Battery Residual Capacity Display Stabilization
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Solution Overview
Problem
Existing methods for displaying the residual capacity of a secondary battery in motor-driven vehicles often result in an unnatural and uncomfortable underestimation of battery capacity due to polarization effects when power supply is restarted, leading to inaccurate readings.
Innovation Solution
A method and device that calculate and display the residual capacity of a secondary battery by using both open-circuit voltage and integrated charging/discharging current values, with error correction and polarization stabilization time considerations, to provide a more accurate and stable reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the residual capacity is calculated based on open-circuit voltage after power supply stops, then the measurement precision is improved, but the reliability deteriorates when power is restarted due to polarization effects
Solution Approach 1:
The system stores the residual capacity value calculated at the time of power supply stop in advance. When power is restarted, this pre-stored value is displayed instead of calculating a new value that would be affected by polarization, thus preventing inaccurate readings.
Solution Approach 2:
A storage unit acts as an intermediary to preserve the accurate residual capacity value obtained before polarization occurs. This stored value serves as a reference during power restart, bridging the gap between accurate measurement and reliable display.
2Productivity
If the residual capacity is displayed immediately after power restart, then the productivity is improved, but the measurement precision deteriorates due to polarization
Solution Approach 1:
The residual capacity value is calculated and stored in advance during normal operation. When power restart occurs, this pre-calculated value is immediately displayed without waiting for polarization to stabilize, thus maintaining fast response while ensuring accuracy.
3Adaptability or versatility
If the residual capacity fluctuates during power restart, then the adaptability is improved, but the stability deteriorates causing occupant discomfort
Solution Approach 1:
The system prepares and stores the accurate residual capacity value before power stop. Upon restart, this stable pre-stored value is displayed immediately, avoiding the instability and fluctuations that would otherwise occur during the polarization period.
Solution Approach 2:
The system monitors power supply state and automatically switches between displaying the stored pre-stop value during restart and normal real-time values during operation. This feedback mechanism ensures stable display by selecting the most appropriate value based on operational conditions.
Data Source
AI summary
A method of displaying a residual capacity of a secondary battery causes a computer of a display device to calculate a residual capacity of a secondary battery that stores electric power for driving a motor-driven vehicle based on an estimated value of an open-circuit voltage of the secondary battery storing the residual capacity calculated at the time of stopping of supply of electric power of the secondary battery and displaying the residual capacity at the time of stopping of supply of electric power on a display at the time of starting of supply of electric power of the secondary battery and subsequently displaying the residual capacity of the secondary battery on the display within a range with an upper limit value and a lower limit value with respect to the residual capacity at the time of stopping of supply of electric power.