Multi-Polar Magnetic Ring Position Sensing System
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Solution Overview
Problem
Existing motor position sensing systems face challenges in accurately determining absolute positions over multiple turns or revolutions, especially in space-limited applications, as they often require large single absolute position sensor chips or costly turn counters.
Innovation Solution
A system comprising multi-polar magnetic rings and processing units, along with external sensors, is used to determine absolute positions by combining angular position data from one pole pair with coarse position information from a Hall sensor array, allowing for accurate position determination across multiple pole pairs without the need for large sensor chips or turn counters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large single absolute position sensor chip is used to cover multiple pole pairs, then the absolute position measurement range is improved, but the device area and complexity increase
Solution Approach 1:
The patent divides the absolute position sensing function into multiple smaller sensor chips, each responsible for a specific pole pair. Instead of using one large sensor chip to cover all pole pairs, multiple small chips are distributed across different pole pairs, with each chip providing local position information that is then combined to determine the overall absolute position.
Solution Approach 2:
The patent transitions from a single-dimensional sensing approach (one large chip covering all poles) to a multi-dimensional approach where multiple small chips are spatially distributed across different pole pairs. This spatial distribution across multiple dimensions allows the system to achieve the same measurement range as a large chip while using smaller individual components.
2Measurement precision
If a turn counter is implemented to determine absolute position over multiple turns, then the measurement range is improved, but the device complexity and cost increase
Solution Approach 1:
The patent merges the absolute position sensing function directly into the magnetic ring structure itself. The magnetic ring is designed with specific magnetic pole configurations that encode position information, eliminating the need for separate turn counter components. The sensors read the magnetic field patterns directly from the ring, combining position detection and counting functions into a unified system.
Solution Approach 2:
The magnetic ring structure is designed to be self-describing, where the magnetic pole patterns themselves contain the information needed for both position detection and turn counting. The system uses the magnetic field signatures inherent in the ring structure to automatically determine absolute position without requiring external counter mechanisms or additional processing components.
3Area of stationary object
If multiple small sensor chips are used instead of one large chip, then the device area is reduced, but the system complexity increases
Solution Approach 1:
Each small sensor chip is designed to be universal and interchangeable, with identical functionality for detecting magnetic field patterns from any pole pair. This standardization allows the system to use multiple simple, identical components rather than complex integrated systems, reducing overall system complexity while maintaining the ability to cover multiple pole pairs.
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 enables precise and cost-effective determination of absolute motor positions over multiple turns or revolutions, improving accuracy and reducing complexity in motor control systems, while accommodating space constraints.
Implementation Method 1
Timken's MPS32XF produces high resolution signals from a wide range of magnetic pole widths. This motor sensor is programmable and equipped with a Hall sensor array.
Data Source
AI summary
A system for determining an absolute position of a motor. The system includes first and second multi-polar magnetic rings, first and second processing units, and at least one external sensor. The first multi-polar magnetic ring is concentrically positioned around the motor, and has a plurality of pole pairs. The second multi-polar magnetic ring is concentrically positioned around the first multi-polar magnetic ring, and has at least one pole pair. The first processing unit is positioned near the first multi-polar magnetic ring to determine an angular position over one of the pole pairs of the first multi-polar magnetic ring. The sensor is positioned external to the processing unit and over the second multi-polar magnetic ring to indicate a state of the pole pair of the second multi-polar magnetic ring. The second processing unit generates an absolute position of the motor based on the angular position and the state.