Magnetic Encoder Resolving Ambiguous Angle Signals

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Solution Overview

Problem

Existing magnetic encoders using magnetoresistance sensor chips cannot measure the absolute electrical angle of a magnet as they are only sensitive to the magnitude, not the polarity, of the magnetic field, resulting in ambiguous signal output during a full rotation.

Innovation Solution

A magnetic encoder system that includes a magnetoresistance sensor and a magnetic field auxiliary coil, generating an auxiliary magnetic field to influence the 2D magnetic field components, allowing the sensor to detect the resultant field and calculate the absolute electrical angle using trigonometric formulas and compensation signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a magnetoresistance sensor is used to detect magnetic field components, then the sensor can detect the magnitude of the magnetic field, but it cannot detect the polarity of the magnetic field

Engineering Contradiction:

Improvemagnetic field detection capabilityVSAvoidmagnetic field polarity information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

A magnetic field auxiliary coil is introduced as an intermediary element to generate an auxiliary magnetic field that interacts with the target magnetic field. This auxiliary field serves as a mediator that enables the magnetoresistance sensor to indirectly detect polarity information through the combined effect of the target field and auxiliary field, resolving the limitation of the sensor's inability to detect polarity directly

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the magnetic field parameters by superimposing an auxiliary magnetic field with controllable strength and direction onto the target magnetic field. By adjusting the auxiliary field parameters and analyzing the sensor's response to these changes, the system can infer polarity information that would otherwise be undetectable by the magnetoresistance sensor alone

Inventive Principle:

Principle #35Parameter changes

2Productivity

If the magnetic field rotates 360 degrees, then the magnetic field completes one entire period, but the output signal changes for two periods causing ambiguity

Engineering Contradiction:

Improvemeasurement coverageVSAvoidabsolute electrical angle measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The magnetic field auxiliary coil acts as a reference mediator that provides a known magnetic field pattern. By comparing the sensor output under different auxiliary field conditions, the system can distinguish between the two signal periods that occur during a 360-degree rotation, thereby resolving the ambiguity and enabling accurate absolute electrical angle measurement

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Instead of trying to directly interpret the ambiguous sensor signal, the system inverts the approach by actively modifying the magnetic field environment using the auxiliary coil. By applying auxiliary fields in different directions and analyzing how the signal changes, the system can determine the absolute angle position, effectively solving the ambiguity problem through reverse engineering of the measurement condition

Inventive Principle:

Principle #13The other way round (Inversion)

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

Accurately determines the absolute electrical angle by differentiating between N and S poles based on angle changes, enhancing measurement precision and resolving ambiguity in signal output.

Implementation Method 1

the coil current control circuit being configured to supply current to the magnetic field auxiliary coil, to allow the magnetic field auxiliary coil to generate an auxiliary magnetic field

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

The magnetic encoder includes a magnetoresistance sensor, a magnetic field auxiliary coil and a coil current control circuit electrically connected with the magnetic field auxiliary coil

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS11448527B2Magnetic encoder, method, system for detecting absolute electrical angle, and readable storage medium

Publication Date: 2022.09.20 FORTIOR TECHNOLOGY (SHENZHEN) CO LTD

AI summary

Disclosed is a magnetic encoder, a method and system for detecting an absolute electrical angle, and a readable storage medium. The magnetic encoder includes a magnetoresistance sensor, a magnetic field auxiliary coil and a coil current control circuit electrically connected with the magnetic field auxiliary coil, the magnetoresistance sensor being a planar component, the coil current control circuit being configured to supply current to the magnetic field auxiliary coil, to allow the magnetic field auxiliary coil to generate an auxiliary magnetic field, the auxiliary magnetic field influencing the magnetic field component in the first direction and the magnetic field component in the second direction, forming a resultant magnetic field, and the magnetoresistance sensor being configured to detect the resultant magnetic field and the component of the 2-dimension magnetic field generated by the magnet.