EV Battery Cooling Control for Fast Charging Temperature Limits
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Solution Overview
Problem
The challenge is to balance maximizing the electric vehicle (EV) battery charge current during direct current fast charging (DCFC) while maintaining battery temperature and gradient temperature below derate thresholds, thereby ensuring battery longevity and performance.
Innovation Solution
A battery cooling model is employed to determine the specific amount of cooling needed for the EV battery during DCFC, ensuring that both battery temperature and gradient temperature remain below their respective derate thresholds by adjusting the charging current and providing targeted cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high-power direct current fast charging is used to maximize charge current, then charge time is reduced, but battery temperature and gradient temperature exceed derate thresholds
Solution Approach 1:
The cooling system is activated before the battery temperature reaches the derate threshold during DCFC. The controller predicts temperature rise based on charge current and activates cooling in advance, allowing the battery to charge at maximum current without exceeding temperature limits, thus reducing charge time while maintaining temperature control.
Solution Approach 2:
A coolant system acts as an intermediary between the battery and the environment to manage heat transfer. The coolant absorbs heat from the battery during DCFC, enabling high charge currents to be sustained without temperature excursions that would trigger derating.
2Reliability
If cooling is applied to maintain battery temperature below thresholds, then battery health is maintained, but charge duration increases due to reduced charge current
Solution Approach 1:
The cooling system operates dynamically with variable coolant flow rate and temperature setpoints that adjust based on real-time battery temperature, charge current, and state of charge. This dynamic control allows maximum charge current to be maintained while only applying the necessary cooling to stay below derate thresholds, minimizing charge duration while protecting battery health.
Solution Approach 2:
The controller continuously monitors battery temperature and charge current, using feedback to adjust cooling system operation. This closed-loop control ensures the battery remains below temperature thresholds without unnecessarily reducing charge current, optimizing both battery health and charge speed.
3Temperature
If cooling is applied early in the charge process, then temperature control is maintained, but charge time increases due to reduced charge current
Solution Approach 1:
The cooling system is activated selectively at specific points during the charge process based on predicted temperature rise, rather than continuously from the start. This allows the battery to charge at maximum current during early stages when temperature rise is minimal, activating cooling only when necessary to prevent threshold exceedance.
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 efficient DCFC at maximum charge current without exceeding temperature thresholds, thereby minimizing charge time while maintaining battery health and performance.
Implementation Method 1
heat can be produced within the battery. This heat, unless dissipated, can impact the longevity and performance of the battery
Data Source
AI summary
Technical solutions provide a model-based cooling control of an EV battery during a direct current fast charging (DCFC) event. The technical solutions can include a processor coupled with memory to identify a state of charge (SOC), a temperature threshold and a gradient threshold for a difference in temperature between at least two cells of an EV battery. The processor can determine an amount of cooling to apply during a charge of the battery based at least on the SOC, the temperature of the battery and the difference in temperature input into a model for cooling the battery to maintain the temperature below the temperature threshold and the difference in temperature below the gradient threshold. The processor can provide to the battery the amount of cooling determined by the model to maintain the temperature below the temperature threshold and the difference in temperature below the gradient threshold during the charge.