Electric Vehicle Charging Infrastructure for Buildings

About this course.

EV charging has become a building issue because vehicles increasingly draw their energy from the building they are parked at, rather than from a separate fuel network, so the building's electrical supply, wiring and management must now accommodate a substantial new load. Where a petrol car is refuelled at a service station that has nothing to do with the owner's home or workplace, an electric vehicle is most often charged where it is parked — at home overnight or at work during the day — which places the charging equipment, its cabling and its demand squarely inside the building's electrical system. That makes charging a matter for designers, builders, electricians and building managers. The two main types of charging are AC charging and DC fast charging.

The starting point is to understand that "charging" always means delivering direct current into the vehicle's battery, but the point at which the conversion from alternating current happens differs between the two families. Buildings are supplied with alternating current, while batteries store and release direct current, so a conversion must occur somewhere between the supply and the battery. In AC charging, that conversion is done by a converter built into the vehicle itself — the on-board charger — and the equipment on the wall or pedestal simply supplies controlled AC and communicates with the car. In DC fast charging, the conversion happens inside the (much larger and more expensive) charging unit, which delivers direct current straight to the battery, bypassing the on-board charger's limits.