Hall Sensor Position Detection Using Fourier Calibration

Solution Overview

Problem

Current position sensor systems face challenges in accurately determining the position of a magnetic field transducer relative to a position sensor, especially in environments with stray fields and inaccurate geometry, requiring robust and cost-effective solutions.

Innovation Solution

The use of a calibration function represented by a Fourier series with multiple Fourier coefficients allows for precise determination of position information, even in asymmetrical signal profiles, by solving the calibration function using a processing unit that adapts to changing sensor arrangements and compensates for stray fields.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If magnetic synros with paramagnetic rings and coil arrangements are used, then robustness against stray fields is improved, but device complexity and manufacturing cost increase due to precise arrangement requirements and special assembly parts

Engineering Contradiction:

Improverobustness against stray fieldsVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical magnetic synro system with a Hall sensor-based detection system. Instead of using paramagnetic rings and coil arrangements that require precise mechanical assembly, the invention uses a Hall sensor to detect the magnetic field generated by a magnet on the drive shaft. This substitution eliminates the need for complex mechanical structures like stators, rotors, and assembly parts while maintaining the ability to detect rotational position accurately.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the detection parameter from mechanical magnetic coupling modulation to direct magnetic field measurement using a Hall sensor. By measuring the magnetic field strength at different positions around the magnet's rotation, the system can determine angular position without requiring the complex paramagnetic ring and coil arrangement. This parameter change simplifies the device while maintaining robustness.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If magnetic synros with precise arrangement of stator and rotor are used, then measurement accuracy is improved, but ease of manufacture deteriorates due to precise arrangement and permanent fixation requirements

Engineering Contradiction:

Improveaccuracy of measured angleVSAvoidease of manufacture

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical magnetic synro system with a Hall sensor-based detection system. Instead of using paramagnetic rings and coil arrangements that require precise mechanical assembly, the invention uses a Hall sensor to detect the magnetic field generated by a magnet on the drive shaft. This substitution eliminates the need for complex mechanical structures like stators, rotors, and assembly parts while maintaining the ability to detect rotational position accurately.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The Hall sensor system is self-aligning and does not require precise mechanical arrangement like the magnetic synro system. The sensor naturally detects the magnetic field regardless of minor positional variations, eliminating the need for special assembly parts and precise fixation. The system automatically adapts to the magnetic field configuration, making manufacturing much easier while maintaining measurement accuracy.

Inventive Principle:

Principle #25Self-service

3Ease of manufacture

If simple sensor design is used, then ease of manufacture and cost-effectiveness are improved, but measurement precision deteriorates in environments with stray fields and inaccurate geometry

Engineering Contradiction:

Improvecost-effectivenessVSAvoidaccuracy of position determination

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent replaces the mechanical magnetic synro system with a Hall sensor-based detection system. Instead of using paramagnetic rings and coil arrangements that require precise mechanical assembly, the invention uses a Hall sensor to detect the magnetic field generated by a magnet on the drive shaft. This substitution eliminates the need for complex mechanical structures like stators, rotors, and assembly parts while maintaining the ability to detect rotational position accurately.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses feedback from the Hall sensor measurements to determine the angular position. By measuring the magnetic field strength at different positions and using this information to calculate the angle, the system achieves high measurement precision with a simple sensor design. The processing unit analyzes the magnetic field data to compensate for any geometric inaccuracies or stray field effects.

Inventive Principle:

Principle #23Feedback

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables consistent and precise determination of position information, reducing errors and maintaining robustness against stray fields, while allowing for a simple and cost-effective sensor design.

Implementation Method 1

the position sensor is designed to generate at least one periodic measurement signal when the magnetic field transducer moves relative to the position sensor

Methodology Applied

Scientific EffectMagnetic field detection: Magnetic Field

Implementation Method 2

Examples of position sensors have magnetic field sensors, such as xMR sensors or Hall sensors, wherein xMR denotes different magnetoresistive effects such as AMR (anisotropic magnetoresistance), GMR (GMR=giant magnetoresistance) and TMR (TMR=tunnel magnetoresistance)

Methodology Applied

Scientific EffectMagnetoresistive effect: Magnetoresistance

Implementation Method 3

the assigned calibration function represents the respective periodic measurement signal using a Fourier series having a respective plurality of Fourier coefficients which differ from zero and are of an order greater than zero

Methodology Applied

Scientific EffectFourier series analysis:

Implementation Method 4

the magnetic field transducer generates a varying, for example a periodic, magnetic field during a rotation of the axis of rotation, which magnetic field is captured by the position sensor

Methodology Applied

Scientific EffectMagnetic field generation: Magnetic Field

Data Source

PatentUS11788864B2Determination of an item of position information relating to a position of a magnetic field transducer relative to a position sensor

Publication Date: 2023.10.17 INFINEON TECHNOLOGIES AG

AI summary

An apparatus for determining an item of position information relating to a position of a magnetic field transducer relative to a position sensor. The position sensor is designed to generate at least one periodic measurement signal when the magnetic field transducer moves relative to the position sensor. A processing unit of the apparatus is designed to determine the position information based on a respective measurement signal value of a respective periodic measurement signal using a calibration function assigned to the respective periodic measurement signal. The assigned calibration function represents the respective periodic measurement signal using a Fourier series having a respective plurality of Fourier coefficients which differ from zero and are of an order greater than zero. The processing unit is designed to at least approximately solve the assigned calibration function for the respective measurement signal value in order to determine the position information.