Rotor Segment Track Sensing for Compact Angular Position Detection
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Solution Overview
Problem
Existing methods for determining angular position in rotating machines, such as hall sensors and gear toothed wheels, are costly and impractical for applications with limited packaging space, especially when a large number of gear teeth are required, necessitating motor redesign.
Innovation Solution
A system using a rotor with a repeating sequence of segments on a track around its shaft, coupled with a sensor on a fixed stator, generates a decoupled output related to the segment sequence, allowing for angular position determination without requiring changes in diameter, using sensors like magneto-resistive chips or inductive sensors mounted on a printed circuit board.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gear toothed wheels with large number of teeth are used to achieve precise angular position detection, then measurement precision is improved, but device complexity and packaging space requirements worsen
Solution Approach 1:
The track is segmented into multiple discrete segments arranged in a repeating sequence around the rotor shaft. Each segment acts as an independent sensing target, allowing precise angular position detection through the sequential detection of these segments by the sensor, without requiring a complex gear structure with many teeth.
Solution Approach 2:
The patent replaces the mechanical gear toothed wheel system with a simpler track and sensor system. Instead of using mechanical gears with defined tooth pitches, the invention uses a track with segments detected by a sensor (such as a magneto-resistive or inductive sensor), eliminating the need for complex mechanical gearing while achieving the same angular position detection function.
2Measurement precision
If gear toothed wheels are used for angular position detection, then position information is obtained, but packaging space requirements increase
Solution Approach 1:
The track is arranged in a circular pattern around the rotor shaft at a specific diameter, utilizing the radial dimension around the shaft. This allows the angular position detection to occur in the circumferential direction without increasing the axial length or radial footprint of the motor, thereby maintaining compact packaging while achieving precise position detection.
Solution Approach 2:
The track serves multiple functions: it provides the repeating sequence of segments for angular position detection, maintains a compact form factor suitable for integration within the rotor, and can be manufactured as part of the rotor structure itself. The sensor mounted on the stator serves both as a position detector and integrates with the motor control system.
3Measurement precision
If hall sensors or optical position encoders are used for motor commutation, then accurate angular position information is obtained, but cost and implementation complexity increase
Solution Approach 1:
The patent uses a simple track structure that can be manufactured as a thin, lightweight component, potentially as a printed circuit board or laminated structure. The sensor used is a solid-state magneto-resistive or inductive sensor that is cheaper and more robust than optical encoders, providing sufficient accuracy for motor commutation without the complexity of optical systems.
Solution Approach 2:
The track with its repeating segment sequence automatically provides the periodic signal needed for commutation as the rotor rotates. The sensor detects the segments passing by and generates commutation signals directly, without requiring external processing or complex electronics. The system is self-contained and integrates seamlessly with the motor control function.
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
Enables efficient angular position detection with minimal packaging space, generating sine and cosine waveforms for motor commutation, adaptable to various diameters by altering track features, reducing costs and complexity.
Implementation Method 1
A sensor is positioned to face the track and is fixed relative to the stator. The track and the sensor may be disposed in a common plane and face each other.
Implementation Method 2
using sensors like magneto-resistive chips or inductive sensors mounted on a printed circuit board
Data Source
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AI summary
Systems and methods for determining angular position in rotating machines. A repeating sequence of segments are arranged in a track disposed at a diameter around a shaft of a rotor that rotates about an axis. A sensor is positioned to face the track and is fixed relative to the stator. The track and the sensor face to each other, which may be in directions that are parallel to the axis. The sensor generates an output that is decoupled from the diameter of the track and is related to the repeating sequence of segments.