Steering Control Apparatus Phase-Difference Current Mode Switching
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Solution Overview
Problem
Conventional electric power steering systems face challenges in smoothly switching between automatic and manual steering modes, particularly in optimizing torque control and reducing noise and vibration, while also managing heat generation and sensor detection errors.
Innovation Solution
The steering control apparatus incorporates a control unit that generates control signals for a rotary electric machine, switching between manual and automatic steering modes by differentiating current control, using phase-difference current supply to reduce torque ripple, noise, and vibration, and optimizing heat management through integrated machine-electronics configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional torque control is used for mode switching, then the steering system can operate in both manual and automatic modes, but the switching between modes is not smooth and causes torque ripple
Solution Approach 1:
The patent applies periodic action by using phase-difference current supply where three-phase currents are supplied with specific phase differences to the rotary electric machine. This periodic current supply pattern reduces torque ripple during mode switching while maintaining smooth operation between manual and automatic steering modes.
Solution Approach 2:
The patent changes control parameters by differentiating current control modes between manual and automatic steering. By adjusting current supply parameters and phase differences based on the operating mode, the system achieves smooth mode switching while minimizing torque ripple and vibration.
2Power
If conventional current control is used, then the rotary electric machine can provide steering torque, but noise and vibration are increased
Solution Approach 1:
The patent reduces noise and vibration by implementing periodic phase-difference current supply to the rotary electric machine. The controlled phase differences create a smoother torque delivery pattern that minimizes mechanical vibrations and associated noise while maintaining required steering torque output.
Solution Approach 2:
The patent converts the potential harm of direct current supply into benefit by intentionally introducing controlled phase differences. This transforms what would be harmful torque ripple and vibration into a controlled periodic action that reduces overall noise and vibration while maintaining power output.
3Power
If high current is supplied to the rotary electric machine, then steering torque is improved, but heat generation increases
Solution Approach 1:
The patent manages heat generation by changing current control parameters based on operating mode. By optimizing current supply patterns with phase differences and adjusting current magnitudes according to steering requirements, the system maintains adequate steering torque while reducing excessive heat generation in the rotary electric machine.
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 solution enables smooth mode switching, reduces noise and vibration, and improves heat management, enhancing steering performance and driver comfort by optimizing current control and system integration.
Implementation Method 1
an electric power steering apparatus, which is provided with a rotary electric machine
Implementation Method 2
using phase-difference current supply to reduce torque ripple, noise, and vibration
Data Source
AI summary
Inverter circuits are provided for motor winding sets, respectively. Control units are provided for the motor winding sets to generate control signals related to driving of the inverter circuits and control currents flowing through the motor winding sets, respectively, thereby controlling driving of a motor. The control mode includes a manual steering mode for controlling the motor according to a steering operation on a steering wheel by a driver and an automatic steering mode for controlling the motor independently of the steering operation on the steering wheel by the driver. The control units are capable of switching the control modes and differentiate the current control according to the control mode. By making the current control different according to the control mode, it is possible to attain optimal characteristics which correspond to each control mode.