Current Sensor Linearization via Tangential Signal Processing
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Solution Overview
Problem
Current sensors using magnetoresistive elements do not provide a linear relationship between the sensor signal and the detection current, leading to varying detection accuracy based on the linearity of the sensor signal output.
Innovation Solution
A current sensor with a magnetic field generating element and a magnetoresistive element comprising a pin layer, tunnel layer, and free layer, where the signal processing unit calculates the tangential value of the angle between the second magnetic field and the synthetic magnetic field, outputting a sensor signal proportional to the detection current, thereby ensuring linear output with improved detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetoresistive element is used to detect current through magnetic field interaction, then the sensor can detect current magnitude, but the sensor signal output is non-linear with respect to the detection current
Solution Approach 1:
The patent divides the detection into two independent components: a first magnetoresistive element that detects the component of magnetic field perpendicular to the bias field, and a second magnetoresistive element that detects the component parallel to the bias field. This segmentation allows the non-linear responses from both elements to be combined through trigonometric relationships to produce a linear overall response, resolving the contradiction between detection accuracy and signal processing complexity
Solution Approach 2:
The patent introduces a bias magnetic field as an intermediary that interacts with the current magnetic field to produce a synthetic magnetic field. This intermediary field enables the magnetoresistive elements to respond in a controlled manner, and through the combination of two such elements with different orientations, achieves linearization of the output signal without requiring complex external circuitry
2Measurement precision
If the sensor signal is made linear with respect to detection current, then detection accuracy improves, but the structure becomes more complex
Solution Approach 1:
The patent merges the outputs of two magnetoresistive elements into a single linear sensor signal through mathematical combination. The first element provides a sine component and the second element provides a cosine component of the magnetic field angle, and these are combined to produce a tangent relationship that is linear with respect to the detection current, achieving both linearity and compact structure
Solution Approach 2:
The patent changes the orientation parameter of the magnetoresistive elements relative to the bias magnetic field. By setting the first element perpendicular and the second element parallel to the bias field, the system exploits the trigonometric relationships between sine and cosine to achieve linearization. This parameter optimization allows the sensor to maintain a relatively simple structure while achieving linear output characteristics
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
The solution ensures a linear relationship between the sensor signal and the detection current, enhancing detection accuracy without requiring additional components, thus maintaining cost-effectiveness and reducing temperature-related variations in the sensor signal.
Implementation Method 1
a magnetic sensor having a magnetoresistive element whose resistance value changes according to a magnetic field applied thereto
Implementation Method 2
a bias magnet generating a bias magnetic field
Implementation Method 3
a current magnetic field is generated in a direction perpendicular to the bias magnetic field
Data Source
AI summary
In a current sensor for detecting an electric current flowing in a current path, a magnetic field generating element generates a second magnetic field perpendicular to a first magnetic field generated by the electric current of the current path, and a magnetic sensor generates at least one of a first signal containing a sine value according to an angle defined between the second magnetic field and a synthetic magnetic field composed of the first magnetic field and the second magnetic field and a second signal containing a cosine value according to the angle. A signal processing unit includes a calculation circuit that calculates a tangential value according to the angle using the at least one of the first signal and the second signal, and outputs a sensor signal containing the tangential value.