Electric Power Steering Control Apparatus Phase Compensation
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Solution Overview
Problem
Conventional electric power steering systems face challenges in achieving accurate ripple accuracy of torque and velocity, generating abnormal noises, and causing uncomfortable steering due to non-identical resistance values between phases of a brushless DC motor and the control unit, which limits the ability to arbitrarily adjust dynamic characteristics.
Innovation Solution
The control apparatus compensates each-phase characteristics of the motor and control unit by arranging filters at each pathway, converting these characteristics into desired values, allowing for improved ripple accuracy, reduced noise, and customizable transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control adjusts voltage supplied to the motor to achieve accurate assist torque, then control precision is improved, but torque ripple and velocity ripple occur due to non-identical resistance values between phases
Solution Approach 1:
The patent changes the electrical parameters (resistance and inductance) of each phase by introducing filters with specific L/R ratios that match the motor's phase characteristics. This parameter adjustment compensates for the non-identical resistance values between phases, eliminating torque ripple while maintaining accurate assist torque control.
Solution Approach 2:
The patent introduces filters as intermediary components between the PWM control unit and the motor phases. These filters act as mediators that smooth out the current variations caused by unequal phase resistances, thereby reducing torque ripple without affecting the overall control accuracy.
2Measurement precision
If feedback control adjusts voltage supplied to the motor to achieve accurate assist torque, then control precision is improved, but abnormal noises are generated due to torque ripple
Solution Approach 1:
By adjusting the electrical parameters of each phase through filters with matched L/R ratios, the patent eliminates the root cause of abnormal noises (torque ripple), thereby maintaining accurate control while removing the harmful noise effect.
Solution Approach 2:
The patent converts the harmful effect of unequal phase resistances into a benefit by deliberately designing filters with specific L/R ratios that match the motor characteristics. This transformation eliminates torque ripple and abnormal noises while preserving control precision.
3Device complexity
If conventional control without phase-specific filters is used, then device complexity is reduced, but ripple accuracy of torque and velocity deteriorates
Solution Approach 1:
The patent applies local quality by introducing filters only where needed - specifically in phases with non-identical resistance values. Each filter is designed with L/R ratios matching the specific phase characteristics, providing localized compensation that improves torque ripple accuracy without unnecessarily complicating the entire control system.
4Device complexity
If conventional control without phase-specific filters is used, then device complexity is reduced, but abnormal noises and uncomfortable steering feel are generated
Solution Approach 1:
The patent applies local quality by introducing filters only where needed - specifically in phases with non-identical resistance values. Each filter is designed with L/R ratios matching the specific phase characteristics, providing localized compensation that eliminates abnormal noises and uncomfortable steering feel without unnecessarily complicating the entire control system.
Data Source
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AI summary
[Problem] An object of the present invention is to provide a control apparatus for an electric power steering apparatus that improves ripple accuracy of a torque, a velocity and so on, does not generate abnormal noises and does not generate an uncomfortable feeling with respect to a steering by compensating each-phase characteristics of a motor and the control apparatus and converting into a desired characteristic, and at the same time conforming each-phase characteristics. [Means for solving the problem] The present invention is a control apparatus for an electric power steering apparatus that calculates a steering assist torque command value based on a steering torque generated in a steering shaft and a velocity, calculates each-phase current command values from the steering assist torque command value, and controls a motor that provides a steering mechanism with a steering assist torque based on current control values calculated from the each-phase current command values and each-phase current values of the motor, comprising: arranging filters having a characteristic that compensates each-phase characteristics of the motor and the control apparatus at each pathway, and conforming the each-phase characteristics of the motor and the control apparatus, and at the same time, making the each-phase characteristics of the motor and the control apparatus becoming a desired characteristic.