Method for initializing a rotary angle measurement system based on a wiegand sensor and rotary angle measurement system

Abstract

The invention relates to a method for initializing a rotary angle measuring system (10) and to a rotary angle measuring system (10) with a corresponding configured initialization unit (36). According to the invention, after the installation of a Wiegand sensor-based rotary angle measuring system (10) at the place of use, an initialization alternating current (IS) is fed into a sensor coil (26) radially surrounding a Wiegand wire (24) for initialization, wherein the initialization alternating current (IS) is provided with a current direction alternating over time and with a current amplitude (ISA) decreasing over time. In this way, a potentially existing magnetization of the Wiegand wire (24) can ideally be completely eliminated or at least significantly reduced. This provides a reliable Wiegand sensor-based rotary angle measuring system (10).

Description

Technical Field

[0001] This invention relates to a method for initializing a Wiegand-based rotation angle measurement system, and to a Wiegand-based rotation angle measurement system for detecting rotational motion of a shaft, the system comprising a permanent magnet excitation unit that can be mounted to rotate with the shaft to be detected, and a stationary Wiegand sensor comprising Wiegand wires and a sensor coil radially surrounding the Wiegand wires. Background Technology

[0002] Rotation angle measurement systems based on Wiegand sensors are well known in the art and are particularly used for controlling and monitoring electric motors, especially servo motors, in machines, factories, or vehicles. Rotation angle measurement systems are also frequently referred to as angle measuring devices, rotation angle sensors, or rotary encoders.

[0003] The permanent magnet excitation unit is mounted to rotate with the shaft and is configured such that, as the excitation unit rotates, an alternating excitation magnetic field is generated at the location of the Wiegand sensor. The Wiegand conductor of the Wiegand sensor is magnetically bistable, wherein the magnetization direction of the Wiegand conductor is abruptly reversed under the influence of a sufficiently strong excitation magnetic field, pointing in the opposite direction to the magnetization direction of the Wiegand conductor. This abrupt reversal of the Wiegand conductor's magnetization generates short voltage pulses in the sensor coil radially surrounding the Wiegand conductor. During the rotation of the excitation unit, the resulting alternating excitation magnetic field thus continuously generates voltage pulses in the sensor coil of the Wiegand sensor, wherein the frequency of the voltage pulses is proportional to the rotational speed of the excitation unit, and therefore proportional to the rotational speed of the shaft.

[0004] If the Wiegand sensor is exposed to a strong magnetic field, such as during transport or installation, the Wiegand wires can become strongly magnetized, making the excitation magnetic field generated by the excitation unit insufficient to completely reverse the magnetization of the Wiegand wires during operation of the rotation angle measurement system. As a result, only a relatively weak voltage pulse is generated in the sensor coil, which cannot be reliably detected by the evaluation unit of the rotation angle measurement system. Furthermore, due to the relatively weak voltage pulse, malfunctions may occur in rotation angle measurement systems based on energy-self-sufficient Wiegand sensors, where the electrical energy of the voltage pulse is used to power the entire rotation angle measurement system due to insufficient energy supply. Summary of the Invention

[0005] In this context, the task is to create a reliable rotation angle measurement system based on Wiegand sensors.

[0006] This task is addressed through a method for initializing a Wiegand sensor-based rotation angle measurement system, and through the Wiegand sensor-based rotation angle measurement system.

[0007] In the method according to the invention for initializing a Wiegand sensor-based rotation angle measurement system, the rotation angle measurement system is first installed at the point of use. Specifically, a permanent magnet excitation unit is mounted on the shaft to be detected so as to rotate with the shaft, and a Wiegand sensor having Wiegand wires and a sensor coil radially surrounding the Wiegand wires is arranged such that, during rotation of the excitation unit, an alternating excitation magnetic field is generated by the excitation unit at the location of the Wiegand sensor. During the installation process, the excitation unit is typically attached directly to the axial end of the shaft. The Wiegand sensor is typically housed in a housing, which is placed on the axial end of the shaft that holds the excitation unit during installation.

[0008] According to the present invention, after the rotation angle measuring system is installed at the location of use, an initialization alternating current is fed into the sensor coil radially surrounding the Wiegand wire by the initialization unit of the rotation angle measuring system. This initialization alternating current is provided with a current direction that alternates with time and a current amplitude that decreases with time. Thus, an initialization magnetic field pointing in an axial direction parallel to the Wiegand wire is generated inside the coil, i.e., at the location of the Wiegand wire. The direction of this magnetic field alternates with time, and its amplitude / intensity decreases with time.

[0009] Because the Wiegand wire is ferromagnetic, the so-called "fundamental magnets" within it tend to align themselves along an externally applied magnetic field. Due to the alternating initial magnetic field, these fundamental magnets are thus continuously "flipped," with the proportion of fundamental magnets flipping as the initial magnetic field strength decreases with each reversal in direction. This produces a relatively disordered arrangement of the fundamental magnets within the Wiegand wire, such that, from a macroscopic perspective, the Wiegand wire is essentially unpolarized, i.e., it is not magnetized.

[0010] The method for initializing a Wiegand sensor-based rotation angle measurement system according to the invention thus allows for the ideal complete elimination or at least significant reduction of the magnetization of the Wiegand conductors that may potentially be caused by the transport or installation of the rotation angle measurement system. This allows for the reliable reversal of the Wiegand conductor magnetization during operation via the excitation magnetic field generated by the permanent magnet excitation unit, and therefore allows for reliable detection of shaft rotation. The initialization method according to the invention thus provides a reliable Wiegand sensor-based rotation angle measurement system.

[0011] Preferably, the direction of the initial alternating current fed into the sensor coil, and the direction of the resulting initial magnetic field, are thus changed at least 5 times, preferably at least 10 times, and particularly preferably at least 20 times. This allows the magnetization of the Wiegand wire to be reliably reduced.

[0012] In a preferred embodiment of the invention, when the initial alternating current is fed into the sensor coil, the initial current amplitude of the initial alternating current is at least twice, preferably at least three times, the termination current amplitude of the initial alternating current when the initial alternating current is fed into the sensor coil, in order to reliably reduce the magnetization of the Wiegand conductor.

[0013] Advantageously, before feeding the initial alternating current, the permanent magnet excitation unit of the rotating angle measurement system is arranged such that the excitation magnetic field generated by the excitation unit at the location of the Wiegand conductor is transverse to the axial direction of the Wiegand conductor, such that the magnetic field lines of the excitation magnetic field are essentially transverse to the axial direction of the Wiegand conductor. Preferably, the excitation unit is arranged such that the angle between the axial direction of the Wiegand conductor and the excitation magnetic field is 70° to 110°, particularly preferably 80° to 100°. Therefore, the excitation magnetic field has little or no component parallel to the axial direction of the Wiegand conductor, so that the excitation magnetic field has no significant effect on reversing the magnetization of the Wiegand conductor. This allows the magnetization of the Wiegand conductor to be reliably reversed, thus reliably reducing the magnetization of the Wiegand conductor.

[0014] In an optional advantageous embodiment of the invention, when feeding the initial alternating current, the excitation unit rotates at a constant rotational frequency, and the initial alternating current is pulsed in such a manner that the initial alternating current pulse is fed into the sensor coil periodically when the excitation magnetic field generated by the excitation unit at the position of the Wiegand conductor is tangential to the axial direction of the Wiegand conductor. Preferably, in each case, the initial alternating current pulse is fed into the sensor coil when the angle between the axial direction of the Wiegand conductor and the excitation magnetic field is 70° to 110°, particularly preferably 80° to 100°. The excitation magnetic field can be detected using a Wiegand sensor or an additional magnetic field sensor. As described above, exciting the sensor coil when the excitation magnetic field is tangential to the axial direction of the Wiegand conductor allows for reliable reversal of the magnetization of the Wiegand conductor, and thus reliably reduces the magnetization of the Wiegand conductor. This is achieved without the need for precise positioning of the excitation unit, due to the uniform rotation of the excitation unit and the controlled pulses of the initial alternating current.

[0015] In another advantageous embodiment of the invention, during the application of the initial alternating current to the sensor coil, the permanent magnet excitation unit is moved such that the parallel component of the excitation magnetic field generated by the excitation unit at the location of the Wiegand conductor, parallel to the axial direction of the Wiegand conductor, and the parallel component of the initial magnetic field generated at the location of the Wiegand conductor by feeding the initial alternating current into the sensor coil, parallel to the axial direction of the Wiegand conductor, always point in the same direction, i.e., always in the same direction. In this context, the terms "always" and "always" are to be interpreted such that during the main time portion of the feeding process, the parallel component of the excitation magnetic field and the parallel component of the initial magnetic field point in the same direction, such that the excitation magnetic field "supports" the initial magnetic field during the reversal of the magnetization of the Wiegand conductor. This allows for reliable reduction of the magnetization of the Wiegand conductor with a relatively low current amplitude and therefore with relatively low electrical energy, without requiring precise positioning of the excitation unit.

[0016] Preferably, during the feeding of the initial alternating current, the excitation unit rotates at a constant rotational frequency, wherein the rotational frequency of the excitation unit is proportional to the alternating frequency of the initial alternating current. Here, the proportionality coefficient is equal to the reciprocal of the number of magnetic poles of the excitation unit, such that the alternating frequency of the excitation magnetic field generated at the location of the Wiegand sensor is equal to the alternating frequency of the initial magnetic field generated by feeding the initial alternating current into the sensor coil. This represents a relatively easy way to move the excitation unit in such a way that the parallel components of the excitation magnetic field and the initial magnetic field always point in the same direction throughout the feeding of the initial alternating current, since the excitation unit only needs to be rotated for alignment once before the feeding of the initial alternating current begins.

[0017] In an optional preferred embodiment of the invention, the excitation unit rotates clockwise and counterclockwise during the feeding of the initial alternating current, such that the alternating frequency of the excitation unit's rotation direction is proportional to the alternating frequency of the initial alternating current. This allows the excitation unit to move in such a way that the parallel components of the excitation magnetic field and the initial magnetic field always point in the same direction throughout the feeding of the initial alternating current, without requiring significant absolute rotation of the excitation unit and therefore the shaft to which it is attached.

[0018] Particularly preferably, the excitation unit is rotated in such a manner that the rotation angle of the excitation unit, either clockwise or counterclockwise, decreases over time. As a result, at the extreme moment of initializing the alternating current, the absolute value of the parallel component of the excitation magnetic field decreases over time, which allows for a particularly efficient reduction in the magnetization of the Wiegand conductor.

[0019] The rotation angle measurement system based on a Wiegand sensor for detecting the rotational motion of a shaft, according to the present invention, includes a permanent magnet excitation unit that can be mounted to rotate together with the shaft to be detected. The excitation unit can be formed of a single permanent magnet or can have multiple permanent magnets attached to a magnet carrier. The excitation unit is typically rotationally symmetric and has magnetic poles uniformly distributed along the circumference of the excitation unit. The excitation unit is typically directly attached to the axial end of the shaft.

[0020] The rotation angle measurement system based on a Wiegand sensor for detecting the rotational motion of a shaft according to the present invention comprises a stationary Wiegand sensor having Wiegand wires and a sensor coil radially surrounding the Wiegand wires. The general design and operation of Wiegand sensors are well known in the prior art. The Wiegand sensor is arranged such that an alternating excitation magnetic field is generated by the excitation unit at the location of the Wiegand sensor when the excitation unit rotates. The Wiegand sensor is typically housed in a housing placed on the axial end of the shaft that fixes the excitation unit.

[0021] Additionally, according to the invention, an initialization unit is provided, configured to feed an initialization alternating current into the sensor coil, wherein the initialization alternating current is provided with a current direction that alternates over time and a current amplitude that decreases over time. Therefore, the initialization unit is configured to generate an initialization magnetic field at the location of the Wiegand conductor, the initialization magnetic field pointing in a direction parallel to the axial direction of the Wiegand conductor, the direction of which alternates over time, and its amplitude / intensity decreasing over time. The initialization unit may be constructed from dedicated circuitry and / or a suitably programmed integrated circuit or microcontroller. The initialization unit may include a built-in current source electrically connected to the sensor coil, or it may be configured to control a separate current source electrically connected to the sensor coil.

[0022] As described above, the initialization unit allows for the elimination or at least significant reduction of the magnetization of the Wiegand wires that may potentially be caused by the transport or installation of the rotation angle measurement system, thus providing a reliable rotation angle measurement system based on Wiegand sensors.

[0023] Preferably, the rotation angle measurement system based on a Wiegand sensor according to the present invention includes an evaluation unit with a current source, wherein the evaluation unit is configured to feed a detection current to the sensor coil via the current source for detecting the magnetization direction of the Wiegand wire, and wherein an initialization unit is configured to feed an initialization alternating current to the sensor coil via the current source of the evaluation unit. The evaluation unit may be constructed from dedicated circuitry and / or a suitably programmed integrated circuit or microcontroller. Particularly preferably, the evaluation unit and the initialization unit are constructed from a single integrated circuit. This provides a compact and simple-to-construct rotation angle measurement system based on a Wiegand sensor. Attached Figure Description

[0024] The following describes embodiments of the rotation angle measurement system based on the Wiegand sensor according to the present invention, and different embodiments of the method for initializing the rotation angle measurement system based on the Wiegand sensor according to the present invention, with reference to the accompanying drawings.

[0025] Figure 1 A schematic diagram of a rotation angle measurement system based on a Wiegand sensor according to the present invention is shown.

[0026] Figure 2 The method for initialization is shown. Figure 1 The possible initialization positions of the excitation unit relative to the Wiegand sensor in the first and second embodiments of the initialization method for the rotation angle measurement system of the invention.

[0027] Figure 3 It is shown that the feed is sent during the initialization method according to the invention. Figure 1 A schematic trace of the initial alternating current in the sensor coil of the Wiegand sensor in the rotation angle measurement system, and a schematic trace of the initial magnetic field generated by the feed.

[0028] Figure 4 A schematic portion of the trajectory of the initialization alternating current fed to the sensor coil during a second embodiment of the initialization method according to the invention is shown, along with the position of the excitation unit relative to the Wiegand sensor at the extreme moments of the initialization alternating current.

[0029] Figure 5 The possible initial positions of the excitation unit relative to the Wiegand sensor according to the third, fourth, and fifth embodiments of the initialization method according to the present invention are shown, and

[0030] Figure 6 A portion of the schematic trajectory of the initialization alternating current fed to the sensor coil during the third and fourth embodiments of the initialization method according to the invention is shown, as well as the position of the excitation unit relative to the Wiegand sensor at the extreme moment of the initialization alternating current. Detailed Implementation

[0031] Figure 1 A rotation angle measurement system 10 based on a Wiegand sensor is shown, mounted on the axial end of a shaft 12. The rotation angle measurement system 10 includes a housing 14 having a housing bottom 16 mounted on the shaft 12 and radially surrounding the shaft, and a housing cover 18 attached to the housing bottom 16.

[0032] The rotation angle measurement system 10 based on the Wiegand sensor further includes a permanent magnet excitation unit 20, which is rotatably attached to the end face of the shaft 12 and concentrically positioned relative to the shaft 12. In this embodiment, the excitation unit 20 is a fully magnetized disk magnet with a single magnetic north pole N and a single magnetic south pole S. The excitation unit 20 generates an excitation magnetic field EM.

[0033] The rotation angle measurement system 10 based on a Wiegand sensor further includes a Wiegand sensor 22 having a Wiegand wire 24 and a sensor coil 26 radially surrounding the Wiegand wire 24. The Wiegand sensor 22 is arranged on a printed circuit board 28, which is fixed in a housing and axially spaced from the excitation unit 20. The Wiegand sensor 22 is arranged such that the Wiegand wire 24 extends perpendicular to the axial direction of the shaft 12 and is concentrically positioned relative to the excitation unit.

[0034] The rotation angle measurement system 10 based on the Wiegand sensor further includes an integrated circuit 30, which constitutes an evaluation unit 32 having a current source 34 and an initialization unit 36. The integrated circuit 30 is arranged on a printed circuit board 28 and electrically connected to the Wiegand sensor 22.

[0035] Evaluation unit 32 is configured to evaluate the voltage pulse generated in sensor coil 26. In order to detect the magnetization direction of Wiegand wire 24, evaluation unit 32 is further configured to feed a detection current to sensor coil 26 via current source 34.

[0036] In order to generate an initial magnetic field IM with a magnetization direction that changes over time and a magnetic field amplitude IMA that decreases over time, the initialization unit 36 ​​is configured to feed an initial alternating current IS with a current direction that changes over time and a current amplitude ISA that decreases over time to the sensor coil 26 via the current source 34 of the evaluation unit 32.

[0037] After being mounted on shaft 12, the initialization of the rotation angle measurement system 10 based on Wiegand sensors is performed by initialization unit 36.

[0038] In the first embodiment, in order to initialize the rotation angle measurement system 10 based on the Wiegand sensor, according to Figure 2 One of the two arrangements schematically shown is that the excitation unit 20 is aligned with the Wiegand sensor 22. Therefore, the excitation unit 20 is arranged such that the excitation magnetic field EM is perpendicular to the axial direction of the Wiegand conductor 24, that is, the magnetic field lines of the excitation magnetic field EM extend substantially perpendicular to the axial direction of the Wiegand conductor 24.

[0039] Subsequently, the initial alternating current IS is fed into the sensor coil 26 by the initialization unit 36, wherein the fed initial alternating current IS has Figure 3 The time trajectory is schematically shown in the diagram. By feeding an initial alternating current IS into the sensor coil 26, an initial magnetic field IM is generated parallel to the axial direction of the Wiegand conductor 24; that is, the magnetic field lines extend substantially parallel to the axial direction of the Wiegand conductor 24. The direction of the initial magnetic field IM is defined by the current direction of the initial alternating current IS.

[0040] Figure 3 The schematic trajectory of the initial alternating current IS over time t is shown, as well as the schematic trajectory of the initial magnetic field IM generated at the location of the Wiegand wire 24 by feeding the initial alternating current IS into the sensor coil 26. Because the magnetic field amplitude IMA of the initial magnetic field IM is approximately proportional to the current amplitude ISA of the initial alternating current IS, for simplicity, the trajectories of the initial alternating current IS and the initial magnetic field IM are shown by… Figure 3 The initial alternating current IS and the initial magnetic field IM are represented by a single curve. The current direction of the initial alternating current IS and the magnetization direction of the initial magnetic field IM are given by the symbols for the initial alternating current IS and the initial magnetic field IM, respectively. For simplicity, the initial alternating current IS has a rectangular shape. However, in principle, the initial alternating current IS can have any alternating waveform with reduced amplitude. Specifically, the initial alternating current IS can also have a sawtooth or sinusoidal trajectory.

[0041] At the start of feeding, the initial alternating current IS is provided with a relatively large initial current amplitude ISAs, thereby providing the initial magnetic field IM with a relatively large initial magnetic field amplitude IMAs. The current amplitude IMA of the initial alternating current IS continuously decreases with time t, in such a way that at the end of feeding, the initial alternating current IS is provided with a relatively low termination current amplitude ISAe. Consequently, the magnetic field amplitude IMA of the initial magnetic field IM decreases with time t to a relatively low termination magnetic field amplitude IMAe.

[0042] Preferably, the starting current amplitude ISAs is at least twice the ending current amplitude ISAe, and more preferably, the ending current amplitude ISAe is at least three times larger. Preferably, during the feeding period, the current direction of the initial alternating current IS changes at least 10 times, and more preferably at least 20 times.

[0043] In the second embodiment, during the feeding of the initialization alternating current IS, the excitation unit 20 rotates at a constant rotational frequency and detects the excitation magnetic field EM via the Wiegand sensor 22 and / or via an additional magnetic field sensor (not shown). Each time the angle between the axial direction of the Wiegand conductor and the excitation magnetic field is 80° to 100°, i.e., when the excitation magnetic field EM is substantially transverse to the axial direction of the Wiegand conductor, the initialization alternating current pulse ISP is fed from the initialization unit 36 ​​to the sensor coil 26. Here, the initialization alternating current pulse ISP is provided with a current direction that alternates with time and a current amplitude ISA that decreases with time.

[0044] Figure 4 A portion of the trajectory of the initial alternating current IS caused by the rotation of the excitation unit 20 is shown, as well as the orientation of the excitation unit 20 at the moment of the initial alternating current pulse ISP.

[0045] In the third embodiment, according to Figure 5 In one of the two arrangements schematically shown, at the start of initialization of the Wiegand sensor-based rotation angle measurement system 10, the excitation unit 20 is aligned relative to the Wiegand sensor 22. Therefore, the excitation unit 20 is arranged such that the excitation magnetic field EM is parallel to the axial direction of the Wiegand conductor 24, i.e., the magnetic field lines of the excitation magnetic field EM extend substantially parallel to the axial direction of the Wiegand conductor 24.

[0046] At the start of the feeding process, the initial current direction of the initial alternating current IS is always set in such a way that the parallel component of the excitation magnetic field EM (which is parallel to the axial direction of the Wiegand conductor 24) and the parallel component of the initial magnetic field IM (which is parallel to the axial direction of the Wiegand conductor 24) point in the same direction.

[0047] During the feeding of the initial alternating current IS, the excitation unit 20 rotates at a constant rotational frequency, which is greater than half the alternating frequency of the initial alternating current IS, i.e., half the frequency at which the current direction of the initial alternating current changes. This causes the parallel components of the excitation magnetic field EM and the initial magnetic field IM to always point in the same direction.

[0048] Figure 6 A portion of the trajectory of the initial alternating current IS caused by the rotation of the excitation unit 20 is shown, as well as the orientation of the excitation unit 20 at the extreme moment of the initial alternating current IS.

[0049] In the fourth embodiment, from Figure 5Starting with one of the two arrangements schematically shown, the excitation unit 20 does not rotate relative to the Wiegand sensor 22 at a constant rotational frequency, but rather rotates constantly and alternately 180° clockwise and 180° counterclockwise. The rotational alternation frequency, that is, the frequency at which the rotational direction of the excitation unit is reversed, is here exactly the same as the alternation frequency of the initialization alternating current IS, such that the parallel components of the excitation magnetic field EM and the initialization magnetic field IM always point in the same direction.

[0050] The time trajectory of the initial alternating current IS in the fourth embodiment and the alignment of the excitation unit 20 at the extreme moment of the initial alternating current IS caused by the "back and forth rotation" of the excitation unit 20 are substantially the same as those of the fourth embodiment. Figure 6 The trajectory is consistent with that of the third embodiment shown schematically in the diagram.

[0051] In the fifth embodiment, from Figure 5 Starting with one of the two arrangements schematically shown, the excitation unit 20 rotates constantly in alternating clockwise and counterclockwise relative to the Wiegand sensor 22, wherein, as in the fourth embodiment, the alternation frequency of the rotation direction is exactly the same as the alternation frequency of the initial alternating current IS.

[0052] However, unlike the fourth embodiment, the excitation unit in the fifth embodiment does not always rotate back and forth at a constant rotation angle of 180°, but rotates back and forth at a rotation angle that decreases over time, so that the magnitude of the parallel component of the excitation magnetic field EM decreases over time when the extreme value of the alternating current IS is initialized.

[0053] Reference List

[0054] 10 Rotation Angle Measurement System Based on Wiegand Sensor

[0055] 12-axis

[0056] 14 shell

[0057] 16. Bottom of the shell

[0058] 18 housing cover

[0059] 20 excitation units

[0060] 22 Wiegand sensors

[0061] 24 Wiegand wire

[0062] 26 sensor coils

[0063] 28 Printed Circuit Boards

[0064] 30 integrated circuits

[0065] 32 evaluation units

[0066] 34 Current Sources

[0067] 36 initialization units

[0068] EM excitation magnetic field

[0069] IM Initialization Magnetic Field

[0070] The magnetic field amplitude of the IMA initial magnetic field

[0071] The initial magnetic field amplitude of IMAs initialization magnetic field

[0072] The termination magnetic field amplitude of the IMAe initial magnetic field

[0073] IS initialization alternating current

[0074] ISA initialization of alternating current amplitude

[0075] Initial current amplitude of ISAs for initializing alternating current

[0076] ISAe initialization of alternating current termination current amplitude

[0077] ISP Initialize Alternating Current Pulse

[0078] N magnetic north pole

[0079] S-magnetic south pole.

Claims

1. A method for initializing a rotation angle measurement system (10) based on a Wiegand sensor, comprising the following steps: - Install the rotation angle measurement system (10) at the location of use. - An initial alternating current (IS) is fed into a sensor coil (26), which, after installation, is radially wrapped around a Wiegand wire (24), wherein the initial alternating current (IS) is provided with a current direction that alternates over time and a current amplitude (ISA) that decreases over time.

2. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 1, wherein the direction of the initial alternating current (IS) is changed at least 5 times.

3. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 1, wherein the direction of the initial alternating current (IS) is changed at least 10 times.

4. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 1, wherein the direction of the initial alternating current (IS) is changed at least 20 times.

5. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 1, wherein the initial current magnitude (ISAs) of the initial alternating current (IS) at the start of the feed is at least twice the termination current magnitude (ISAe) of the initial alternating current (IS) at the end of the feed.

6. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 1, wherein the initial current magnitude (ISAs) of the initial alternating current (IS) at the start of the feed is at least three times the termination current magnitude (ISAe) of the initial alternating current (IS) at the end of the feed.

7. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to any one of claims 1 to 6, wherein the following method steps are performed prior to the initialization of the alternating current (IS) feed: - Arrange a permanent magnet excitation unit (20) such that the excitation magnetic field (EM) generated by the permanent magnet excitation unit (20) at the position of the Wiegand conductor (24) is transverse to the axial direction of the Wiegand conductor (24).

8. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 7, wherein, The permanent magnet excitation unit (20) rotates at a constant rotational frequency during the feeding of the initialization alternating current (IS), wherein the initialization alternating current (IS) is pulsed in such a way that when the excitation magnetic field (EM) generated by the permanent magnet excitation unit (20) at the position of the Wiegand conductor (24) is transverse to the axial direction of the Wiegand conductor (24), the initialization alternating current pulse (ISP) is fed into the sensor coil (26).

9. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to any one of claims 1 to 6, comprising the following method steps: - The permanent magnet excitation unit (20) is moved during the feeding of the initial alternating current (IS) in such a way that the parallel component of the excitation magnetic field (EM) generated by the permanent magnet excitation unit (20) at the position of the Wiegand conductor (24) and the parallel component of the initial magnetic field (IM) generated at the position of the Wiegand conductor (24) by the feeding from the initial alternating current (IS) to the sensor coil (26) always point in the same direction, wherein, The parallel component of the excitation magnetic field (EM) is parallel to the axial direction of the Wiegand conductor (24), wherein the parallel component of the initialization magnetic field (IM) is parallel to the axial direction of the Wiegand conductor (24).

10. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 9, wherein, During the feeding of the initial alternating current (IS), the permanent magnet excitation unit (20) rotates at a constant rotation frequency, wherein the rotation frequency is proportional to the alternating frequency of the initial alternating current (IS).

11. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 9, wherein, During the feeding of the initial alternating current (IS), the permanent magnet excitation unit (20) rotates alternately clockwise and counterclockwise in such a way that the alternating frequency of the rotation direction of the permanent magnet excitation unit is proportional to the alternating frequency of the initial alternating current (IS).

12. The method for initializing a rotation angle measurement system (10) based on a Wiegand sensor according to claim 11, wherein the permanent magnet excitation unit (20) is rotated in such a manner that the rotation angles of the permanent magnet excitation unit (20) rotating clockwise and counterclockwise decrease over time.

13. A rotation angle measurement system (10) based on a Wiegand sensor for detecting the rotational motion of a shaft, comprising: - Permanent magnet excitation unit (20), which is configured to be mounted so as to rotate together with the shaft (12) to be tested, and -Static Wiegand sensor (22), including • Wiegand wire (24) and • Sensor coil (26) radially surrounding the Wiegand wire (24). Its features An initialization unit (36) is provided, which is configured to feed an initialization alternating current (IS) into the sensor coil (26), wherein the initialization alternating current (IS) is provided with a current direction that changes over time and a current amplitude (ISA) that decreases over time.

14. The rotation angle measurement system (10) based on the Wiegand sensor according to claim 13, comprising an evaluation unit (32) having a current source (34), wherein the evaluation unit (32) is configured to feed a detection current to the sensor coil (26) via the current source (34) for detecting the magnetization direction of the Wiegand wire (24), and wherein the initialization unit (36) is configured to feed the initialization alternating current (IS) to the sensor coil (26) via the current source (34) of the evaluation unit (32).

15. The rotation angle measurement system (10) based on Wiegand sensors according to claim 14, wherein the evaluation unit (32) and the initialization unit (36) are composed of a single integrated circuit (30).

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