Magnetic 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 rotation angle sensor system for detecting rotational movement of a shaft, the rotation angle sensor system comprising: an excitation unit having at least one excitation magnet; a Wiegand sensor unit having a sensor coil and at least one Wiegand wire arranged inside the sensor coil; a magnetic sensor unit; and evaluation electronics, wherein the excitation unit is mounted to rotate with the shaft and is configured to generate an alternating excitation magnetic field at the position of the Wiegand sensor unit and at the position of the magnetic sensor unit as the shaft rotates; the magnetic sensor unit is configured to detect the alternating excitation magnetic field and provide a corresponding magnetic sensor signal; and the evaluation electronics is configured to detect Wiegand sensor voltage pulses and determine a rotation speed based thereon, and to receive the magnetic sensor signal and determine a rotation angle value based on the magnetic sensor signal. [Background technology]

[0002] Unless otherwise defined, the terms "axial," "radial," and "transverse plane" below refer to the shaft sensed by the rotation angle sensor system, regardless of whether the rotation angle sensor system is attached to the shaft. Thus, unless otherwise defined, axial direction is understood to mean a direction extending parallel to the longitudinal axis of the shaft when the rotation angle sensor system is attached, radial direction is understood to mean a direction extending perpendicular to the longitudinal axis of the shaft when the rotation angle sensor system is attached, and transverse plane is understood to mean a plane extending transverse to the longitudinal axis of the shaft when the rotation 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 typical rotation angle sensor system, the Wiegand sensor unit and the magnetic sensor unit are usually arranged slightly apart from each other. Therefore, the magnetization of the Wiegand wire of the Wiegand sensor unit, which is always present during operation of the rotation angle sensor system, generates a large interference magnetic field at the position of the magnetic sensor unit. This causes a systematic error in the magnetic sensor signal provided by the magnetic sensor unit, which in turn causes a systematic error in the rotation angle value determined based on the magnetic sensor signal. Summary of the Invention [Problem to be solved by the invention]

[0004] In light of this background, an object of the present invention is to provide a rotation angle sensor system that detects the rotational movement of a shaft with high reliability and accuracy. [Means for solving the problem]

[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 according to the present invention comprises an excitation unit, a Wiegand sensor unit, a magnetic sensor unit and evaluation electronics.

[0007] The excitation unit includes an excitation magnet consisting of at least one permanent magnet and is configured to be attached to and rotate with the shaft whose rotational motion is to be detected. Typically, the excitation unit is configured to be attached to the shaft, preferably at the end of the shaft. The at least one excitation magnet is configured and arranged such that, when the excitation unit rotates due to the rotation of the shaft, an alternating excitation magnetic field is generated at the location of the fixed Wiegand sensor unit and the location of the fixed magnetic sensor unit. An alternating excitation magnetic field is an excitation magnetic field whose polarity is continuously reversed, so that the (effective) direction of the magnetic field lines continuously changes over time.

[0008] A Wiegand sensor unit includes a sensor coil and at least one Wiegand wire arranged inside the sensor coil. The Wiegand wire, also referred to as an impulse wire in this application, typically 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 Wiegand wire suddenly reverses. This generates a short Wiegand sensor voltage pulse in the sensor coil radially surrounding the Wiegand wire, which can be detected from both ends of the sensor coil. This effect is referred to as the Wiegand effect and is well known in the art. A Wiegand sensor unit typically includes one Wiegand wire, but may also include multiple Wiegand wires, all of which are arranged inside the sensor coil. The Wiegand sensor unit, in particular the sensor coil and the at least one Wiegand wire, are constructed and arranged such that, when the shaft rotates, an alternating excitation magnetic field generated by the excitation unit at the location of the Wiegand sensor unit causes the sensor coil to generate Wiegand sensor voltage pulses in turn, typically one Wiegand sensor voltage pulse per alternation of the excitation magnetic field.

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

[0010] The evaluation electronics is electrically connected to the Wiegand sensor unit and is configured to detect Wiegand sensor voltage pulses and, based thereon, determine the rotation speed in a known manner, particularly based on the number of detected Wiegand sensor voltage pulses and their polarity. The evaluation electronics is also configured to receive magnetic sensor signals from the magnetic sensor unit and, based thereon, determine a rotation angle value in a known manner. The evaluation electronics is typically electrically connected to the magnetic sensor unit and transmits the magnetic sensor signals. The evaluation electronics is preferably arranged on a common circuit board together with the magnetic sensor unit and the Wiegand sensor unit. The evaluation electronics typically includes at least one integrated circuit, particularly 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 electronics can be formed by any electrical circuit suitable for detecting Wiegand sensor voltage pulses and determining the rotation speed therefrom, and suitable for receiving magnetic sensor signals and determining a rotation angle value therefrom.

[0011] When the shaft is rotating, the alternating excitation magnetic field continuously changes the magnetization direction of the Wiegand wire of the Wiegand sensor unit, so that the disturbance magnetic field generated by the magnetized Wiegand wire has different effects on the magnetic field detected by the magnetic sensor unit, i.e., 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 the evaluation electronics. The evaluation electronics are configured to alternately apply the first compensation parameter and the second compensation parameter to the received magnetic sensor signal when determining the rotation angle value to compensate for the two different directional effects on the magnetic sensor signal due to the magnetization of the Wiegand wire occurring during operation. This provides a reliable and accurate rotation angle sensor system. In principle, the two compensation parameters can be implemented as a single compensation value or as a vector of multiple compensation values. Typically, the received magnetic sensor signal has a sine component and a cosine component, where the sine component is proportional to the magnetic field strength of the excitation magnetic field detected in a first spatial direction and the cosine component is proportional to the magnetic field strength of the excitation magnetic field detected in 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 separate compensation values ​​for the sine and cosine components. It is also conceivable that one of the two compensation parameters is zero or a zero vector. Preferably, the compensation parameters are added to or subtracted from the current magnetic sensor signal value when calculated using the magnetic sensor signal. This allows for particularly simple compensation. However, it is also conceivable that the compensation parameters are applied to the magnetic sensor signal by multiplying, dividing, or applying them in a more complex manner. In any case, however, either the first compensation parameter or the second compensation parameter is applied to the magnetic sensor signal alternately, i.e., sequentially. Preferably, the evaluation electronics is configured to determine, based on the detected Wiegand sensor voltage pulses and / or the received magnetic sensor signal, a current quadrant parameter indicating in which 90-degree quadrant of a full 360-degree rotation the excitation unit, which rotates with the shaft, is currently located, and to determine which of the two compensation parameters to apply to the magnetic sensor signal based on the current quadrant parameter.

[0013] In principle, the two compensation parameters can be provided to the evaluation electronics in any suitable way, for example, from an external system via a data interface. However, the rotation angle sensor system of the present invention preferably includes a data storage device in which the first and second compensation parameters are stored and which is at least read-accessible by the evaluation electronics. The data storage device is advantageously non-volatile. This allows, for example, a test bench to determine the two compensation parameters once and store them permanently in the data storage device. The data storage device can be integrated into an integrated circuit or microcontroller together with the evaluation unit, for example, as a so-called flash memory. However, it is also conceivable for the rotation angle sensor system to have a data interface via which the compensation parameters stored in the data storage device can be subsequently changed.

[0014] Typically, a Wiegand wire sensor voltage pulse is generated in the sensor coil each time the magnetization direction of the Wiegand wire changes. The generation of the Wiegand wire sensor voltage pulse thus indicates a change in the magnetization direction of the Wiegand wire. Therefore, the evaluation electronics are preferably 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) upon detecting the Wiegand wire sensor voltage pulse. This allows the time when a change from one compensation parameter to the other should occur to be determined easily and relatively reliably, and no special means are required to detect or monitor the current direction of magnetization of the Wiegand wire.

[0015] As mentioned above, the received magnetic sensor signal typically has a sine and a cosine component, where the sine component is proportional to the field strength of the detected excitation magnetic field in a first spatial direction and the cosine component is proportional to the field strength of the detected excitation magnetic field in a second spatial direction perpendicular to the first spatial direction. Since the Wiegand wire is typically arranged substantially parallel to one of these two spatial directions, either only the sine component of the magnetic sensor signal or only the cosine component of the magnetic sensor signal is significantly affected by the interference field generated by the Wiegand wire. Therefore, in order to be able to particularly easily compensate for the influence of the interference field, the evaluation electronics in this case are preferably configured to apply the first or second compensation parameter only to the sine or cosine component.

[0016] The evaluation electronics preferably include an integrated circuit, particularly preferably an ASIC, configured to detect Wiegand sensor voltage pulses and determine the rotation speed based thereon; and a microcontroller configured to receive the magnetic sensor signal, determine a rotation angle value based on the received magnetic sensor signal, and alternately apply a first compensation parameter and a second compensation parameter to the received magnetic sensor signal when determining the rotation angle value. The detection of the Wiegand sensor voltage pulses and the determination of the rotation speed essentially correspond to an increase or decrease in a counter value when the Wiegand sensor voltage pulse occurs. This can be particularly efficiently achieved by using an ASIC, an integrated circuit specially designed for this purpose. The integrated circuit is electrically connected to the Wiegand sensor unit so as to detect the Wiegand sensor voltage pulses. The integrated circuit is also typically connected to a data storage device in which at least one counter value reflecting the rotation speed is stored. Meanwhile, the determination of the rotation angle value based on the received magnetic sensor signal using the two compensation parameters can be particularly efficiently achieved by a suitably programmed microcontroller.

[0017] Preferably, the integrated circuit is configured to provide a detection signal each time a Wiegand sensor voltage pulse is detected, and the microcontroller is configured to receive the detection signal and, in response to the detection signal, change the parameters 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), thereby resulting in a particularly efficient rotation angle sensor system.

[0018] In many cases, an integrated circuit configured to detect the Wiegand sensor voltage pulse and determine the rotation speed based thereon has already been realized. In order to avoid the reconfiguration / redesign of the integrated circuit, which is generally relatively costly, in an alternative preferred embodiment of the present invention, the microcontroller is electrically connected to the Wiegand sensor unit and configured to directly detect the Wiegand sensor voltage pulse and, upon detecting the Wiegand sensor voltage pulse, change the parameter 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).

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the accompanying drawings, which are described below. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of a rotation angle sensor system according to the present invention that is attached to a shaft to detect the rotational movement of the shaft. [Figure 2] FIG. 2 is a schematic diagram showing the connections between the components of the rotation angle sensor system in a preferred embodiment. [Figure 3] FIG. 3 is a schematic diagram showing the connections between components of a rotation angle sensor system in an alternative preferred embodiment. [Figure 4]FIG. 4 is a schematic diagram illustrating the time progression of a magnetic sensor signal provided by a magnetic sensor unit of the rotation angle sensor system of FIG. 1, a compensated magnetic sensor signal obtained by applying compensation parameters to the magnetic sensor signal, a Wiegand sensor voltage pulse generated in a Wiegand sensor unit of the rotation angle sensor system of FIG. 1, and a detection signal provided by an integrated circuit of the rotation angle sensor system of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0021] 1 shows a rotation angle sensor system 10 arranged at the axial end of a shaft 1 for detecting the rotational movement of the shaft 1. The rotation angle sensor system 10 comprises an excitation unit 12 attached to the shaft 1. The rotation angle sensor system 10 further comprises a Wiegand sensor unit 14 arranged on a circuit board 20 fixed to the housing part 2, a magnetic sensor unit 16 and evaluation electronics 18.

[0022] The excitation unit 12 comprises a magnet carrier 121 attached to the front side of the shaft 1. The excitation unit 12 further comprises an excitation magnet 122 consisting of two permanent magnets, which are magnetized and arranged on the magnet carrier 121 such that an alternating excitation magnetic field is generated by the excitation magnet 122 both at the position of the Wiegand sensor unit 14 and at the position of the magnetic sensor unit 16 when the shaft 1 rotates.

[0023] The Wiegand 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 Wiegand wire 142 disposed inside the sensor coil 141. As shown schematically in Fig. 4, the sensor coil 141 and the Wiegand wire 142 are configured and disposed such that, when the shaft 1 rotates, an alternating excitation magnetic field generated by the excitation magnet 122 sequentially generates a Wiegand sensor voltage pulse WP in the sensor coil 141, where the Wiegand sensor voltage pulse WP can be detected from both ends of the sensor coil 141.

[0024] The magnetic sensor unit 16 is arranged opposite the Wiegand sensor unit 14 on the axial side of the circuit board 20 facing the shaft 1. The magnetic sensor unit 16 is configured to detect the 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 shown schematically in Figure 4. In this embodiment, the sine component S1 is proportional to the field strength of the excitation magnetic field detected with respect to a spatial direction parallel to the longitudinal axis of the Wiegand wire 142, and the cosine component S2 is proportional to the field strength of the excitation magnetic field detected with respect to a spatial direction perpendicular to the longitudinal axis of the Wiegand wire 142.

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

[0026] The integrated circuit 181 is electrically connected to the Wiegand sensor unit 14 and configured to detect Wiegand sensor voltage pulses WP generated by the sensor coil 141. The integrated circuit 181 is further configured to determine the number of rotations N based on the number and polarity of the detected Wiegand 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, from the data storage device 183, a first compensation parameter K1 stored therein and a second compensation parameter K2 stored therein. 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 shown schematically in FIG. 4 . Specifically, the microcontroller 182 alternately adds the first compensation parameter K1 and the second compensation parameter K2 to a sine component S1 of the magnetic sensor signal S to determine a compensated sine component S1-comp, which, together with a 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, as shown schematically in FIG. 2, the integrated circuit 181 is configured to provide a detection signal D to electrical contacts intended for this purpose each time a Wiegand sensor voltage pulse WP is detected, as shown schematically in FIG. 4. In this embodiment, the microcontroller 182 is electrically connected to the respective electrical contacts of the integrated circuit 181 and configured to receive the detection signal D. Furthermore, in this case, the microcontroller 182 is configured to, in response to each reception of the detection signal D, change the parameter added to the sine component S1, from the first compensation parameter K1 to the sine component S1, to the second compensation parameter K2, or vice versa. That is, the microcontroller 182 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 rotation angle sensor system 10 schematically shown in Fig. 3, the microcontroller 182 is electrically connected to the Wiegand sensor unit 14 and configured to detect Wiegand sensor voltage pulses WP generated in the sensor coil 141. Furthermore, in this case, the microcontroller 182 is configured to change the parameter added to the sine component S1 from the first compensation parameter K1 to the sine component S1 or vice versa each time a Wiegand sensor voltage pulse WP is detected. That is, the microcontroller 182 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. [Explanation of symbols]

[0030] 1 shaft 2 Housing 10 Rotational Angle Sensor System 12 Excitation unit 121 Magnet Carrier 122 Excitation magnet 14 Wiegand sensor unit 141 Sensor coil 142 Wiegand Wire 16 Magnetic sensor unit 18 Evaluation electronic equipment 181 Integrated Circuits 182 Microcontroller 183 Data storage devices 20 Circuit Board A rotation angle value D detection signal K1, K2 compensation parameters N rotation speed S Magnetic sensor signal S1 sine component S2 cosine component S-comp Compensated magnetic sensor signal S1-comp Compensated sine component WP Wiegand sensor voltage pulse

Claims

1. A magnetic rotation angle sensor system (10) for detecting rotational movement of a shaft (1), comprising: an excitation unit (12) having at least one excitation magnet (122); a Wiegand sensor unit (14) having a sensor coil (141) and at least one Wiegand wire (142) disposed inside the sensor coil (141); a magnetic sensor unit (16); evaluation electronics (18); the excitation unit (12) is mounted to rotate with the shaft (1) and is configured to generate an alternating excitation magnetic field at the position of the Wiegand sensor unit (14) and at the position of the magnetic sensor unit (16) when the shaft (1) rotates; The Wiegand sensor unit (14) is configured such that a Wiegand 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 electronics (18) are configured to detect the Wiegand sensor voltage pulses (WP) and determine a rotation speed (N) based thereon, and to 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 the evaluation electronics (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 rotation angle value (A).

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

3. 2. The magnetic rotation angle sensor system according to claim 1, wherein the evaluation electronics is configured to change the parameter applied to the received magnetic sensor signal from the first compensation parameter to the second compensation parameter or from the second compensation parameter to the first compensation parameter upon detection of a Wiegand sensor voltage pulse.

4. the received magnetic sensor signal (S) has a sine component (S1) and a cosine component (S2); 2. The magnetic rotation angle sensor system according to claim 1, wherein the evaluation electronics 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.

5. an integrated circuit (181) configured to detect the Wiegand sensor voltage pulses (WP) and determine the number of revolutions (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).

6. the integrated circuit (181) is configured to provide a detection signal (D) upon detection of a Wiegand sensor voltage pulse (WP); 6. The magnetic rotation angle sensor system according to claim 5, wherein the microcontroller is configured to receive the detection signal and, in response to the received detection signal, change a parameter to be applied to the received magnetic sensor signal from the first compensation parameter to the second compensation parameter, or from the second compensation parameter to the first compensation parameter.

7. 6. The magnetic rotation angle sensor system according to claim 5, wherein the microcontroller is configured to detect the Wiegand sensor voltage pulse and, upon detecting the Wiegand sensor voltage pulse, change a parameter applied to the received magnetic sensor signal from the first compensation parameter to the second compensation parameter, or from the second compensation parameter to the first compensation parameter.

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