Battery Temperature Estimation Using Impedance Features
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Solution Overview
Problem
Existing battery temperature monitoring systems, such as those using thermistors, are costly, add weight, and suffer from temperature lag due to thermal transfer delays, leading to inaccuracies in core temperature estimation.
Innovation Solution
Employing Electrochemical Impedance Spectroscopy (EIS) to measure battery cell temperature using current and voltage measurements, utilizing multiple impedance features to estimate temperature without additional wiring or sensors, achieving less than 1°C error over a wide frequency and temperature range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermistors are used for battery temperature monitoring, then temperature measurement is achieved, but cost increases, weight increases, and temperature lag occurs due to thermal transfer delays
Solution Approach 1:
The patent replaces the mechanical/thermal sensing system (thermistors requiring physical contact and thermal transfer) with an electrical measurement system using EIS. The temperature is inferred from electrical impedance characteristics of the battery cell itself, eliminating the need for separate thermal sensors and their associated wiring, thereby reducing weight while maintaining measurement capability.
Solution Approach 2:
The battery cell itself serves as the sensing element through its impedance characteristics. The EIS technique utilizes the battery's own electrical properties to provide temperature information, eliminating the need for external sensing components. The battery cell's impedance naturally varies with temperature, allowing it to 'sense' its own temperature state without additional hardware.
2Measurement precision
If thermistors are used for battery temperature monitoring, then temperature measurement is achieved, but additional wiring and sensors are required, increasing device complexity
Solution Approach 1:
The EIS measurement system serves multiple functions: it characterizes battery health, state of charge, and temperature simultaneously through impedance analysis. The same electrical measurements used for general battery monitoring also provide temperature information when analyzed with appropriate EIS techniques, eliminating the need for dedicated temperature sensing hardware and reducing overall system complexity.
Solution Approach 2:
The patent replaces the separate thermal sensing system with the existing electrical measurement infrastructure. By analyzing impedance spectra from standard electrical tests, temperature information is extracted without requiring additional sensors, wiring, or mechanical components, thereby simplifying the device architecture.
3Measurement precision
If thermistors are used for battery temperature monitoring, then temperature measurement is achieved, but temperature lag occurs due to thermal transfer delays
Solution Approach 1:
The patent replaces thermal conduction-based measurement (which is inherently slow due to thermal mass and conductivity limitations) with electrical impedance measurement. Electrical signals respond instantaneously to temperature changes at the electrode-electrolyte interface, providing real-time temperature information without the thermal lag inherent in contact-based thermal sensing methods.
Solution Approach 2:
The patent uses electrical impedance as an intermediary parameter that directly reflects temperature at the electrochemical interface. Instead of measuring temperature directly through thermal contact, the impedance serves as a mediator that correlates with temperature through well-established electrochemical relationships, providing immediate temperature information without thermal transfer delays.
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
Provides accurate core temperature estimation with minimal error and reduced hardware requirements, enabling rapid monitoring and preventive actions against battery failures.
Implementation Method 1
Employing Electrochemical Impedance Spectroscopy (EIS) to measure battery cell temperature using current and voltage measurements
Implementation Method 2
The temperature estimation circuit is configured to estimate an impedance based on the frequency component
Implementation Method 3
estimate a temperature based on a feature vector including at least two features of the impedance
Data Source
AI summary
A temperature estimation apparatus includes a measurement circuit and a temperature estimation circuit. The measurement circuit is configured to acquire a voltage measurement and a current measurement. The voltage measurement and the current measurement include a frequency component. The temperature estimation circuit is coupled to the measurement circuit. The temperature estimation circuit is configured to estimate an impedance based on the voltage measurement and the current measurement, and estimate a temperature based on a feature vector including at least two features of the impedance.