Battery Internal Temperature Estimation from Admittance and Surface Heat
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Solution Overview
Problem
Existing methods for estimating the internal temperature of power batteries in new energy vehicles lack precision due to not considering the real-time charging and discharging states of the battery, resulting in an average temperature estimation rather than the actual internal temperature.
Innovation Solution
A battery temperature estimation method that fits a first function relationship using admittances at different test temperatures and combines it with a temperature distribution model based on the battery's shape and size to determine a second function relationship for estimating internal temperatures using real-time surface temperature and admittances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the internal temperature is estimated by collecting current, voltage, and battery surface temperature, then the estimation can be performed in real time, but the estimation precision is not high because it only provides average temperature rather than actual internal temperature
Solution Approach 1:
The patent introduces admittance as an intermediary parameter to indirectly reflect the internal temperature state. Instead of directly measuring internal temperature, the system uses admittance (measured through electrochemical impedance spectroscopy) as a mediator that correlates with internal temperature, thereby achieving precise internal temperature estimation without direct internal sensors.
Solution Approach 2:
The patent transforms the measurement approach by changing from direct temperature measurement to measuring electrical parameters (admittance, impedance) that correlate with temperature. By measuring current, voltage, and impedance at different frequencies, the system derives admittance values that serve as proxies for internal temperature, improving measurement precision without physical temperature sensors inside the battery.
2Ease of operation
If the internal temperature is estimated by obtaining a relationship between feature quantities of electrochemical impedance spectroscopy and ambient temperature in a stable state, then the measurement can be simplified, but the effect of real-time charging and discharging states on the measured impedance values is not considered
Solution Approach 1:
The patent transitions from static temperature estimation (based on stable state ambient temperature) to dynamic estimation that accounts for real-time charging and discharging states. The system continuously measures admittance during operation and uses the temperature distribution model to adjust estimates based on current operational conditions, making the measurement process adaptive to changing battery states.
Solution Approach 2:
The patent segments the battery into multiple temperature zones (surface temperature and internal temperature) and develops separate measurement and estimation approaches for each. By measuring surface temperature directly and using admittance to estimate internal temperature, the system creates a segmented temperature profile that captures the complexity of thermal distribution without requiring sensors throughout the entire battery volume.
3Area of stationary object
If the average temperature of the entire battery is obtained instead of the actual temperature inside the battery, then the measurement scope is expanded, but the estimation precision of the internal temperature is not high
Solution Approach 1:
The patent uses admittance as an intermediary that specifically reflects internal temperature conditions rather than average temperature. While surface temperature sensors provide broad coverage, the admittance measurement acts as a targeted probe for internal thermal state, enabling precise internal temperature estimation without sacrificing measurement coverage.
Solution Approach 2:
The patent applies local quality by using different measurement strategies for different battery regions: surface temperature for external conditions and admittance-based estimation for internal conditions. The temperature distribution model incorporates local thermal characteristics, allowing the system to provide region-specific temperature information rather than a single average value.
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 effectively improves the precision of internal temperature estimation by considering the battery's real-time charging and discharging states, providing a more accurate representation of the internal temperature.
Implementation Method 1
the internal temperature of the power battery of the new energy vehicle is estimated by obtaining a relationship between feature quantities of electrochemical impedance spectroscopy and an ambient temperature in a stable state and measured impedance values
Data Source
AI summary
A battery temperature estimation method includes fitting, when a battery is in an offline state, a first function relationship according to corresponding admittances of the battery at different test temperatures, and obtaining a temperature distribution model of the battery according to the shape and the size of the battery, and determining a second function relationship corresponding to internal temperatures and a surface temperature by combining with the first function relationship. The second function relationship is used for estimating the internal temperature of the battery by using the surface temperature and the admittances of the battery.