Angle Sensor Harmonic Error Reduction via Detection Unit Segmentation

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Solution Overview

Problem

Existing angle sensors face challenges in reducing angular errors caused by error components corresponding to fifth or higher-order harmonics, which require complex signal processing and are difficult to design due to the need for precise magnetoresistance element configurations.

Innovation Solution

The angle sensor system includes multiple detection units with specific positional and phase relationships to generate signals with reduced error components, using magnetic detection elements with magnetoresistance properties to calculate the detected angle value by performing simple operations on the signals from these units.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If complex signal processing is used to reduce angular errors from fifth or higher-order harmonics, then measurement precision is improved, but device complexity increases

Engineering Contradiction:

Improveangular error reductionVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The detection system is divided into multiple detection units (first and second detection units) with specific positional relationships. Each unit generates detection signals that are processed independently, and the results are combined to cancel out higher-order harmonic errors. This segmentation allows complex error reduction to be achieved through multiple simple detection points rather than one complex processing system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent uses multiple copies of the same detection mechanism (magnetoresistance elements) arranged in specific positions. The first detection unit and second detection unit are substantially the same structure, but positioned differently relative to the magnetic field generation unit. This copying approach allows error cancellation through signal combination without requiring fundamentally different detection mechanisms.

Inventive Principle:

Principle #26Copying

2Measurement precision

If precise magnetoresistance element configurations are used to reduce higher-order harmonics, then measurement precision is improved, but ease of manufacture deteriorates

Engineering Contradiction:

Improveangular error reductionVSAvoidmagnetoresistance element design difficulty

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Instead of changing the complex internal structure of magnetoresistance elements, the patent changes the positional parameters of the detection units relative to the magnetic field generation unit. The first and second detection units are positioned at specific angular relationships (ideally 90 degrees apart) to enable error cancellation. This parameter-based approach simplifies manufacturing by avoiding precise internal element configuration while achieving the same error reduction effect.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If multiple detection units with specific positional relationships are used, then angular error from higher-order harmonics is reduced, but device complexity increases

Engineering Contradiction:

Improvedetected angle value accuracyVSAvoiddetection unit configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the output signals from multiple detection units through signal processing operations (addition and subtraction). By merging the signals from the first and second detection units in a specific way, the system cancels out fifth-order and higher harmonic errors while maintaining the simplicity of individual detection units. This combining approach achieves high precision without requiring each individual unit to be complex.

Inventive Principle:

Principle #5Merging (Combining)

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 allows for easy reduction of angular errors from higher-order harmonics with simpler operations, improving the accuracy of detected angle values without the need for complex signal processing and simplifying the design of magnetoresistance elements.

Implementation Method 1

The magnetic detection element includes, for example, a spin-valve magnetoresistance element including a magnetization pinned layer whose magnetization direction is pinned, a free layer whose magnetization direction varies depending on the direction of the rotating magnetic field

Methodology Applied

Scientific EffectMagnetoresistance: Magnetoresistance

Data Source

PatentUS10545032B2Angle sensor and angle sensor system

Publication Date: 2020.01.28 TDK CORP

AI summary

An angle sensor includes a first to a fourth detection unit and an angle detection unit. Each of the first to the fourth detection unit generates two detection signals. The first to the fourth detection unit are arranged in a positional relationship that establishes predetermined phase relationships among the detection signals they generate. The angle detection unit performs operations using the detection signals to generate a first and a second signal in which an error component corresponding to a fifth or higher-order harmonic and an error component corresponding to a harmonic of the order other than the fifth order are lower than those in the detection signals. The angle detection unit then calculates a detected angle value on the basis of the first and the second signal.