Battery Charge Control via Temperature Rise Rate Monitoring
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Solution Overview
Problem
Existing charge control systems fail to appropriately limit charging and promptly stop charging when an abnormality occurs in the charging system, particularly under low-temperature conditions, as they rely on battery temperature thresholds that may not accurately reflect overcharging states.
Innovation Solution
A charge control apparatus and method that dynamically adjust the upper limit of charging power based on temperature rise rates, using multiple temperature sensors to determine overcharging and trigger power reductions, and stop charging when an overcharging state is confirmed, with threshold values adjusted according to temperature and current integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge control is based on battery temperature threshold, then charging can be limited when temperature exceeds allowable value, but charging cannot be appropriately limited under low-temperature environment when abnormality occurs
Solution Approach 1:
The patent applies dynamics by making the upper limit value of charging power dynamically adjustable based on temperature rise rate rather than using a fixed temperature threshold. The control device continuously monitors the temperature rise rate and adjusts the charging power limit in real-time, enabling the system to adapt to varying thermal conditions and detect abnormalities even in low-temperature environments where static thresholds fail.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the temperature rise rate of the battery and using this information to adjust the charging power limit. The detection device measures temperature changes, the control device calculates the rise rate, and this feedback loop enables the system to respond to abnormal heating patterns regardless of the ambient temperature, solving the limitation of threshold-based control in low-temperature conditions.
2Reliability
If upper limit value of charging power is lowered based on temperature rise rate, then charging can be appropriately limited, but charging cannot be stopped promptly if abnormality detection is delayed
Solution Approach 1:
The patent applies preliminary action by first lowering the upper limit value of charging power when the temperature rise rate exceeds the threshold, before fully determining an overcharging state. This intermediate protective action reduces charging power early in the abnormal heating process, buying time for the system to confirm overcharging conditions while already mitigating thermal runaway risk, thus preventing both delayed response and false alarms.
Solution Approach 2:
The patent implements beforehand cushioning by reducing charging power as a preventive measure when abnormal temperature rise is detected, creating a buffer zone before full overcharging occurs. This intermediate power reduction acts as a cushion that slows down the heating process, allowing the system to confirm overcharging status while already having reduced the rate of temperature increase, thus preventing catastrophic failure.
3Device complexity
If temperature threshold is used for overcharging detection, then simple control is achieved, but detection precision is insufficient under varying temperature conditions
Solution Approach 1:
The patent applies parameter changes by shifting from using absolute temperature as the detection parameter to using temperature rise rate as the critical parameter. This change in detection parameter allows the system to identify abnormal heating patterns regardless of ambient temperature conditions, significantly improving detection precision while maintaining relatively simple control logic through continuous rate monitoring rather than complex threshold adjustments.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively limits charging power and promptly stops charging in case of overcharging, preventing temperature rises and ensuring safe operation even under low-temperature conditions, thereby addressing the limitations of existing systems.
Implementation Method 1
a detection device for detecting a temperature of the electrical storage device
Implementation Method 2
when the temperature of the electrical storage device rises due to charging of the electrical storage device
Data Source
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AI summary
ECU executes program including the steps of turning on an overcharge tentative determination flag (S112) and performing limitation on charging power upper limit value Win (S114) in a case where a rising rate ΔTB is higher than or equal to threshold value ΔTB(0), and a current average value IBs is a value on a side of charging (YES in S108), and the steps of turning off the overcharge tentative determination flag (S116) and cancelling the limitation on charging power upper limit value Win (S118) in a case where the rising rate ΔTB is lower than or equal to a threshold value ΔTB(1), or the current average value IBs exhibits a value on a side of discharging (YES in S110), and the steps of determining that a battery (70) is in the overcharging state (S124) and executing a fail safe process (S126) in a case where the integrated value IBs of current from a time point at which the overcharge tentative determination flag is switched from an off-state to an on-state becomes greater than or equal to a threshold value IBs(0) (YES in S 120, YES in S 122).