Q: Why did you choose to use CHAdeMO?
When we started thinking about integrating our inductive charging technology to EV charging, the critical question for WPT to function was which interface to use between the WPT-system and the vehicle’s energy management system. This interface enables the EV and the WPT-system to communicate, so that the WPT-system knows when the vehicle is to be charged and how much power is required by the battery.
The norm in development for this WPT interface is expected to provide a standard for low-powered (3.6 kW and 7.2 kW) inductive charging within the next 3-4 years. This power level is enough to recharge a typical EV like the Nissan LEAF overnight or while the driver is at work.
On the other hand, our WPT system (developed based on experience gained from a previous collaborative project with other industry partners and the Transrapid dynamic WPT application) could transfer almost ten times that power level. A level of power that can provide 100 km of driving range in little more than half an hour of charging, or over 3 km of range for every minute of charging.
For us it was evident to choose an existing charging standard, rather than to wait for the low power standardisation process to take form, so when INTIS partnered with the Bavarian University “Technische Hochschule Deggendorf” (THD) at the end of 2015, we decided to investigate the possibility of using the CHAdeMO fast charging standard to interface our technology with EVs.
We chose CHAdeMO because it is a well-established standard for DC conductive charging and is used by a number of electric vehicle manufacturers, including the world’s best-selling electric vehicle, the Nissan LEAF. It also made sense to use a DC interface as the power feeding unit would be set outside of the vehicle.
Q: How does it work? What exactly are the system components?
All vehicles are charged via the vehicles’ existing CHAdeMO DC fast charging interface, with no alteration of the vehicles’ electronics. All vehicles’ safety systems remain intact and unaltered. The fast charging system in each vehicle “sees” a cable connection, so no alteration of the standard was required either.
More concretely, each vehicle in our project was outfitted with a receiving secondary coil (“pickup”) underneath the vehicles (appx 90cm x 90cm) as well as two boxes of power electronics in the engine compartment: the first box (the “matching” box) contains equipment to regulate power coming from the WPT and “match” it to vehicle requirements. It is connected to the second “CHAdeMO” box which contains the DC fast charging emulation equipment and plays the interface between the vehicle and the inductive charging system, through which all power and communication links run. There is also a positioning assistant to aid the correct positioning of the vehicle over the charging plate as well as all the necessary safety systems, such as foreign object detection and living object protection system. An additional display was installed in each vehicle to act as the human machine interface.