Electric Car Wireless Charging: How Does It Work?

Manufacturers News

Aug 26th, 2020

Electric Car Wireless Charging: How Does It Work?

Australia has just completed laying the foundation of electric car technology recently. Meanwhile, technology has once again taken a fast step as other global regions are moving ahead with electric car wireless charging

One would even think that Australia is but playing catch to Norse in this game, and rightly so. The Scandinavian group, for some time now, has been a trend-setter in the automotive industry, and their latest feat confirms it. Norway has become the first country in the world to employ wireless technology to charge taxis.

Wireless Charging History

Although it hasn’t been implemented in autos until recently, wireless charging has been around for some time now. The underlying concepts of the technology were first discovered in the late 19th century by Serbian inventor Nikola Tesla. 

Tesla proved magnetic resonant coupling – the technology behind transmitting electricity through the air. This technology didn’t find application in many areas until the 21st century. Today, various industries, including the automotive sector, are applying it. 

How does wireless electric car charging work?

This might surprise you but charging cars without the cord works just the same as wireless phone charging. The only difference is that, for electric car wireless charging, it is on a larger scale. The distance measurements change from a few millimetres to inches. 

Wireless EV charging is based on a concept called inductive charging that allows electricity to be transferred through the air from one magnetic coil (transmitter) to another (receiver). One coil is fitted in the charger, whereas the second one is installed within the car. For charging to take place, you need to park your vehicle in a way that allows the alignment of coils.

Inductive charging typically involves three primary elements, i.e. a power source, a ground assembly component (say, an induction pad), and the corresponding component installed in the vehicle to receive the charge.

The currently available wireless car chargers in the market (for instance, those supplied by Plugless), transmit electricity across a distance of 4 inches. They also require you to have a wireless adaptor set on the underside of the car.

Which cars can be charged wirelessly today?

At present, there aren’t many models that are compatible with wireless EV charging. BMW announced that it would begin commercial sales of a wireless charging pad this year for its executive plug-in hybrid sedan, 530e iPerformance. 

It’ll take 3 ½ hours to fully charge a battery. The pad connects to a standard power outlet and wirelessly charges a car, which should be parked in the correct position. US-based electric equipment manufacturer Plugless also has wireless chargers for several EVs, including Nissan Leaf, Chevrolet Volt, and Tesla Model 3.

The Plugless wireless EV charging system involves a charger and a power receiver. The receiver requires an expert to install it and is removable. Prices for the chargers start at $1,260 (AUD 1,765) for Chevrolet’s Volt and go up as high as over $3,000 (AUD 4,200) for the Model 3.

In Norway, the induction plates will be fitted in Jaguar I-Pace taxis. Momentum Dynamics will supply the induction plates, which will be installed by Fortum Recharge. With this device, the taxis will be able to charge as they wait for customers. 

Australia hasn’t been left behind in this. Aussie-based firm Lumen Freedom has recorded tremendous progress in its quest to implement wireless electric car charging. The company recently became the first to have wireless EV charging technology approved for public use.

Wireless Charging: Static and Dynamic 

Broadly, there are two types of wireless electric car charging: static and dynamic.

Static wireless charging happens when a car is parked idle in the designated charging zone, while dynamic occurs on the go as you drive, e.g. along an electric wireless highway. The static technology is much more advanced compared to dynamic, which is on its infancy.

Why is there a need to invest in a project that’s complex and wide-ranging as an electric charging highway? General Manager Rod Wilson of Lumen Freedom explains that the new technology is centred on removing range anxiety by providing widespread access to charging. Wilson compares dynamic charging to snack-charging such that car owners can add juice to their EVs at points such as traffic lights since there’ll be a blanket area for EVs with inductive charging.

Are all EVs compatible with public wireless charging?

This is a question many car owners ask, and to answer it - No. EV Council CEO Behyad Jafari states that, so far, only the Jaguar I-Pace is compatible, but adds that Nissan, BMW, and Mercedes Benz are also working to embrace this technology. 

On whether there are any public wireless electric car charging facilities in Australia, Behyad answers that there is none, although some companies are working on it.  

Momentum Dynamics, the company that supplies induction plates to the Oslo project, has its operation stationed in the US but plans on extending to other countries in Europe.

Benefits of Wireless Charging

Convenience remains to be the most significant advantage, just like wireless charging in smartphones. Just imagine how simplified it is for your EV to start charging as soon as you park it in the garage. You don’t have to worry about finding the charging cable and plugging it.

According to Momentum Dynamic’s head of communication Michael McHale, wireless charging is a boon for the Oslo taxi project in Norway. He further explains the four-fold benefit of the technology. 

  • It ensures high utilisation of vehicles, which means no revenue is lost. 
  • It also extends range, which means that fewer vehicles are needed to fulfil a duty cycle.
  • Partial charging ensures the batteries remain in mid-range, a factor that extends their life. 
  • Wireless EV charging lowers the overnight load on the depot as the vehicles return in a high state of charge.

Another benefit of electric car wireless charging is that it makes things easier for people with disabilities. One of the biggest challenges of wired charging, as explained by McHale, is ensuring that the height is set right for easy access to people with disabilities. Wireless charging eliminates this difficulty.

Lastly, it keeps the environment cleaner and more aesthetically pleasing. Instead of having a series of cable chargers in the streets, we’ll have invisible charging points. 

It is even possible to have a wireless charger for your EV at home, although there aren’t many such options in Australia yet. Most of the wireless charges being built have a spec range of 11kW-75kW, which are ideal for overnight charging as opposed to fast charging during the day. Wilson explains that this will advance as the wireless EV charging technology keeps progressing by the day.

Momentum Dynamics has already built rapid DC wireless charging that goes up to 450kW, which means it can charge a vehicle battery up to 80% in 15 minutes. The Norway project, on the other hand, has wireless charging in the range of 75kW, which is capable of charging a battery to full capacity in about an hour or so. 

Wrap Up

It doesn’t take a lot to connect the dots and discover how practical wireless EV charging would be to the autonomous cars of the future. Self-driving taxis would be able to stay charged continuously on the road as they drive, eliminating any need for human intervention. 

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