Dual Winding Motor Rotation Detection Error Correction
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Solution Overview
Problem
Rotation angle detection devices are prone to errors and deviations during rotation calculations due to inaccuracies in threshold values, leading to unreliable number of rotations calculations, which can affect the accuracy of other calculations in electric power steering systems.
Innovation Solution
A rotation detection device with an electronic control unit (ECU) that includes a motor and a speed-reduction gear, utilizing a dual motor winding configuration with a 30-degree phase difference to optimize current supply and reduce torque ripple, noise, and vibration, while incorporating redundant systems for error detection and correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If rotation angle detection is performed using a single motor winding configuration, then the device complexity is reduced, but the measurement precision of rotation angle deteriorates due to errors and deviations in threshold values
Solution Approach 1:
The patent combines two motor windings with different phase angles (30 degrees apart) into a single motor structure. Both windings cooperate to drive the motor, and their combined output is used for rotation detection, thereby improving measurement precision while maintaining relatively simple device structure
Solution Approach 2:
The patent creates a redundant detection system by using two motor windings that generate similar but phase-shifted signals. This copying approach allows the system to detect and correct errors by comparing the two signals, improving rotation angle detection accuracy without significantly increasing device complexity
2Ease of manufacture
If the ECU and motor are integrated in separate packages, then the ease of manufacture is improved, but the volume of the overall system increases, making it difficult to install in restricted spaces
Solution Approach 1:
The patent merges the ECU and motor into a single integrated package, reducing the overall system volume and making it suitable for installation in restricted spaces. The integration maintains manufacturing feasibility by designing the package as a unified structure with standardized interfaces
Data Source
AI summary
An electric power steering apparatus has a rotation detection device that includes a sensor section that detects a rotation of a motor and outputs a mechanical angle and a count value, and a signal obtainer that obtains the mechanical angle and the count value from the sensor section. The rotation detection device also includes an absolute angle calculator that calculates an absolute angle based on the mechanical angle and the count value and a storage area for storing a reference value that is used for correcting calculation errors in the absolute angle.