DE10036260A1 - Process for integrating path signal generation in linear induction motor, involves using evaluation circuit for detecting position-dependent currents and voltages of exciter coils - Google Patents

Abstract

A process for integrating path signal generation in linear induction motors having a part with two exciter coils (1,2) and a magnetic ground (4) which can also be a guide and a second part with an electrically conductive short circuit runner (3), with either part forming a fixed stator or a movable runner, with a periodic generation of a varying electromagnetic field suitable for the control of the individual coils. An evaluation circuit is used to detect the position-dependent currents and voltages of the exciter coils. The evaluation circuit derives a position-dependent, quasi-continuous voltage value for the relative position between the two parts from the runner position-dependent alteration of the complex resistances of the exciter coils.

Description

The invention relates to a method for integrated path signal generation in induction linear motors of special design. According to one described in the literature "Trial by Elihu Thomson" can be an electrically conductive ring or a magnetic one encloses conductive linear guide and is arranged on this linearly movable in Movement can be set by an electrical also enclosing the guide AC coil is applied.

Because the direction of movement of the conductive ring, also called rotor in the following, always leads away from the energized coil, a linear motor can be constructed by a second coil is attached to the opposite end of the linear guide.

The rotor ring now located between the two coils can be selected Energizing one of the two coils on the linear guide moves in both directions become.

The electrical coils thus represent excitation windings, the electrically conductive ring in contrast, a short-circuit winding in which a current is induced by the field windings becomes. This induced current, a short-circuit current, is the primary current in the Er opposite winding and is therefore repelled by him.

To use the between the two main components of the motor, the exciter wick and the short-circuit winding, acting force is one of the two components (e.g. the excitation system) stationary, and the other (in the example the short-circuit winding) the movable output of the arrangement.

Motors of this design have no internal measuring standards and have none Self-locking on. Moving to a certain position or holding a position requires the implementation of a complete control loop with at least one measurement system for distance measurement or when constant constant motion is required with a measuring system for speed.

External measuring systems coupled to linear motors are known, or internal measuring systems mechanically integrated into the overall structure, which, however, generally use separate components that are independent of the drive winding (e.g. Kallenbach, E .; Bögelsack, G .: Equipment Technology Drives. Carl Hanser Verlag, Munich , Vienna 1991. Pages 97 ff. And 249 ff.).

Methods are also known for in linear asynchronous motors without a measuring system To be able to derive information about the rotor position, for example described in:

[1] German patent application AZ: 100 25 885.9
[1] Refers to asynchronous linear motors which are based on the principle of an electric traveling field. It uses the influences of a short-circuit winding, which is asymmetrical in the direction of movement, on the drive coils of an asynchronous linear motor to generate a position-dependent signal. In order to enable an integrated path measurement, however, the rotor must have a shape that deviates from the technically ideal design, for example by making a radial bore.

Methods are also known for deriving information about the rotor position, preferably in the case of rotary asynchronous motors without a measuring system, for example described in:
[2] Zinger, DS; Profumo, F .; Lipo, TA; Novotny, DW: A Direct Field-Oriented Control ler for Induction Motor Drives Using Tapped Stator Windings. IEEE Transactions on Power Electronics. Vol. 5, No. 4, 1990, pp. 446-453.
[3] European patent application EP 0 860 939 A1, 1997.
[2] evaluates the change in magnetic conductivity occurring in grooved rotary asynchronous machines due to the rotor grooving. When the rotor rotates in the stator windings, voltages are induced which are proportional to the rotational frequency. They are measured and used to determine the position and speed. Because the amplitudes of the induced voltages decrease with the speed, the method can no longer be used for low speeds and at standstill.
[3] uses the dependency of the leakage inductances of the stator winding on the rotor position in rotary asynchronous and reluctance machines and then calculates the rotor position from the known dependence of the total leakage inductances on the rotor position. Two methods are described for incremental rotor position determination on commercially available asynchronous machines with an inverter. After the inverter has switched, the sum of the three phase voltages is tapped at the motor. This total voltage depends on the rotor position, since the leakage inductances of the drive windings change with the position of the short-circuit winding (s). In this way, the rotor position can be determined within a groove pitch increment. However, a three-phase inverter control is absolutely necessary here. In principle, the method can only be used when working with a traveling field as described.

Methods 2 and 3 are linked to the grooving that is customary in rotary asynchronous motors. They also only allow a comparatively low resolution of the situation. The resolution per revolution is at most equal to the number of slots. Measurements at standstill and at low speeds are also not possible with 2 and 3. Method 3 requires three-phase inverter control.

In addition to methods for integrated measurement signal generation in asynchronous motors, comparable methods for rotary and linear DC motors or for rotary reluctance motors have also been developed:
[4] European patent EP 457 389 B1.
[5] Utility Model No. 297 05 315.9
[6] DE 197 48 647 A1.
[7] Cardoletti, L .; Cassata.; Jufer, M .: Sensorless Position and Speed Control of a brushless DC Motor from Start-up to Nominal Speed. EPE Journal, Vol.2, No. 1, 1992, pp. 25 to 34.
[8] Schroedl, M .; Weinmeier, P .: Sensorless Control of Reluctance Machines at Arbitrary Operating Conditions including Standstill. IEEE Transactions on Power Electronics. Vol. 9, No. 2, 1994, pp. 225-231.
To enable position detection in rotary and linear DC motors without an additional measuring system, [4] suggests electromagnetically coupling the various sub-coils of the motor via a short-circuit winding, which is located on the other coil-less, passive motor part, and in one of the sub-coils in addition to the control signal to couple in a measurement signal in order to achieve a transformer-dependent coupling which is dependent on the position of the passive motor part and which can be used as a measurement signal for the rotor position in at least one other partial coil which is not traversed by the measurement signal. The disadvantage of this solution is the fact that the active motor part (stator with coil system) must not have its own transformer coupling in the form of a short-circuit winding or an electrically conductive magnetic return. Due to the lack of a magnetic yoke, the achievable engine power and thus the usability of the engine is very badly affected. Another disadvantage is that with a weak electromagnetic coupling of the drive coils via the movable motor part practically no path signal can be derived.
[5] describes a method for measuring the path of a direct current linear motor via the dual use of the partial coils as drive and measuring winding by applying the direct current control signal with a measuring alternating voltage and subsequent evaluation in the form of a difference or quotient formation between the amplitudes of the two partial measuring alternating voltages. The disadvantage of this method is that it is tied to analogue power amplifiers and is therefore only suitable for very small motor outputs.

The measurement dynamics are also severely restricted by the filters used in this process for signal processing. In addition, both of the aforementioned proposals require an additional measuring AC voltage for generating the path signal.
[6] protects a method or DC linear motors with integrated path signal generation, in which a path or angle-proportional, quasi-continuous measurement value, independent of the resulting motor current, for the relative position between the first subsystem containing the permanent magnets is measured from the voltage curves across a part coil of a pulse-width-modulated motor of the motor and the second subsystem including the coil system.
[7] describes a method that uses the drive winding of DC motors at the same time to detect the position of transitions between different field areas and thus to derive a commutation signal via the detection of saturation phenomena. However, a considerable amount of electronic effort is required for this very rough location assignment. Measuring and operating processes must also be carried out separately from one another. For this reason, full load operation is also impossible with this measuring method, since cyclical switching to measuring operation is always necessary. In addition to generating the operating currents, separate signals must be generated for the measurement. A precise, position-proportional measurement signal for absolute measurement of the rotor position can practically not be derived.
[8] uses the local change in the magnetic conductance due to iron saturation in reluctance machines. The application is limited to motors with high saturation.

The methods 4 to 7 relate to preferably permanently excited DC motors. The method 4 uses an additional winding for coupling in the signal transmitted by the transformer; the disadvantages here are, in particular, the low shear forces due to the inevitable absence of a magnetic yoke. In method 4 for the dual use of the sub-coils by coupling an AC measurement voltage to the DC control signal, the main disadvantage is the restriction to the use of analog DC output stages and thus also the restriction to small thrust forces and motor outputs. In addition, both solutions require the additional measuring AC voltage mentioned. Methods 5 to 7 are also tied to the typical design of a DC motor with an iron-based rotor or at least with a rotor with high permeability. Method 8 requires a reluctance runner.

The object of the invention is to overcome the disadvantages of the prior art  eliminate and create a method and corresponding device that a sensorless position detection on special induction motors according to Elihu Thomson here described design both during movement and at a standstill he possible. The electrical control of the motors can be implemented in a variety of ways, For example, clocked, controlled by vibration packets with zero voltage switches or Phase angle controlled.

This object is achieved by a method according to claim 1 for induction linear motors solved after Elihu Thomson. Advantageous embodiments of the invention are shown in the subclaims 2 to 12.

It is initially an induction motor structure suitable for this measurement method linear motor. The motor can be rotationally symmetrical or in another design be executed. To implement such a rotationally symmetrical linear motor with In principle, integrated displacement measurement is sufficient for a cylindrical, magnetically conductive body as a guide for the short-circuit rotor, the short-circuit rotor itself, consisting of Example of a simple aluminum ring and two on the ends of the guide wound excitation coils. In the short-circuit rotor during operation by the Excitation coils induce the currents necessary for the power delivery.

The electrical signal curves over both or a energized excitation coil becomes according to claim 1 about the inventive method with the Invention devices a path-dependent, quasi-continuous measured value for the Relative position between the stator and the rotor derived, so that an additional, there is no need for an external or internal position measuring system consisting of separate components.

The electronics required to operate the engine, for example consisting of Microcontroller and power amplifier, controls one of the two excitation coils so that one alternating electromagnetic field arises. By the induced in the short-circuit rotor Electricity creates a force effect that drives the rotor away from the energized coil examined. Since at least one excitation coil is attached to both ends of the guide is the sign of the rotor force by energizing the appropriate coil choose.

In order not to exert any force on the rotor and still measure separately in each coil  , both excitation coils must be alternately cyclically de-energized. The resulting total force is then zero on average over time. A complete one Disconnecting from the power supply over a long period of time is forbidden, since then no integrated distance measurement would be more possible. By a suitable combination of duty cycles of both Excitation coils, which are repeated cyclically, can be any on average Runner power can be achieved.

The evaluation method according to claim 2 uses a rectangular voltage signal. This square wave signal is used to generate the rotor force and is also used for uses the integrated distance measurement.

The evaluation of the flowing excitation coil current is necessary. By differentiating the current profiles over the measuring resistor belonging to the individual excitation coils stood at a constant point in time after the edge change in a rectangular shape The control signal becomes a path-dependent, quasi-continuous voltage value for the relative po sition of the runner. These path-related changes in signal slopes arise from reaction with the currents induced in the squirrel-cage rotor. The Evaluation is based on an inductance analysis for path determination, the switching behavior of inductors in a serial LR network is exploited. In contrast anyway, the use of additional high-frequency measuring voltages existing actuating voltage in its clocked form with regard to the depicted therein Path information used for evaluation. With the path signal can then ge implement a closed control loop.

According to claim 3, the evaluation method can also be used for sine control be modified. Because there is a more complex position-dependent position for each excitation coil Resistance results, path detection can also be realized with an analog actuator and thus not limited to rectangular control. For example, if Sinusoidal voltage with fixed amplitude applied to the excitation coil variable complex resistance of this coil, i.e. depending on the rotor position, also a flowing current with variable amplitude. This current amplitude can with a suitable evaluation circuit and used to determine the rotor position become.  

Claim 4 enables increased accuracy of the method according to claim 3 by capturing the current amplitude at several times and in the evaluation is included.

According to claim 5, there is also the possibility of control with sinusoidal voltage not to measure the current amplitude value but the effective value of the current and so to realize an integrated distance measurement.

According to claim 6 is an injection of currents, instead of as previously described Voltages in the excitation coils are also possible and can also be integrated Path measurement can be used. Instead of evaluating the flowing excitation coils currents with the help of the voltages falling across the measuring resistors can then simply the voltage that can be measured at the excitation coil terminals for position detection be used. The methods of evaluation are identical.

Claim 7 describes an advantageous embodiment of one for the integrated Path measurement of a suitable induction linear motor.

According to claim 8, the motor principle can be expanded to more than two excitation coils by placing additional coils coaxial to the existing ones. This allows either the achievable forces are increased or other advantages are achieved.

According to claim 9, the rotor movement range does not have to be on an excitation coil end, but with a suitable constructive design can also extend beyond. This is particularly important in connection with claim 8 and leads to Also required for multi-phase motor systems with integrated position detection.

Advantageous refinements of the method by using adapted induction linear Motors describes claim 11.

According to claim 12, the overall system can comprise an electronic regulator circuit, which compares the measured path signal with a specified path setpoint and from the difference between the two signals, the input variable for a position controller or  Path controller delivers, which in turn adjusts the drive currents so that the rotor position on the position setpoint or the movement is adjusted to a set travel curve.

The advantages achieved with the invention are, in particular, that separate path measuring systems or separate additional components for path measurement Linear induction motors of the type described are eliminated and are therefore essential simpler less expensive and miniaturizable structure can be achieved. The The inventive method for position detection can on the other hand with clocked control signal, and thus switching output stages, as well as with analog output stages, Phase control or oscillation packet control with zero voltage switches are used.

An embodiment of a correspondingly constructed induction linear motor with clocked control and integrated path signal generation as well as block diagrams of the Measured value processing and basic signal curves are shown in the drawings and are described in more detail below.

They represent:

Fig. 1 is a sectional view of the basic structure of an embodiment of an induction linear motor according to Elihu Thomson suitable for integrated path signal generation.

Fig. 2 is an electrical equivalent circuit diagram of such a motor.

Fig. 3 is an electrical equivalent circuit diagram of such a motor in addition with the switches required for the rotor force direction selection and two measuring resistors for the integrated displacement measurement.

Fig. 4 shows the voltages on the motor terminals to exert continuous maximum force in one direction with clocked control.

Periods with an undefined level are highlighted in gray.

Fig. 5 shows the voltages at the motor terminals for generating a rotor zero force with clocked control. Periods with an undefined level are highlighted in gray.

Fig. 6 The voltage profiles at an excitation coil terminal and across the associated measuring resistor with a short-circuit rotor located near the coil.

Fig. 7 The voltage waveforms at an excitation coil terminal and across the associated measuring resistor with a short-circuit rotor located at a greater distance.

Fig. 8, the two obtained by the transmitter, the path-dependent voltages as a function of the rotor position.

Fig. 9 Exemplary embodiment of an evaluation, control and control electronics for integrated path signal generation with clocked control.

An induction linear motor suitable for the method according to the invention for integrated displacement measurement after the experiment by Elihu Thomson consists in the exemplary embodiment shown in FIG. 1 of a cylindrical, magnetically conductive linear guide ( 4 ) at its two ends two mutually independent excitation windings ( 1 ) and ( 2 ) are firmly applied (subsystem 2 ). The rotor ( 3 ) is arranged coaxially to the linear guide ( 4 ) and movable on it (subsystem 1 ). The rotor is also an electrical short-circuit winding and must therefore consist of an electrically conductive material.

It is irrelevant for the principle of the integrated displacement measurement whether there are other excitation coils over which the rotor ( 3 ) can slide if the design is suitable. The presence or, as in FIG. 1, the absence of further elements for flow guidance is of no importance for the integrated path measurement. The axis x in FIG. 1 indicates the direction of the motor movement, a movement with a positive as well as a negative sign being possible. It is irrelevant whether subsystem 1 or subsystem 2 is designed to be stationary and thus forms the stator. When the motor is operating, the excitation coils ( 1 ) and ( 2 ) are supplied with currents in a well-known manner, which currents have to be variable over time. Which function these currents follow in detail is of minor importance for the possibility of integrated path measurement. Only the evaluation electronics have to be adapted accordingly. In the exemplary embodiment shown, the integrated path measurement for a rectangular clocked voltage application is explained.

Fig. 2 shows the electrical equivalent circuit diagram showing an embodiment of the linear induction motor. The motor terminals U1a and U1b are assigned to the beginning and the end of the excitation coil ( 1 ) in FIG. 1. The inductance L1 and the ohmic resistance R1 correspond to the internal inductance and the internal resistance of the excitation coil ( 1 ), respectively. This applies analogously to U2a, U2b, L2 and R2 for the excitation coil ( 2 ). The resistor R3 and the inductance L3 map the properties of the squirrel-cage rotor. The elements of the motor are electromagnetically coupled to one another.

The additional components shown in Fig. 3 are required for the operation of the motor and the integrated path measurement. These are switches S1 and S2, which switch the electrical signal from input E to the excitation coils, and the two measuring resistors RM1 and RM2.

In the present example, the electrical signal applied is a rectangular AC voltage without a DC component. However, other voltage or current profiles are also possible. The switches S1 and S2 are advantageously constructed in semiconductor technology as is the state of the art. The switches S1 and S2 can be closed and opened by an associated electrical circuit described in FIG. 9.

The current of the excitation coils assigned to them flows through the measuring resistors. By the resulting voltage drop across the measuring resistors RM1 and RM2, which at the Terminals U1a and U2a can be tapped against ground, can currently be in the Excitation coils flowing current can be inferred. The one over the excitation coils currently falling voltage can be applied to the excitation coil terminals U1a and U1b, and U2a and U2b, respectively.

FIG. 4 shows the voltage profiles at the excitation coil terminals U1b and U2b, as are necessary, for example, for the application of a rotor force in the positive x direction. By closing the switch S1, the right corner signal, which is constantly present at input E, is applied to terminal U1b.

Switch S2 remains open, which means that terminal U2b is at an undefined level. This is indicated in Fig. 4 by a gray background. No current can therefore flow in the excitation coil ( 2 ). In contrast, an alternating electromagnetic field is generated in the excitation coil ( 1 ). This induces an alternating current in the squirrel-cage rotor ( 3 ). This leads to a force effect on the squirrel-cage rotor in the positive x direction.

Fig. 5 shows the voltage waveforms to the exciting coil terminals U1b and U2b as are necessary for example for the application of a rotor zero force at the same time integrated displacement measurement. By alternately closing and opening switch S1 and opening and closing switch S2, the rectangular voltage signal constantly present at input E is alternately connected to terminals U1b and U2b. Terminals U1b and U2b are temporarily at an undefined level when the associated switch is open. This is indicated in Fig. 5 by a gray background.

Since the rotor force is directed away from the energized coil, the force exerted on the rotor is canceled out on average over time when the rotor is in the middle position and a signal curve as in FIG. 5. With rotor positions other than the middle position, the switch-on times of switches S1 and S2 must be adjusted accordingly, since the rotor force is not independent of the distance to the excitation coils. It is also possible to further reduce the switch-on times of both switches in a suitable ratio in order to minimize the total switch-on times and thus to reduce the thermal load on the motor.

In FIG. 6, the voltage waveform at the excitation coils U1b terminal when the switch S1 and the voltage drop across the respective measuring resistor RM1 is shown at directly and present in the vicinity of the exciting coil 1 squirrel cage (3). The voltage across the measuring resistor RM1 is directly proportional to the current flowing in the excitation coil ( 1 ). The voltage curve of U1a over time thus depends on the impedance of the excitation coil ( 1 ). However, this is coupled to the x distance of the short-circuit rotor. The voltage curve of U1a thus contains rotor position information, which can be obtained by sampling at two defined points in time after a signal edge change, here for example tA1 and tA2.

FIG. 7 shows the same voltages U1b and U1a with a short-circuit rotor further away in the x direction. Due to the greater this removal of the squirrel-cage rotor (3) of the exciter winding (1) an increased impedance results in the excitation coil (1) in comparison to Fig. 6. As can be clearly seen, the excitation coil is varied by comparison with FIG. 6 increased impedance ( 1 ) the course of U1a. The pulse values of the voltage U1a obtained at the same times tA1 and tA2 have a greater difference than in FIG. 6.

In Fig. 8, the differences in voltage U1a between times tA2 and tA1 and the differences in voltage U2a are plotted as a function of the rotor path and named U1x and U2x.

FIG. 9 shows an example of a possibility of obtaining and further processing the signals U1x and U2x. The central control element is a microcontroller ( 8 ) which can open and close the semiconductor switches S1, S2, StA1 and StA2 electronically. To those in Fig. 6 and Fig. 7 on the time axis noted times tA1 and tA2 includes the microcontroller (8) and release the switch STA1 or STA2. As a result, the capacitors in the modules ( 6 ) charge up to the currently applied voltage. The units ( 5 ) and ( 6 ) thus form a sample as it is prior art. Subtractors ( 7 ) then form the difference between these two instantaneous voltages recorded at times tA1 and tA2, both for the branch of excitation coil 1 and for the branch of excitation coil 2 . These voltage values can be converted into binary form using a multi-channel analog-digital converter contained in the microcontroller ( 8 ). With knowledge of the functions shown in FIG. 8, the microcontroller is able to calculate the current rotor position from one of these differences, but more precisely taking both differences into account. The fact that both voltage differences are generally not determined at the same time, since only one of the two excitation coils is energized in each case is of no importance if the switchover is frequent enough. Even if at maximum force operation, as shown in FIG. 4, only a voltage difference is determined, an integrated path measurement is possible, albeit with reduced accuracy.

In order to close the control loop, a position setpoint xsoll can also be read into the controller ( 8 ). Appropriate control of switches S1 and S2 then enables operation in a closed control loop with well-known algorithms. With the aid of the output stage ( 9 ), the voltage signal to be applied to input E in FIG. 3 can be easily generated under controller control.

Claims (12)

1. Method for integrated path signal generation in induction linear motors, which consists of a first subsystem with preferably two excitation coils ( 1 ) and ( 2 ) and a magnetic return ( 4 ), which can simultaneously be a guide, and a second subsystem, formed by an electrically conductive short circuit Runner ( 3 ), of which each subsystem can form the fixed stator or the movable rotor, with a suitable control for the occasional generation of an electromagnetic alternating field of the individual excitation coils, characterized by an evaluation circuit which consists of the electrical currents required for motor operation and Voltages in the individual excitation coils derive a path-dependent, quasi-continuous voltage value for the relative position between the first and the second subsystem from the change in the complex resistances of the excitation coils depending on the rotor position. 2. Process for integrated path signal generation in induction linear motors Claim 1, characterized in that the excitation coils in the Bestro case with a rectangular voltage signal and the evaluation circuit by separate, time-discrete or continuous time ches differentiating the current profiles in the excitation coils to one each constant point in time after the edge change in the control signal gene, quasi-continuous voltage value for the relative position between the first subsystem of the motor containing the excitation coils and the second, derives the short-circuit winding subsystem. 3. Process for integrated path signal generation in induction linear motors Claim 1, characterized in that the excitation coils in the Bestro case with a sinusoidal voltage signal of constant amplitude be suggested and the evaluation circuit by separately determining the Current amplitudes in the excitation coils at a constant time the beginning of the application of the sinusoidal voltage signal path-dependent, quasi-continuous voltage value for the relative position  between the first subsystem of the motor containing the excitation coils and the second subsystem containing the short-circuit winding. 4. Process for integrated path signal generation in induction linear motors Claim 1, characterized in that the excitation coils in the Bestro case with a sinusoidal voltage signal of constant amplitude be suggested and the evaluation circuit by separately determining the Current amplitude curves in the excitation coils to several, but each con constant times after the start of the application of the sinusoidal Voltage signal a path-dependent, quasi-continuous voltage mean for the relative position between the first one containing the excitation coils Subsystem of the motor and the second, including the short-circuit winding Derives subsystem. 5. Process for integrated path signal generation in induction linear motors Claim 1, characterized in that the excitation coils in the Bestro case with a sinusoidal voltage signal of constant amplitude be suggested and the evaluation circuit by separately determining the RMS values of the currents flowing in the excitation coils to a con constant time after the start of the application of the sinusoidal Voltage signal a path-dependent, quasi-continuous voltage value for the relative position between the first part containing the excitation coils system of the motor and the second, including the short-circuit winding Derives subsystem. 6. Process for integrated path signal generation in induction linear motors at least one of the aforementioned claims, characterized in that that instead of the described voltage impressed in the field windings Corresponding impressed current curves of constant amplitude Application come and instead of the excitation winding current to the excitation winding voltage applied to the integrated path measurement is used. 7. Process for integrated path signal generation in induction linear motors  at least one of the aforementioned claims, characterized in that that an induction linear motor is used, its coil system and Short-circuit rotors are essentially cylindrical and have a common symmetry have tri-axis, either the squirrel-cage rotor or the winding system, possibly together with additional support elements or parts of the magnetic circuit, displaceable to a direction parallel to the common seeds are arranged symmetry axis. 8. Process for integrated path signal generation in induction linear motors at least one of the aforementioned claims, characterized in that that an induction linear motor is used that has more than two axial contains mutually arranged excitation windings. 9. Process for integrated path signal generation in induction linear motors at least one of the aforementioned claims, characterized in that that an induction linear motor is used, the short-circuit rotor of which range over one or more excitation coils of suitable diameter leads out. 10. Method for integrated path signal generation in induction linear motors at least one of the aforementioned claims, characterized in that that an induction linear motor is used alongside a magnetic one conductive inference a linear guide that is both electrical or magnetic can be conductive as well as electrically or magnetically non-conductive, which supports or influences the electromagnetic field distribution of the coil system enced. 11. Method for integrated path signal generation in induction linear motors according to at least one of the preceding claims, characterized in that an induction linear motor is used, the squirrel-cage rotor ( 1 ) of which includes an additional magnetic return path, which can be both electrically conductive and electrically non-conductive, which electromagnetic field distribution supports or influences. 12. Method for integrated path signal generation in asynchronous linear motors at least one of the aforementioned claims, characterized in that that the overall system comprises an electronic control circuit which compares the measured path signal with a specified path setpoint and off the difference between the two signals is the input variable for a position or Path controller delivers, which in turn controls the drive signals so that the rotor po sition on the position setpoint or the movement on a set travel curve is regulated.