the drive speed against the target torque.

According to another feature of the invention, the loop for controlling the absolute speed relative to the ground of the movable part of the driven unit includes, in addition to devices for speed control and target torque value generation, dynamic effects due to clearance closure in the mechanism. intermediate countermeasures for modifying the target torque in order to reduce it, i.e. gradient circuits that gradually introduce the target torque, so that the magnitude and duration of the stresses acting on the driven unit are the same during periods of acceleration and deceleration. and a device for limiting the maximum value of the target torque.

According to a further feature of the invention, the loop controlling the absolute ground speed of the moving part of the driven unit is capable of commanding a steady torque at the entrance of the torque loop through periods of acceleration, speed maintenance, or deceleration. It is equipped with a processing stage. This target torque is determined by the torque gradient circuit and correction circuit included in the absolute ground speed control loop of this driven unit moving part, as well as the loop for the speed difference between the absolute ground speed of the driven unit moving part and the drive speed. and can be modified by a drive speed differentiator circuit.

According to another characteristic of the invention, the device according to the invention provides a three-phase It can be used for the control of electric motors or special three-phase electric motors with low inertia rotors, or for the control of any type of drive mechanism capable of commanding a steady torque.

In the following, a detailed description of the invention will be provided with reference to the accompanying drawings, which illustrate one embodiment of the invention. The attached drawings, given by way of non-limiting example, will enable a better understanding of the features of the invention.

In FIGS. 1 and 2, the drive device is a slip-ring induction or resistance squirrel cage three-phase electric motor M, which is controlled by a device according to the invention.

The device according to the present invention is constructed by combining the following four basic circuits A, B, C, and D.

A Drive torque control loop consisting of a and b below.

a. Enables change of the direction of rotation of the motor by switching between two phases. Enables to dictate the required drive torque by varying the stator voltage in three phases using a thyristor built into the stator circuit. A four-quadrant power supply unit 1 of a conventionally known type.

b. A closed-loop electric motor torque electronic control system composed of a torque control device 2 and an electromagnetic torque calculation device 3 that calculates torque from three-phase stator voltage and current. This system allows the indication of a predetermined torque in all operating phases, in particular in acceleration, deceleration and braking phases.

B. connected to the torque control system;
A loop that controls the absolute ground speed of the moving part of a driven unit using a cascade method (controlling a torque loop using a speed loop). This loop is composed of the following a, b, c, d, e, and f.

a Device that indicates desired speed XVGY. By simply operating this manually, the desired speed can be automatically obtained depending on the actual speed of the movable element of the driven unit.

b GY, for example a gyroscope-type transducer (gyro-swivel meter) or an accelerometer-type transducer, independent of any elastic coupling with the target machine, for measuring the absolute ground speed of the moving element. This device provides a velocity-proportional voltage, positive or negative depending on the direction of motion, which is input into a velocity loop and compared to the voltage of the indicating device. Potentiometer P1
The purpose of the adjustment).

c. A speed control device 4 that controls the torque control loop and accurately outputs the target torque signal at A. Unless the commanded speed XVGY is achieved,
An error voltage exists between the indicated voltage and the value measured by exchanger GY. The amplified and processed error voltage is converted to a steady state torque indication, which is corrected by the action of various components described below. The gain (proportionality effect) of the speed loop can be controlled by potentiometer P2.

d. A circuit 5 for modifying the command torque such that the acceleration or deceleration times are equal, taking into account that for efficiency reasons the required torque at motor level is smaller in the deceleration phase than in the acceleration phase. . After all, the effect on the driven unit is the same for both acceleration and deceleration. This is achieved by an electronic circuit 6 that detects quadrants that require acceleration and distinguishes them from quadrants that require deceleration. In a preferred embodiment, this electronic circuit directs the direction of the indicated torque and the direction of the actual speed to dividing bridges R14-R15, R16-R1 located between the DC voltage ±U and the zero reference voltage.
7, R18-R19 and R20-R21 by comparison. The contact r of this circuit is closed in the driving quadrant and at rest, and opens in the deceleration quadrant.
The target torque level input at point B is transmitted unchanged to point B in the drive quadrant and at rest, and is damped by the splitting bridge in the deceleration quadrant.

e Gradient circuit 7 that gradually introduces the target torque in order to reduce the dynamic effects due to gap blockage in the mechanism. In a preferred embodiment, this gradient circuit is based on the charging of the capacitor C1 under the action of a constant current flowing through the potentiometer P4, the terminal voltage of said potentiometer P4 being:
It is kept constant by diodes D1 and D2. Amplifier CI2 acts as a voltage follower, and its output terminal potential follows its positive input terminal potential. On the other hand, resistor R7 limits the current of diodes D1 and D2 to the current of potentiometer P4, such that the charging current of capacitor C1 is the current flowing through potentiometer P4. The gradient of the gradient circuit can be adjusted via the potentiometer P4 (pre-adjustment depending on the machine). The gradient circuit is of a symmetrical type due to the parallel connection of two diodes D1 and D2, and therefore it is possible to input a target value at terminal B of the gradient circuit, regardless of whether it is positive or negative.

f Device 8 for adjusting the maximum level of the target torque by pre-adjustment by potentiometer P3, in order to ensure that no torque exceeding the permissible maximum torque is transmitted to the driven unit.

C. Loop for the speed difference between the ground speed of the moving element (detected by a measuring transducer and, for example, a gyro turn meter GY) and the motor speed (detected by a speed detection device DY, such as a tachometer dynamo). The purpose of this loop is to reduce the dynamic shocks due to the kinetic energy stored in the rotor, thereby preventing parts of the driven unit from being subjected to greater stresses than the maximum allowable stress. For this purpose, an error signal between said two speeds is indicated at 9 and compared at 10 with a fixed threshold, and information is sent to the target torque to reduce the drive torque or reverse its direction. In a preferred embodiment, Zener diodes DZ5 and DZ6 form a fixed threshold circuit. Velocity measurement GY and
When the voltage at point D, processed by amplifier CI9, does not exceed the Zener threshold, the potential at F is zero and the indicated torque is L.
will not be subject to any amendments. In the opposite case, the potential at point F increases in proportion to the upper limit of the threshold value, and a torque correction (reduction or direction reversal) is performed at L. Potentiometer P5 fixes the speed difference threshold, potentiometer P7 fixes the corrective action gain, the summation is via potentiometer P3 between the slope and the maximum torque level, amplifier/summer 11,
This is done by inserting C17. This corrective action thus occurs during the twisting and relaxation phases of the elastic support, reducing the dynamic effects.

D capacitor C2, potentiometer P6 and resistor R
Motor speed differentiation circuit 1 composed of 25
2. This circuit resists the target torque and introduces a derivative of the motor speed to stabilize the dynamic behavior of the machine. A potentiometer P6 makes it possible to balance the corrective action.

In one particular embodiment, the drive M is a special low-inertia squirrel-cage three-phase electric motor. The control device may be the same as described above, except that it has a different control unit than the speed difference loop and the motor speed differentiator circuit. However, these two components can be omitted. The reason is,
This is because the drive device is a low-inertia motor, so the inertia effects of the motor rotor and the mechanical components of the target system are sufficiently suppressed.

Further, any other drive device may be used as long as it is possible to instruct steady torque using this device. However, if the inertia of the rotating portion of the drive is large, a speed difference loop and a drive speed differentiator circuit are essential; if the inertia is extremely small, the two components described above are not necessarily required.

Furthermore, depending on the type of horizontal movement to be provided by the drive, the components of the control device according to the invention can be combined in various ways.

The operating principle of the device according to the invention is as follows.

When the device is at rest, when the driver specifies a desired speed, this speed is sent to the speed loop as a command torque. Pre-adjustment with a potentiometer is carried out in advance depending on the type of driven unit. Thus, once a target steady-state torque is specified, the torque is maintained constant throughout the entire period of acceleration by the action of the torque control loop, unless the target torque is modified as necessary by the modification time. Quadrant detection is 1
It is not performed during the acceleration period. The stationary part of the device assumes an equilibrium position as soon as a torque is commanded. The moving part is then actuated and the difference between the commanded speed and the instantaneous speed of the moving part maintains the target torque level unless the achieved speed is equal to the planned speed. Once the planned speed is achieved, the target torque is reduced to the resistance torque maintenance level.

When the target device is in operation, a new target torque is introduced, for example by a zero speed indication.
The moving part is decelerated and finally stopped by a principle similar to acceleration time. However, apart from this deceleration period, the quadrant detection circuit operates to reduce the target torque.

The advantages of the device according to the invention compared to previously known systems are as follows.

- The actual speed of the movable part of the driven unit can be freely controlled by the operator simply instructing the desired speed from zero speed to maximum speed.

- The operator does not have to take any action regarding the torque level, and the torque level does not exceed the permissible values of each part of the driven unit.

- The introduction of a steady-state torque is represented by a quasi-stable equilibrium position of the elastic reaction support or elastic connection, without any dead time, and by a rapid start-up of the moving part of the driven unit.

- elastic reaction supports or elastic connections by introducing steady-state torques and measures to reduce the dynamic effects of mechanism clearances, drive inertia or acceleration of the drive on the moving parts of the driven unit; No vibration occurs. As a result, the movable part of the driven unit can be started without impact, and the fatigue of the elastic support can be significantly reduced.

- the movable parts of the driven unit are maintained in the position indicated by the operator even in the presence of external disturbances, for example wind; In particular, if an external factor acts in the direction of moving the movable part while the braking device is not working, the moving part speed measuring device immediately detects this and the drive device applies a torque to counteract the external factor. The moving part remains stationary.

- Stable operation is achieved because the stress acting on the driven unit is the same during the acceleration and deceleration periods.

In conclusion, with the device according to the invention,
Quick, accurate, and reliable maneuvering of the driven unit is possible, and fatigue of the driven unit can be minimized. The safety and economy of using the driven unit is therefore improved;
Furthermore, the driven unit can be made smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the device according to the invention,
FIG. 2 is a circuit diagram of the device of the invention, given as a non-limiting example. 1... Four image limit power supply unit, 2... Torque control device, 3... Electromagnetic torque calculation device, 4... Speed control device, 5... Instruction torque correction device, 6... Drive and deceleration image limit detection device, 7... Gradient device, 8...
Maximum torque level indicating device, 9... Speed difference level indicating device, 10... Fixed threshold comparison device, 11...
Amplifier/inverter (adder), 12... Differential circuit.

Claims (1)

[Scope of Claims] 1. A device for controlling a drive mechanism that imparts horizontal movement to a driven unit via an elastic reaction support or elastic coupling, comprising: A. a four-quadrant power supply unit of a conventionally known type, and a torque control device; B. a closed-loop drive torque electronic control system consisting of a device and a drive torque calculation device of the conventionally known type; A loop for controlling the absolute ground speed of the driven unit moving part that generates a reference torque value for achieving and maintaining the speed; a speed difference loop for reducing or reversing said target torque when a fixed threshold is exceeded; and D. a drive speed derivative for modifying the target torque by introducing a derivative of the drive speed against the target torque. A device for controlling a drive mechanism characterized by being formed by combining circuits. 2. The ground absolute speed control loop of the driven unit movable part includes various devices necessary for speed control and target torque value generation, namely, a desired speed manual indicating device and a ground absolute speed measuring device of the driven unit movable part. and a speed control device that provides a target torque value by comparing the desired speed and the measured speed, and intermediate devices for modifying the target torque, that is, the target torque value according to the acceleration period and deceleration period. 2. The apparatus of claim 1, further comprising a torque modifying circuit, a target torque gradient device, and a target torque limiting device. 3. The absolute ground speed control loop of the movable part of the drive unit is controlled during the acceleration phase, except when corrections are made by the torque gradient device and correction circuit included in this loop, and by the speed difference loop and drive speed differentiator circuit. , comprising a speed control device that processes an error voltage between the commanded speed and the actual speed so as to command steady torque at the entrance of the torque loop through the speed maintenance period or the deceleration period. Apparatus according to scope 2. 4. The device according to any one of claims 1 to 3, characterized in that it can be used for controlling a three-phase electric motor. 5. Claims 1 to 5 which can be used for controlling a special low-inertia rotor type three-phase electric motor when the speed difference loop and the drive mechanism speed differentiation circuit are appropriately adjusted or removed. Apparatus according to any one of clause 3. 6. The device according to any one of claims 1 to 3, which can be used to control any type of drive device capable of indicating steady torque.