Integrated Multi-Turn Position Sensor for High Pole Count Motors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing motor position sensing technologies face challenges in providing high resolution absolute position feedback over multiple rotations without requiring external power or additional mechanical components, especially for high pole count motors, and do not offer a compact configuration with sufficient resolution for self-powered coarse absolute sensors.
Innovation Solution
The integration of coarse sensing elements, such as bi-stable Barkhausen effect sensors, with fine sensor pickup coils within the motor's magnetic structure, allowing for absolute position tracking across an arbitrary range without external power and minimizing additional components, while using the motor's magnetic structure to enhance resolution and reduce footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple encoder sections or resolver sections with mechanical gearing are used to obtain absolute multi-turn position feedback, then the absolute position sensing capability is improved, but the device complexity and mechanical component count increase
Solution Approach 1:
The patent combines coarse absolute position sensing and fine position sensing into a single integrated sensor assembly mounted on the motor shaft, eliminating the need for separate mechanical gearing sections. The coarse sensing elements (e.g., Hall effect sensors) and fine sensing elements (e.g., encoder) are integrated to provide multi-turn absolute position feedback without mechanical gearing between sections.
Solution Approach 2:
The patent extracts the position sensing function from complex mechanical gearing systems and implements it through magnetic sensing elements mounted directly on the motor shaft. This extraction eliminates the mechanical transmission components while maintaining the absolute position sensing capability across multiple rotations.
2Measurement precision
If sensors with battery backup and electronic counters are used to achieve absolute position feedback, then the position tracking capability is improved, but the device complexity and power requirements increase
Solution Approach 1:
The patent implements self-powered coarse position sensing using Hall effect sensors that generate their own operating power from the motor's back-EMF during operation. This eliminates the need for separate battery backups while maintaining absolute position tracking capability. The fine encoder provides complementary position information without requiring additional power sources.
3Measurement precision
If high resolution cyclic absolute position sensors are combined with coarse multi-turn absolute position sensors, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent merges coarse absolute position sensing (using Hall effect sensors or similar magnetic sensors) with fine position sensing (using optical or magnetic encoders) into a single integrated sensor assembly. Both sensing functions are mounted on the motor shaft and processed together to provide high-resolution multi-turn absolute position feedback without requiring separate mechanical or electronic systems.
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 solution enables high resolution position feedback over multiple rotations with reduced power consumption and component count, maintaining position accuracy and minimizing system size and weight, suitable for applications like solar tracking where power efficiency is critical.
Implementation Method 1
Two or more large Barkhausen jump sensing elements, such as Wiegand effect sensors, are each located between magnetically soft flux directing elements
Implementation Method 2
The magnetic circuits of both the multiple revolution capable feedback and the high resolution partial revolution feedback are based on the existing motor magnetic circuits
Data Source
AI summary
Absolute multi-turn position sensing integrated within the structure of a hybrid stepper motor implemented by sharing the magnetic structure of the motor with the sensing means. An alternating magnetic field is obtained from a single magnet within the stepper motor rotor by use of alternating flux paths directed to large Barkhausen jump effect sensing elements. Pulses generated from the large Barkhausen sensing are decoded electronically and stored in a non-volatile memory to absolutely locate the motor position within a fraction of 1 electrical cycle of the motor over an arbitrary range. This coarse position sensing can optionally be extended by use of a higher resolution absolute within-electrical-cycle sensing means to provide integrated high resolution position sensing over an arbitrary number of revolutions.