Motor Control Unit for Electric Power Steering with Dynamic Inductance Adjustment
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Solution Overview
Problem
Existing electric power steering apparatuses with multi-system motor windings experience noisy sounds and vibrations when switching systems, leading to physical discomfort for drivers due to changes in current response characteristics during failures, such as open-circuit failures in motor windings or inverters.
Innovation Solution
A motor control unit with a 3-phase current feedback system that adjusts parameters of the current control section based on the number of driving systems, specifically using motor inductance parameters to perform current feedback control for 3-phases across two systems, ensuring smooth transitions and minimizing noise and vibration by optimizing current response characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If system switching is performed in multi-system motor windings during failure, then system reliability is improved, but noisy sound and vibration are generated due to changes in current response characteristics
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting current control parameters (inductance values L1, L2, L3) based on the operating mode (normal or failure mode). When switching from normal to failure mode, the controller changes the inductance parameters to match the actual motor winding configuration, thereby maintaining consistent current response characteristics and eliminating noise and vibration during system switching.
2Manufacturing precision
If current control parameters are changed during system switching, then current response characteristics are optimized, but noisy sound and vibration occur due to abrupt parameter transitions
Solution Approach 1:
The patent implements preliminary action by pre-calculating and storing the appropriate current control parameters (inductance values) for both normal and failure modes before switching occurs. When a failure is detected, the controller immediately switches to the pre-determined parameters for failure mode, avoiding abrupt transitions and the associated noise and vibration.
3Adaptability or versatility
If multi-system motor windings are used for continued operation during failure, then system availability is improved, but complex control switching is required which may cause vibration and noise
Solution Approach 1:
The patent applies universality by designing a unified current control section that can operate in both normal and failure modes using the same hardware infrastructure. The control section universally handles different operating conditions by switching parameters rather than requiring separate control circuits, thereby maintaining system availability while minimizing complexity and avoiding vibration and noise from complex switching mechanisms.
Data Source
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AI summary
[Problem] An object of the present invention is to provide a motor control unit that does not make an occurrence of a noisy sound and a vibration and does not give a steering discomfort by changing parameters of a current feedback control section even if an electric characteristic of the motor varies with a system-switching due to a failure occurrence, and to an electric power steering apparatus using the same and a vehicle. [Means for solving the problem] The present invention relates to a motor control unit that controls a motor having multi-system motor windings by means of a 3-phase current feedback system provided with a current control section through a motor driving circuit of each winding system, having: a function that changes by switching parameters of the current control section corresponding to a driving system number of the multi-system motor windings.