E S S E N T I A L S M E M B E R S
Plugged In: Explaining Electric & Hybrid Vehicle Tech “MOST EVS HAVE AN ON-BOARD CHARGER THAT RECTIFIES AC FROM THE MAINS GRID AND THEN PROVIDES DC EV CHARGING STANDARDS TO CHARGE THE BATTERIES.” AND INFRASTRUCTURE KEITH MINCHIN TECHNICAL ELECTRICAL TRAINER MTA INSTITUTE
ALL ELECTRIC AND Plug-in Hybrid Vehicles require a source of AC (Alternating Current) or DC (Direct Current) power to recharge their batteries. The power is usually supplied from the power grid, and in Australia residential charging is usually sourced from a 230V/240V single-phase 10-amp socket. Although there are variants such as 15A outlets and other specialised industrial applications, most vehicles will be connected to a 10amp socket in the home environment. In this case the power available to charge the vehicle is limited to 240V x 10A = 2400 Watts. Electric vehicles are usually supplied with a charger that has a wall socket on one end and a vehicle plug on the other end. In addition, the vehicle will most likely be supplied with another charging lead to allow connection to a fast charger. Ok, so nothing you didn’t already know here. But maybe we should take a deeper dive into charging connections and how they work?
HIGH POWER CHARGING A hardwired single-phase charger can provide much higher levels of power than connecting to a standard 10A domestic socket. The exact amount of power available will depend upon the individual premises and grid connection. However, increases in power availability up to 98 | Motor Trader October 2020
around 7.2kW can be achieved with a single-phase connection. To supply the higher levels of power required for even faster charging, a threephase connection is required. It’s worth noting at this point that a three-phase connection could be wasted when charging some PHEV’s (plug-in hybrids) and EVs since they are not capable of taking a higher rate of charge, so a hardwired single-phase charger may be sufficient. Three-phase is commonly used in industrial applications and can provide higher levels of power due to the fact that there are three active phases 120° apart at a frequency of 50Hz supplied at around 400/415V. Three-phase chargers are not commonly used in residential applications.
DC FAST CHARGING Due to the complexity of the equipment and the amount of power needed, DC fast chargers are rarely found in residential premises. Most EVs have an on-board charger that rectifies AC from the mains grid and then provides DC to charge the batteries. Cost and thermal constraints will limit how much power the on-board rectifier can handle. For charge rates exceeding around 240V/30A, it is better to have an external charge station provide a vehicle with DC. Power limitation when charging from a DC fast charger is more likely to be