Backup Power Control With SOC Warning Before Vehicle Stop
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Solution Overview
Problem
Existing power supply control systems for autonomous vehicles fail to prevent confusion for drivers when retreat travel is forcibly ended due to backup power supply failure, and may lead to irreversible depletion of the backup power supply.
Innovation Solution
A power supply control device with a controller that manages the connection between a main and backup power system, providing fail-safe control, advance notice, and power stop processes to prevent backup power supply failure, ensuring safe retreat travel without confusing the driver.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply is interrupted to forcibly end retreat travel when SOC falls below the lower limit, then the backup power supply is protected from over-discharge failure, but the driver becomes confused
Solution Approach 1:
The system performs preliminary action by notifying the driver in advance before forcibly ending retreat travel. When SOC reaches the first threshold (higher than the lower limit), the system activates notification devices to inform the driver before the actual power interruption occurs, allowing the driver to prepare mentally for the upcoming stop.
Solution Approach 2:
The system applies beforehand cushioning by creating a buffer period between the notification point (first threshold) and the actual stop point (second threshold/lower limit). This cushioning period allows the driver to react to the notification before the forced stop occurs, reducing confusion and improving the overall user experience.
2Duration of action of moving object
If the backup power supply is used without limitation during fail-operational control, then retreat travel can be maintained, but the backup power supply may fail due to over-discharge
Solution Approach 1:
The system implements feedback by continuously monitoring the SOC of the backup power supply and comparing it against predetermined thresholds. Based on the SOC level, the system automatically adjusts its behavior: notifying the driver when SOC reaches the first threshold and forcibly stopping retreat travel when SOC reaches the second threshold, thus preventing over-discharge while maintaining retreat travel as long as possible.
Solution Approach 2:
The system changes operational parameters based on SOC levels. It transitions from normal retreat travel operation to notification mode when SOC reaches the first threshold, and then to forced stop mode when SOC reaches the second threshold. This parameter-based control allows the system to maximize retreat travel duration while protecting the backup power supply.
3Reliability
If the connector is interrupted to supply power from backup power supply, then fail-safe control is achieved, but the backup power supply may be depleted below safety limit
Solution Approach 1:
The system takes preliminary action by monitoring SOC and triggering notification and stop procedures before the backup power supply is depleted below the safety limit. This prevents irreversible damage to the backup power supply while maintaining fail-safe operation.
Solution Approach 2:
The system uses feedback control by continuously monitoring SOC and adjusting retreat travel operation accordingly. The feedback mechanism ensures that the backup power supply is used efficiently and stopped before depletion, maintaining both fail-safe reliability and preserving backup power availability.
Data Source
AI summary
A controller of a power supply control is configured to: in response to a failure of a main power supply being detected, execute a fail-safe control in which a connector is interrupted and electric power from a backup power supply is supplied to a second load; in response to a state value indicating a charging state of the backup power supply decreasing to a first threshold during the fail-safe control, execute an advance notice process for giving a user advance notice that a vehicle will be stopped; and in response to the state value decreasing to a second threshold which is smaller than the first threshold and which indicates a safety limit of the backup power supply, execute a power supply stop process for stopping supply of the electric power from the backup power supply.