FEATURE POWER ELECTRONICS
OVERCOMING THE COOLING CHALLENGE IN ELECTRIC VEHICLE CHARGING
Dielectric cooling liquid within the connector is offering an advanced solution for electric vehicles as Marc Hartwig, business development manager, automotive electrification at 3M explains
T
he market for consumer electric vehicles has seen some significant
challenges: the cost of vehicles; limited range and customer ‘range anxiety’; access to charging stations; and efficient, fast charging. Solving the first of these three challenges is well under way, but until recently, rapid charging was a problem yet to be solved: while refuelling a conventional vehicle takes minutes, charging electrical cars has typically taken hours. That is now changing, with the
introduction of high power DC charging units, such as the DC high power charging unit solution from ITT Cannon. This uses innovative liquid cooling to achieve effective heat dissipation, delivering a 60 mile charge in three to five minutes. The consequence is that longer journeys in electric vehicles become far more viable, a vital enabler to making EV technology more mainstream. This innovation has been developed in response to automotive original equipment manufacturers (OEMs) asking ITT Cannon for a charging solution able to go up to 400 A/1000 volts, in compliance with IEC 62196-3 connector standards. Their request for this is understandable, because while existing AC systems are adequate for short journeys and overnight charging (providing up to 43kW in Europe, or 22kW in the US), DC and High Power Charging (HPC) DC charging solutions are needed for longer trips, where recharging is going to be more frequent. However, the greater power transmitted introduces a requirement for heat dissipation within the charging system. The solution ITT Cannon came up with
was to use dielectric cooling liquid within the connector, not just the cable, resulting in excellent heat dissipation performance. Cooling the connector itself internally, instead of just the cable, keeps temperatures as low as possible. The coolant flows through the cable and then cools the contacts to control the temperature at the connection, so that a consistent temperature can be achieved. When charging at full power, the zone with the lowest temperature in the entire assembly is the contact between the car and the connector. The coolant goes from the cooling unit to the cable to the connector, and back again.
22 MARCH 2018 | ELECTRONICS
didn’t want to choose oil-based coolants, because if these were spilled, they would be messy and potentially hazardous. The way that the Novec Engineered Fluids from 3M have been designed with the environment in mind is important too.” Novec Engineered Fluids from 3M are a
Figure 1:
ITT Cannon came up with a solution using dielectric cooling liquid within the connector, not just the cable, resulting in excellent heat dissipation performance
Using liquid cooling also means that the size of the cable can be minimised: important for the end-user experience, since a solid copper cable would be heavier (up to 40 per cent) and more unwieldy, making it difficult for consumers to handle. Ralf Glocker, ITT Cannon’s Senior Product Manager for Electrical Vehicle solutions says: “From the beginning, our engineering team was focused on a prime handling experience. We considered the needs of every kind of consumer, with varying degrees of physical ability or strength.”
NOVEC ENGINEERED FLUIDS FROM 3M
Figure 2:
Cooling the connector itself internally, instead of just the cable, keeps temperatures as low as possible
The cooling liquid being used is Novec Engineered Fluid from 3M, chosen for its efficient cooling properties, safety and environmental profile. Glocker Continues, “Core to our activities and specification was safeguarding uncompromised product safety. This is essential; no automotive OEM is going to adopt a charging solution unless consumer safety is paramount. We
family of fluids developed by 3M to deliver excellent performance in many heat transfer applications, with no compromise on either worker safety or environmental sustainability. Novec fluids are dielectric and non-flammable, making them an advanced alternative to traditional cooling fluids such as mineral oils and water glycol. In case of vandalism or serious damage, there is no safety risk or residue staining the ground. The charging system, which is now
commercially available, was of course rigorously tested, including application of various temperature sensors to critical positions. ITT Cannon has developed significant capability in high definition (HD) simulation to reduce development time, supported by an iterative design methodology which enables greater agility, greater customisation and quicker time- to-market.
LOOKING AHEAD Beyond cooling charging units, liquid cooling has benefits in other parts of e- mobility design. Liquid cooling of the battery itself provides efficient heat management and contributes significantly to reducing weight. “Manufacturers want to reduce the weight of electrical vehicles as much as possible,” says Glocker. “Having a cooled system based on existing components could significantly contribute to reducing the weight of the overall vehicle.” While that potential step in automotive
design is still in the future, the use of liquid cooling within the latest generation of DC-based high power charging solutions could certainly make a major contribution to the mass-market adoption by consumers of electrical cars over the next few years.
3M
www.3M.co.uk/Novec T: 08705 360036
/ ELECTRONICS
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