Vehicle Battery Rest Temperature Estimation Using Ignition Cycle Averages
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Solution Overview
Problem
Existing methods for estimating the rest temperature of electric power storage devices fail to accurately account for environmental temperature changes when the vehicle is stationary, leading to inaccurate degradation assessments.
Innovation Solution
An electric power storage system that includes a temperature sensor and controller to detect and average temperatures when the ignition switch is turned ON, using the average of maximum and minimum temperatures to estimate the rest temperature, thereby reflecting environmental conditions and reducing the impact of regularity in ignition timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the rest temperature is estimated from a single temperature measurement, then the estimation process is simple, but the accuracy of rest temperature estimation deteriorates because it cannot reflect environmental temperature changes
Solution Approach 1:
The patent combines multiple temperature measurements (maximum and minimum temperatures) taken at different times to estimate the rest temperature. By merging these measurements and calculating their average, the system achieves more accurate rest temperature estimation that reflects environmental temperature changes, resolving the contradiction between measurement accuracy and system complexity.
2Measurement precision
If temperature is measured only when ignition switch is ON, then the measurement system is simple, but the rest temperature cannot be accurately captured since the battery is not at rest
Solution Approach 1:
The patent performs preliminary temperature measurements during the period when the ignition switch is ON, before the battery enters complete rest. By measuring the maximum and minimum temperatures during this transition period and using their average as the rest temperature, the system captures the environmental temperature influence without requiring the battery to be at rest for an extended period, thus resolving the contradiction between measurement accuracy and time loss.
3Reliability
If single temperature measurement is used, then the data processing is simple, but the degradation assessment is inaccurate due to not accounting for environmental temperature variations
Solution Approach 1:
The patent changes the temperature parameter from a single static measurement to a dynamic range measurement by recording both maximum and minimum temperatures. By processing these two parameters and calculating their average, the system achieves more reliable degradation assessment that accounts for environmental temperature variations, resolving the contradiction between reliability and data processing complexity.
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 allows for accurate estimation of rest temperatures, improving the assessment of battery degradation and reflecting environmental changes, even when the ignition switch is OFF, by using a two-temperature average to mitigate timing-related differences.
Implementation Method 1
the battery temperature for a rest period between external charging completion and ignition switch ON is estimated from a radiation amount of the electric power storage unit
Data Source
AI summary
An electric power storage system for a vehicle includes an electric power storage device, a temperature sensor, and a controller. The vehicle includes an ignition switch. The electric power storage device is mounted on the vehicle. The temperature sensor is configured to detect a temperature of the electric power storage device. The controller is configured to estimate a rest temperature of the electric power storage device at a time when the ignition switch is OFF. The controller is configured to acquire the temperature of the electric power storage device at a time when the ignition switch is ON by using the temperature sensor when the ignition switch is turned ON. The controller is configured to estimate the rest temperature by using an average value of at least two of a plurality of the temperatures acquired during a predetermined period. The plurality of temperatures are the temperatures of the electric power storage device which are acquired at a time when the ignition switch is turned ON during the predetermined period.