Rotation Angle Detection Device Using Magnetic Sensor Correction
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Solution Overview
Problem
Existing rotation angle detection devices for automotive drive motors, such as those used in electric power steering, face inaccuracies due to errors in magnetic sensor positions and eccentricity of the rotating body, leading to unreliable rotor angle measurements.
Innovation Solution
A rotation angle detection device with a rotating body featuring magnetic tracks with varying numbers of magnetic pole pairs, paired with magnetic sensors that output sine and cosine signals, utilizes correction calculations based on preset magnetic sensor correction information to improve signal accuracy, enabling precise phase detection and absolute angle calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If magnetic sensors are used to detect rotor angle, then rotation angle detection is enabled, but detection accuracy deteriorates due to sensor position errors and eccentricity
Solution Approach 1:
The patent applies preliminary action by pre-calculating correction values for sine and cosine signals based on known sensor position errors and eccentricity characteristics. These correction values are stored in advance and applied during operation to compensate for systematic errors before they affect measurement accuracy, thereby resolving the contradiction between enabling detection and maintaining precision.
2Measurement precision
If correction calculations are performed on sine and cosine signals, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies parameter changes by modifying the sine and cosine signal parameters through correction calculations. Specifically, it adjusts the amplitude and phase parameters of these signals using pre-determined correction values, thereby improving measurement precision while keeping the complexity manageable through systematic parameter adjustment rather than complex structural changes.
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 device enhances the detection accuracy of the absolute angle by correcting sine and cosine signals in real-time, reducing errors caused by sensor position inaccuracies and eccentricity, thereby providing reliable rotor angle information for improved motor control.
Implementation Method 1
a plurality of magnetic sensors each configured to detect a magnetic field of a corresponding one of the magnetic tracks and output a sine signal and a cosine signal
Data Source
AI summary
A rotation angle detection device includes: a rotating body having magnetic tracks on which magnetic pole pairs are arranged at even intervals in concentric ring shapes; magnetic sensors each configured to detect a magnetic field of a corresponding one of the magnetic tracks and output a sine signal and a cosine signal; storage configured to store magnetic sensor correction information; a correction calculator configured to correct the sine signal and the cosine signal based on the magnetic sensor correction information; a phase detector configured to calculate a phase of the corrected sine signal and the corrected cosine signal; a phase difference detector configured to calculate a phase difference between a plurality of the phases; and an angle calculator configured to convert the phase difference into an absolute angle.