Electric Power Steering Filter for Vibration Suppression
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Solution Overview
Problem
Existing electric power steering control systems face issues with torque ripple, noise, and vibrations, particularly in high-speed and high-torque regions, leading to reduced responsiveness and increased software complexity due to the use of multiple maps for d-axis current command value calculations.
Innovation Solution
An electric power steering control apparatus that includes a filter section between the motor rotation speed detecting section and the target d-axis current setting section, which subjects the motor rotation speed to filter processing to suppress vibrations and noise without limiting the d-axis current command value, using a smaller software configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the d-axis current command value is limited through software processing to suppress vibrations and noise, then the generation of noise and vibrations is reduced, but the responsiveness is deteriorated
Solution Approach 1:
A filter section is introduced as an intermediary component between the motor rotation speed detecting section and the target d-axis current setting section. This filter processes the rotation speed signal before it is used to determine the d-axis current command value, thereby suppressing vibrations and noise without directly limiting the current command value itself, thus maintaining responsiveness.
2Object-affected harmful factors
If multiple maps are prepared for calculating d-axis and q-axis current command values to handle different operating regions, then the suppression of vibrations and noise is improved, but the software scale of CPU is increased and the software becomes complicated
Solution Approach 1:
The invention extracts the vibration suppression function from the complex multi-map software structure and implements it through a dedicated filter section that processes the motor rotation speed signal. This separation allows the system to achieve vibration suppression with simpler software configuration, as the filter handles the problematic high-frequency components without requiring multiple separate calculation maps.
3Object-affected harmful factors
If field weakening control is performed in the high-torque region to reduce torque ripple, then the generation of noise and vibrations is suppressed, but the responsiveness is reduced due to the control limitations
Solution Approach 1:
The filter section dynamically processes the motor rotation speed signal based on the operating conditions, allowing the system to adaptively suppress torque ripple and vibrations while maintaining responsiveness. The filter characteristics can be adjusted according to the motor's operational state, enabling optimal performance across different torque and speed regions without the rigid limitations of traditional field weakening control.
Data Source
AI summary
In a CPU (10) for calculating a control amount of an electric power steering control apparatus including a motor for assisting a steering force of a steering wheel generated by a driver of a vehicle, a filter section (18) subjects a value of a motor rotation speed calculating section (17) for calculating an rotation speed of a motor (4) to filter processing, to thereby output the resultant value to a target d-axis current value setting section (11b). With this configuration, in a high-torque and high-motor-rotation speed region, responsiveness of a target d-axis current value with respect to the motor rotation speed is decreased, to thereby suppress vibrations and noise when the steering wheel is operated.