Automotive

BMW developing wireless inductive charging system for electric vehicles

The BMW charging system uses a primary coil in the floor and a secondary coil in the car
The BMW charging system uses a primary coil in the floor and a secondary coil in the car
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Architecture and structure of inductive charging
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Architecture and structure of inductive charging
The system can aid in parking over the primary coil
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The system can aid in parking over the primary coil
Diagram of the charging system
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Diagram of the charging system
The charging system provides updates via an app
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The charging system provides updates via an app
The BMW charging system uses a primary coil in the floor and a secondary coil in the car
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The BMW charging system uses a primary coil in the floor and a secondary coil in the car
The system provides charging updates
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The system provides charging updates
Coil positioning aid in operation
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Coil positioning aid in operation
The system can charge an all-electric car overnight
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The system can charge an all-electric car overnight
Details of the charging system
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Details of the charging system

Electric vehicles and plug-in hybrids may be green and sustainable, but that doesn't mean much if you forget to plug them in the night before. To overcome this frustrating morning surprise, BMW Group is developing a new generation of wireless inductive charger technology that’s comparable in speed to cables, but requires no more effort than parking and pressing a button.

BMW sees premium market electric cars as a major part of the automotive future. The company already has its all-electric i3 and i8 plug-in hybrid sports car, both of which are designed for quick charging using the BMW i Wallbox. Now the company wants to take this a step further with an induction charging system as a way to make electric cars more attractive to the public.

The new induction system is designed to work with the BMW i car batteries and those under development by the company. In addition, Daimler and BMW have entered into joint development of standardized inductive chargers with the aim of making electric cars more mainstream. Inductive charging has the advantages of being user friendly and there’s no need for connectors, which BMW sees as the crucial advantage of the new charger.

Architecture and structure of inductive charging
Architecture and structure of inductive charging

Not having connectors means one less thing to remember and one less thing to suffer from mechanical wear. Without the need for a connection, the driver has only to drive over the charge station, activate it with a press of a dashboard button. The system then does the rest while keeping the driver updated on charge status and time remaining by means of a Wi-Fi connection between charger and car and a smartphone app. BMW says the app can even help the driver park the car properly over the charger.

How it works

The system consists of two components – a primary coil that is installed in a base plate on the floor of a garage or car port, and a secondary coil that is installed in the floor of the car. Both coils are circular to keep them compact, lightweight, and the magnetic field confined to a small area for safety. An alternating magnetic field in the primary coil transmits power to the secondary coil at a rate of 3.6 kW, which is enough to fully charge the high-voltage batteries in many plug-in hybrids in under three hours.

BMW says that the prototype system has an efficiency of 90 percent and can charge the BMW i8 in less than two hours. To make the charger suitable for all electric cars instead of hybrids, the company is working on boosting the charge rate to 7 kW, which would charge a BMW i3 overnight.

Since all the system's conductive components are protected, weather conditions don't have an effect on the power feed, meaning it can be installed indoors or out. The system continually monitors the space between th primary and secondary coils, so that If a foreign object enters the field, the system cuts out automatically.

BMW says its medium term goal is to put into production a user-friendly inductive charging system that is reliable and non-wearing that will be compatible with the batteries in its existing i cars, as well as the high-voltage batteries in future plug-in hybrid models.

Source: BMW

10 comments
myale
So to the question on efficiency and whether the 10% loss during charging would be incorparated into the miles per charge equation - my guess is it would probably be not
Mel Tisdale
I'm going to need a warning when I open the driver's door that I haven't switched it on. Failing that, there will some tantrums the following morning, and I cannot guarantee that naughty words won't be used. On an even more serious note, how can we say that electric cars are any real replacement for petroleum fuelled ones when it is going to take overnight to charge some of them. What an awful situation. After a lovely meal, the girlfriend asks you if you would like to go back to her place for a 'coffee' and you have to worry about not being able to get to work in the morning. I know what I would choose (I never really did like the job, all that much, anyway.)
pmshah
So what would happen to all the magnetically conductive components of the car that fall within the field of the charge system ? Won't this also act as an induction hot plate? One could probably cook a meal sliding a pot under the car !
StWils
Mel: make sure your date does NOT know she was chosen because she was less than 50% of your vehicle's range from home. This small bit of information probably would not be interpreted kindly. This is sort of like Elaine, (on Seinfeld), deciding if a possible date is "spongeworthy" or not.
Don Duncan
Obviously there will be a warning light & alarm as a reminder to press: "charge". And every shopping mall will provide chargers. probably free. This is so much better than plugging in. It allows charging while out & about or at work without hassle. And if you just make it to the charger on empty, your phone will alert you when the battery will get you home. It may mean waiting an extra 30-90 minutes but this is a learning curve. Soon, you will know the waiting time for all your destinations, and can plan accordingly.
Bob
I have been wondering about a special lane on the highway that would provide induction charging for cars and trucks so that they could charge on the go. Putting these on uphill grades could greatly extend the range of electrics.
Foofaraw
Sorry...don't want to plan around my car. I don't need to now, so why should Electric Car be any different. Too busy and time is money. Is that advancement when you need to wait? No, it's not. I want my future vehicle to be more efficient and better all the way around...or scrap it.
christopher
Conductive tires and a charge-grid-floor, just like dodgem/bumper cars use at the showground, sounds a much more sensible idea.
Jacob Hernandez
@pmshah I don't think this is normal induction charging method, like the one in toothbrushes. I believe it can span that much larger distance due to resonant inductive coupling. on a side note this does solve some problems in the future, eventually it could be more like a supercharger or even more. One of the problems is for high amperage situations, very large bulky cables are required
Tuppe
I planned about this system few years ago, to cars' blockheater for winter time in Finland. 100% of the cars have to be plugged in every day if you want to start it in the next day without blowing up the engine in -20-30c environment. I cancelled the project due to lack of resources, and possible hazards due to retrofitting high energy magnetic fields without having all around protection to the car's electronics. I wish this system becomes available soon. Plugging wires everyday is so 1940s.