EV CHARGING IN VEHICLE CONNECTOR COOLING
EV charging is classified into DC charging and AC charging interface according to the current and voltage
Faster charging times are important in the wider adoption of EVs. Transferring more energy to EV batteries involves using higher voltages and higher currents. Increasing the voltage is important but is also limited. Most of the EVs on the road today have battery pack voltages of about 400 V, with 800 to 900 V battery packs representing the leading edge. The goal of XFC is to deliver up to 500 kW of charging power. Even with a 900 V battery pack, that demands lots of current and dissipates lots of heat.
EV charger connectors have been regionally standardized to support current charging technologies. In the future, AC charging Level 1 and Level 2 connectors are expected to continue to be used. But to get higher-power DC charging to support XFC and other technologies, connector technology needs to change. One proposal being pursued is the addition of liquid cooling in the cable and connector to enable existing DC fast charging connector formats to support higher power levels without overheating. In addition, SAE recently introduced the J3105 standard that defines charging interfaces for heavy-duty vehicles. J3105 not only anticipates charging rates over 1MW is also supports new connection mechanisms, including pantograph, cross rail, and pin-and-socket connections. Pantograph and cross rail connections are expected to support the opportunity charging of large EVs. In addition, wireless charging technologies are being developed for all types of EV charging applications, including opportunity charging.
Integrating a liquid coolant system into the cable assembly and connector housing of electric vehicle (EV) charging infrastructure moves coolant around the high-current wires and connectors. The liquid coolant circulates through jackets or channels built into the parts, removing heat from them
High temperatures can be caused by a poor connection, a malfunctioning charger, or the cable being used at its maximum current rating.
Factors Affecting Temperature:
- Charging Current: Higher currents generate more heat.
- Ambient Temperature: Hot weather can contribute to higher connector temperatures.
- Size and type of wires in the charging cable can affect how much heat is generated.
- Different connector types have different temperature limitations.
- Battery Temperature: Charging a cold battery can also generate more heat.
- If the connector or cable is too hot to touch, it’s a sign that something is wrong.
- If the prongs of the wall plug are burning hot after charging, it may indicate a faulty receptacle.
- High temperatures can be caused by a poor connection between the charger and the vehicle.
- A malfunctioning charger can also cause excessive heating.
In summary, a warm charging cable is normal during charging, but excessive heat could indicate a problem that needs to be addressed to ensure safety and efficient charging.
When it can be used, air cooling is the preferred solution. It combines simplicity with low cost. But it’s limited in its ability to dissipate large amounts of heat. Water-based liquid cooling systems can be up to 10 times more effective at dissipating heat. Using other liquids can further increase thermal efficiency. Liquid cooling systems can be prefabricated, sealed designs with liquid inside, and ready for installation. That can simplify initial system fabrication, maintenance, and upgrades.
High currents are a key to faster EV charging, but high currents produce high thermal dissipation. Liquid-cooled connectors and connectors for liquid cooling are key components that will enable the delivery of XFC EV charging. Future generation EV chargers may employ advanced cooling technologies like two-phase subcooled flow boiling to support current levels up to 2,500 A and reduce EV charging times to 5 minutes or less.
