EV Battery Degradation Estimation Switching
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Solution Overview
Problem
Conventional electric vehicles provide low estimation accuracy of secondary battery degradation, leading to potential incorrect information for drivers.
Innovation Solution
An electric vehicle system with multiple estimation units (on-board, charging, and server-based) that estimate battery degradation using different methods, allowing the display control unit to switch between and display these estimates, along with options for digit precision, explanatory text, and accuracy display, all controllable by the driver, and notification to a server via wireless communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single estimation method is used for battery degradation, then the device complexity is low, but the measurement precision of degradation state is insufficient
Solution Approach 1:
The battery degradation estimation system is segmented into multiple independent estimation units (first estimation unit using Coulomb counting method, second estimation unit using open-circuit voltage method). Each unit independently estimates degradation using different methods, and the display control unit selects which estimation result to display based on battery state, thereby improving measurement precision without overwhelming complexity
Solution Approach 2:
The system changes the estimation method parameter based on battery state parameters (charge state, temperature). The display control unit determines which estimation result to display by evaluating battery parameters, switching between different estimation methods optimally suited for current battery conditions, thus improving accuracy while managing complexity through adaptive parameter selection
2Measurement precision
If multiple estimation methods are provided, then the measurement precision improves, but the ease of operation decreases due to multiple display options
Solution Approach 1:
The display control unit automatically determines and displays the appropriate estimation result based on battery state parameters without requiring manual selection by the driver. The system serves itself by autonomously selecting the most reliable estimation method based on current battery conditions (charge state, temperature), improving ease of operation while maintaining high measurement precision
Solution Approach 2:
The display content dynamically changes based on battery state. The display control unit continuously monitors battery parameters and automatically switches between displaying first estimation results (Coulomb counting) or second estimation results (open-circuit voltage method) depending on which method is more reliable under current conditions, providing adaptive, context-aware display without user intervention
3Loss of information
If only one estimation result is displayed, then the ease of operation is high, but the loss of information occurs due to inability to show accuracy variations
Solution Approach 1:
The system performs preliminary evaluation of estimation reliability by the display control unit before displaying results. The control unit pre-determines which estimation method provides more accurate results based on battery state parameters, and automatically displays the more reliable estimation along with appropriate accuracy indicators, preventing information loss about estimation quality while maintaining display simplicity through automated selection
Data Source
AI summary
To prevent a driver from being given incorrect information regarding the estimation of a degradation state of a secondary battery. An electric vehicle (1) running by driving a motor by electric power of a secondary battery (2), includes a first estimation unit (10A) that estimates a degradation state of the secondary battery (2), a second estimation unit (10B) that estimates the degradation state of the secondary battery (2) by a method different from that of the first estimation unit (10A), a display unit (7) that displays estimation results by the first and second estimation units (10A, 10B), and a display control unit (8) that controls display of the display unit (7). The display control unit (8) switches between and displays the estimation result by the first estimation unit (10A) and the estimation result by the second estimation unit (10B) on the display unit (7).