Rotor Angular Position Measurement Using Calibration Signatures
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Solution Overview
Problem
Existing sensor systems struggle to accurately measure the mechanical angular position of a rotor with respect to a stator over more than 360 degrees, due to the periodic nature of contrast areas on the target, which leads to ambiguity in determining the actual angular position.
Innovation Solution
A method that involves acquiring electrical measurement signals from multiple measurement locations, using a target with multiple contrast areas, and employing a calibration and setting phase to determine an electrical signature that allows for the correction of the electrical angular position to obtain the mechanical angular position over multiple turns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a target with multiple contrast areas is used to measure angular position over 360 degrees, then the measurement range is extended, but the periodic nature of contrast areas creates ambiguity in determining the actual angular position
Solution Approach 1:
The target is divided into multiple contrast areas (at least two) that are angularly distributed around the rotor. Each contrast area generates a measurement signal with a specific amplitude characteristic. By segmenting the target this way, the system can distinguish between different angular positions within a 360-degree range while maintaining extended measurement capability through multiple periods.
Solution Approach 2:
Different contrast areas on the target have different local electromagnetic characteristics (different amplitudes of measurement signals). This local quality differentiation allows the system to identify which contrast area is currently being measured, thereby resolving the ambiguity that would otherwise exist due to the periodic repetition of contrast areas.
2Measurement precision
If multiple measurement locations are used to acquire electrical signals, then the accuracy of angular position measurement is improved, but the device complexity increases
Solution Approach 1:
Multiple measurement locations are combined into a single detector unit that acquires signals from all locations simultaneously. The detector integrates the measurement functions from multiple positions into one compact device, reducing overall system complexity while maintaining the accuracy benefits of multi-point measurement.
Solution Approach 2:
The detector is designed to perform multiple functions: it simultaneously measures the angular position based on signals from multiple contrast areas and provides calibration information. This multi-functionality reduces the need for separate calibration devices and simplifies the overall measurement system.
3Device complexity
If the number of measurement locations is reduced for compactness, then the sensor size is reduced, but the accuracy of angular position measurement may be compromised
Solution Approach 1:
Multiple measurement functions are merged into a single detector that can simultaneously process signals from multiple contrast areas. This merging allows the sensor to maintain accuracy despite having fewer physical measurement locations, as the detector integrates information from all active contrast areas in a unified manner.
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 method enables accurate measurement of the mechanical angular position over 2Pi radians, providing a bijective relationship between the sensor output and the actual angular position, while maintaining the compactness and simplicity of the sensor system.
Implementation Method 1
the detector includes one or more measuring cells capable of measuring the magnetic field, or the variation of the magnetic field, created by the target in the vicinity of the cell
Implementation Method 2
the detector includes induction means and means for measuring the variation of the induction incurred by the target or by its relative displacement with respect to the detector
Data Source
AI summary
The invention relates to a method and a device for measuring the mechanical angular position of a rotor including, during a calibration phase and then a setting phase:acquiring Ns measurement signals, at measurement locations offset by a corresponding mechanical angle, modulo 2Pi/Nc radians of angle, to Pi/(2×Nc) radians for Ns=2 and 2Pi/3Nc radians for Ns=3;compute an instantaneous electrical angular position value taking into account the arctangent of the ratio of the values of the two measurement signals for the time under consideration, or the arctangent of the ratio of the values of the two transforms obtained by a Clarke transform, applied to three measurement signals;determine electrical calibration (SIGcb) and setting (Sigi) signatures;determine an angular measurement offset value by an operation of resetting the signatures.