Dynamic Power Ratio Selection for EV Drivable Distance
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Solution Overview
Problem
Conventional drivable distance calculation devices for electric vehicles face issues in accuracy when the route is not set, leading to anxiety for drivers due to fluctuating estimates and increased risk of running out of electricity, especially when the battery capacity is low.
Innovation Solution
A drivable distance calculation device that calculates and stores multiple power consumption ratios based on different driving units, selecting the appropriate ratio based on the remaining battery capacity to provide a more accurate and stable estimate, reducing anxiety and the risk of running out of electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the drivable distance is estimated based on the battery consumption in the link at the time of estimation, then the instantaneous accuracy of the estimated drivable distance is high, but the estimated drivable distance can change considerably each time the vehicle travels to a different link
Solution Approach 1:
The system changes the parameter of power consumption ratio selection based on the remaining battery capacity. When remaining capacity is high, it uses power consumption ratios from longer time periods (lower frequency), providing stable estimates. When remaining capacity is low, it switches to power consumption ratios from shorter time periods (higher frequency), providing more accurate instantaneous estimates. This dynamic parameter adjustment resolves the contradiction between accuracy and stability.
Solution Approach 2:
The system dynamically adjusts the calculation method based on the remaining battery capacity threshold. It transitions from using historically averaged power consumption ratios to using more recent power consumption ratios as the battery depletes. This dynamic adaptation allows the system to maintain both stability during normal operation and accuracy during critical low-battery conditions.
2Stability of the object's composition
If the drivable distance is calculated based on the consumption of the battery which is indefinitely predicted from daily driving, then the drivable distance does not change significantly, but its problem in accuracy simply increases the risk of running out of electricity
Solution Approach 1:
The system changes the time period parameter for power consumption ratio calculation based on remaining battery capacity. For high remaining capacity, it uses longer time periods (e.g., several days) for averaging, ensuring stability. For low remaining capacity, it shortens the time period (e.g., recent hours or days), improving accuracy and reducing the risk of running out of electricity.
Solution Approach 2:
The system preliminarily calculates and stores power consumption ratios for multiple time periods in advance. When the vehicle operates, it can quickly switch between pre-calculated ratios based on remaining battery capacity, avoiding the need for real-time recalculation and ensuring both stability and accuracy are maintained.
3Device complexity
If a single power consumption ratio is used for drivable distance calculation, then the calculation is simple, but the accuracy deteriorates when the remaining battery capacity becomes small
Solution Approach 1:
The system segments the power consumption ratios into multiple groups based on different time periods (e.g., recent hour, recent day, recent week). Each segment serves a specific purpose: longer segments provide stability, while shorter segments provide accuracy. The system selects the appropriate segment based on remaining battery capacity, maintaining simplicity in operation while improving accuracy through structured segmentation.
Solution Approach 2:
The system creates a universal calculation framework that handles both high and low battery capacity scenarios using the same underlying structure. By storing multiple power consumption ratios with different time characteristics, the system can universally apply the appropriate ratio based on current conditions, rather than requiring separate calculation systems for different scenarios.
Data Source
AI summary
A drivable distance calculation device calculates a drivable distance that the vehicle equipped with the device can travel. The drivable distance calculation device includes a remaining battery capacity sensor which calculates a remaining capacity of a battery installed in the vehicle; and a arithmetic unit which calculates multiple power consumption ratios for different units of driving in accordance with variations in the remaining battery capacity calculated by the remaining battery capacity sensor and calculates the drivable distance based on the remaining battery capacity calculated by the remaining battery capacity sensor and a power consumption ratio selected from among the calculated multiple power consumption ratios.