Battery Thermal State Compensation Using Aging Offset
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Solution Overview
Problem
Lithium-based batteries in electronic systems face challenges in accurately monitoring thermal states due to poor thermal conductivity of modern battery housings, leading to inaccurate detection of hot spots and inadequate thermal management, especially as batteries age and internal resistance increases.
Innovation Solution
A method and apparatus that sense temperature proximate to battery cells, calculate a temperature offset value based on aging factors such as charge-discharge cycles or heat generation, and adjust the sensed temperature to provide a more accurate thermal state assessment, triggering thermal management events if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a thermistor is positioned on a PCB adjacent to battery cells to monitor temperature, then the thermal protection circuit can detect temperature changes, but the poor thermal conductivity of modern battery housings causes hot spots to be located at substantial distances from the thermistor, resulting in inaccurate temperature sensing
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the temperature offset value based on battery aging parameters (charge-discharge cycles, heat generation). As the battery ages and internal resistance increases, the system modifies the offset parameter to compensate for increased self-heating, thereby maintaining accurate temperature measurement despite the fixed physical distance between the thermistor and hot spot.
2Reliability
If the internal resistance of lithium-based batteries increases with age, then the voltage at the terminals drops under load and maximum current draw is reduced, but the increased resistance causes the battery cell to generate more heat during operation, leading to inadequate thermal management
Solution Approach 1:
The patent implements feedback by continuously monitoring battery parameters (charge-discharge cycles, heat generation) and using this information to dynamically adjust the temperature offset value. The system feeds back the aging state information to modify the thermal management strategy, increasing the offset compensation as the battery ages and generates more heat, thereby maintaining reliable thermal management throughout the battery's lifecycle.
Solution Approach 2:
The patent applies dynamics by making the temperature offset value dynamic rather than static. The offset value changes based on the battery's aging state and operational conditions, allowing the thermal management system to adapt to the increasing heat generation that occurs as internal resistance increases with age.
3Measurement precision
If fixed temperature offsets are used in thermal protection systems to account for poor thermal conductivity, then some level of temperature compensation is provided, but the offsets do not account for battery aging and cannot accurately reflect the increase in internal resistance and resultant heating
Solution Approach 1:
The patent transforms the static fixed offset approach into a dynamic adaptive system. The temperature offset value is no longer fixed but dynamically adjusted based on battery aging parameters such as charge-discharge cycles and heat generation. This allows the system to adapt to changing battery characteristics over time, maintaining accurate temperature compensation throughout the battery's operational life.
Solution Approach 2:
The patent implements self-service by having the battery's own operational data (charge-discharge cycles, heat generation) serve as the basis for adjusting the temperature offset. The system uses the battery's self-generated information about its aging state to automatically modify the compensation parameter, eliminating the need for external calibration or manual adjustment.
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
This approach provides a more accurate assessment of the thermal state of lithium-based batteries, enhancing safety and reducing the risk of overheating by accounting for battery aging, thereby preventing premature degradation and potential safety hazards.
Implementation Method 1
The thermistor changes its resistive properties in response to changes in temperature, thereby allowing a voltage applied across the thermistor to change as the temperature changes.
Implementation Method 2
the increased resistance associated with aging causes the battery cell to generate more heat during operation for a consistent amount of supplied current
Data Source
AI summary
An electronic system, or its battery thermal management system, determines a thermal state of a battery used in the electronic system. A temperature at a position proximate the battery's cell is sensed during operation of the electronic system to produce a sensed value. Additionally, a temperature offset value is determined based on an aging factor for the battery. The sensed value is then adjusted based on the offset value to produce an adjusted value representative of the thermal state of the battery. According to one embodiment, a relationship between temperature offset value and battery aging factor is prestored in a memory of the electronic system. In such a case, the offset value may be retrieved from memory periodically or in response to a trigger event based on a determined aging factor. According to another embodiment, the offset value may be computed in real time based on a determined aging factor.