Pulling Wires for Wireless

The discussion surrounding electric vehicles has been about getting more wires out on the street for EVSE equipment, but slowly the trend is going for less wires and looking at wireless power transfer. The trend has come a long way since it first appeared at a TED in 2009.


Last week KAIST made some big splashes in the news again with their latest development. KAIST is now testing their wirelessly charged busses in an actual urban environment, in the South Korean city of Gumi. Previously test runs have been done at an amusement park and at KAIST's campus.

The power comes from cables embedded in the road

The power comes from cables embedded in the road

What is new about KAIST's project now is they are using wires instead of the conventional coils. Competitors have so far all used magnetic coils to transfer power from the surface of the road into the vehicle. Now KAIST can do the same, but with a set of cables. The main advantage is installation costs and time. The main benefits for cables has been explained to me about a year ago by professor Pavol Bauer from TU Delft; putting a large number of coils in the road requires you to break open a large area of road. Putting a cable in you can achieve by just milling a long slot to put the cable in; a lot cheaper and quicker!

Benefits of Wirelss Power Transfer:
  • Can charge on the go
  • No fiddling with cables at stops
  • Can use smaller battery
  • Lighter bus
  • More room/capacity for passengers
Benefits of KAIST Method:
  • Cables are easier to install
  • ables are cheaper to install
  • Only 5-15% road surface required
  • 85% transfer efficiency achieved
The first race of the Formula E will be Sept 2014 in Rome

The first race of the Formula E will be Sept 2014 in Rome

Formula E

The concept of electric vehicles that can go on forever while being charged wirelessly is very appealing; instead of having to stop the race after the batteries are drained, you can drive a full Le Mans on electricity! It was to my amazement that back in 2011 the FIA had not fully considered inductive charging as an option to race with for their (then) upcoming Formula E Championship. I was even more delighted when I got the opportunity to come over to Paris and explain in person the pros and cons of such an inductive charged race to them. The inductive race did not make it (yet) for the Formula E Championship, but one team does look promising for this technology: Drayson Racing.

Drayson's Electric Racing Vehicle, capable of achieving over 200mph for their World Record, is made ready for inductive charging

Drayson's Electric Racing Vehicle, capable of achieving over 200mph for their World Record, is made ready for inductive charging

Drayson Racing

Drayson Racing was one of the first teams to sign on with the Formula E, they have made headlines with their World Record and they can charge their battery wirelessly with Qualcomm Halo technology. Their aim is to have a full inductive race.

Inductive Racing

While the Formula E is staged for city races and inductive technology is not that widely available yet, being able to get a race track ready by simply installing a few cables is much easier to accomplish than digging up the city and installing a lot of coils to get the same effect.

Electric Vehicle - The power of inductive charging

Charging your electric vehicle is something special if you do it for the first time. It either becomes something you hardly notice, or something of a nuisance after having plugged in your car. Or worse, after having forgotten to plug it in at night and only discovering first thing in the morning that your vehicle has not properly charged up yet.

Currently inductive charging is at a state at which it can deliver wireless charging of your vehicle, while parked. True, it comes at an increased cost versus the conventional charger, there is also a small extra loss involved due to the decrease in efficiency, but the concept of 'Park and forget' is appealing nonetheless.

Inductive charging - Also on your toothbrush

For those of you who have missed out on this, inductive charging is a technology that is similar to what is used in most electric toothbrushes and electric water kettles. It uses two coils to transfer power from one coil to the other and requires no direct contact. In case of the toothbrush and the kettle, this allows you to safely use and charge the appliance in an environment with water (the bathroom or kitchen) without having to worry if water can cause short-circuit. The principle is already tried and tested in this way; the technology is hardly 'new'. What is new about it is the appliance to electric vehicles and the much larger powers involved with them now.

The inductive charger allows you to 'Park and forget' your car in your garage for example. You do not have to remember to plug it in, just drive it over at the designated parking space that is fitted with the technology and charging automatically starts.

There are many other possibilities out there around inductive charging, a few of my favorite I'll cover here. The most obvious one is the charger in your parking space. Park your car and let it charge while it is there idling and you are out to shop or work for example.

The Connexxion Bus that uses Inductive Charging in Utrecht - Link [Dutch]

A current example is the inductive charging of a bus on one of its stops. In my hometown in Utrecht, there is a bus line going through the older parts of the city centre and getting that bus to drive on electricity can seriously help preserve the old buildings, while also enabling a cleaner environment to live in obviously. The route of the bus is a shorter one than the average, but on one of its stops it has a special inductive charger build into the road at the bus stop. This stop is located at the central station and it is one of the longer stops in the route. It is here that the bus tops up the battery with some electricity while the driver goes for a coffee or to the restroom. This way of operating the bus allows it to run a full shift all day without sacrificing the service. It also helps reducing the required size of the battery; it does not have to carry all power for the entire day along. A smaller battery results in a cheaper bus and also a lighter bus.

Drayson Racing - Plans to use Inductive Charging in race conditions

The other application that recently hit the news was to have inductive charging being used in the motor sports; Drayson in the UK plans to have a competition set up for electric car racing and the cars would then recharge in the pit lane by an inductive charger. Compared to for example Formula 1, this would take out the people responsible for refueling the car. Less people around the car during a pit stop results in less potential accidents. Also the other mechanics could still change tires if needed.

More of a really nice futuristic scenario is fitting this inductive charging technology onto our highways, allowing you to speed over the highways and getting charged while doing so. The main benefits from this would be that the battery size can be reduced a lot and that you don't have to stop to recharge your car when doing those long road trips.