Angular Position Sensor Using Differential Hall Signals for 360° Measurement
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Solution Overview
Problem
Existing angular position sensor systems face challenges in achieving a 360° measurement range, robustness against external disturbance fields, sensitivity to sensor element defects, and compactness without compromising accuracy, while being cost-effective and suitable for automotive and functional safety applications.
Innovation Solution
A two-pole magnet system with a sensor device comprising three horizontal Hall elements, integrated on a single semiconductor substrate, calculates angular position using pairwise differences of sensor signals, providing redundancy for error detection and correction, and insensitivity to external fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If four Hall elements are used to achieve 360° measurement range, then measurement range is improved, but device complexity increases
Solution Approach 1:
The patent divides the measurement task into segments by using only three Hall elements positioned at specific angles (0°, 120°, 240°) rather than four elements at 90° intervals. This segmentation allows the system to achieve 360° measurement capability with fewer elements by strategically positioning them to capture sufficient magnetic field information for complete angular determination.
Solution Approach 2:
The patent uses exactly three Hall elements, which is less than the conventional four elements, yet achieves the same 360° measurement capability. This partial action principle demonstrates that fewer elements can suffice when positioned optimally, reducing device complexity while maintaining full measurement range.
2Measurement precision
If more sensor elements are used to improve accuracy, then measurement precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent achieves sufficient measurement precision using only three Hall elements instead of four or more, reducing the bill of materials cost and simplifying the manufacturing process. The three elements are positioned at 0°, 120°, and 240° to provide adequate angular resolution and accuracy for automotive applications without the added cost of additional sensor elements.
Solution Approach 2:
The patent changes the angular positioning parameters of the Hall elements from the conventional 90° spacing to 120° spacing, which optimizes the measurement precision for three-element configurations. This parameter change enables accurate 360° measurement with fewer elements, thereby reducing manufacturing cost while maintaining or improving accuracy.
3Device complexity
If three Hall elements are used to reduce device complexity, then device complexity is reduced, but reliability decreases
Solution Approach 1:
The patent implements error detection and correction mechanisms that use the three Hall element signals to monitor system health and detect faults. By processing the signals from the three elements and comparing their relationships, the system can identify when an element fails or when measurements become unreliable, providing feedback that maintains operational reliability despite the reduced number of elements.
Solution Approach 2:
The patent incorporates preliminary error detection and correction capabilities into the three-element design, allowing the system to identify and compensate for potential failures before they compromise measurement reliability. This preliminary action ensures that the reduced element count does not sacrifice reliability, as the system is pre-equipped to handle element failures.
4Volume of moving object
If Hall elements are positioned closer together to compact the device, then device volume is reduced, but sensitivity to external fields increases
Solution Approach 1:
The patent positions the three Hall elements at 120° intervals around the magnet, creating a symmetric configuration where each element experiences equivalent magnetic field conditions. This equipotential arrangement ensures that external disturbance fields affect all elements uniformly, allowing the differential measurement technique to reject common-mode noise and maintain insensitivity to external fields even in a compact configuration.
Solution Approach 2:
The patent arranges the Hall elements in a circular pattern around the magnet rather than in a linear or rectangular configuration. This curved, radial arrangement optimizes the sensing geometry for detecting rotational position while maintaining compact size. The circular symmetry helps equalize the influence of external fields across all elements, reducing their harmful effects despite the close spacing enabled by the compact design.
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
The system achieves a 360° measurement range, insensitivity to external disturbances, compact design, and error detection/correction capabilities, ensuring high accuracy and reliability for automotive and functional safety applications.
Implementation Method 1
a magnetic sensor device comprising a plurality of horizontal Hall elements including at least a first, a second and a third horizontal Hall element
Data Source
Figure 1(a)~1(c)
Figure 1(d)~1(e)
Figure 2(a)~2(c)
AI summary
An angular position sensor system, comprising a two-pole magnet rotatable about a rotation axis; a magnetic sensor device comprising a plurality of horizontal Hall elements including at least a first, second and third horizontal Hall element located on a virtual circle, the circle having a centre located on the rotation axis; the Hall elements being spaced by multiples of 90°; wherein the magnetic sensor device further comprises a processing unit connected to the horizontal Hall elements for obtaining a first, second and third signal (h1, h2, h3), and for determining a first pairwise difference (d1) between the first and second sensor signal (d1, d2), and for determining a second pairwise difference (d2) between the second and third sensor signal (h2, h3), and for determining an angular position (θ) of the magnet relative to the sensor device based on a ratio of these pairwise differences (d1, d2).