EV Battery Thermal Control During Fast Charging
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Solution Overview
Problem
Conventional fast charging methods for electric vehicle batteries often fail to balance temperature control effectively, leading to potential battery degradation and reduced charging efficiency.
Innovation Solution
A thermal control strategy involving multiple stages, where the system heats the battery to prevent lithium plating, shifts thermal load to optimize cooling capacity, and adjusts temperature to ensure safe operating conditions during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If fast charging is performed without thermal management, then charging speed increases, but battery temperature rises causing degradation and safety issues
Solution Approach 1:
The system performs pre-conditioning heating of the battery before fast charging to ensure optimal temperature for lithium ion mobility. This preliminary thermal preparation prevents lithium plating during subsequent fast charging, enabling high charge rates while maintaining battery safety and longevity.
Solution Approach 2:
The thermal management system dynamically adjusts coolant flow rate, temperature, and circulation patterns based on real-time battery temperature monitoring. During fast charging, the system increases coolant flow to high-power regions to extract heat, while during pre-conditioning, it reduces flow to allow controlled heating, thereby maintaining optimal thermal parameters throughout the charging process.
2Productivity
If battery temperature is increased to prevent lithium plating, then charging efficiency improves, but risk of overheating increases
Solution Approach 1:
The system employs multiple temperature sensors distributed throughout the battery pack that continuously monitor cell temperatures. This feedback information is fed to the thermal management controller, which dynamically adjusts heating and cooling operations in real-time. When temperatures approach critical thresholds during fast charging, the system automatically increases cooling capacity, thereby maintaining high charging efficiency while preventing overheating through closed-loop control.
Solution Approach 2:
The thermal management system transitions from static temperature control to dynamic adaptation throughout the charging process. During pre-conditioning, the system applies heating to raise battery temperature to optimal levels. During active fast charging, it dynamically switches to cooling mode and adjusts coolant flow rates based on real-time thermal conditions, enabling the system to adapt its thermal response to the changing thermal demands at different charging stages.
3Temperature
If thermal management system is oversized to handle maximum heat, then cooling capacity is sufficient, but system cost and complexity increase
Solution Approach 1:
The system applies targeted thermal management only where and when needed during fast charging. Instead of uniformly cooling the entire battery pack, the thermal management system directs coolant flow preferentially to high-power regions generating excessive heat. This partial action approach provides sufficient cooling capacity at critical locations while using a smaller, less complex thermal management system compared to uniform full-pack cooling.
Solution Approach 2:
The battery pack is divided into multiple thermal zones with independent temperature monitoring and cooling control. Each zone has its own temperature sensors and coolant flow control, allowing the thermal management system to address thermal issues locally rather than requiring a monolithic oversized cooling system. This segmentation enables precise thermal control with reduced system complexity and lower component sizing requirements.
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 extends battery life, increases fast charge rates, reduces charging time, and allows for downsizing of compressor and chiller components by effectively managing thermal mass.
Implementation Method 1
A heating element or other thermal control device may be used to heat the thermal mass
Implementation Method 2
A cooling element or other thermal control device may be used to cool the thermal mass
Implementation Method 3
The controller may control the thermal control device(s) to direct the thermal mass along a flow path
Data Source
AI summary
A device for charging an energy storage device includes a controller to initiate a charging operation for the energy storage device and control, during a first stage of the charging operation, a thermal control system to direct a first volume of the thermal mass along a first flow path to heat the energy storage device to a first desired temperature. The controller controls, during a second stage of the charging operation, the thermal control system to direct a second volume of the thermal mass along a second flow path to cool the energy storage device from the first desired temperature towards a second desired temperature.