Rotation Angle Detection Circuit for Motor Leakage Flux Compensation
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Solution Overview
Problem
In rotation angle detection systems, temperature changes and leakage magnetic flux from motor field windings cause errors in the output signal of magnetic sensors, leading to rotation angle errors.
Innovation Solution
A rotation angle detection apparatus that includes a magnet, a magnetic sensor, a magnet magnetic flux detection circuit, a disturbance magnetic flux detection circuit, and a correction circuit. The correction circuit calculates and corrects the rotation angle error based on the detected magnet magnetic flux and disturbance magnetic flux, using temperature and current data to ensure accurate angle detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic sensor is provided at a distance from the magnet to detect rotation angle, then the basic detection function is achieved, but temperature changes cause magnet magnetic flux variations leading to rotation angle errors
Solution Approach 1:
The patent introduces a feedback mechanism where the detected magnet magnetic flux is fed back to the correction circuit. The correction circuit uses this feedback signal to calculate and apply a correction value to compensate for temperature-induced flux variations, thereby maintaining reliable rotation angle detection under temperature changes.
Solution Approach 2:
The patent compensates for temperature effects by detecting changes in magnet magnetic flux and using these parameter changes to calculate correction values. This allows the system to adapt to temperature variations by dynamically adjusting the detection results based on the measured flux changes.
2Power
If field windings are provided to the rotor core and current flows through them, then the motor generates magnetic field for operation, but leakage magnetic flux is generated that interferes with the magnetic sensor causing rotation angle errors
Solution Approach 1:
The patent segments the magnetic flux into two distinct components: magnet magnetic flux (useful signal) and leakage magnetic flux (interference). By using separate detection circuits for each component, the system can identify and compensate for the harmful leakage flux while maintaining the useful detection signal, thus reducing interference without sacrificing motor power.
Solution Approach 2:
The patent introduces an intermediary correction circuit that processes both the useful magnet magnetic flux signal and the harmful leakage magnetic flux signal. This intermediary circuit calculates the appropriate correction based on the detected leakage flux and applies it to the final detection result, effectively mediating between the motor's power generation function and the sensor's accurate detection function.
3Measurement precision
If correction circuits and additional detection circuits are added to compensate for magnetic flux variations and leakage, then rotation angle accuracy is improved, but device complexity increases
Solution Approach 1:
The correction circuit is designed to perform multiple functions: it detects magnet magnetic flux variations, detects leakage magnetic flux, calculates correction values, and applies corrections to the final detection result. This multi-functionality reduces the need for separate dedicated circuits for each compensation task, thereby improving precision while limiting the increase in overall device complexity.
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 prevents rotation angle errors by accurately distinguishing and correcting for changes in magnet magnetic flux and disturbance magnetic flux, ensuring reliable rotation angle detection even under varying temperature and current conditions.
Implementation Method 1
a magnet that is provided to a rotating shaft of a rotating body and rotates with the rotating shaft to generate magnetic flux
Implementation Method 2
a magnetic sensor that is provided at a distance from the magnet and detects a magnetic flux interlinked with the magnetic sensor
Data Source
AI summary
A rotation angle detection apparatus includes a magnet that is provided to a rotating shaft of a rotating body and rotates with the rotating shaft to generate magnetic flux and a magnetic sensor that is provided at a distance from the magnet and detects a magnetic flux interlinked with the magnetic sensor. The rotation angle detection apparatus has a magnet magnetic flux detection circuit that detects a magnet magnetic flux generated from the magnet, a disturbance magnetic flux detection circuit that detects a disturbance magnetic flux, which is a magnetic flux other than the magnet magnetic flux and is interlinked with the magnetic sensor, and a correction circuit that corrects a result of detection of the magnetic sensor based on a result of detection of the magnet magnetic flux detection circuit and a result of detection of the disturbance magnetic flux detection circuit.