Steering Control Unit Vibration Compensation
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Solution Overview
Problem
The sensorless control of electric power steering systems can cause motor vibrations and synchronization loss due to fluctuations in the estimated electrical angle, affecting steering feel.
Innovation Solution
A steering control unit that adjusts the additional angle calculation to vary the amount of change in the estimated electrical angle, thereby controlling motor vibrations and synchronization loss, using a control circuit that calculates and accumulates additional angles based on voltage and steering torque to improve steering feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless control is used to eliminate rotation angle sensor, then device complexity is reduced, but measurement precision of electrical angle deteriorates causing motor vibration and synchronization loss
Solution Approach 1:
The patent introduces an intermediary calculation process that uses easily measurable quantities (terminal voltage, phase current, estimated electrical angle) to compute a compensation value that corrects the estimated electrical angle. This intermediary computation acts as a mediator between the sensorless control system and the required precision, eliminating the need for a rotation angle sensor while maintaining measurement accuracy through mathematical compensation.
Solution Approach 2:
The patent replaces the mechanical/physical rotation angle sensor with an electrical/computational system that estimates the electrical angle through mathematical calculations based on voltage and current measurements. By substituting the physical sensing mechanism with an electrical computation approach enhanced by compensation algorithms, the system reduces device complexity while maintaining the necessary measurement precision.
2Adaptability or versatility
If additional angle is accumulated to calculate estimated electrical angle, then adaptability of control is improved, but stability of electrical angle estimation deteriorates due to vibration components
Solution Approach 1:
The patent implements a feedback mechanism where the calculated electrical angle and its derivative are continuously monitored, and a compensation value is computed based on the relationship between these quantities. This feedback loop detects vibration components in the accumulated additional angle and actively compensates for them, maintaining stability while preserving the adaptability benefits of sensorless control.
Solution Approach 2:
The patent converts the harmful vibration components introduced by accumulating the additional angle into a beneficial compensation signal. By analyzing the relationship between the electrical angle and its derivative, the system identifies vibration patterns and generates compensating values that cancel out these harmful effects, transforming the stability problem into an opportunity for enhanced control accuracy.
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
This approach allows for flexible adjustment of steering feel by reducing motor vibrations and synchronization loss, enhancing the driver's steering experience by minimizing interference and drag during steering operations.
Implementation Method 1
an additional angle calculated on the basis of a voltage (a counter electromotive voltage) induced in the motor
Data Source
AI summary
Provided is a steering control unit for improving influence of fluctuations in an estimated electrical angle on steering feel. A steering control unit includes a microcomputer that performs sensorless control of the driving of a motor by using an estimated electrical angle estimated by calculation. The microcomputer calculates the estimated electrical angle from a value that is obtained by selectively accumulating a first additional angle or a second additional angle. The microcomputer adjusts a vibration component of fluctuations in the estimated electrical angle by varying the amount of change in the first additional angle and the second additional angle.