Wireless charging of electric vehicles: Share your views!

Electric vehicles (EV) can be charged in different ways, with different technologies. The conventional charging method is using a cable (also known as conductive charging or plug-in charging) to connect the EV to the charging infrastructure. This method requires the EV to be compatible with the charging infrastructure
(also known as charging point) by having a compatible connector (consisting of plugs and sockets). There is a number of charging point types, each able to deliver different levels of power to the EV and therefore charge it in different amount of time but will typically take from around 7-8 hours to charge a fully depleted battery from a slow/domestic-type charger to 20-30 minutes to charge a battery to 80% from a rapid charger. The construction of the charging point will differ depending on the power supply it is designed to
provide to the EV, and therefore the price and complexity also varies considerably. Charging points are usually part of various charging schemes and require users to gain access to the charger by using some form of smart card or a pin number. Then, the user is able to plug in their EV.

The other method of charging is wirelessly, using wireless power transfer (WPT), also sometimes referred to as inductive charging or inductive power transfer (IPT). It should be noted that WPT is not a complete replacement for plug-in charging but is an additional method of charging. When using WPT to charge an EV there is no physical connection or contact between the vehicle to be charged and the power supply. As there is no need for the user to plug in, the process is also typically fully automated, requiring no interaction from the user other than from the vehicle dashboard to confirm the start of the charging process. The charging process automatically stops when the user drivers away. Although the technology for WPT is well
developed and has been applied in industrial applications for many years, its application in the transport sector is still new.

As the charging process is automated and there is no need for the driver to get out of the vehicle or to physically connect to any device, WPT charging can be used while the vehicle is moving or is stationary for short periods of time at traffic lights or other stops (also known as en-route charging). As the application of WPT charging in transport is still new, there are some possible disadvantages such as uncertainty over whether different manufacturers' systems will be interoperable, additional cost and weight of the vehicle coils and the cost of the ground coils. It is also likely that different types of coils will be required for different vehicle classes with larger coils necessary for higher power transfer in larger vehicles such as buses and trucks and smaller coils required for cars and vans.

The biggest possible impact of using WPT is that it allows much more opportunistic charging of EV batteries. Opportunistic charging is any charging process that takes place over a short period of time during the vehicle's typical use. This charging is typically done ad-hoc, as opposed to predetermined charging at work place or overnight at home. Opportunistic charging has the potential to significantly improve EV range without increasing the size and cost of the batteries. It may even allow for use of smaller batteries; therefore, reducing the price and weight of required EV batteries. By allowing more EVs to complete more electric miles, WPT charging (particularly en-route charging) could have an overall impact on reducing
emissions, improving air quality and reducing running costs for EVs further. It may also allow for a greater variety of vehicles to be electric as battery size, weight and range may no longer be a constraint.

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