Battery Temperature Estimation via Cooling Fan Thermal Dynamics
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Solution Overview
Problem
The installation of external temperature sensors for lithium ion battery systems is costly and prone to physical damage, and high voltage systems require additional insulation, increasing costs further, while also being unnecessary for accurately predicting outdoor air temperature for battery lifetime and operation.
Innovation Solution
An electricity storage device with a temperature detector and controller that estimates outdoor air temperature based on the change in temperature during cooling unit operation and non-operation periods, eliminating the need for external temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an external temperature sensor is installed outside the electricity storage rack, then the outdoor air temperature can be measured directly, but the sensor is subjected to physical impact from the outside and cost increases due to protection cover and insulation requirements
Solution Approach 1:
The patent introduces the cooling fan as an intermediary element. Instead of placing the temperature sensor directly outside where it faces physical damage risks, the sensor is positioned inside the rack near the cooling fan. The fan's operation creates a controlled thermal environment that allows indirect measurement of outdoor temperature through the temperature difference method, mediating between the sensor's protected position and the outdoor environmental conditions.
Solution Approach 2:
The patent creates a thermal copy or representation of the outdoor temperature condition through the cooling fan's operation. By measuring the temperature change caused by the fan's operation (which draws outdoor air into the rack), the system obtains a replicated thermal signal that represents outdoor temperature without requiring direct exposure of the sensor to outdoor conditions.
2Reliability
If a protection cover is attached to the temperature sensor, then the sensor is protected from physical impact, but cost increases
Solution Approach 1:
The cooling fan serves as an intermediary that eliminates the need for protective covers. By positioning the sensor inside the rack where it is naturally protected by the rack structure, and using the fan's thermal effect to indirectly measure outdoor temperature, the system achieves both protection and functionality without additional protective cover components.
Solution Approach 2:
The cooling fan performs multiple functions: it provides necessary cooling for the battery cells and simultaneously serves as a means to indirectly measure outdoor temperature. This multi-functionality eliminates the need for separate protective infrastructure and dedicated external temperature sensing, reducing overall system cost.
3Reliability
If insulation is added between the inner electricity storage system and the outer temperature sensor for high voltage systems, then safety is improved, but cost increases
Solution Approach 1:
The cooling fan and the resulting temperature difference measurement method act as intermediaries that eliminate direct electrical contact requirements. By measuring temperature indirectly through the fan's thermal effect rather than placing sensors outside, the system maintains electrical insulation safety without requiring additional insulating materials or complex isolation structures.
Solution Approach 2:
The system creates a thermal copy of the outdoor temperature condition that can be measured safely inside the insulated rack. This replicated thermal information allows the system to obtain outdoor temperature data without breaking electrical insulation barriers, maintaining safety while avoiding additional insulation costs.
4Measurement precision
If the temperature sensor is installed outside the electricity storage rack, then the outdoor air temperature can be measured, but device complexity increases due to external installation requirements
Solution Approach 1:
The patent merges the temperature measurement function with the existing cooling fan system. The temperature sensor is integrated inside the rack near the fan, and the measurement process utilizes the fan's operational characteristics. This combination eliminates separate external installation requirements and simplifies the overall system architecture.
Solution Approach 2:
The cooling fan serves as a mediator that connects the indoor sensor position with outdoor temperature measurement. By using the fan's air flow and thermal effects as an intermediary mechanism, the system achieves outdoor temperature measurement functionality while maintaining simple internal sensor installation without complex external mounting structures.
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 method allows for accurate estimation of outdoor air temperature without external sensors, reducing costs and improving reliability by using internal temperature detection and cooling unit operation data.
Implementation Method 1
a temperature detector installed in the casing and configured to detect a temperature of the electricity storage unit
Implementation Method 2
a cooling unit configured to cool the electricity storage unit
Data Source
AI summary
A temperature detector detects a temperature of an electricity storage unit installed in a casing. A controller estimates a temperature outside the casing on the basis of a detection temperature of the electricity storage unit detected by the temperature detector. The controller estimates an outdoor air temperature outside the casing on the basis of a change amount of detection temperature per a predetermined period detected in a state where a cooling unit is operated and a change amount of detection temperature per the predetermined period detected in a state where the cooling unit is stopped.