Battery Thermal Circuit With Ejector for Fast-Charging Temperature Control
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Solution Overview
Problem
Current battery thermal management systems for electric and hybrid electric vehicles lack energy efficiency and complexity, with existing systems failing to effectively control battery temperatures during high-speed charging and varying environmental conditions.
Innovation Solution
A dual-evaporator vapor compression system equipped with an ejector is implemented, which boosts the compressor's inlet pressure without increasing system complexity, using directional control valves to manage refrigerant and coolant flows for efficient heating and cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional vapor compression system is used for battery thermal management, then the system structure is simple, but the energy efficiency is poor and power consumption is high
Solution Approach 1:
The system divides the thermal management into two independent circuits: a refrigerant circuit for cooling and a coolant circuit for battery temperature control. This segmentation allows each circuit to be optimized independently, with the refrigerant circuit providing efficient cooling only when needed, thereby reducing overall power consumption while maintaining manageable system complexity through modular design
Solution Approach 2:
The coolant circuit acts as an intermediary between the battery and the refrigerant circuit. The coolant absorbs heat from the battery and transfers it to the refrigerant circuit via the chiller, enabling efficient heat transfer while allowing the refrigerant system to operate at optimal conditions, thus improving energy efficiency without requiring direct complex coupling
2Productivity
If fast charging is implemented, then the charging speed increases, but heat generation in battery cells increases significantly
Solution Approach 1:
The system proactively cools the battery before and during fast charging operations by activating the refrigerant circuit and coolant circulation in advance. This preliminary cooling action prevents excessive temperature rise during high-speed charging, enabling faster charging rates to be safely implemented without compromising battery temperature control
Solution Approach 2:
The coolant pump and refrigerant system operate continuously during fast charging to maintain constant cooling of the battery. This continuous cooling action ensures that heat generated during high-speed charging is immediately removed, allowing sustained high charging speeds without temperature-related interruptions or damage
3Adaptability or versatility
If separate HVAC and battery cooling systems are used, then the functions are dedicated, but the system complexity increases
Solution Approach 1:
The system merges the HVAC and battery thermal management functions by using a common refrigerant circuit and integrating the battery cooling through the coolant circuit that interfaces with the refrigerant chiller. This combination allows both passenger cabin climate control and battery temperature management to be achieved through a unified system architecture, providing functional versatility while avoiding the complexity of completely separate systems
Solution Approach 2:
The refrigerant circuit serves multiple functions: it cools the passenger cabin through the evaporator and simultaneously cools the battery through the chiller and coolant circuit. This multi-functionality allows a single refrigerant system to handle both HVAC and battery thermal management needs, increasing adaptability while reducing overall system complexity compared to dedicated separate systems
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 enhances energy performance and operational efficiency by optimizing temperature control within the battery, reducing power consumption, and simplifying installation and operation.
Implementation Method 1
an ejector which is configured to increase an inlet pressure of the compressor
Implementation Method 2
a compression device, a condenser, a throttle device, and an evaporator
Implementation Method 3
a compression device, a condenser, a throttle device, and an evaporator
Implementation Method 4
The refrigerant circuit is linked via the chiller to cool a coolant of the battery
Data Source
AI summary
A battery thermal management system (BTMS) for an electric vehicle and a hybrid electric vehicle is provided. The BTMS includes a refrigerant circuit having an evaporator, a chiller, one or more condensers, a compressor, an ejector, a primary directional control valve (DCV), a secondary DCV, an ejector DCV, a compressor input and output DCVs, a reference DCV, throttling valves, and controller to cool or heat the battery and passenger cabin. A coolant circuit having the battery, battery cooler, a battery output DCV, and a battery input DCV is communicated with the refrigerant circuit via the chiller. The battery input and output DCVs are coupled to the battery cooler and coupled to each other to isolate the refrigerant circuit. The controller controls the DCVs based on an optimal battery temperature range, coolant temperature, ambient temperature, passenger cabin temperature, and optimal passenger cabin temperature range.