Rotation Angle Detector Spill Magnetic Flux Correction
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Solution Overview
Problem
Conventional rotation angle detectors for electric machines face errors due to assembly inaccuracies and spill magnetic flux caused by electric currents, especially when conductive wires cannot be positioned symmetrically, leading to inaccurate detection of rotation angles.
Innovation Solution
A rotation angle detector system that includes a sensor part and a controller with a pre-correction angle calculator, a first corrector, and a second corrector. The pre-correction angle calculator calculates a mechanical angle based on detection values, while the first corrector corrects assembly errors using a first correction value, and the second corrector corrects errors due to spill magnetic flux using a second correction value, ensuring accurate angle detection regardless of component positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conductive wires are arranged point-symmetric to cancel spill magnetic flux, then detection accuracy is improved, but manufacturing complexity increases due to precise positioning requirements
Solution Approach 1:
The patent pre-calculates correction values for spill magnetic flux errors before actual operation. By storing correction data in advance and applying it during runtime, the system compensates for manufacturing imperfections without requiring precise symmetric wire arrangement, thus resolving the contradiction between manufacturing ease and detection accuracy
Solution Approach 2:
The patent changes the approach from geometric parameter precision (symmetric wire positioning) to computational parameter correction (applying correction values). By using calculation-based compensation instead of strict geometric arrangement, the system achieves high detection accuracy while simplifying manufacturing requirements
2Measurement precision
If assembly process errors occur in magnet and sensor positioning, then detection accuracy deteriorates, but re-assembling to correct errors increases time consumption
Solution Approach 1:
The patent performs preliminary error correction by pre-calculating correction values based on actual assembly positions. Instead of re-assembling components to eliminate errors, the system calculates correction data in advance and applies it computationally, thus maintaining detection accuracy without time-consuming reassembly
Solution Approach 2:
The patent replaces mechanical adjustment (re-assembling components to correct positioning errors) with computational correction (applying calculated correction values). This substitution eliminates the need for physical reassembly while maintaining detection accuracy, resolving the contradiction between precision and time consumption
3Ease of manufacture
If connection lines are positioned on the sensor mounting surface to simplify wiring, then ease of manufacture improves, but spill magnetic flux error increases
Solution Approach 1:
The patent converts the harmful spill magnetic flux effect into a correctable parameter by pre-calculating correction values that account for the specific wiring arrangement. Instead of avoiding the harmful effect through complex wire routing, the system accepts the simplified wiring configuration and compensates for the resulting magnetic flux errors computationally, thus transforming a manufacturing advantage into an acceptable detection accuracy
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 effectively corrects initial assembly errors and spill magnetic flux errors, enabling precise rotation angle detection even when symmetric positioning of conductive wires is not possible, thus improving the accuracy of rotation angle measurement.
Implementation Method 1
The sensor part senses a change of a magnetic field of a detectee that rotates with the shaft
Implementation Method 2
a spill magnetic flux that is generated by a supply of an electric current to the winding wire
Data Source
AI summary
A rotation angle detector has a rotation angle sensor and a microcomputer, where the sensor detects a change of a magnetic field of a magnet that rotates with a shaft. The microcomputer has a first corrector for correcting a pre-correction mechanical angle, based on a first correction value that corrects an error due to an assembly process for assembling the magnet and the sensor, and a second corrector for correcting the pre-correction mechanical angle based on a second correction value that corrects an error due to a spill magnetic flux that is generated by a supply of an electric current to a winding wire. In such configuration, the rotation angle detector may correct the error due to the spill magnetic flux, thereby enabling an accurate detection of a mechanical angle.