DE2853889A1 - AC motor with infinitely variable control for machine tool - has DC brake winding, speed and displacement measurement system and D=A converter - Google Patents

Abstract

A single or three-phase electric motor is provided with infinitely variable control of the speed or angular displacement. The motor is connected to a gear system or a drum to effect linear movement which can be in the horizontal, vertical or both directions. It can be used in a machine tool or stage handling system where a number of drives, each with different loading can be synchronised. The motor has a d.c. brake winding and a measuring system for the speed and the displacement. There is a d-a converter, a pulse shaper and a counter. The control module has an acceleration, normal and delay phases which can all be manually adjusted.

Description

The invention relates to a method and an apparatus

for stepless speed and angle of rotation control of single- or three-phase Electric motors (AC motors), which with a gear or a drum for the execution of linear e.g. horizontal and / or vertical movements are.

Such drives can be used, for example, in machine tools or also with cable pulling devices come into use by theater studios, where it is particularly important to have a more or less large number. of drives with different loads can, exactly in true-to-path synchronism to move and stop.

Single or three-phase electric motors are used because of their simpler Structure and the type of electricity available everywhere compared to the more expensive ones DC motors generally preferred. However, they are more difficult to regulate. Of the Start-up takes place abruptly, e.g. with the known star-delta connection. The acceleration and the delay is mostly uncontrolled. Additional required mechanical Brakes for deceleration are subject to high wear and require a ongoing maintenance. Up to now, special motors were used for more precise speed control with expensive frequency converters necessary. An exact synchronous operation of several Motors with an exact speed and angle of rotation correspondence is not without it further possible.

The object of the invention is to provide a method and a device create that makes it possible in those with a single-phase or three-phase electric motor connected drives, the movement of the driven object at each point of a to run the predetermined path at a certain speed, with The particular object of the invention is to have several such drives in synchronism to regulate with exact speed and angle of rotation correspondence.

The inventive method consists in that with a DC brake winding and a motor provided with a device for speed and distance measurement from a digital-to-analog converter, the alternating voltage pulses from a pulse arrester from the mains received via a counter, and from a control unit connected to it certain path / speed curves (n = f (s)), consisting of an acceleration phase sl, a normal phase s2, a delay phase s3 and a run-out phase s4 is controlled, the individual phases by a number of fixed and of Manually adjustable setpoint generators for the speed and the path are specified and each of which is driven by an actual value transmitter for the speed and the path determines the actual speeds and paths and a number of Comparators are supplied, of which according to the comparison with the setpoint values the motor via an electronic acceleration and deceleration controller as well as the associated power controller, metered network energy is supplied.

The method according to the invention is distinguished from the on the The field of single- and three-phase electric motors by known control methods extremely high accuracy. This is mainly due to the fact that the individual phases one after the other using a system of setpoint generators and several comparators for the speed to which the measuring devices act and the path to be controlled, which in combination with each other the course of the phases influence. In addition, this is done with the invention with relatively simple means achieved that are commercially available and therefore inexpensive.

The control principle also makes it possible to have several in a simple manner Such motors that attack one or more objects, such as cable systems of stages, to be regulated absolutely synchronously, with each motor from one in the same Way adjusted control device is regulated.

Even better synchronization is achieved by the motors can be regulated by a single control device (setpoint electronics) and via a comparison of the measured actual speed or distance values are also linked to each other.

Such a method is according to the invention that all Motors from a single digital-to-analog converter and one connected to it single control device, which the individual phases are controlled by the setpoint generator are specified, while the deviations occurring in the individual motors the speed and the distance from the setpoints from the assigned actual value encoder and comparators are determined and from these via the acceleration and dosed the deceleration controller and the power controller according to the motors Mains energy is supplied, additionally from the actual distance values of the individual Motors (measuring voltages) a path mean value is formed and the deviation of the actual path value of the individual motor from this mean value as an additional control variable to the acceleration and fed to the deceleration controller of the motor.

Another possibility of linking is that instead of the actual distance values from the actual speed values of all motors (measuring voltages) a speed mean value and the deviation of the actual speed value of the individual motor from this mean value as an additional control variable for the acceleration and deceleration controllers of the motor is supplied.

A particularly high synchronization accuracy can be achieved in a further embodiment achieve the invention that at the same time from the actual path values and the The actual speed values of all motors are averaged and the deviations the actual values of the individual motor from these mean values as additional control variables the acceleration and deceleration controllers of the motor.

This double linkage of the motors is extremely precise Speed and angle of rotation control possible for many areas of drive technology such as B. the control of machine tools or cable devices of Theater stages is important.

In the drawings, the invention is based on exemplary embodiments, which also show further details, explained in more detail: Fig. 1 shows two speed / travel curves (n = f (s)), which have different speeds and different path lengths, Fig. FIG. 2 shows a block diagram for regulating a motor, FIG. 3 shows a block diagram for controlling the synchronism of two or more motors when taken into account of the path mean value, FIG. 4 shows a block diagram for the regulation of the synchronization two or more motors taking into account the average speed value, Fig. 5 shows a block diagram for controlling the synchronization of two or more Motors taking into account the distance and speed mean value.

In Fig. 1, (I) shows the speed / path curve in which a speed n2 = 1200 rpm and (II) the speed / path curve for which a speed n2 = 720 RPM has been set. (n2 = target speed of normal phase s2).

o As the total path length at which the path comparator switches off the motor and the shoe brake is switched on, at (I) three meters, at (II) two meters set.

The curves consist of the branches: a) Acceleration phase with the Path segment sl and the speeds nl, b) normal phase with the path segment s2 and the speed n2, c) deceleration phase with the path segment s3 and the speeds n3, d) run-out phase with path segment s4 and speed n4.

In both cases, only the speed is used in the deceleration phase s3 n4 = 240 rpm, which is permanently set, delayed with that in the run-down phase s4 continued to run until the final stop at 3 or 2 m will. The presence of a phase-out phase is very beneficial in that it is a part of it shutdown is safer, especially when several motors are being controlled at the same time controlled.

To the run-out phase s4 and thus the run-out time with a permanent To keep changes in the speeds n2 as low as possible, it may be useful to initiate the beginning of the delay phase s3 as a function of n2, so that the Deceleration phase earlier at a higher speed n2 and earlier at a lower speed Speed n2 starts later.

In Fig. 2, 1 denotes the drive, consisting of a three-phase motor with squirrel cage rotor, the stator of which is provided with a DC brake winding is, and a gear connected to it with a cable drum e.g. for the Cable pull of a theater stage, the drive with a holding brake and with a Device 2 is provided, which the actual speed value encoder 3 and the actual position value encoder 4 drives.

5 is the control unit (gate logic) and 6 is the digital-to-analog converter connected to it. This is connected to the network through the pulse from conductor 7, from which he voltage pulses via the up / down counter 8 receives.

After the start, the pulses are counted by the counter 8 in the acceleration phase sl forward and after switching in the deceleration phase s3 backwards, whereby the current counter reading is within the acceleration resp. Delay and run-out phase correspond to the target speeds specified for control unit 5 is equivalent to.

With the control unit 5 are the target speed sensor 9, with which the target speed n2 of the normal phase s2 is set, and the speed comparator lo is connected, which compares the respective speeds nl with n2 and sends control commands to the control unit 5 there. The path comparators are also connected to the control unit 5 and also to the counter 8 11 and 12 connected.

Both are in connection with the travel setpoint generator 13, through the the total travel s = sl + s2 + s3 + s4 is set. 11 and 12 compare the actual path covered with the set target path. 12 initiates the start of the delay phase s3 a.

To simplify matters, the path comparator 12 can be set in such a way that that the delay phase s3 is initiated at a constant distance from the end of the path will. To avoid unnecessarily long run-out paths s4 at low speeds n2 and a constant To avoid changing the setting of 12, it is beneficial to do 12 with the speed setpoint generator 9 to couple that it automatically starts the delay phase at lower speeds n2 initiates later and at higher speeds n2 earlier.

Another path comparator 14 is between the actual path value transmitter 4 and the travel setpoint generator 13 is switched on. He also compares the whole Actual travel with the set target travel and is directly linked to the power controllers 17 and 18 of the drive 1 in connection.

With the control unit 5 is the electronic acceleration controller 15 and the electronic delay controller 16 are connected. This is also the one Speed actual value encoder 3 connected. The controllers with P, PI or PID behavior can be equipped, are connected to corresponding power controllers 17 and 18, supply the dosed net energy to the motor. For quick adjustment of large control deviations (Difference between setpoint and actual value) and a simultaneous supply of drive and to avoid braking energy or to limit it to a short time, these are Outputs of the controller via lines 15a / 16a alternately with the input of the connected to others. The power controller 17 also changes the direction of rotation.

The power controllers 17 and 18 are also connected to the path comparator 14 connected, which causes the shutdown.

With 19 the start button is referred to, which on the start / stop logic 20 works. When operating several motors, 19 is also provided with a start / stop logic Mistake.

In the drawing, the connecting lines are with a steady flow of signals (Analog quantities) with full arrows, and the lines with only between two Mark signals that change values (digital quantities) with empty arrows.

In Figures 3 to 5, which are the block diagrams of the control show two (or more) motors, the reference numerals of Fig. 2 are retained, where the circuit diagrams through the terminals a - f in a setpoint electronics (above) and a motor electronics (below) are separated and to the setpoint electronics here two engine electronics are connected.

In Fig. 3 is for the purpose of linking the motors in the motor electronics each motor in the line leading from the actual position value transmitter 4 to the position comparator 11 parallel to a resistor 21 for the formation of a path mean value of the motors another path comparator 22 is arranged, which with the acceleration and the Delay regulator 15 and 16 is connected.

In Fig. 4 is for the purpose of linking the motors in the motor electronics each motor in that of the actual speed value encoder 3 to the acceleration and deceleration controller 15 and 16 in parallel with a resistor 23 for the formation of an average speed value the motors a further speed comparator 24 is arranged, which with the acceleration and the delay regulators 15 and 16 are connected.

In Fig. 5 is for the purpose of a particularly high synchronization accuracy in the motor electronics of each motor additionally both a path comparator 22 and also a speed comparator 24 for forming a distance and speed mean value arranged.

The operation of the device according to the invention is as follows: 1) Preparation The desired speed n2 is set at the speed setpoint generator 9 Normal phase s2 is set, the desired target travel is set on travel setpoint generator 13 s = sl + s2 + s3 + s4.

Furthermore, n4 is fixed in the speed comparator lo.

2) Acceleration phase sl By pressing the start button 19, the start / stop logic 20 switched on, which unlocks the power adjusters 17/18 and the mechanical holding brake on drive 1 releases.

At the same time, the electronic counter 8 is turned on, so that this receives alternating voltage pulses from the mains (50 Hz) via the pulse arrester 7, counts and passes on to the digital-to-analog converter 6. The counter 8 can e.g. a maximum range of 250 pulses = 1200 rpm corresponding to 5 seconds. The counted pulses, which correspond to the target speeds, are transmitted by the digital-to-analog converter 6 as increasing voltage values to the control unit 5 (gate logic) and the speed comparator lo fed.

The control unit 5 gives as long as the speeds nl below the These voltage values lie in the setpoint speed n2 set in the speed setpoint generator 9 to the electronic acceleration and deceleration controllers 15/16, which the Power controller connected to the three-phase network with appropriately metered network energy supply so that the motor starts with a corresponding acceleration.

The respective actual speed is linked to the drive stationary speed actual value encoder 3 is determined and fed to the controllers 15/16, which also work as a comparator and the actual speed with that of the control unit 5 Compare the supplied setpoint speed and, according to a possible deviation, the Adjust the actual speed.

The controller 15 feeds acceleration energy to the motor via the power controller 17, the controller 16 decelerating energy via the power controller 18 of the brake winding of the motor to. So there is a closed control loop between 1, 2, 3, 15/16, 17/18 for the speed.

For fast adjustment of larger control deviations, the mutual connections 15a / 16a of the controller with each other to the controller 15 the Output signal of the controller 16 supplied and vice versa, this only from a certain size, but then amplifies the output signal of the other controller influence.

During the acceleration phase, the counter 8 counts up.

3) Normal phase S2 As soon as the speed nl is set in the speed setpoint generator 9 has reached the set target speed n2 at the end of sl, the speed comparator lo, the upward counting of the counter 8 is stopped and the signal for the speed n2 fed through the control unit 5 to the controllers 15/16.

The motor runs at speed n2 during normal phase s2.

4) Delay phase s3 The delay phase is determined by the path comparator 12 initiated, which is connected to the position setpoint generator 13 and the position actual value generator 4 stands.

It is here on a certain constant path length of s3 + s4 = 1.3 m set. When the traveled path length of s - (s3 + s4) is determined, it switches the path comparator 12 via the control unit 5 from the path setpoint generator 9 and the Counter 8 counts down, which means that the Control unit 5 via the digital-to-analog converter 6 is given a falling speed n3, which leads to a corresponding loading of the acceleration and deceleration controller 15/16 leads, with the corresponding motor windings through the power controller 17/18 be applied.

The motor is decelerated until the speed n4 is reached.

5) Run-down phase s4 As soon as the speed comparator detects lo has that the speed n3 reaches the fixed predetermined speed n4 of e.g. 240 rpm it turns off counter 8. The signal for this speed remains via the Receive control unit 5 on controllers 15/16 and the engine runs at this speed continue until the end of s4. This is achieved when the path comparator 14 the Agreement of the actual path with the target path s ascertains.

At this point in time, the power controller suddenly becomes through 14 over 2o 17/18 locked and the holding brake of the drive switched on.

At the same time, the count of the counter 8 increases from 14 to 20 0 set.

There is between 1, 2, 4, 14, 20 and 17/18 egg closed Control loop for the way.

The regulation of several motors according to FIGS. 3-5 works according to the same principle.

In Fig. 3 takes place in the additional path comparator 22, which is via the terminal c is connected to the path comparator 11, the formation of a path mean value of the motors as a voltage value that the acceleration and deceleration controllers 15/16, which indicates a possible deviation in the actual path value of a motor from this mean value as an additional controlled variable and register a corresponding Acting on the power controller 17/18 bring about, as the case may be whether the motor is leading or lagging the mean value.

In Fig. 4 is in the additional speed comparator 24, its additional output terminal f with the speed comparisons 24 of the other motors is connected, a speed mean value is formed as a voltage value, which the controller 15/16 is fed in, which indicates a possible speed deviation of the motor from this mean value register as an additional control variable and just like before a corresponding application the power controller 17/18 bring about.

In FIG. 5, an additional one takes place simultaneously but independently of one another Control according to the path and speed averaging, as described for Fig. 3 and 4.

The regulating device according to the invention can also be implemented by other functions having the same effect Means are formed as those specified. E.g. it can also be exclusively from Digital building blocks.

Although not specifically mentioned at the beginning, falls under the scope of protection the application without further ado the application of the invention to the regulation of rarer special motors that are connected to a network with a higher number of phases operate.

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Claims (14)

"Method and device for stepless speed and angle of rotation control of single- or three-phase electric motors, which are equipped with a gearbox or a Drum connected to perform linear movements are "claims: Method for stepless speed and angle of rotation control of a single or three-phase Electric motor, which with a gear or a drum for the execution of linear movements, characterized in that the with a DC brake winding and a motor provided with a device (2) for speed measurement and distance measurement (1) from a digital-to-analog converter (6), which from a pulse arrester (7) from the Network receives alternating voltage pulses via a counter (8), and from one with this connected control unit (5) according to certain path / speed curves (n = f (s)), consisting from an acceleration phase (sl), a normal phase (s2), a deceleration phase (s3) and a run-out phase (s4) is controlled, the individual phases through a number of fixed and manually adjustable setpoint generators for the speed (9) and the path (13) are specified and each of which is provided by the device (2) driven actual value encoder for the speed (3) and the distance (4) the actual Speeds and distances determined and a number of comparators (lo, 11, 12, 14) are supplied, of which according to the comparison with the Setpoint values to the motor via an electronic acceleration (15) and a deceleration controller (16) and associated power controllers (17, 18) metered network energy supplied will. 2) Method for stepless speed and angle of rotation control of several synchronous motors according to claim 1, characterized in that all motors from a single digital-to-analog converter (6) and a single one connected to it Control unit (5) are controlled, which the individual phases by the setpoint generator (9, 13) can be specified, while the deviations occurring in the individual motors the speed and the distance from the setpoints from the assigned actual value encoders (3, 4) and comparators (lo, 11, 12, 14) are determined and from these over the acceleration and deceleration controllers (15, 16) and the power controller (17,18) is supplied to the motors appropriately dosed network energy, with additional in comparators (22) from the actual distance values of the individual motors (measuring voltages) a mean value is formed and the deviation of the actual distance value of the individual Motor from this mean value as an additional control variable to the acceleration and the deceleration controller (15, 16) of the motor is fed. 3) Method for stepless speed and angle of rotation control of several synchronous motors according to claim 1, characterized in that all motors from a single digital-to-analog converter (6) and a single one connected to it Control unit (5) are controlled, which the individual phases by the setpoint generator (9, 13) can be specified, while the deviations occurring in the individual motors the speed and the Away from the setpoints from the assigned Actual value sensors (3, 4) and comparators (1o, 11, 12, 14) are determined and by this via the acceleration and deceleration controllers (15, 16) and the power controller (17, 18) is supplied to the motors appropriately dosed network energy, with additional in comparators (24) from the actual speed values of the individual motors (measuring voltages) Speed mean value is formed and the deviation of the actual speed value of the individual Motor from this mean value as an additional control variable to the acceleration and the deceleration controller (15, 16) of the motor is fed. 4) Method for stepless speed and angle of rotation control of several synchronous motors according to claims 1 - 3, characterized in that additionally at the same time in comparators (22 and 24) from the actual distance values and the actual speed values a mean value is formed for each of the individual motors and the deviation of the actual values of the individual motor from these mean values as additional control variables to the acceleration and the deceleration controller (15, 16) of the motor. 5) Device for performing the method according to the claims 1 - 4, characterized in that the one assigned to the digital-to-analog converter (6) Counter (8) can be switched as an up / down counter that uses the pulse from conductor (.7) counts AC voltage pulses coming from the grid after the start, namely during the acceleration phase (sl) with counting up and during the delay phase (s3) with downward counting, the current count being the within the acceleration or. the delay and run-out phase to the control unit - (5) corresponds to specified target speeds. 6) Device for performing the method according to the claims 1 - 4, characterized in that an adjustable speed setpoint generator (9) is arranged by which the speed (n2) of the normal phase is determined and a speed comparator (lo), which compares the respective speed (nl) with (n2) or (n3) compares with (n4). 7) Device for performing the method according to the claims 1 - 4, characterized in that an adjustable travel setpoint generator (13) is arranged is by which the total path (s = sl + s2 + s3 + s4) is determined and three Path comparators (11), (12) and (14), of which (11) and (14) the actual path with the target path compare, where (14) also switches the direction of movement, and (12) the Start of the delay phase (s3). 8) Device according to claim 7, characterized in that the path comparator (12) is set so that the delay phase (s3) remains constant at a Distance from the end of the path is initiated. 9) Device according to claim 7, characterized in that the path comparator (12) is coupled to the speed setpoint generator (9) in such a way that it eliminates the delay phase (s3) automatically at lower speeds (n2) later and at higher speeds (n2) begins earlier. lo) Device for performing the method according to the claims 1 - 4, characterized in that the output of the electronic acceleration controller (15) via a line (15a) in addition to the input of the electronic delay controller (16) is connected. 11) Device for performing the method according to the claims 1 - 4, characterized in that the output of the electronic delay controller (16) via a line (16a) in addition to the input of the electronic acceleration controller (15) is connected. 12) Device for performing the method according to the claims 2 and 4, characterized in that in the from the actual position encoder (4) to the distance comparator (11) Leading line, parallel to a resistor (21) for the formation of a Distance mean value of the motors, a further distance comparator (22) is arranged which with the acceleration and deceleration controller (15, 16) of the relevant Motor is connected. 13) Device for performing the method according to the claims 3 and 4, characterized in that in the range from the actual speed sensor (3) to the acceleration and delay regulator (15, 16) carrying line, in parallel with a resistor (23), a further speed comparator for calculating an average speed value for the motors (24) is arranged, which is connected to the acceleration and deceleration controllers of the relevant motor and also with the speed comparators (24) of the other motors connected is. 14) Device for performing the method according to the claims 4, 11 and 12, characterized in that both a path comparator (22) and a speed comparator (24) for the formation of mean values of distance and speed of the Motors is arranged.