Traction Battery Power Control After Parking Temperature Soak
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Solution Overview
Problem
Electric vehicles face challenges in efficiently measuring and managing battery cell temperatures due to variations within the battery pack, particularly between cells near the outer surface and those in the middle, as direct measurement with thermistors is often impractical and can lead to inefficient vehicle operation.
Innovation Solution
A controller adjusts the maximum output power of the traction battery based on recorded temperatures, ambient conditions, and parking duration to account for temperature gradients within the battery pack, using thermal modeling and compensation to ensure efficient vehicle operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermistors are installed on each battery cell for direct temperature measurement, then measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent uses a thermal model to create a virtual copy of the battery pack's thermal behavior, allowing temperature estimation of individual cells without physical sensors on each cell. The model replicates the thermal characteristics based on limited sensor data and environmental conditions
Solution Approach 2:
The patent introduces a thermal model as an intermediary between the physical battery cells and the temperature measurement system. Instead of directly measuring each cell, the model mediates by calculating temperatures based on ambient conditions, parking duration, and thermal diffusion principles
2Productivity
If the vehicle operates at full power after parking, then productivity is improved, but reliability decreases due to potential overheating of battery cells
Solution Approach 1:
The patent performs preliminary thermal assessment during the parking event by monitoring ambient temperature changes and calculating thermal diffusion. This preliminary action allows the system to predict battery temperature state before the vehicle starts, enabling proactive power management decisions
Solution Approach 2:
The patent dynamically adjusts the maximum output power based on the estimated battery temperature state. The power limitation is not fixed but adapts in real-time based on thermal conditions, allowing full power when safe and reduced power when thermal risks exist
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 battery cell temperatures and optimized power management, enhancing vehicle efficiency and safety by reducing the risk of overloading cells with uneven cooling.
Implementation Method 1
the cells located at the end of the battery pack cool down faster than those cells located in the middle of the battery pack due to their proximity to the outer surface of the battery pack
Data Source
AI summary
After start of a vehicle following a parking event having a duration that exceeds a duration threshold, a controller may adjust a maximum output power of a traction battery responsive to temperatures of the traction battery, derived from a temperature of the traction battery at a beginning of the parking event, ambient temperature during the parking event, and the duration, exceeding a first threshold difference.