Lithium Battery Contactor Delay Control for Utility Vehicle Fault Handling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electric vehicles experience sudden loss of speed control and unpleasant braking when a contactor immediately disconnects the lithium-battery pack upon detecting an unsafe condition, leading to abrupt stops and discomfort for the driver.
Innovation Solution
Implementing a control system with a predefined time delay to react to fault conditions, allowing for remedial operations to address or slow down the vehicle before disconnecting the lithium battery, thereby providing an opportunity to correct the fault and enabling a more gradual stop if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contactor immediately opens upon detection of an unsafe condition, then the safety of the lithium-battery system is improved, but the vehicle experiences sudden loss of speed control and abrupt stops causing driver discomfort
Solution Approach 1:
The control circuitry initiates remedial operations before the contactor opens to address the fault condition. This preliminary action allows the system to attempt correction of the fault (such as adjusting motor controller parameters or activating backup systems) while maintaining power connection, thereby preserving vehicle controllability and driver comfort while still addressing the safety concern.
Solution Approach 2:
The system transitions from a static immediate-disconnection response to a dynamic multi-stage response. The contactor operation is made conditional based on the outcome of remedial operations. If the fault is cleared within the predefined time period, the contactor remains closed; if not, the contactor opens. This dynamic approach optimizes both safety and operational continuity.
2Reliability
If the contactor immediately opens upon detection of a fault condition, then the fault condition is isolated quickly, but the vehicle cannot be slowed down gradually and must stop abruptly
Solution Approach 1:
The control circuitry performs remedial operations that may include gradual speed reduction maneuvers before the contactor opens. This preliminary action allows the vehicle to slow down in a controlled manner using the motor controller or regenerative braking, rather than experiencing an abrupt stop, thereby maintaining speed control during the fault isolation process.
3Ease of operation
If the contactor remains closed indefinitely after fault detection, then the vehicle maintains full operational control, but the fault condition persists potentially causing safety issues
Solution Approach 1:
The system implements a time-based dynamic decision process where the contactor state depends on whether the fault condition persists beyond a predefined time period. During this period, the vehicle maintains full operational control for safety and comfort reasons. If the fault clears within the time period, the contactor remains closed. If the fault persists, the contactor opens to isolate the fault, ensuring safety is ultimately protected.
Solution Approach 2:
The control circuitry continuously monitors the fault condition during the predefined time period and uses this feedback to determine the final contactor state. This feedback mechanism allows the system to adapt its response based on whether the remedial operations successfully cleared the fault, optimizing both operational control and safety assurance.
Data Source
AI summary
A control system for handling a fault condition on a utility vehicle includes a lithium battery, a contactor configured to control electrical access to the lithium battery, and control circuitry coupled with the lithium battery and the contactor. The control circuitry is configured to detect, while the contactor is closed to provide a set of loads of the utility vehicle with electrical access to the lithium battery, onset of a fault condition. The control circuitry is further configured to perform, in response to detection of the onset of the fault condition, a set of remedial operations to address the fault condition. The control circuitry is further configured to perform, after a predefined amount of time has elapsed since the onset of the fault condition, a subsequent operation which opens the contactor if the fault condition remains and maintains closure of the contactor if the fault condition does not remain.