Redundant Electric Power Steering Control Units
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric power steering apparatus with redundant control systems face challenges in cost, mountability, and inconsistent motor control when an abnormality occurs, as they may not adapt control strategies based on the specific nature of the abnormality, potentially leading to insufficient or unnecessary motor drive continuation.
Innovation Solution
The apparatus features two independent control units with power supply, input, inverter, drive, and CPU circuits, where each CPU can detect abnormalities and adjust control commands based on input information from both units, allowing for adaptive control strategies to maintain optimal motor operation even when one unit experiences an issue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant control system with two sets of control unit components is adopted, then reliability is improved, but device complexity and cost increase
Solution Approach 1:
The control system is segmented into two independent control units (first control unit 1a and second control unit 1b), each capable of independently controlling the motor. This segmentation allows the system to maintain reliability through redundancy while managing complexity by dividing functions into modular, independent units with separate power supply circuits, input circuits, inverter circuits, drive circuits, and CPUs.
Solution Approach 2:
The system changes the operational parameters of the control units based on abnormality detection. When an abnormality is detected in one control unit, the system transitions from dual-unit operation to single-unit operation, adjusting the control parameters and power distribution dynamically. This allows the redundant system to adapt its complexity level based on operational needs, maintaining reliability while reducing unnecessary complexity when one unit is already failed.
2Reliability
If a redundant control system with two sets of control unit components is adopted, then reliability is improved, but cost increases
Solution Approach 1:
The control system is divided into two independent control units (first control unit 1a and second control unit 1b), each with complete functional components including power supply circuit, input circuit, inverter circuit, drive circuit, and CPU. This segmentation enables standardized manufacturing of modular units that can be produced independently and assembled, potentially reducing overall manufacturing cost while maintaining reliability through redundancy.
Solution Approach 2:
The system dynamically adjusts its operational parameters based on abnormality detection, transitioning between full dual-unit operation and single-unit operation. This parameter change allows the system to maintain reliability when needed while reducing operational cost and resource consumption when one unit is already failed, optimizing the cost-reliability tradeoff.
3Reliability
If motor control is continued using only the normal control system when an abnormality occurs, then reliability is maintained, but motor drive may be insufficient
Solution Approach 1:
The system implements feedback through abnormality detection functionality in each CPU that monitors the status of its own control unit and the other control unit. When an abnormality is detected, the feedback mechanism triggers a transition to single-unit operation, allowing the system to maintain reliability while being aware of the reduced capacity. The feedback loop enables continuous monitoring and adaptive response to maintain optimal motor drive performance under varying operational conditions.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Each of two control units configured in a double system has a CPU, each CPU obtains input information of the control unit of the other CPU, each CPU independently drives an electric motor at a normal time, and continues the motor drive by utilizing the input information of the control unit of the other CPU when an abnormality relating to input information is detected, and when an abnormality relating to information other than input information is detected, the control unit in which the abnormality has occurred controls the electric motor so as to continue the drive or stop the drive in accordance with details of the abnormality, and the control unit on the normal side controls the electric motor so as to at least continue the drive as normal.