US-20260126303-A1 - SYSTEMS AND METHODS FOR ERROR CHECKING IN MAGNETIC FIELD SENSING APPLICATIONS

US20260126303A1US 20260126303 A1US20260126303 A1US 20260126303A1US-20260126303-A1

Abstract

Disclosed are example systems and methods for error checking in magnetic field sensing applications. In particular, described are example systems and methods for error checking in magnetic field sensors used for determining a rotation angle of an object that rotates. In some embodiments, a plurality of signals representative of a magnetic field generated by a magnetic target may be received. The plurality of signals may be combined to determine a value, and a determination made as to whether the determined value is an expected value. When the determined value is not an expected value, an output signal representing an error may be output.

Inventors

German Grinberg
Franco Noel Martin Pirchio
Juan Manuel Cesaretti
Lucas Intile

Assignees

ALLEGRO MICROSYSTEMS, LLC

Dates

Publication Date: 20260507
Application Date: 20241107

Claims (20)

1 . A method of identifying an error in measuring a characteristic of a target, comprising: receiving, by electronic circuitry, a plurality of signals representative of a magnetic field generated by the target; combining, by the electronic circuitry, the plurality of signals to determine a value; determining, by the electronic circuitry, whether the value is an expected value; and outputting, by the electronic circuitry, an output signal representing an error when the value is not the expected value.
2 . The method of claim 1 , wherein the plurality of signals represents signals output from differentially coupled pairs of magnetic field sensing elements.
3 . The method of claim 2 , wherein the plurality of signals comprises three signals, each of the three signals being a channel signal representing signals output from a differentially coupled pair of magnetic field sensing elements.
4 . The method of claim 3 , wherein a first signal of the plurality of signals is a first channel (CH 1 ) signal representing signals output from a first pair of differentially coupled magnetic field sensing elements, a second signal of the plurality of signals is a second channel (CH 2 ) signal representing signals output from a second pair of differentially coupled magnetic field sensing elements, and a third signal of the plurality of signals is a third channel (CH 3 ) signal representing signals output from a third pair of differentially coupled magnetic field sensing elements.
5 . The method of claim 4 , wherein combining the plurality of signals to determine the value comprises combining the plurality of signals according to the formula CH 1 - CH 2 + CH 3 = X ⁢ 1 where X1 is the value and is expected to be zero.
6 . The method of claim 5 , wherein determining whether the value is the expected value comprises determining whether X1 is above a threshold value for a predetermined time.
7 . The method of claim 4 , wherein combining the plurality of signals to determine the value comprises combining the plurality of signals according to the formula CH 1 2 + CH 2 2 + CH 3 2 = X ⁢ 2 where X2 is the value and is expected to be constant over time.
8 . The method of claim 7 , wherein determining whether the value is the expected value comprises determining whether X2 varies beyond a threshold amount for a predetermined time.
9 . The method of claim 4 , wherein combining the plurality of signals to determine the value comprises combining the plurality of signals according to the formula B IN = 1 3 × ( 3 2 ⁢ ( CH 2 + CH 3 ) ) 2 + ( CH 1 + 1 2 ⁢ ( CH 2 - CH 3 ) ) 2 where B IN is the value and is proportional to a magnitude of the magnetic field generated by the target.
10 . The method of claim 9 , wherein determining whether the value is the expected value comprises determining whether B IN deviates from an expected B IN for a predetermined time.
11 . The method of claim 1 , wherein combining the plurality of signals to determine the value comprises summing the plurality of signals.
12 . The method of claim 11 , wherein determining whether the value is an expected value comprises determining whether the value is within a threshold amount of zero for a predetermined time.
13 . The method of claim 11 , wherein determining whether the value is an expected value comprises determining whether the value is within a threshold amount of a constant value for a predetermined time.
14 . A system comprising electronic circuitry configured to: receive a plurality of signals representative of a magnetic field generated by a target; combine the plurality of signals to determine a value; determine whether the value is an expected value; and output an output signal representing an error when the value is not the expected value.
15 . The system of claim 14 , further comprising at least six magnetic field sensing elements.
16 . The system of claim 15 , wherein the magnetic field sensing elements are Hall-effect plate sensing elements.
17 . The system of claim 15 , wherein the at least six magnetic field sensing elements comprise three pairs of differentially coupled magnetic field sensing elements.
18 . The system of claim 14 , wherein the plurality of signals represents signals output from differentially coupled pairs of magnetic field sensing elements.
19 . The system of claim 18 , wherein the plurality of signals comprises three signals, each of the three signals being a channel signal representing signals output from a differentially coupled pair of magnetic field sensing elements.
20 . The system of claim 19 , wherein a first signal of the plurality of signals is a first channel (CH 1 ) signal representing signals output from a first pair of differentially coupled magnetic field sensing elements, a second signal of the plurality of signals is a second channel (CH 2 ) signal representing signals output from a second pair of differentially coupled magnetic field sensing elements, and a third signal of the plurality of signals is a third channel (CH 3 ) signal representing signals output from a third pair of differentially coupled magnetic field sensing elements.

Description

BACKGROUND Various standards have been developed to classify risk and define safety requirements, such as the Safety Integrity Level (SIL) used in the International Electrotechnical Commission (IEC) standard 61508. This standard has been adapted to the road vehicle industry specifically, namely as Automotive Safety Integrity Level (ASIL) defined by the International Organization for Standardization (ISO) standard 26262. The highest classification of injury risk that requires the most stringent level of safety measures is ASIL-D, required for safety critical automotive applications such as automotive control systems. Sensor devices are often used to monitor parameters of a system. For example, sensor devices may be used to measure an angle of rotation of a rotation object, such as of a rotor of an electric motor. The measured angle information may then be used to control the motor. For example, a controller may continuously receive a measured angle of rotation of the rotor, and may use this information to commutate the motor. That is, the measured angle information may be used by the controller to switch currents in motor windings, producing magnetic fields that cause the rotor to rotate. The controller can then control aspects of the motor, such as speed and torque, based on the measured angle information. Sensor devices are also used in some safety critical automotive applications, such as in detecting the angle of rotation of an automobile steering column relative to its neutral position to signal an electric power steering system that assists in wheel turning. Numerous applications in industries, spanning from industrial automation and robotics, to electronic power steering and motor position sensing, may require monitoring of a rotation angle of a rotating shaft. SUMMARY Disclosed are example systems and methods for error checking in magnetic field sensing applications. In particular, described are example systems and methods for error checking in magnetic field sensors used for determining a rotation angle of an object that rotates. In some embodiments, a plurality of signals representative of a magnetic field generated by a magnetic target may be received. The magnetic target may be the object that rotates (if magnetic) or a magnet attached to the object and that rotates with the object. The plurality of signals may be combined to determine a value, and a determination made as to whether the determined value is an expected value. When the determined value is not an expected value, an output signal representing an error may be output. In accordance with some embodiments, there is provided a method of identifying an error in measuring a characteristic of a target. The method comprises receiving, by electronic circuitry, a plurality of signals representative of a magnetic field generated by the target. The method also comprises combining, by the electronic circuitry, the plurality of signals to determine a value, and determining, by the electronic circuitry, whether the value is an expected value. The method further comprises outputting, by the electronic circuitry, an output signal representing an error when the value is not the expected value. In some embodiments, the plurality of signals represents signals output from differentially coupled pairs of magnetic field sensing elements. In further embodiments, the plurality of signals comprises three signals, each of the three signals being a channel signal representing signals output from a differentially coupled pair of magnetic field sensing elements. In still further embodiments, a first signal of the plurality of signals is a first channel (CH1) signal representing signals output from a first pair of differentially coupled magnetic field sensing elements, a second signal of the plurality of signals is a second channel (CH2) signal representing signals output from a second pair of differentially coupled magnetic field sensing elements, and a third signal of the plurality of signals is a third channel (CH3) signal representing signals output from a third pair of differentially coupled magnetic field sensing elements. In some embodiments, combining the plurality of signals to determine the value comprises combining the plurality of signals according to the formula CH1-CH2+CH3=X⁢1where X1 is the value and is expected to be zero. In further embodiments, determining whether the value is the expected value comprises determining whether X1 is above a threshold value for a predetermined time. In still further embodiments, combining the plurality of signals to determine the value comprises combining the plurality of signals according to the formula CH12+CH22+CH32=X⁢2where X2 is the value and is expected to be constant over time. In some embodiments, determining whether the value is the expected value comprises determining whether X2 varies beyond a threshold amount for a predetermined time. In further embodiments, combining the plurality of signals to determine