Magnet Arrangement for Direct Position Sensor

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Solution Overview

Problem

Existing position sensor technologies can only indirectly determine position by integrating speed, making direct position determination challenging in certain applications.

Innovation Solution

A magnet arrangement with a modulated magnetic field in one direction and a constant field in a perpendicular direction, allowing a magnetic field sensor to directly determine position by evaluating the sensed magnetic field components and their ratios.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If periodic magnetic field modulation is used to sense position, then speed determination is improved, but direct position determination becomes impossible

Engineering Contradiction:

Improvespeed determinationVSAvoiddirect position determination

Core Design Contradiction:

SpeedVSMeasurement precision

Solution Approach 1:

The magnetic field is segmented into two independent components: one providing periodic modulation for speed sensing and another providing a constant reference field for direct position determination. This segmentation allows both functions to operate simultaneously without interference.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution introduces an additional spatial dimension by creating a magnetic field configuration where field lines extend in multiple directions. The constant field component provides a reference that varies with position in a different dimension than the periodic modulation, enabling direct position measurement alongside speed measurement.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Speed

If magnetic field sensors are used with periodic modulation, then speed sensing is achieved, but position measurement requires integration which accumulates errors

Engineering Contradiction:

Improvespeed sensingVSAvoidposition measurement accuracy

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

A constant magnetic field component acts as an intermediary reference that directly relates to position without requiring integration. This reference field mediates between the periodic modulation signal and the position measurement, providing a reliable direct measurement path that eliminates integration error accumulation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If a magnet arrangement provides position information, then direct position determination is enabled, but the system becomes sensitive to sensor position variations

Engineering Contradiction:

Improvedirect position determinationVSAvoidrobustness against sensor position variations

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The magnetic field is designed with homogeneous characteristics in the region of interest, where both the periodic and constant field components maintain consistent spatial relationships. This homogeneity ensures that small variations in sensor position do not significantly affect the measurement accuracy, as the field properties remain uniform across the measurement zone.

Inventive Principle:

Principle #33Homogeneity

4Measurement precision

If magnetic field components are used for position sensing, then position information can be obtained, but homogenous disturbance fields affect measurement accuracy

Engineering Contradiction:

Improveposition sensingVSAvoidimpact of homogenous disturbance fields

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The constant magnetic field component, which could be considered a disturbance in traditional periodic modulation systems, is converted into a beneficial reference signal. By deliberately introducing this constant field component, the system gains a stable reference that enables direct position determination and provides immunity against external homogenous disturbance fields through differential measurement techniques.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

Enables direct and unambiguous position determination, increasing the range of travel while being robust against variations in sensor position, and reducing the impact of homogenous disturbance fields.

Implementation Method 1

A magnet arrangement (10) and a position sensor device are provided. The magnet arrangement (10) is configured to provide a magnetic field which is modulated in a first direction (13), while the magnetic field is essentially constant in a second direction (14)

Methodology Applied

Scientific EffectMagnetic field modulation: Magnetic Field

Data Source

PatentUS10978229B2Magnet arrangement for position sensor device and corresponding position sensor device

Publication Date: 2021.04.13 INFINEON TECHNOLOGIES AG

AI summary

A magnet arrangement including at least one magnetic element providing a modulated magnetization in a first direction and an essentially constant magnetization in a second direction different from the first direction.