Controlled electric motor arrangement for a tension mechanism

“FIELD-ORIENTED CONTROL METHODS FOR ELECTRIC ACTIVATION AND OPERATION FOR A DRIVE TO TRACT AN OBJECT, ELECTRIC MOTOR ARRANGEMENT, AND, POSITION AND / OR SPEED CONTROLLER FOR ELECTRIC FIELD-ORIENTED CONTROL” [0001] The invention relates to a field-oriented method for controlling an electric drive comprising a plurality of electric motors, for example, to implement a traction mechanism, especially for load cable and / or gear media. In the control method, measurements are taken from a real multi-phase motor current. The measured values ​​are transformed into a direct current component and a quadrature current component, based on a magnetic rotor field angle or flow angle, in a rotor based d, q coordinate system. The measured quadrature current component is compared with a predetermined transverse current component of a current command value, to obtain a command value for motor current control.

[0002] The invention also relates to an electric motor arrangement, which is especially suitable for implementing the control method, with at least two electric motors that can be operated as multi-phase motors. The invention also relates to a position and / or speed controller for the field-oriented control of an electric drive, which is especially suitable for use in the above mentioned control method or in the above mentioned electric motor arrangement.

[0003] The invention also relates to a starting method for a traction drive and, therefore, an arrangement for preparing electric motors.

[0004] For a wire steering system, a

Petition 870190050315, of 05/29/2019, p. 7/44 / 22 steering actuator is proposed (DE 101 03 667 Al), in which two electric motors are provided. The pinions of the electric motors act on a gear wheel, which drives, for example, a rack and pinion steering transmission or a steering column, to which a steering wheel is fixed. When the actuator is required to generate only low levels of torque, then the two electric motors are controlled in such a way that they are displaced relative to each other, therefore no play occurs in the gear between pinion and gear wheel. This is ensured when the pinion tooth flanks and the gear wheel are positioned against each other with zero play. Zero gear drive of the gear wheel can be achieved through the appropriate control of the two electric motors, in which the rotation directions of the two electric motors are oriented towards each other. It is also proposed that each of the two electric motors can be provided with a rotor position sensor, as a provision for redundancy against a possible failure of one of the two electric motors.

[0005] In contrast to this, in the interest of efficient control of the multi-motor electric drive, the control method disclosed here is proposed. An electric motor arrangement that is appropriate for implementing the control method is set out here. A position and / or speed controller, which also falls under the general idea of ​​the invention, is also exposed here. Advantageous optional exemplary embodiments of the invention are also described.

[0006] The invention comprises the basic idea of ​​connecting two synchronous motors in series through their phase windings, thus allowing their two magnetic wheels and magnetic rotor flows to rotate with a phase or angular displacement in relation to each other. The use according to the invention of two synchronous motors, which are characterized by effective controllability, a high level of

Petition 870190050315, of 05/29/2019, p. 8/44 / 22 efficiency and a high power factor, while at the same time having a low construction volume, contributes to increased efficiency, resulting in advantages for servo applications, such as with traction mechanisms. In particular, synchronous machines are characterized by means of a rotating main field, which is fixed to the rotor, and the magnetic flux coupling is very often based on permanent magnets which are mounted on the rotor surface and result in a flow of approximately constant rotor, which facilitates controllability.

[0007] With the method of the invention, the magnetic wheels or rotors of the two synchronous motors are displaced relative to each other with their magnetic flux couplings or other magnetic alignments at an angle, so that one and the same phase current can act on one motor as a current component forming flow (continuous) and on the other motor as a current component forming torque (quadrature). The phase or angular displacement is defined with respect to stationary or permanent coordinates, especially with respect to a stator-based coordinate system.

[0008] This paves the way for the next method characteristic according to the invention, more specifically that the two synchronous motors are supplied with the same phase current from a single shared power converter. Therefore, only a single power converter, especially a frequency converter or an inverter, is required, which provides substantial savings in terms of structural components.

[0009] In the context of the control according to the invention, a reference or command value for a pre-traction or traction torque is predetermined, which, on the one hand, is superimposed by the quadrature current component of the value of current control. On the other hand, this predetermined value of the traction torque command, with an opposite sign, is

Petition 870190050315, of 05/29/2019, p. 9/44 / 22 used at the same time as a command value for the DC component. Because of the aforementioned angular displacement of the magnetic flux, this DC component acts on the second synchronous motor as a quadrature current component forming torque, while the quadrature current component that is applied to the first motor then originates the direct component forming flow in the second engine.

[00010] In this way, a coordinated and synchronized movement of the electric motors can be achieved, which is especially well suited to implement a traction mechanism for the purpose of eliminating play in gear or cable means. The coordination of the motion sequences is based on the coupling of the respective flow couplings of the synchronous motors through the angular displacement, in which one and the same phase current works as a quadrature current component in a motor, and as a component of direct current in the other motor.

[00011] To simplify the complexity in terms of control technique, it is desirable to maintain the angular displacement of the respective magnetic fluxes of the synchronous motor rotors and the command value for the pre-tension torque, constant during continuous operation. In this way, the respective phase current of the two synchronous motors can be easily and systematically adjusted to predetermined control values.

[00012] The synchronous motor arrangement that is within the scope of the general idea of ​​the invention is characterized by its connection in series. This can be implemented in that the second synchronous motor is connected through the conductors of its phase windings with the ends of the phase windings of the first synchronous motor, which in turn is connected through the conductors of its phase windings with the power converter. This results in a coupling of the two motors

Petition 870190050315, of 05/29/2019, p. 10/44 / 22 synchronous with the power converter. With this series connection of the power converter, especially the inverter, the first synchronous motor and the second synchronous motor, the method characteristic of the invention is achieved in which the same phase current flows through both motors. In this case, only one of the two synchronous motors is connected directly to the power converter. Consequently, synchronous motors are coupled to each other serially through their phase windings, in such a way that each synchronous motor is supplied with the same phase currents by the power converter.

[00013] What is important is that the magnetic alignments of the magnetic wheels or rotors of the two synchronous motors are displaced not in phase, but in relation to each other at an angle of displacement. In principle, this angle can measure between 0 and ± 180 °, thus, for example, ± 45 °. In practical use, angular displacements of 90 ° have proved to be optimal.

[00014] To implement phase shift or angular displacement between the magnetic flux couplings or magnetic alignments of the two synchronous motors, a mechanical coupling is used, according to the invention, which can be implemented, for example, using cable means or gear between the rotors or magnetic wheels. This implementation is also efficient for the application of the traction mechanism according to the invention, because the mechanical coupling can then be produced using the load cable means or the gear wheel or other gear means. If the load cable means or the gear means are pulled, then the mechanical coupling between the rotors of the synchronous motors, and therefore also the angular displacement between their flow couplings or magnetic flow alignments, are established or defined .

[00015] The basic principle of the invention presents not only the form of implementation of the double electric motor drive having only one

Petition 870190050315, of 05/29/2019, p. 11/44 / 22 inverter or power converter, but also the fact that only one of the two synchronous motors is equipped with a position detection device (sensor system and / or rotor model). This, consequently, results in the other embodiment of the invention, which reduces the number of components and is, therefore, cost-effective, in that a controller that controls an inverter is allocated to both synchronous motors within the structure of a drive control circuit. The additional savings in terms of components and costs, combined with an increase in technical reliability, are obvious.

[00016] Another problem solved by means of the invention consists in the fact that the traction drive according to the main invention has not been defined in its initial state, without current flow. The magnetic wheels of the two synchronous motors can be freely rotated against each other, without requiring the desired phase shift, preferably 90 ° between the two magnetic wheels. Another objective of the invention is, therefore, to achieve that, during starting, the desired phase shift is generated between the magnetic wheels of the two synchronous motors in the traction drive.

[00017] This objective is achieved through the method of operation described here. Advantageous optional embodiments of the method of operation are also described. Suitable applications: starting method for traction of machine elements and assemblies that are subjected to play, such as gear mechanisms, mechanical transmissions and coupling elements, which, in the untractioned state, do not occupy a clearly defined position.

[00018] The operating method of the invention is provided for a drive to pull an object that is flexible or that has play (clearance, tolerance) as at least two electric motors that can be operated as polyphasic motors are obstructing the object by means of forces

Petition 870190050315, of 05/29/2019, p. Opposite 12/44 / 22. A control and / or regulation device is used to control the electric motors. For starting or starting when the traction drive is in an idle state or off with no current, first only one of the two electric motors is actuated for a traction movement until a first pre-specified stopping criterion is detected by means of the control and / or regulation device. Then, optionally, the second electric motor is activated for a traction movement, until a second pre-specified stopping criterion is detected by means of the control and / or regulation device. The method of the invention for controlled starting of a drive system, consisting of a drive motor and traction motor, comprises the steps: when starting from the non-current mode, the traction torque is first generated in order to take the element to be pulled to a defined position; allowing a transition to the desired operation.

[00019] According to an exemplary embodiment of the invention, during the operation of the first or second electric motor, the respective other electric motor is short-circuited and / or otherwise decoupled from the control and / or regulation device. This is based on the fact that a short-circuit three-phase motor behaves like an electrodynamic brake. Therefore, during the operation of one of the electric motors, the respective other motor is used as an electrodynamic brake by means of a short circuit (S1, S2) of its phase windings. Advantageously, an increase in the motor current flow and / or range from a predetermined motor position and / or a predetermined synchronization period serves as a stopping criterion. Advantages of the multi-motor arrangements of the invention: individual control of two motors connected in series through a single converter; generation of an effective braking moment by simply shorting the motor windings. [00020] In the context with the method of operation of the invention, it is

Petition 870190050315, of 05/29/2019, p. 13/44 / 22 advantageous when the phase windings of one or both electric motors are equipped with switching elements, which are arranged to decouple one or both electric motors from the control and / or regulation device.

[00021] A control structure according to an aspect of the invention, which is functionally adapted to the invention, comprises a device for generating a command value or setpoint of pretraction or traction torque. On the one hand, its output is superimposed by a controller output for the motor torque, which is known in the art; on the other hand, the traction torque output of the controller - with signal reversal - is made available for further processing as a direct current component, particularly after being weighted with the reciprocal value of the motor flow coupling. Thus, it can be subjected to a command value / actual value comparison with an actual measured value for the DC component, and the difference is fed to a current controller, in a known manner. The respective control current d or q resulting from direct current and quadrature controllers results in one synchronous motor to form flow and the other synchronous motor to form torque.

[00022] Technical reliability and operational safety, especially for the application of the traction mechanism, can be increased with an advantageous optional embodiment of the invention, in which the quadrature and direct current command value outputs are each equipped with a limiting element. Each such limiting element is configured to restrict the command value output allocated to a range that has uniform signals. According to the invention, the signals from the two control value outputs are kept opposite each other by means of the limiting elements. The advantage achieved with this is that the mechanical coupling, and therefore a phase shift or angle of

Petition 870190050315, of 05/29/2019, p. 14/44 / 22 The displacement between the magnetic flux couplings of the two synchronous motors is always ensured, so that one and the same phase current can act to form torque in one synchronous motor and to form flow in the other synchronous motor. In addition, in the application involving “traction of a flexible belt or some other flexible element”, the stretch can be excluded with a high degree of reliability.

[00023] In order to be able to use the motor torque range to its maximum possible extent, a form of embodiment of the speed controller of the invention is proposed, in which the output of the motor torque control and / or command value generator is supplied, preferably in total, not only for the branch of the quadratic current command value component, but also for the branch of the direct current command value component. Expressing this idea in concrete terms, a sum point is provided for this purpose, with the motor control torque and, with a negative sign, the pre-traction torque being supplied for its two inputs. From the difference, the direct current component is derived using a reciprocal weighting with a value for a flow coupling (which is determined based on the circumstances of the individual technical case). Because, with this particularly advantageous embodiment, the motor torque control value is processed and / or used to generate and supply not only the quadrature current component command value, but also the current component command value continuous, the available torque control range can be activated or controlled or used up to 100% in both directions.

[00024] According to another advantageous embodiment of the invention, a pre-tension torque is adjusted, which corresponds to approximately 50% of the maximum possible motor torque. With this, at least approximately 50% of the maximum possible motor torque can still be activated or controlled in both directions, even without the

Petition 870190050315, of 05/29/2019, p. 15/44 / 22 described above, insertion of the motor torque command value.

[00025] Other details, striking features, combinations of features, advantages and effects based on the invention can be found in the following description of preferred embodiments of the invention, and in the set of drawings, where:

Figure 1 shows a sketch outlining the device engineering principle of an application according to the invention involving the traction and positioning of a pull cable, Figure 2 shows a sketch outlining the device engineering principle, of an application according to the invention to drive a gear train, Figure 3 shows an electrical arrangement of the traction drive, Figure 4 shows a block diagram of a control structure, adapted in terms of the function of the invention, Figure 5 shows a block diagram of an additional control structure, adapted in terms of the function of the invention, Figures 6a-6c show vector diagrams of current and flow for various applications, Figure 7 shows an arrangement of electric motor to perform the method of operation, Figure 8 shows a device outline for the proposal according to the method of operation, and Figure 9 shows an alternative electric motor arrangement for performing the method of operation.

[00026] According to figure 1, the respective rotors (not shown) of two synchronous motors M1, M2 are mechanically coupled through a traction line 1, which is suitable for a variety of purposes. If the two synchronous motors M1, M2 are controlled using

Petition 870190050315, of 05/29/2019, p. 16/44 / 22 opposite torques (see below), opposite accelerations b1, b2 are applied at the ends of the traction line 1 through the respective rotors of the synchronous motors M1, M2. This results in traction of the traction line 1, for example, a traction cable or traction belt, so that arching between the synchronous motors M1, M2 is prevented. In addition, traction causes the respective rotors of the synchronous motors M1, M2 to be kept in place at their angular position in relation to each other. According to the invention, this fixation in place is achieved by the fact that the respective magnetic flux couplings Ψνι, Ψμ2 (see figure 6) have a phase shift or an angular shift of preferably 90 ° relative to each other. In order to enable a controllable drive of the two synchronous motors, one or both are equipped with a position sensor 2, in which, in principle, it is sufficient, in principle, for only one of the two synchronous motors M1, M2 to be scanned by means of of a position sensor 2.

[00027] According to figure 2, to drive a gear train, two synchronous motors M1, M2 are placed in positive engagement with a central gear wheel 3 through gear wheels that are coupled with their respective rotors. However, in most cases, this engagement of gear wheels is associated with undesirable play between the tooth flanks, which impairs positioning accuracy. To restrict or prevent opposing gear wheel play, torques or accelerations b1, b2 are again applied to the two synchronous motors M1, M2. In this way, the opposite tooth flanks of the gear wheels that are engaged with each other rest directly against each other without play, in other words, they are pulled. The synchronous motor rotors are then definitely fixed in terms of their angular position, relative to each other. In addition, the statements made in reference to figure 1 can be applied here,

Petition 870190050315, of 05/29/2019, p. 17/44 / 22 correspondingly.

[00028] According to figure 3, the two synchronous motors M1, M2 are preferably supplied with the same nominal current level, connected in series, and from a shared power converter 4, for example, an inverter. For this purpose, the conductors of the motor phase windings Wu1, Wv1, Ww1 of the first torque synchronous motor M1 are directly connected to the U, V, w power converter phase terminals. The ends of the motor phase windings of the M1 synchronous motor are directly connected with the conductors of the motor phase windings Wu2, Wv2, Ww2 of the second synchronous motor M2, according to the series connection. According to figure 3, the ends of the phase windings of the second synchronous motor M2 are connected in a star connection, however they can also be connected in a delta connection. The single power converter 4 is controlled via a control device 5, which is allocated to the two synchronous motors M1, M2 together.

[00029] According to figure 4, the control device 5 comprises, in a known manner, a speed command / actual value comparison point 6, a speed controller 7 positioned downstream of it, preferably configured as a PI controller, with a limiter 8 at its output, and a current controller 9. The outputs of the current controller 9 for the quadrature current and direct current components usq_ref, usd_ref are used to control a PWM pulse width modulator, positioned downstream of the latter, which is used in a known manner to control the converter power or inverter 4.

[00030] Between speed controller 7, which supplies a command or reference value m_ref for a motor torque at its output, and current controller 9, a device 10 for deriving a value of

Petition 870190050315, of 05/29/2019, p. 18/44 / 22 quadrature current component command isq_ref, called quadrature current command value controller ”10 below, and downstream of this, a quadrature current command / real value comparator1 1 are arranged . In the example embodiment shown in figure 4, the quadrature current command value controller 10 comprises a multiplication element 12 to weight the motor torque control value m_ref, of arrival with the reciprocal value of a coupling of magnetic flux ψ, and an added signal limiter 13 positioned downstream of that. This limits the quadrature current command value component isq_ref that arrives from multiplication element 12 to a positive range.

[00031] In addition, between speed controller 7 or motor torque controller 7, 8, consisting of the output of speed controller 7 and limiter 8, and current controller 9, a pre-set torque controller traction 14 is arranged, the output of which is provided, on the one hand, to a first summation point 15. Its second input is connected with the output of the motor torque controller 7, 8. On the other hand, the output of the pre-tension torque controller 14 is connected via a signal reversing element 16 to a direct current command value controller 17, through whose output a current command value component isd_ref is supplied for a direct current / actual value command value comparator 18. The direct current control value controller 17 also has a multiplication element 12 for reciprocal weighting of the control value for a pre-tension torque with the magnetic flux coupling Ψ and a negative output limiter 19. The latter limits the direct current command value isd_ref coming from the multiplication element 12 for a range of negative sign - in a function analogous to that of the above described positive limiter 13.

[00032] With the two limiters of positive and / or negative signs, it is

Petition 870190050315, of 05/29/2019, p. 19/44 / 22 ensured, especially with regard to application as a traction mechanism, that each of the current components that form torque in the first synchronous motor M1 and in the second synchronous motor M2 have signals that are opposite to each other, or the torques of the two M1, M2 engines work opposite each other to achieve traction. For this purpose, according to an example embodiment of figure 4, the traction torque controller 14 is arranged to provide a constant reference value for the pretension_torque traction torque. The constant traction reference value is conveniently approximately 50% of the maximum motor torque, so that a residual motor torque control range of 50% can be used for actuation or control, [00033] According to the figure 5, to increase the available motor torque control range to approximately 100%, a second summation point 20 is arranged between the motor torque controller 7, 8 and the current controller 9, for an input from which the output of the traction torque controller 14 with a negative sign is supplied. The output of the motor torque controller 7, 8 or the motor torque control value m_ref is supplied to the other input, without signal reversal. The output of the second summation point 20 is supplied to the direct current control value controller 17 (see above). In this way, the motor torque command value, which is provided by speed controller 7, can be used until its total extraction for both quadrature current command value controller 10 and command value controller direct current 17. The reference value for pretension_torque is additively or subtractively superimposed on the first or second summation points 15, 20. While, in the example embodiment according to figure 4, an adjustable torque range results for an acceleration from -50% to + 50%, in the example embodiment according to figure 5, a range is achieved of adjustable torque for the acceleration of Petition 870190050315, of 05/29/2019, p. 20/44 / 22

100% to + 100%. With the example embodiment according to figure 5, the pre-tension torque controller 14 is conveniently configured to be externally adjustable.

[00034] According to figure 6a-c, the magnetic flux coupling ΨΜ2 of the second synchronous motor M2 is electrically displaced by approximately 90 ° delay because of the mechanical couplings according to figures 1 and 2, in the previous direction of rotation, in relation to the magnetic flux coupling Ψμ1 of the first synchronous motor M1. The stator current components, more precisely the quadrature current components iq1 and iq2, and the direct current components id1 and id2 of the first or second synchronous motor M1 or M2, respectively, are represented in field coordinates for the operating conditions a - idling status - b - acceleration to the left with respect to figure 1 - and c - acceleration to the right with respect to figure 1. Assuming that the two synchronous motors M1, M2 are magnetically approximately 100% symmetrical, the torque can be calculated as follows for the example embodiment of figure 4 (adjustable torque range: 500 / o) for the three operating conditions a, b, c:

Operating condition a - idle state [00035] An idle state is present when the torques of the two synchronous motors M1, M2 are at equal levels and are driven in opposition to each other, or have opposite signals. For this, the command value “torque 0” is issued via the current controller, according to figure 4. Therefore, in each case, only one control value of the same level for pretension_torque traction torque is supplied both for quadrature current command value controller 10 and DC command value controller 17, the last with a reverse sign. The quadrature current components iq1, iq2 that result in the stators of the synchronous motors M1, M2 and are torque forming are

Petition 870190050315, of 05/29/2019, p. 21/44 / 22 equal in terms of magnitude, however they have inverse signs. As a result, opposite torques of the same magnitude result from the respective vector products Ψνι \ iq1 (for the first synchronous motor M1) and ^ M2X iq2 (for the second synchronous motor M2), resulting in the idle state.

Operating condition b - acceleration to the left with respect to figure 1 [00036] Based on a motor torque control value m_ref, which is generated via speed controller 7 and output via motor torque controller 7, 8, a command value for increasing the quadrature current command value component is provided for the command value controller of quadrature current 10 according to figure 4, in which at the first summation point 15 a motor torque control value is added to the value for pretension_torque traction torque. The quadrature current command value component isq_ref, which is increased significantly in this way, is interpreted in the first synchronous motor M1 as an increased quadrature current iq1 with a corresponding increase in torque (see the above mentioned vector product with Vm1) , while this increased current component acts on the second synchronous motor M2 only as a flow forming component id2. As a result, the first synchronous motor M1 applies a higher level of torque than the second to implement the movement to the left of the traction line 1, which can import a maximum of twice the torque of the second synchronous motor M2.

Operating condition c - acceleration to the right according to figure 1 [00037] Based on the corresponding motor torque control value output mref with a negative sign from the motor torque controller 7, 8, once when the traction torque command value having

Petition 870190050315, of 05/29/2019, p. 22/44 / 22 a positive signal was added, a relatively significant lowering of the quadrature current command value component results in the quadrature current command value controller 10, which is illustrated in figure 6c by means of a vector correspondingly reduced for the quadrature current component iq1. This current component acts on the second synchronous motor M2 as a direct current component forming an id2 flow, indicated after this by means of a dashed line is the current or phasor vector, which corresponds to the pretension_torque pre-set adjusted for a constant. This is reflected, with its supply to the direct current command value controller 17, in the constant quadrature current component forming torque iq2 of the second synchronous motor M2 (a corresponding current value is used in the first synchronous motor M1 only as forming flow). In this case, the torque applied by means of the first synchronous motor M1 makes up only a fraction of the torque generated by the second synchronous motor M2, which is attributable only to the fixed output of the traction torque controller 14.

[00038] According to figure 7, among the first and second motors M1, M2, respectively, the W2 windings of the second motor M2, which is not equipped with an encoder or position sensor, are short-circuited. This is done by activating the switch S2 located between the two motors M1, M2. Its individual switching elements connect the end terminals of said W2 windings. Then, only the M1 motor with the G sensor remains connected to the inverter. A basic idea of ​​the invention comprises short-circuiting one of the two motors during the starting phase, so that the other motor can be controlled and operated independently of the short-circuit motor.

[00039] Starting proposal: The second M2 motor is short-circuited and acts as a brake. The first M1 motor, coupled with the position sensor G and its phase windings W1 now connected in a connection in

Petition 870190050315, of 05/29/2019, p. 23/44 / 22 star, is controlled like a normal servo motor, and is moved to a defined position, until an increased current flow through the motor can be identified (for example, through a current controller). If the current intensity increases substantially, this means that an intensified reverse torque is present as a load, for example, due to the motor being short-circuited and braking M2. It also means that the traction object, for example, the gear or traction cable 1, has been pulled. A partial bend L1, L2 of the traction cable 1, shown in figure 8 by means of a line of dashes and points, has been eliminated.

[00040] Alternative starting proposal: First, the M1 motor with sensor, like a servo motor, is moved to a defined rotational position previously specified (first stopping criterion). Whether or not the traction object is pulled at this moment is irrelevant. In a second step, the second motor M2 is then released from its small circuit, and is moved until an increased current flow through the first motor M1 can be detected (second stopping criterion). This means that increased torques have to be overcome, and the traction object has been pulled.

[00041] According to figure 7, as for starting, the second motor M2 without a sensor is short-circuited. The first M1 motor is then moved until an increased current flow can be detected. This increased current flow occurs when the first M1 motor has to pull hard, for example, against the M2 motor, which is acting as a short circuit brake. Although the example embodiment shown in figure 1 illustrates the basic principle of the invention, a number of disadvantages still persist, for example, with respect to flexible pull cables 1, as shown in figure 8.

[00042] On the pull cable 1 shown in figure 8, a central section A, which is preferably not to be displaced or out of phase, is

Petition 870190050315, of 05/29/2019, p. 24/44 / 22 checked. The end sections L1, L2, among which the central section A is located, are hanging loosely multiple times at the beginning of the starting phase. In the first starting step, the first M1 motor with a G sensor is moved to a certain position (for example, the previous end position when it was switched off) as a servo motor. The loosely hanging end sections L1, L2 of the pull cable (indicated by a line of dashes and dots in figure 8) are not necessarily pulled yet.

[00043] Another refinement of the starting method of the invention: with the M1 motor, because of its G position encoder, the terminal position occupied at the time of the previous shutdown can be stored, in which the M1 motor was switched off. The next time it starts, it is moved first to this end portion or previous terminal (first stopping criterion). In this way, the first initially loose end section L1 can also be stretched. The other loose end section L2 may remain loose; it is coupled with the second motor M2 (without sensor).

[00044] With the traction mechanism shown in figure 8, it is required that the central cable section A is not moved backwards and forwards in a longitudinal direction, and instead remains pulled. This central section ends at the two loose cable sections L1 and L2. A refinement on the basis of the invention now consists of the following (see also figure 9 with the associated text):

[00045] First, a first switching set S1 according to figure 9 is closed, with the result that the windings W2 of the second motor M2 (without sensor) are bridged. For this purpose, each phase winding is allocated to a switching element of the first switching set S1. So, only the first M1 engine with G encoder can be controlled. This is then controlled in such a way

Petition 870190050315, of 05/29/2019, p. 25/44 / 22 way the servo motor M1 is moved back to an end point previously vacated (first stopping criterion). This causes the loose end section L1 to be pulled. Due to certain circumstances, the central section A is not out of step or displaced. The second loose end section L2 first remains loose. In the subsequent step, the first switching set 81 is opened and a second switching set S2 (arranged between said two motors M1, M2) or their switching elements, respectively, are closed. The M1 servo motor is then short-circuited and acts as an electrodynamic brake. This offers the advantage that the L1 end section remains tight or pulled. For the second special motor "M2, position detection in any form is also feasible, whether this is done by means of an extra sensor or software using an injection technique and / or an engine model (so-called sensorless method" ). “The special motor M2, also called a“ slave ”, is then moved, in the appropriate direction according to a position detection, until an increased current flow can be detected by means of a current controller based on a torque of high load (according to stopping criteria). The drive mechanism is then fully operational and the start-up procedure may change to normal operation.

[00046] According to figure 9, the drive system comprises a drive motor and a traction motor, where an M1 of the two motors is preferably a standard synchronous motor with a G encoder. The other second motor M2 is a special motor, the winding ends of which are configured on a terminal board, and the windings of which can be short-circuited or bridged via the first switching set (S1). In addition, a second switching set (S2) is also present, which makes it possible to short-circuit all the connection poles between the two motors. This short

Petition 870190050315, of 05/29/2019, p. 26/44 / 22 circuit is preferably implemented through switching elements, which are integrated in the special motor M2, so that in series connection of these two motors (M1 and M2), either the M1 motor or the M2 motor can be separately controlled using short circuit switches.

List of Reference Symbols

<td> [00047]</td><td>M1 first synchronous motor</td>

<td> [00048]</td><td>M2 second engine (special) without sensor</td>

<td> [00049]</td><td>1 Traction line</td>

<td> [00050]</td><td>b1, b2 Acceleration</td>

<td>[00051] synchronous</td><td>Vm1, Vm2 Flow connection of the first or second motor</td>

<td> [00052]</td><td>2 Position sensor</td>

<td> [00053]</td><td>3 Gear wheel</td>

<td> [00054]</td><td>4 Power converter</td>

<td> [00055]</td><td>Wu1.2 Motor torque phase winding</td>

<td> [00056]</td><td>Wv1, 2 Motor torque phase winding</td>

<td> [00057]</td><td>Wwu Motor torque phase winding</td>

<td> [00058]</td><td>U, V, W Power converter phase terminals</td>

<td> [00059]</td><td>5 Control device</td>

<td>[00060] real value</td><td>6 Speed ​​command value comparison point /</td>

<td> [00061]</td><td>7 Speed ​​controller</td>

<td> [00062]</td><td>8 Limiter</td>

<td> [00063]</td><td>9 Current controller</td>

<td> [00064]</td><td>usq_ref Quadrature current component</td>

<td> [00065]</td><td>usd_ref DC component</td>

<td> [00066]</td><td>PWM Pulse Width Modulator</td>

<td> [00067]</td><td>m_ref Motor torque control value</td>

<td> [00068]</td><td>isq_ref Current component command value in</td>

Petition 870190050315, of 05/29/2019, p. 27/44 / 22 quadrature

<td>[00069] square</td><td>10 Current command value controller in</td>

<td> [00070]</td><td>11 Current command value comparator in</td>

square / actual value

<td> [00071]</td><td>12 Multiplier element</td>

<td> [00072]</td><td>ψ Magnetic flux connection</td>

<td> [00073]</td><td>13 Add signal limiter</td>

<td> [00074]</td><td>7, 8 Motor torque controller</td>

<td> [00075]</td><td>14 Traction torque controller</td>

<td> [00076]</td><td>15 First summation point</td>

<td> [00077]</td><td>16 Signal reversal element</td>

<td> [00078]</td><td>17 DC current control value controller</td>

<td> [00079]</td><td>18 Current command value comparator</td>

continuous / actual value

<td>[00080] to be continued</td><td>isd_ref Current command value component</td>

<td> [00081]</td><td>19 Negative limit</td>

<td> [00082]</td><td>bias_torque Pre-traction torque</td>

<td> [00083]</td><td>20 Second summation point</td>

<td> [00084]</td><td>iq1, iq2 Quadrature current components of the first</td>

or second synchronous motor Ml or M2, respectively

<td> [00085]</td><td>id1, id2 Direct current component</td>

<td> [00086]</td><td>v Angular displacement</td>

<td> [00087]</td><td>G sensor</td>

<td> [00088]</td><td>Wl, W2 motor windings</td>

<td> [00089]</td><td>Ll, L2 pull line end sections 1</td>

<td>U, V, W</td><td>phases</td>

Petition 870190050315, of 05/29/2019, p. 28/44