Magneto Rotation Angle Sensor System

Abstract

The present invention relates to a magnetic rotary angle sensor system (10) for detecting the rotational movement of a shaft (1), comprising an excitation unit (12) having at least one excitation magnet (122), a Weigand sensor unit (14) having a sensor coil (141) and at least one Weigand wire (142) arranged inside the sensor coil (141), a magnetic sensor unit (16), and an evaluation electronics (18). The excitation unit (12) is mounted so as to rotate together with the shaft (1), and generates an alternating excitation magnetic field at the position of the Weigand sensor unit (14) and the position of the magnetic sensor unit (16) when the shaft (1) rotates. The Weigand sensor unit (14) generates a Weigand sensor voltage pulse (WP) in the sensor coil (141) by the alternating excitation magnetic field. The magnetic sensor unit (16) detects the alternating excitation magnetic field and provides a corresponding magnetic sensor signal (S). The evaluation electronics (18) is configured to detect the Weigand sensor voltage pulse (WP), determine the rotational speed (N) based thereon, receive the magnetic sensor signal (S), and determine a rotation angle value (A) based on the magnetic sensor signal (S). The evaluation electronics (18) is provided with a first compensation parameter (K1) and a second compensation parameter (K2), and is configured to alternately apply the first compensation parameter (K1) and the second compensation parameter (K2) to the received magnetic sensor signal (S) when determining the rotation angle value (A).

Description

Technical Field

[0001] The present invention relates to a magnetic rotary angle sensor system for detecting the rotational movement of a shaft, comprising an excitation unit having at least one excitation magnet, a Weigand sensor unit having a sensor coil and at least one Weigand wire arranged inside the sensor coil, a magnetic sensor unit, and an evaluation electronics. The excitation unit is mounted so as to rotate together with the shaft and is configured to generate an alternating excitation magnetic field at the positions of the Weigand sensor unit and the magnetic sensor unit when the shaft rotates. The magnetic sensor unit is configured to detect the alternating excitation magnetic field and provide a corresponding magnetic sensor signal. The evaluation electronics is configured to detect a Weigand sensor voltage pulse, determine the rotational speed based thereon, receive the magnetic sensor signal, and determine a rotational angle value based on the magnetic sensor signal.

Background Art

[0002] Unless otherwise defined, the following terms "axial direction", "radial direction" and "cross section" refer to the shaft detected by the rotary angle sensor system, regardless of whether or not the rotary angle sensor system is attached to the shaft. Therefore, unless otherwise defined, the axial direction is understood to mean the direction extending parallel to the longitudinal axis of the shaft in a state where the rotary angle sensor system is attached, the radial direction is understood to mean the direction extending perpendicular to the longitudinal axis of the shaft in a state where the rotary angle sensor system is attached, and the cross section is understood to mean the plane extending across the longitudinal axis of the shaft in a state where the rotary angle sensor system is attached.

[0003] A rotation angle sensor system is also known as a rotary encoder or a rotation angle encoder. In a general rotation angle sensor system, since the Weigand sensor unit and the magnetic sensor unit are usually arranged slightly apart from each other, a large interfering magnetic field is generated at the position of the magnetic sensor unit due to the magnetization of the Weigand wire of the Weigand sensor unit that always exists during the operation of the rotation angle sensor system. This causes a systematic error in the magnetic sensor signal provided by the magnetic sensor unit, and thereby also causes a systematic error in the rotation angle value determined based on the magnetic sensor signal. Summary of the Invention Problems to be Solved by the Invention

[0004] Against such a background, an object of the present invention is to provide a rotation angle sensor system that accurately detects the rotational movement of a shaft with high reliability. Means for Solving the Problems

[0005] This object is solved by a rotation angle sensor system for detecting the rotational movement of a shaft having the features of claim 1.

[0006] The rotation angle sensor system for detecting the rotational movement of a shaft of the present invention includes an excitation unit, a Weigand sensor unit, a magnetic sensor unit, and evaluation electronics.

[0007] The excitation unit includes an excitation magnet composed of at least one permanent magnet, and is attached to a shaft where rotational motion is detected and configured to rotate together. Usually, the excitation unit is configured to be attached to the shaft, and preferably configured to be attached to the end of the shaft. When the shaft rotates and the excitation unit rotates accordingly, at least one excitation magnet is configured and arranged such that an alternating excitation magnetic field is generated at the position of the fixed Weigand sensor unit and the position of the fixed magnetic sensor unit. The alternating excitation magnetic field refers to an excitation magnetic field whose polarity continuously reverses and the (effective) direction of the magnetic force lines continuously changes over time.

[0008] The Weigand sensor unit includes a sensor coil and at least one Weigand wire disposed inside the sensor coil. The Weigand wire in the sense of this application is also referred to as an impulse wire and usually has a hard magnetic sheath and a soft magnetic core, or vice versa. Under the influence of an external magnetic field, the magnetization direction of the Weigand wire rapidly reverses. Thereby, a short Weigand sensor voltage pulse is generated in the sensor coil surrounding the Weigand wire in the radial direction, and the Weigand sensor voltage pulse can be detected from both ends of the sensor coil. This effect is called the Weigand effect and is well known in the art. The Weigand sensor unit usually includes one Weigand wire, but may have a plurality of Weigand wires, all of which are disposed inside the sensor coil. The Weigand sensor unit, particularly the sensor coil and at least one Weigand wire, is configured and arranged such that when the shaft rotates, the alternating excitation magnetic field generated by the excitation unit at the position of the Weigand sensor unit causes the sensor coil to generate Weigand sensor voltage pulses in sequence, usually generating one Weigand sensor voltage pulse for each alternation of the excitation magnetic field.

[0009] The magnetic sensor unit is configured to detect an alternating excitation magnetic field and provide a corresponding magnetic sensor signal. The magnetic sensor unit can include, for example, a TMR sensor, a GMR sensor, an AMR sensor, or a Hall sensor. Preferably, the magnetic sensor unit and the Weigand sensor unit are arranged on a common circuit board, and it is advantageous for the magnetic sensor unit and the Weigand sensor unit to be arranged on opposite sides of the circuit board. The magnetic sensor signal can be, for example, an analog signal whose amplitude is proportional to the magnetic field strength or orientation of the detected excitation magnetic field. Or, for example, it can be a digital signal including a series of magnetic sensor signal values respectively proportional to the magnetic field strength or direction of the detected excitation magnetic field. Usually, the magnetic sensor signal includes a sine component and a cosine component. The sine component is proportional to the magnetic field strength of the excitation magnetic field detected with respect to the first spatial direction, and the cosine component is proportional to the magnetic field strength of the excitation magnetic field detected with respect to the second spatial direction perpendicular to the first spatial direction. Usually, the magnetic sensor signal is provided via one or more electrical contacts. However, in principle, the magnetic sensor signal can be provided in any way.

[0010] The evaluation electronic device is electrically connected to the Weigand sensor unit, detects Weigand sensor voltage pulses, and based on them, particularly based on the number of detected Weigand sensor voltage pulses and their polarities, is configured to determine the rotational speed in a known manner. The evaluation electronic device is also configured to receive a magnetic sensor signal from the magnetic sensor unit and determine a rotation angle value based on the magnetic sensor signal in a known manner. The evaluation electronic device is usually electrically connected to the magnetic sensor unit to transmit the magnetic sensor signal. The evaluation electronic device is preferably arranged on a common circuit board together with the magnetic sensor unit and the Weigand sensor unit. The evaluation electronic device usually includes at least one integrated circuit, in particular a so-called application-specific integrated circuit (ASIC) and / or a so-called "field programmable gate array" (FPGA) and / or a microcontroller. However, in principle, the evaluation electronic circuit can be formed by any electrical circuit suitable for detecting Weigand sensor voltage pulses and determining the rotational speed based on them, and for receiving a magnetic sensor signal and determining the rotation angle value based on it.

[0011] When the shaft is rotating, the magnetization direction of the Weigand wire of the Weigand sensor unit continuously changes due to the alternating excitation magnetic field, so that the disturbance magnetic field generated by the magnetized Weigand wire has a different influence on the magnetic field detected by the magnetic sensor unit, that is, on the magnetic sensor signal provided by the magnetic sensor unit, depending on the current magnetization direction.

[0012] Therefore, in the present invention, a first compensation parameter and a second compensation parameter are provided to an evaluation electronic device, and the evaluation electronic device, when determining a rotation angle value, alternately applies the first compensation parameter and the second compensation parameter to the received magnetic sensor signal to compensate for the effects in two different directions on the magnetic sensor signal due to the magnetization of the Weigand wire occurring during operation. Thereby, a highly reliable and accurate rotation angle sensor system is provided. The two compensation parameters can, in principle, be realized as a single compensation value or as a vector of a plurality of compensation values. Usually, the received magnetic sensor signal has a sine component and a cosine component, the sine component being proportional to the magnetic field strength of the excitation magnetic field detected with respect to a first spatial direction, and the cosine component being proportional to the magnetic field strength of the excitation magnetic field detected with respect to a second spatial direction perpendicular to the first spatial direction. In this case, for example, it is conceivable that the two compensation parameters each include an individual compensation value for the sine component and the cosine component. It is also conceivable that one of the two compensation parameters is zero or a zero vector. Each compensation parameter is preferably added to or subtracted from the current magnetic sensor signal value when calculated using the magnetic sensor signal. This enables particularly simple compensation. However, in principle, it is also conceivable that each compensation parameter is applied to the current magnetic sensor signal value by multiplication, division, or a more complex method when applied to the magnetic sensor signal. However, in any case, alternately, that is, in sequence, either the first compensation parameter or the second compensation parameter is applied to the magnetic sensor signal. Preferably, the evaluation electronic device determines a current quadrant parameter indicating in which 90° quadrant of a full rotation of 360° the excitation unit rotating with the shaft is currently located based on the detected Weigand sensor voltage pulse and / or the received magnetic sensor signal, and based on the current quadrant parameter, determines which of the two compensation parameters is to be applied to the magnetic sensor signal.

[0013] As a rule, the two compensation parameters can be provided to the evaluation electronic device in any suitable way, for example, via a data interface from an external system. However, in the rotational angle sensor system of the present invention, it is preferable that the first compensation parameter and the second compensation parameter are stored, and the evaluation electronic circuit is provided with a data storage device to which at least read access is possible. It is advantageous for the data storage device to be non-volatile. This makes it possible, for example, to determine the two compensation parameters once on a test bench and store them permanently in the data storage device. The data storage device can be integrated into an integrated circuit or a microcontroller together with the evaluation unit, for example, as a so-called flash memory. However, it is also conceivable that the rotational angle sensor system has a data interface, and via this data interface, the compensation parameters stored in the data storage device can be changed later.

[0014] Generally, every time the magnetization direction of the Weigand wire changes, a Weigand wire sensor voltage pulse is generated in the sensor coil. In this way, the generation of the Weigand sensor voltage pulse indicates a change in the magnetization direction of the Weigand wire. Therefore, it is preferable that the evaluation electronic device is configured to change the parameters applied to the received magnetic sensor signal from the first compensation parameter (K1) to the second compensation parameter (K2), or from the second compensation parameter (K2) to the first compensation parameter (K1), when the Weigand sensor voltage pulse is detected. This makes it possible to simply and relatively reliably determine the point in time at which the change from one compensation parameter to the other should be made, so that no special means are required for detecting or monitoring the current direction of magnetization of the Weigand wire.

[0015] As described above, the received magnetic sensor signal usually has a sine component and a cosine component. The sine component is proportional to the magnetic field strength of the excitation magnetic field detected in the first spatial direction, and the cosine component is proportional to the magnetic field strength of the excitation magnetic field detected in the second spatial direction perpendicular to the first spatial direction. Since the Weigand wire is usually arranged substantially parallel to one of these two spatial directions, the interference magnetic field generated by the Weigand wire significantly affects only the sine component of the magnetic sensor signal or only the cosine component of the magnetic sensor signal. Therefore, in order to particularly easily compensate for the influence of the interference magnetic field, it is preferable that the evaluation electronic device in this case is configured to apply the first compensation parameter or the second compensation parameter to either only the sine component or only the cosine component.

[0016] The evaluation electronic device preferably includes an integrated circuit, particularly preferably an ASIC, configured to detect a Weigand sensor voltage pulse and determine the rotational speed based on it, and a microcontroller configured to receive a magnetic sensor signal, determine a rotation angle value based on the received magnetic sensor signal, and alternately apply the first compensation parameter and the second compensation parameter to the received magnetic sensor signal when determining the rotation angle value. The detection of the Weigand sensor voltage pulse and the determination of the rotational speed basically correspond to the increase and decrease of the count value when the Weigand sensor voltage pulse occurs. This can be particularly efficiently realized by using an ASIC, which is an integrated circuit specially designed for this purpose. The integrated circuit is electrically connected to the Weigand sensor unit so as to be able to detect the Weigand sensor voltage pulse. The integrated circuit is usually also connected to a data storage device in which at least one count value reflecting the rotational speed is stored. On the other hand, the determination of the rotation angle value based on the received magnetic sensor signal using the two compensation parameters can be particularly efficiently realized by a properly programmed microcontroller.

[0017] The integrated circuit is configured to provide a detection signal each time a Weigand sensor voltage pulse is detected, and the microcontroller is configured to receive the detection signal and, in response to the detection signal, change the parameter applied to the received magnetic sensor signal from a first compensation parameter (K1) to a second compensation parameter (K2), or from the second compensation parameter (K2) to the first compensation parameter (K1). Preferably, this results in a particularly efficient rotational angle sensor system.

[0018] Integrated circuits configured to detect Weigand sensor voltage pulses and determine the rotational speed based thereon have often already been realized. In order to generally avoid the reconfiguration / redesign of integrated circuits which generally require relatively high costs, in an alternative preferred embodiment of the present invention, the microcontroller is electrically connected to the Weigand sensor unit and is configured to directly detect the Weigand sensor voltage pulse and, when the Weigand sensor voltage pulse is detected, change the parameter applied to the received magnetic sensor signal from a first compensation parameter (K1) to a second compensation parameter (K2), or from the second compensation parameter (K2) to the first compensation parameter (K1).

[0019] Embodiments of the present invention will be described below with reference to the accompanying drawings described below.

Brief Description of the Drawings

[0020]

Figure 1

Figure 2

Figure 3

Figure 4

DETAILED DESCRIPTION OF THE INVENTION

[0021] FIG. 1 shows a rotational angle sensor system 10 disposed at an axial end of a shaft 1 for detecting the rotational movement of the shaft 1. The rotational angle sensor system 10 includes an excitation unit 12 attached to the shaft 1. The rotational angle sensor system 10 further includes a Wiedemann sensor unit 14, a magnetic sensor unit 16, and an evaluation electronics 18, which are disposed on a circuit board 20 fixed to the housing portion 2.

[0022] The excitation unit 12 includes a magnet carrier 121 attached to the front surface of the shaft 1. The excitation unit 12 further includes an excitation magnet 122 composed of two permanent magnets, and these permanent magnets are magnetized and disposed on the magnet carrier 121 such that an alternating excitation magnetic field is generated by the excitation magnet 122 at both the position of the Wiedemann sensor unit 14 and the position of the magnetic sensor unit 16 when the shaft 1 rotates.

[0023] The Wiedemann sensor unit 14 is disposed on the axial side of the circuit board 20 away from the shaft 1, and includes a sensor coil 141 and a Wiedemann wire 142 disposed inside the sensor coil 141. The sensor coil 141 and the Wiedemann wire 142 are configured and disposed such that, as schematically shown in FIG. 4, an alternating excitation magnetic field generated by the excitation magnet 122 when the shaft 1 rotates sequentially generates a Wiedemann sensor voltage pulse WP in the sensor coil 141, where the Wiedemann sensor voltage pulse WP can be detected from both ends of the sensor coil 141.

[0024] The magnetic sensor unit 16 is arranged on the axial side of the circuit board 20 facing the shaft 1, on the opposite side of the Wiedemann sensor unit 14. The magnetic sensor unit 16 is configured to detect an alternating excitation magnetic field and provide a corresponding magnetic sensor signal S having a sine component S1 and a cosine component S2 at an electrical contact intended for this purpose, as schematically shown in FIG. 4. In the present embodiment, the sine component S1 is proportional to the magnetic field strength of the excitation magnetic field detected with respect to the spatial direction parallel to the longitudinal axis of the Wiedemann wire 142, and the cosine component S2 is proportional to the magnetic field strength of the excitation magnetic field detected with respect to the spatial direction perpendicular to the longitudinal axis of the Wiedemann wire 142.

[0025] The evaluation electronic device 18 includes an integrated circuit 181, a microcontroller 182, and a data storage device 183.

[0026] The integrated circuit 181 is electrically connected to the Wiedemann sensor unit 14 and is configured to detect the Wiedemann sensor voltage pulse WP generated by the sensor coil 141. The integrated circuit 181 is further configured to determine the rotational speed N based on the number and polarity of the detected Wiedemann sensor voltage pulses WP and store it in the data storage device 183.

[0027] The microcontroller 182 is electrically connected to the electrical contacts of the magnetic sensor unit 16 for providing the magnetic sensor signal S and is configured to receive the magnetic sensor signal S. The microcontroller 182 is further configured to read out from the data storage device 183 a first compensation parameter K1 stored in the data storage device 183 and a second compensation parameter K2 stored in the data storage device 183. The microcontroller 182 is further configured to alternately apply the first compensation parameter K1 and the second compensation parameter K2 to the magnetic sensor signal S to determine a compensated magnetic sensor signal S-comp, as schematically shown in FIG. 4. Specifically, the microcontroller 182 alternately adds the first compensation parameter K1 and the second compensation parameter K2 to the sine component S1 of the magnetic sensor signal S to determine a compensated sine component S1-comp, and the compensated sine component S1-comp together with the cosine component S2 constitutes the compensated magnetic sensor signal S-comp. The microcontroller 182 is further configured to determine a rotation angle value A based on the compensated magnetic sensor signal S-comp and store it in the data storage device 183.

[0028] In a preferred embodiment of the rotation angle sensor system 10 schematically shown in FIG. 2, the integrated circuit 181 is configured to provide a detection signal D to the electrical contacts intended for this purpose each time a Weigand sensor voltage pulse WP is detected, as schematically shown in FIG. 4. In this embodiment, the microcontroller 182 is electrically connected to each electrical contact of the integrated circuit 181 and is configured to receive the detection signal D. Further, in this case, each time the microcontroller 182 receives the detection signal D, in response thereto, it is configured to change the parameter added to the sine component S1 from the first compensation parameter K1 to the second compensation parameter K2 for the sine component S1 or vice versa. That is, it is configured to change the parameter applied to the magnetic sensor signal S from the first compensation parameter K1 to the second compensation parameter K2 or vice versa.

[0029] In an alternative embodiment of the rotational angle sensor system 10 schematically shown in FIG. 3, the microcontroller 182 is electrically connected to the Weigand sensor unit 14 and is configured to detect the Weigand sensor voltage pulse WP generated in the sensor coil 141. Further, in this case, each time the Weigand sensor voltage pulse WP is detected, the microcontroller 182 is configured to change a parameter added to the sine component S1 from the first compensation parameter K1 to the second compensation parameter K2 for the sine component S1, or vice versa. That is, the parameter applied to the magnetic sensor signal S is configured to be changed from the first compensation parameter K1 to the second compensation parameter K2, or vice versa.

Explanation of Signs

[0030] 1 Shaft 2 Housing part 10 Rotational angle sensor system 12 Excitation unit 121 Magnet carrier 122 Excitation magnet 14 Weigand sensor unit 141 Sensor coil 142 Weigand wire 16 Magnetic sensor unit 18 Evaluation electronics 181 Integrated circuit 182 Microcontroller 183 Data storage device 20 Circuit board A Rotational angle value D Detection signal K1, K2 Compensation parameters N Rotational speed S Magnetic sensor signal S1 Sine component S2 Cosine component S-comp Compensated magnetic sensor signal S1-comp Compensated sine component WP Weigand sensor voltage pulse

Claims

1. A magnetic rotary angle sensor system (10) for detecting the rotational movement of a shaft (1), comprising: An excitation unit (12) having at least one excitation magnet (122); A Weigand sensor unit (14) having a sensor coil (141) and at least one Weigand wire (142) disposed inside the sensor coil (141); A magnetic sensor unit (16); An evaluation electronic device (18); The excitation unit (12) is attached to rotate with the shaft (1), and is configured to generate an alternating excitation magnetic field at the position of the Weigand sensor unit (14) and the position of the magnetic sensor unit (16) when the shaft (1) rotates; The Weigand sensor unit (14) is configured such that a Weigand sensor voltage pulse (WP) is generated in the sensor coil (141) by the alternating excitation magnetic field; The magnetic sensor unit (16) is configured to detect the alternating excitation magnetic field and provide a corresponding magnetic sensor signal (S); The evaluation electronic device (18) is configured to detect the Weigand sensor voltage pulse (WP), determine the rotational speed (N) based thereon, receive the magnetic sensor signal (S), and determine a rotational angle value (A) based on the magnetic sensor signal (S); The evaluation electronic device (18) is provided with a first compensation parameter (K1) and a second compensation parameter (K2), and the evaluation electronic device (18) is configured to alternately apply the first compensation parameter (K1) and the second compensation parameter (K2) to the received magnetic sensor signal (S) when determining the rotational angle value (A). Magnetic rotary angle sensor system (10).

2. The magnetic rotary angle sensor system (10) according to claim 1, further comprising a data storage device (183) accessible to the evaluation electronic device (18) in which the first compensation parameter (K1) and the second compensation parameter (K2) are stored.

3. The evaluation electronic device (18) is configured to change a parameter applied to the received magnetic sensor signal (S) from the first compensation parameter (K1) to the second compensation parameter (K2), or from the second compensation parameter (K2) to the first compensation parameter (K1) when detecting a Weigand sensor voltage pulse (WP). The magnetic rotary angle sensor system (10) according to claim 1.

4. The received magnetic sensor signal (S) has a sine component (S1) and a cosine component (S2), The evaluation electronic device (18) is configured to apply the first compensation parameter (K1) or the second compensation parameter (K2) to only the sine component (S1) or only the cosine component (S2) respectively in this order. The magnetic rotary angle sensor system (10) according to claim 1.

5. An integrated circuit (181) configured to detect the Weigand sensor voltage pulse (WP) and determine the rotational speed (N) based thereon, A microcontroller (182) configured to receive the magnetic sensor signal (S), determine the rotation angle value (A) based on the received magnetic sensor signal (S), and alternately apply the first compensation parameter (K1) and the second compensation parameter (K2) to the received magnetic sensor signal (S) when determining the rotation angle value (A). The magnetic rotary angle sensor system (10) according to any one of claims 1 to 4.

6. The integrated circuit (181) is configured to provide a detection signal (D) every time a Weigand sensor voltage pulse (WP) is detected, The microcontroller (182) is configured to receive the detection signal (D) and change a parameter applied to the received magnetic sensor signal (S) from the first compensation parameter (K1) to the second compensation parameter (K2), or from the second compensation parameter (K2) to the first compensation parameter (K1) in response to the received detection signal (D). The magnetic rotary angle sensor system (10) according to claim 5.

7. The microcontroller (182) is configured to detect the Weigand sensor voltage pulse (WP) and, when the Weigand sensor voltage pulse (WP) is detected, change a parameter applied to the received magnetic sensor signal (S) from the first compensation parameter (K1) to the second compensation parameter (K2) or from the second compensation parameter (K2) to the first compensation parameter (K1), the magneto-rotary angle sensor system (10) according to claim 5.

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