Motor Rotor Angle Correction Using Current-Based Magnetic Sensing
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Solution Overview
Problem
Conventional motor control systems using magneto resistive sensors struggle to accurately detect the rotational position of a rotor due to external magnetic field interference, positional shifts, and sensor characteristic variations, which limits the accuracy of rotor position detection.
Innovation Solution
A motor control device that includes a calculator to calculate angle information from a magnetic sensor output and a corrector to correct this information using a function involving motor current, power source current, and mechanical angle, with a shielding portion to reduce external magnetic field influence, improving detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If a magneto resistive sensor is used to detect rotor position, then the detection capability is improved, but the accuracy is reduced due to external magnetic field interference and sensor variations
Solution Approach 1:
A correction value is introduced as an intermediary element to mediate between the magnetic sensor output and the final rotor position calculation. The correction value compensates for errors caused by external magnetic fields and sensor variations, thereby improving measurement precision while maintaining detection capability
Solution Approach 2:
The system implements feedback by calculating a correction value based on the relationship between magnetic sensor outputs and rotor position, then applying this correction back to the detection results. This closed-loop approach continuously improves accuracy by eliminating systematic errors
2Measurement precision
If correction methods are applied to improve accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system performs self-correction by automatically calculating and applying correction values based on its own sensor outputs and pre-stored correction data. This self-service mechanism improves precision without requiring external intervention or complex additional hardware
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 solution effectively enhances the detection accuracy of the rotor's rotational position by correcting electrical angle errors using the correction amount expressed by the function, particularly useful in applications like vehicle steering systems where precise position detection is critical.
Implementation Method 1
a magnetic sensor axially opposing the sensor magnet across a gap
Implementation Method 2
a shielding portion that shields a magnetic flux
Implementation Method 3
The magnetic sensor is a sensor that includes a magnetoresistance effect element and outputs signals of two systems out of phase with each other by 180°
Data Source
AI summary
A motor control device that controls a motor includes a calculator to calculate angle information related to a rotation angle of a rotor of the motor based on an output from a magnetic sensor, and a corrector to correct the angle information calculated by the calculator. The magnetic sensor is a sensor that includes a magnetoresistance effect element and outputs signals of two systems out of phase with each other by 180°. The corrector corrects the angle information using a correction amount expressed by a function including a current value of a motor current supplied to a stator of the motor and a phase angle of the motor current, a current value of a power source current supplied to the motor control device, and a mechanical angle of the rotor calculated based on an output from the magnetic sensor.