On-axis magnetic field angle sensors, systems and methods

摘要

Embodiments relate to magnetic field sensors, such as magnetic field angle sensors with generally on-axis arrangements of sensor elements relative to a rotation axis of a magnet or shaft. The shaft comprises or is coupled to an end portion that comprises a soft magnetic material, in embodiments, with the end portion having an end surface proximate the sensor that is rotationally asymmetric with respect to the rotation axis running through the length of the shaft. The sensor comprises at least three magnetic field sensing elements arranged in a plane generally perpendicular to the shaft and rotation axis. Circuitry forming part of or coupled to the sensor is configured to estimate a rotational position of the shaft by combining the signals of the at least three magnetic field sensing elements.

主权项

1. A magnetic field angle sensor system comprising:
a shaft rotatable around a rotation axis; an end portion rotatable with the shaft and being rotationally asymmetric with respect to the rotation axis; a sensor die spaced apart from the end portion and comprising a first surface being substantially perpendicular to the rotation axis; at least three magnetic field sensor elements arranged spaced apart from one another on the first surface around a projection of the rotation axis onto the first surface; a magnetic field source; and circuitry coupled to the at least three magnetic field sensor elements and configured to estimate a rotational position of the shaft by combining signals of the at least three magnetic field sensor elements when, in operation, the end portion is magnetized by the magnetic field source and alters a magnetic field sensed by the at least three magnetic field sensor elements when the end portion rotates with the shaft, wherein the circuitry is configured to estimate a rotational position of the shaft by combining signals of the at least three magnetic field sensor elements to determine a real part Re{σn} and an imaginary part Im{σn} of a complex pointer σn and to determine an angle between the complex pointer and a positive real axis.