Arrangement, Method and Sensor for Measuring an Absolute Angular Position Using a Multi-Pole Magnet

• US 20150226581A1
• Filed: 08/23/2013
• Published: 08/13/2015
• Est. Priority Date: 08/23/2012
• Status: Active Grant

• Current Assignee: Melexis Technologies NV (Sensinnovat BVBA)
• Original Assignee: Melexis Technologies NV (Sensinnovat BVBA)
• Inventors: Schott, Christian, Huber, Samuel
• Granted Patent: US 10,309,801 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 5/145 influenced by the relative movement between the Hall device and magnetic fields see G01R33/06
• CPC Class Codes: G01D 5/24438 Special design of the sensing element or scale

Abstract

An arrangement for measuring an angular position of a rotor with respect to a stator, comprises a multi-pole magnet mounted on the rotor, and a sensor mounted on the stator and a plurality of sensor elements organized in two groups or four groups for measuring a magnetic field component. A method for calculating the angular position comprises making a sum of signals of the elements of each group, a ratio of the two sums, and an arctan function. Alternatively the method may comprise making a sum of signals, the difference of sums, a ratio of the differences, and an arctan function. An integrated sensor, and the use of such arrangement or sensor in an automotive environment.

Claims

1-31. -31. (canceled)

32. An arrangement for measuring an angular position of a rotor with respect to a stator, the arrangement comprising:

the rotor rotatable around a rotation axis;

the stator having a fixed position with respect to the rotation axis;

a magnetic source mounted on the rotor for creating a magnetic field, the magnetic source being a multi-pole magnet having a number of magnetic poles for generating a periodically repetitive magnetic field pattern with respect to the rotation axis, the number of magnetic poles being at least four;

a sensor mounted on the stator and comprising a plurality of sensor elements for measuring at least one magnetic field component of the magnetic field and for providing a measurement signal indicative of the at least one magnetic field component, the number of sensor elements being twice the number of magnetic poles of the multi-pole magnet, the sensor being located centered around the rotation axis and being located in a plane perpendicular to the rotation axis at a first distance from the magnetic source;

the sensor elements being located on a circle at a second distance from the rotation axis, and being oriented for detecting the at least one magnetic field component;

the plurality of sensor elements being partitioned in at least a first group and a second group and a third group and a fourth group, the elements within each group being located at equidistant angular positions on the circle, the angular distance between an element of the first group and an element of the second group being equal to 180°

divided by the number of magnetic poles of the magnetic source, the angular distance between an element of the third group and an element of the first group being equal to 360°

divided by the number of magnet poles of the magnetic source, and the angular distance between an element of the fourth group and an element of the first group being equal to 540°

divided by the number of magnet poles of the magnetic source;

means for calculating the angular position of the rotor from the provided signals, the means for calculating being adapted for calculating a first sum or first average of the signals provided by the sensor elements of the first group, and for calculating a second sum or second average of the signals provided by the sensor elements of the second group, and for calculating a third sum or third average of the signals provided by the elements of the third group, and for calculating a fourth sum or fourth average of the signals provided by the elements of the fourth group, and for determining the angular position of the rotor based on one or more values selected from the group consisting of the first sum, first average, the second sum and the second average, the third sum, the third average, the fourth sum and the fourth average.

33. The arrangement according to claim 32, wherein the multi-pole magnet is a permanent magnet.

34. The arrangement according to claim 33, wherein the multi-pole magnet has at least six magnetic poles.

35. The arrangement according to claim 33, wherein the multi-pole magnet has a ring shape having an outer diameter and an inner diameter, and wherein the circle in the sensor has a diameter of 1 to 30% of the outer diameter of the magnet.

36. The arrangement according claim 32, wherein the measured at least one magnetic field component comprises a tangential field component of the magnetic field, oriented tangential to the circle.

37. The arrangement according to claim 36, wherein the sensor elements comprise vertical Hall effect elements having a plate with a normal that is tangential to the circle.

38. The arrangement according to claim 36, wherein each sensing element comprises a pair of horizontal Hall effect elements adapted for providing signals and being located on the circle adjacent to each other, and having plates oriented perpendicular to the rotation axis, and IMC segments for bending the local tangential magnetic field into a direction perpendicular to the plates.

39. The arrangement according to claim 33, wherein the measured at least one magnetic field component comprises a radial field component of the magnetic field, oriented radially to the circle, and wherein the sensor elements comprise vertical Hall effect elements having a plate with a normal that is perpendicular to and intersects with the rotation axis.

40. The arrangement according to claim 32,

wherein each sensor element comprises a horizontal Hall effect element and wherein the arrangement further comprises an integrated magnetic concentrator comprising a central part located on top of the horizontal Hall elements and a plurality of elongated parts located at a distance from the Hall elements and oriented in radial directions;

or

wherein each sensor element comprises a horizontal Hall effect element and wherein the arrangement further comprises an integrated magnetic concentrator comprising a central part and a plurality of elongated parts each located on top of one of the Hall elements and oriented in radial directions.

41. The arrangement according to claim 32,

wherein the means for calculating is further adapted for calculating a first difference between the first sum and the third sum, and for calculating a second difference between the second sum and the fourth sum;

and wherein the means for calculating is further adapted for calculating the ratio of the first difference and the second difference, and for determining the angular position of the rotor based on the arctangent or arc cotangent of said ratio.

42. Method for determining an angular position of a rotor with respect to a stator using the arrangement according to claim 32, comprising:

calculating a first sum or a first average of the signals provided by the first group of sensor elements;

calculating a second sum or second average of the signals provided by the second group of elements;

calculating a third sum or third average of the signals provided by the sensor elements of the third group of elements;

calculating a fourth sum or fourth average of the signals provided by the sensor elements of the fourth group of elements;

determining the angular position of the rotor based on one or more numbers selected from the group consisting of the first sum, the first average, the second sum, the second average, the third sum, the third average, the fourth sum and the fourth average.

43. The method according to claim 42, wherein the measured at least one magnetic field component comprises a tangential field component of the magnetic field, oriented tangential to the circle, and wherein each sensing element comprises a pair of horizontal Hall effect elements adapted for providing signals and being located on the circle adjacent to each other, and having plates oriented perpendicular to the rotation axis, and IMC segments for bending the local tangential magnetic field into a direction perpendicular to the plates;

the method further comprising the step of subtracting the signals of the elements of each pair so as to provide a combined signal for the calculation of the first resp. second, third, fourth sum or first resp. second, third, fourth average.

44. The method according to claim 42, further comprising the step of calculating a first difference between the first sum and the third sum, and calculating a second difference between the second sum and the fourth sum, and calculating the ratio of the first difference and the second difference, and determining the angular position of the rotor based on the arctangent or arc cotangent of said ratio.

45. An integrated sensor circuit for measuring an angular position of a rotor with respect to a stator, the rotor being rotatable around a rotation axis and comprising a magnetic source mounted on the rotor for creating a magnetic field, the magnetic source being a multi-pole magnet having a number of magnetic poles for generating a periodically repetitive magnetic field pattern with respect to the rotation axis, the number of magnetic poles being at least four;

the stator having a fixed position with respect to the rotation axis, the integrated sensor circuit being mountable to the stator in the vicinity of the multi-pole magnet and in line with the rotation axis in a plane perpendicular to the rotation axis at a first distance from the magnetic source, the integrated sensor circuit comprising;

a plurality of sensor elements, the number of sensor elements being twice the number of magnetic poles of the multi-pole magnet, each sensor element being adapted for measuring at least one magnetic field component of the magnetic field and for providing a measurement signal indicative of the strength of the at least one magnetic field component at the location of the sensor element,

the sensor elements being located on a circle at a distance from the rotation axis, and being oriented for detecting the at least one magnetic field component;

the plurality of sensor elements being partitioned in a first group and a second group and a third group and a fourth group, the elements within each group being located at equidistant angular positions on the circle, the angular distance between an element of the first group and an element of the second group being equal to 180°

divided by the number of magnet poles of the magnetic source, the angular distance between an element of the third group and an element of the first group being equal to 360°

divided by the number of magnet poles of the magnetic source, and the angular distance between an element of the fourth group and an element of the first group being equal to 540°

divided by the number of magnet poles of the magnetic source;

means for calculating the angular position of the rotor from the provided signals;

wherein;

the means for calculating being adapted for calculating a first sum or first average of the signals provided by the elements of the first group, and for calculating a second sum or second average of the signals provided by the elements of the second group, and for calculating a third sum or third average of the signals provided by the elements of the third group, and for calculating a fourth sum or fourth average of the signals provided by the elements of the fourth group, and for determining the angular position of the rotor based on one or more number selected from the group consisting of the first sum, first average, the second sum and the second average, the third sum, the third average, the fourth sum and the fourth average.

46. The integrated circuit according to claim 45, wherein each sensor element comprises a vertical Hall effect element having a plate with a normal that is tangential to the circle, or a normal that is perpendicular to and intersects with the rotation axis.

47. The integrated circuit according to claim 45, wherein each sensing element comprise a pair of horizontal Hall effect elements adapted for providing signals and being located on the circle adjacent to each other, and having plates oriented perpendicular to the rotation axis, and IMC segments for bending the local tangential magnetic field into a direction perpendicular to the plates.

48. The integrated circuit according to claim 45,

wherein each sensor element comprises a horizontal Hall effect element and wherein the integrated circuit further comprises an integrated magnetic concentrator comprising a central part located on top of the horizontal Hall elements and a plurality of elongated parts located at a distance from the Hall elements and oriented in radial directions;

or

wherein each sensor element comprises a horizontal Hall effect element and wherein the integrated circuit further comprises an integrated magnetic concentrator comprising a central part and a plurality of elongated parts each located on top of one of the Hall elements and oriented in radial directions.

49. The integrated circuit according to claim 45,

wherein the means for calculating is further adapted for calculating a first difference between the first sum and the third sum, and for calculating a second difference between the second sum and the fourth sum;

and wherein the means for calculating is further adapted for calculating the ratio of the first difference and the second difference, and for determining the angular position of the rotor based on the arctangent or arc cotangent of said ratio.