Published on November 30th, 2017 | by Steve Hanley0
New Wireless EV Charging Standard From SAE Supports Up To 11 kW Charging Power
November 30th, 2017 by Steve Hanley
This story about wireless charging was first published by Gas2.
Standards are critical to making new technology accessible on a wide scale. For instance, it’s not a good thing if your spiffy new EV charger needs an 11 pin socket, even if it will add 300 miles of range in 30 seconds. The same thinking applies to wireless charging. It’s one thing to be able to charge your EV without needing to plug in. It’s not such a good thing if every company has its own proprietary system that won’t work with other systems.
Wireless charging is an important component in the transition to a world where electric cars are predominant. High-power, high-speed chargers may be necessary for those traveling long distances, but for normal daily driving, being able to add some juice to your battery while you are grocery shopping, at the office, or visiting a restaurant could make the difference between being comfortable driving an electric car or being stressed out about getting it home to the charger in your garage.
The Society of Automotive Engineers has just released a new wireless charging specification known as the SAE J2954 Recommended Practice. It differs from prior specifications in that it supports wireless charging systems like WiTricity’s DRIVE 11 package that delivers up to 11 kilowatts of power. (For some EV charging reference, a normal electricity outlet offers 3 or 4 kW, a typical Level 2 charging station offers 6 kW, a more powerful Level 2 charger offers 10 or 11 kW, and the most powerful Tesla wall charger — which is essentially a dual charger — offers up to 22 kW.)
“The Recommended Practice establishes a new methodology using magnetic triangulation for vehicle alignment to assist manual as well as autonomous parking.” SAE says in its announcement about the new specification. “SAE J2954 can assist EV drivers to seamlessly park their vehicles, establish payment and charge without customer interaction. Power transfer enables vehicle ground clearance up to 10 inches with a side to side tolerance of (up to) 4 inches. The alignment method assists the driver to stay within the charging range — and autonomous vehicles with finding parking spots — even in weather like rain or snow.”
WiTricity, headquartered near Boston, says that the Tunable Matching Network incorporated into its DRIVE 11 system “is able to maximize efficiency and power delivery over a very broad range of parking alignment, battery voltage, and power conditions. In addition, DRIVE 11 offers direct to battery charging to eliminate system losses associated with DC-DC converters and onboard chargers and can be configured to handle a wide range of battery voltage including the latest 800V packs used for next-generation high-performance EVs.”
WiTricity systems have a grid-to-battery efficiency of up to 94%, which is higher than many plug-in battery chargers and is surprising for a wireless system. It is working with partners such as Nissan, General Motors, Shindengen, and Delphi to bring wireless charging technology to their electric and plug-in hybrid models.