Wireless electric car charging demo on Chevy Volt could enable 24/7 electric trucks
What if an electric truck, like airport shuttle buses, could run 24/7 by charging a bit every time they stop? According to Momentum Dynamics, developer of a wireless electric car charging system, the company's charging system could mean an all electric airport shuttle bus that can run 24 hours a day, without requiring a long recharging stop, instead staying on the road the whole day picking up and dropping off passengers. To demonstrate the system, the company has outfitted a Chevy Volt with their wireless charging system, to demonstrate wireless charging in operation at this weeks Commercial Vehicle Megatrends USA 2012 conference in Dearborn, MI.
The system works via "closely‐coupled magnetic resonance." That means there are two wire coils, one coil is embedded in a pad on the ground, and the other is located in the car or truck. Electricity is transmitted from one coil to the other, with no wired connection. The two coils are tuned to a specific frequency for optimum energy transfer. To start charging a vehicle equipped with the technology, one simply parks on top of a charging pad, and the Momentum Dynamics system immediately starts a charging session, with no need to plug in to a charging cable.
According to Momentum Dynamics, the system is 91% efficient, versus 96% efficiency in wired electric car charging, and there is no measured heating in the vehicle.
The driver of a vehicle equipped with the Momentum Dynamics system need only park close to "on-target" with the charging pad. A box inside the vehicle emits audible chirps to help with positioning the vehicle over the pad, and there is no need to be ultra-precise. The vehicle starts charging immediately, making it much simpler in operation than wired electric car charging systems.
The current system handles charge rates up to 10 kilowatts, and higher powered systems are under development for a 30 kilowatt, 60 kilowatt and even 100 kilowatt charge rates. The electric cars currently on the market support either a 3.3 kilowatt or 6.6 kilowatt charge rate, resulting in the many hours-long charging times. The on-board charger is a bottleneck that the Momentum Dynamics system does not bypass, and the Chevy Volt the company is demoing takes just as long to charge as a regular Volt.
For demonstration purposes, Momentum Dynamics is working on modifying the Volt's T18 Battery Control Module to allow a higher charge rate, aiming for a 1 hour recharge, or 1/3rd the time required with the Volt's current charger.