Absolute Electrical Angle Detection Using Hall and MR Sensors
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Solution Overview
Problem
Existing magnetic encoders using magnetoresistive sensors cannot accurately measure the absolute electrical angle of a magnetic field due to their sensitivity only to the magnitude, not the polarity, resulting in ambiguous signal output over a 360° cycle.
Innovation Solution
Incorporating both magnetoresistive sensors for detecting magnetic components in specific directions and Hall sensors for polarity detection, with signal processing techniques to calculate scaling compensation signals and determine the absolute electrical angle by correcting for offset errors and harmonics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetoresistive sensors are used to detect magnetic field magnitude, then the sensor output signal changes for two cycles when the magnetic field rotates 360°, but the sensor cannot distinguish polarity resulting in inability to measure absolute electrical angle
Solution Approach 1:
The patent combines magnetoresistive sensors (for detecting magnetic field magnitude in tangential and axial directions) with Hall sensors (for detecting magnetic field polarity) into a unified detection system. This merging allows the system to simultaneously obtain both the magnitude and polarity information of the magnetic field, resolving the contradiction where magnetoresistive sensors alone could measure angle but lost polarity information, making absolute electrical angle measurement impossible.
Solution Approach 2:
The Hall sensor acts as an intermediary element that specifically detects the polarity of the magnetic field, which the magnetoresistive sensors cannot detect. By introducing this intermediary component, the system gains the missing polarity information without compromising the existing angle detection capability of the magnetoresistive sensors, thus enabling absolute electrical angle measurement.
2Measurement precision
If signal processing techniques are applied to compensate for offset errors and harmonics, then the accuracy of absolute electrical angle calculation is improved, but the complexity of the detection system increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values for offset errors and harmonic distortions in lookup tables before actual measurement. During operation, the system simply retrieves and applies these pre-computed compensation values rather than performing complex real-time calculations, thus improving angle accuracy while minimizing the increase in system complexity and computational burden.
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 precise measurement of the absolute electrical angle by distinguishing between N and S poles, enhancing the accuracy of the calculated angle and overcoming the limitations of existing technologies.
Implementation Method 1
a magnetoresistive sensor for detecting a magnetic component in a first direction
Implementation Method 2
a Hall sensor for detecting a magnetic component in a second direction and a polarity position
Data Source
AI summary
The present disclosure provides a method and a system for detecting an absolute electrical angle, and a computer readable storage medium. The method includes: obtaining an angle sine signal corresponding to a magnetic component in a first direction and an angle cosine signal corresponding to a magnetic component in a second direction; calculating a scaling compensation sine signal and a scaling compensation cosine signal according to the angle sine signal, the angle cosine signal, and a scaling compensation formula; determining an angle interval corresponding to the scaling compensation sine signal and the scaling compensation cosine signal, and calculating a relative electrical angle according to a preset trigonometric function corresponding to the angle interval; obtaining a Hall signal detected by the Hall sensor, and determining a polarity position according to the Hall signal; and calculating the absolute electrical angle according to the relative electrical angle and the polarity position.