Magnetic position sensors, systems and methods
Magnetic position sensors, systems and methods are disclosed. In an embodiment, a position sensing system includes a magnetic field source with a dipole moment in a direction along a z-axis; and a sensor module spaced apart from a center of the dipole moment a distance y0 along a y-axis and spaced apart a distance z0 from a center of the dipole moment along a z-axis, at least one of the magnetic field source or the sensor module configured to move relative to the other along a path in the y=y0 plane, the sensor module configured to determine a relative position of the magnetic field source to the sensor module with respect to the path from a ratio of a gradient dBz/dx to a gradient dBz/dy, where Bz is a magnetic field component associated with the permanent magnet, and where an x-axis, the y-axis and the z-axis are at right angles.
1. A position sensing system comprising:
a magnetic field source with a dipole moment in a direction along a z-axis; and
a sensor module spaced apart from a center of the dipole moment a distance y0 along a y-axis and spaced apart a distance z0 from a center of the dipole moment along a z-axis, at least one of the magnetic field source or the sensor module configured to move relative to the other along a path in the y=y0 plane, the sensor module configured to determine a relative position of the magnetic held source to the sensor module with respect to the path from a ratio of a gradient dBz/dx to a gradient dBz/dy, where Bz is a magnetic field component associated with the permanent magnet, and where an x-axis, the y-axis and the z-axis are at right angles.
2. The system of claim 1 , wherein the sensor module comprises a plurality of magnetic sensor elements.
3. The system of claim 2 , wherein a first one of the plurality of magnetic sensor elements detects a difference in a magnetic field component related to the gradient dBz/dx and a second one of the plurality of magnetic sensor elements detects a difference in a magnetic field component related to the gradient dBz/dy.
4. The system of claim 2 , wherein the plurality of sensor elements comprise Hall elements.
5. The system of claim 4 , wherein the plurality of sensor elements comprise Hall elements configured to sense Bz.
6. The system or claim 5 , wherein the sensor module further comprises a plurality of look-up tables, and wherein a minima and a maxima of Bz are used to determine an appropriate one of the plurality of look-up tables.
7. The system of claim 2 , wherein the plurality of sensor elements comprise magnetoresistive (xMR) sensor elements.
8. The system of claim 2 , wherein the plurality of sensor elements are mounted on a surface of as substrate.
9. The system of claim 8 , wherein the surface of the substrate is parallel with an xy-plane.
10. The system of claim 8 , wherein the surface of the substrate is parallel with an xz-plane.
11. The system of claim 10 , wherein the plurality of sensor elements comprise one of vertical Hall elements or magnetoresistive (xMR) elements.
12. The system of claim 1 , wherein an octupole of the magnet vanishes.
13. The system of claim 1 , wherein two times an absolute value of z0 is less than an absolute value of y0.
14. The system of claim 1 , wherein the magnetic field source is selected from the group consisting of a permanent magnet, an electromagnet and a coil winding.