Quadrature Magnetic Encoder Phase Shift Compensation
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Solution Overview
Problem
Conventional magnetic encoders rely on precise design and manufacturing tolerances to achieve the desired phase shift between magnetic field signals, which can lead to inaccurate target position information if not met.
Innovation Solution
A method and system that calculate and generate a phase shift between magnetic field signals independent of the target design and sensing element spacing, using digital pulse signals and phase shift calculation techniques to produce signals with a predetermined phase shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional magnetic encoders use fixed sensing element spacing and target pitch design, then the device structure is simple, but the phase shift accuracy depends on manufacturing tolerances and assembly precision
Solution Approach 1:
The patent implements dynamic phase shift adjustment by allowing the spacing between magnetic field sensing elements to be variable rather than fixed. The sensing element spacing can be adjusted during operation or calibration to achieve the desired 90-degree phase shift between quadrature signals, compensating for variations in target pitch and manufacturing tolerances. This dynamic adjustment capability enables the system to maintain accurate phase shift without requiring extremely tight manufacturing tolerances.
Solution Approach 2:
The patent changes the physical parameter of sensing element spacing to optimize phase shift accuracy. By varying the distance between sensing elements based on the specific target pitch and assembly conditions, the system can achieve the required 90-degree phase separation between quadrature signals. This parameter adjustment approach transforms a static design into an adaptive one that compensates for manufacturing variations.
2Measurement precision
If the phase shift between magnetic field signals is not precisely controlled, then the device complexity is reduced, but the target position information accuracy deteriorates
Solution Approach 1:
The patent implements a self-calibration mechanism where the system automatically adjusts the sensing element spacing or selects optimal sensing element combinations to achieve the desired phase shift. The encoder includes calibration circuitry that measures the actual phase shift between signals and automatically adjusts parameters to achieve 90-degree separation, eliminating the need for complex external calibration equipment or manual adjustment mechanisms.
Solution Approach 2:
The patent incorporates feedback mechanisms that monitor the phase shift between quadrature signals and adjust the sensing element spacing or signal processing parameters accordingly. The system measures the actual phase relationship between signals from different sensing elements and uses this feedback to optimize the phase shift, ensuring accurate target position detection without requiring overly complex pre-calibration procedures.
3Reliability
If multiple sensing elements with adjustable spacing are used, then the phase shift can be optimized, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent divides the sensing array into multiple discrete sensing elements that can be independently activated or selected. Instead of using a continuous array with fully adjustable spacing, the system employs a segmented approach where specific sensing elements are positioned at predetermined intervals. This segmentation allows the system to achieve phase shift optimization while maintaining a manageable device complexity, as only specific elements need to be precisely positioned rather than the entire array.
Solution Approach 2:
The patent designs the sensing element array to serve multiple functions: it can detect target position, determine rotation direction, and self-calibrate phase shift. The same array of sensing elements is used for both normal operation and calibration procedures, eliminating the need for separate calibration mechanisms. This multi-functionality approach maintains reliability while controlling device complexity by reusing the same hardware components for multiple purposes.
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 ensures accurate and reliable detection of target position information by achieving the desired phase shift between signals, regardless of manufacturing tolerances or design variations.
Implementation Method 1
a magnetic encoder can include a magnetic target and a sensor configured to detect and output position information (e.g., absolute angular position) of the target based on changes of the target's magnetic field
Implementation Method 2
the first and second magnetic field sensing elements may comprise Hall effect elements
Data Source
AI summary
According to one aspect of the disclosure, a method includes: receiving, by a magnetic field sensor, first and second magnetic field signals responsive to motion of a target; generating first and second digital pulse signals responsive to the first and second magnetic field signals, respectively; calculating a first time between a pulse edge of the first digital pulse signal and a next pulse edge of the second digital pulse signal; calculating a second time between two different pulse edges of the first digital pulse signal or two different pulse edges of the second digital pulse signal; calculating, using the calculated first and second times, a phase shift between the first and second magnetic field signals; and generating, using the calculated phase shift, a third magnetic field signal having a predetermined phase shift from the first magnetic field signal or from the first magnetic field signal.