Redundant EPS Lock Control to Prevent Motor Locking
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In steer-by-wire (SBW) type electric power steering (EPS) systems with redundant control, motor locking occurs when one steering control circuit fails, leading to arbitrary steering wheel rotation and wheel movement, compromising vehicle stability.
Innovation Solution
A control device with a first and second steering controller, each with an inverter, locking circuit, and gate driver, where a normally operating controller sends a lock disable signal to deactivate the locking circuit of the faulty controller, ensuring continuous steering control by preventing motor locking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a locking circuit is activated in a steering control system, then motor restraint and vehicle stability are improved, but steering control flexibility and continuous operation during partial failures are worsened
Solution Approach 1:
The locking circuit's operational state is dynamically adjusted based on real-time monitoring of steering control circuits. When one circuit fails, the system transitions from a locked state to an unlocked state automatically, allowing continuous steering control while maintaining stability when both circuits are functional
Solution Approach 2:
The system continuously monitors the operational status of both steering control circuits and uses this feedback to control the locking circuit. The locking circuit is deactivated when a failure is detected in one circuit, and reactivated only when both circuits are fully operational, ensuring optimal balance between stability and control continuity
2Object-affected harmful factors
If motor locking is activated upon control circuit failure, then arbitrary steering wheel rotation is prevented, but continuous steering control capability is lost
Solution Approach 1:
The locking circuit is designed to be preemptively deactivated when a failure in one steering control circuit is detected, preventing the harmful effect of arbitrary steering rotation only when absolutely necessary (i.e., when both circuits are functional). This preliminary action maintains continuous steering control capability while providing safety when needed
3Reliability
If redundant control circuits are implemented, then system reliability is improved, but device complexity increases
Solution Approach 1:
The locking control functionality is merged into the existing redundant steering control circuit system, sharing monitoring resources and control logic. The locking circuit is controlled by the same failure detection mechanisms already present in the redundant system, eliminating the need for separate monitoring hardware and reducing overall system complexity
Data Source
AI summary
A control device for an electric power steering (EPS) system may include a first steering controller including a first inverter, a first locking circuit connected to the first inverter, and a first gate driver controlling driving of the first inverter, and a second steering controller including a second inverter, a second locking circuit connected to the second inverter, and a second gate driver controlling driving of the second inverter. If the first steering controller operates normally, the first steering controller may transmit a second lock disable signal for inactivating the second locking circuit, included in the first steering controller, to the second steering controller.