EPS Redundancy Circuit for ECU Fault Detection and Smooth Motor Handover
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Solution Overview
Problem
Conventional electric power steering systems fail to detect abnormalities in both sensors and the electronic control unit, leading to instability and potential control blanks, especially in autonomous vehicles.
Innovation Solution
A redundancy circuit with multiple electronic control units that cross-check for breakdowns and adjust control ratios, using a selection control unit to determine motor control signals, ensuring continuous operation by switching control authority gradually between units.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single electronic control unit is used in the EPS system, then the device complexity is low, but the reliability is insufficient because any breakdown causes complete loss of steering assistance
Solution Approach 1:
The single electronic control unit is segmented into multiple independent control units (first control unit and second control unit), each capable of independently calculating torque and steering angle and generating control signals. This segmentation allows the system to maintain functionality even when one unit fails, thereby improving reliability while keeping individual unit complexity manageable.
Solution Approach 2:
The system implements a breakdown determination unit that proactively monitors the health status of control units before complete failure occurs. By detecting abnormalities in advance and switching to a standby control unit, the system cushions against total failure and maintains continuous steering assistance, improving reliability without requiring complex real-time failover mechanisms.
2Reliability
If multiple sensors are provided for redundancy, then the reliability improves, but the device complexity increases due to additional sensors and synchronization check units
Solution Approach 1:
The patent merges the functions of multiple sensors into a single sensor that can detect both torque and steering angle information. This consolidation reduces the number of physical sensors required while maintaining the reliability benefits of redundant measurement capabilities through software-based cross-validation in the control units.
Solution Approach 2:
The control units perform self-diagnosis and mutual validation of sensor readings through breakdown determination units. Each control unit independently processes sensor data and cross-checks results with the other control unit, enabling the system to detect and compensate for sensor abnormalities without requiring external monitoring systems or complex synchronization mechanisms.
3Reliability
If breakdown determination is implemented, then the reliability improves, but the response time may be delayed due to additional detection and switching processes
Solution Approach 1:
The system maintains continuous operation by implementing parallel breakdown determination and control signal generation. While one control unit is being monitored for abnormalities, the other control unit continues to provide steering assistance without interruption. The switch between control units is seamless, ensuring continuous useful action and preventing control blanks that would delay response.
Solution Approach 2:
The breakdown determination unit continuously monitors control unit status in advance, maintaining a ready standby control unit before failure occurs. This preliminary preparation ensures that when a breakdown is detected, the system can immediately switch to the pre-prepared standby unit without delay, maintaining fast response times while improving reliability.
Data Source
AI summary
The present invention relates to a redundancy circuit of an electric power steering system, the redundancy circuit comprising: a plurality of electronic control units for checking whether a breakdown occurs by crossing each other, and adjusting a control ratio according to the occurrence of the breakdown; and a selection control unit for receiving an input of the control ratio and control amount information of the plurality of electronic control units to determine control amounts of each of motors provided in the same number as the plurality of electronic control units.