A charging station is part of the grid infrastructure installed along a street, parking lot or in a home garage; its primary purpose is to supply the power to the PHEV for charging the battery. There are mainly two types of charging systems, as shown in Table 1-1: AC and DC charging systems.

An AC charger powers the EV battery through the vehicle’s on-board charger, while a DC charger directly charges the vehicle’s battery.

Table 1-1 details the charging stations classified based on power levels.

A Level 1 EVSE uses commonly-available 120 V_AC/230 V_AC power sources, draws current in the order of a 12 A to 16 A range and can take anywhere from 12 to 17 hours to fully charge a 24-kWh battery. L1 chargers can go up to a maximum power of 2 kW and is used in residential applications. A Level 2 EVSE (typically used in commercial spaces such as malls, offices, and so forth) uses poly-phase 240 V_AC sources to power a more robust vehicle charger and draws anywhere between 15 A and 80 A to completely charge a 24-kWh battery in about eight hours (power level up to 20 kW). Figure 1-1 shows a typical block diagram of an AC charging station.

Figure 1-1 AC Charging Station.

The DC charging station is a Level 3 charger which can cater for very high power level in the range of 120 to 240 kW. The L3 chargers typically charge batteries to 80% State of Charge (SOC) in under 30 minutes. To achieve such high power levels modular converters which can be stacked are used. Stacking of converters inside the vehicle makes the vehicle bulky. Hence, these stacked converters are placed outside the vehicle and constitute the EV charging station. The EV charging station is directly interfaced with the battery of the vehicle bypassing the onboard charger. Figure 1-2 shows a typical block diagram of a DC charging station.

Figure 1-2 DC Charging Station.

For more information on on-board chargers and off-board chargers, see the Taking charge of electric vehicles – both in the vehicle and on the grid white paper.