EV Battery Output Limiting Under High Cooling Load
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Solution Overview
Problem
Electric vehicle batteries face temperature challenges, particularly when traveling at high speeds or in high ambient temperatures, leading to potential overheating despite existing output restriction techniques.
Innovation Solution
An automotive battery system with a battery cooling device, temperature sensors, and a control device that adjusts output power based on ambient temperature, traveling load, and cooling load to prevent battery temperature from exceeding safe limits, using a combination of liquid cooling and refrigeration cycles, and utilizing sensors for precise load calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If output restriction is performed to prevent battery temperature from reaching the workable upper limit temperature, then battery temperature can be controlled, but the frequency of output restriction increases when cooling power margin is insufficient
Solution Approach 1:
The control device performs preliminary action by starting output restriction when the battery temperature reaches a lower threshold (first temperature threshold) before it approaches the workable upper limit temperature. This early intervention prevents the battery temperature from rising too high in the first place, reducing the need for frequent or severe output restrictions later. The system proactively manages heat generation rather than reactively responding to overheating conditions.
2Temperature
If the battery cooling device operates at high load to cool the battery efficiently, then battery temperature can be maintained, but the system complexity and energy consumption increase
Solution Approach 1:
The control device dynamically adjusts the output restriction level based on real-time battery temperature measurements and cooling device operating conditions. When the battery temperature approaches the first temperature threshold, the system dynamically modifies the output power limitation to prevent further temperature rise. This dynamic control allows the system to adapt to changing thermal conditions without requiring the cooling device to operate continuously at maximum capacity, thereby managing system complexity and energy consumption more effectively.
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
Effectively suppresses battery temperature rise, preventing overheating and reducing the frequency of output restrictions, while also downsizing the cooling system by sharing components with the air conditioning unit, ensuring stable vehicle performance.
Implementation Method 1
a liquid cooling device that cools the battery with cooling liquid that circulates in the battery and a heat exchanger
Implementation Method 2
a refrigeration cycle device that cools the cooling liquid of the liquid cooling device, with refrigerant of refrigeration cycle, via the heat exchanger
Data Source
AI summary
When the temperature of a battery is high, the output power of the battery is limited to suppress the temperature rise. Upon fulfillment of three conditions of (i) the ambient temperature is equal to or higher than a predetermined temperature, (ii) the vehicle traveling load is equal to or greater than a predetermined traveling load, and (iii) the operating load of a battery cooling device is equal to or greater than a predetermined operating load, the output power of the battery is limited using a high-load output limiting value less than an output limiting value for the normal condition in a temperature range equal to or higher than a second power restrictive lower limit temperature that is equal to or lower than a first power restrictive lower limit temperature for the normal condition.