EV Traction Battery Cooling System Cabin Temperature Stability
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Solution Overview
Problem
Hybrid and electric vehicles experience temperature swings in cabin air due to the use of refrigerant-to-coolant chillers for traction battery cooling, which affects occupant comfort.
Innovation Solution
A traction battery cooling system with a coolant circuit, refrigerant circuit, and flow control valves, managed by a controller that prioritizes cabin cooling over battery cooling until HVAC load decreases, using an electronic expansion valve to delay chiller activation and minimize temperature swings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the chiller is used for traction battery cooling, then battery cooling effectiveness is improved, but cabin air temperature stability deteriorates due to noticeable temperature swings
Solution Approach 1:
The system dynamically adjusts the chiller operation timing based on real-time HVAC load conditions. The controller monitors cabin cooling demand and delays chiller activation until excess refrigerant capacity is available, creating a dynamic response that adapts to changing thermal conditions rather than operating statically
Solution Approach 2:
The controller continuously monitors HVAC load and refrigerant evaporative capacity, using this feedback to determine the optimal timing for chiller activation. This closed-loop control ensures the chiller operates only when it will not disrupt cabin temperature stability, resolving the contradiction between battery cooling needs and cabin comfort
2Loss of time
If the chiller is activated early for battery cooling, then battery cooling is provided sooner, but excess refrigerant evaporative capacity is wasted when HVAC load is still high
Solution Approach 1:
The controller performs preliminary assessment of HVAC load conditions before activating the chiller. By evaluating the current refrigerant evaporative capacity in advance, the system determines the optimal activation moment, preventing both premature activation (which would waste capacity) and excessive delay (which would postpone necessary cooling)
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
The system effectively reduces temperature fluctuations in cabin air, enhancing occupant comfort by prioritizing cabin cooling and utilizing chiller capacity efficiently, ensuring smooth and continuous traction battery cooling with minimal impact on cabin temperature.
Implementation Method 1
a refrigerant-to-coolant chiller that is coupled to the vehicle cabin's air conditioning (HVAC) system
Implementation Method 2
The plurality of flow control valves includes an electronic expansion valve that is provided in the refrigerant circuit between the condenser and the chiller
Implementation Method 3
The refrigerant circuit circulates refrigerant between a compressor, a condenser and either a first cabin evaporator and/or the chiller
Implementation Method 4
The refrigerant circuit circulates refrigerant between a compressor, a condenser and either a first cabin evaporator and/or the chiller
Implementation Method 5
The refrigerant circuit circulates refrigerant between a compressor, a condenser and either a first cabin evaporator and/or the chiller
Data Source
AI summary
A cooling system is provided for a traction battery of an electrified motor vehicle. That cooling system includes a cooling circuit, a refrigerant circuit, a plurality of flow control valves and a control system. That control system includes a controller configured to (a) control operation of the plurality of flow control valves and (b) prioritize cabin cooling over traction battery cooling.