SLLA497 September 2020 TMS320F28P550SG , TMS320F28P550SJ , TMS320F28P559SJ-Q1
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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.
EVSE Type |
Power Supply |
Charger Power |
Charging Time* (approximate) for a 24-kWh Battery |
---|---|---|---|
AC charging station: L1 residential |
120/230 VAC and 12 A to 16 A (Single Phase) |
Approximately 1.44 kW to approximately 1.92 kW |
Approximately 17 Hours |
AC charging station: L2 commercial |
208–240 VAC and 15 A to approximately 80 A (Single/split phase) |
Approximately 3.1 kW to approximately 19.2 kW |
Approximately 8 Hours |
DC charging station: L3 fast chargers |
300 to 600 VDC and (Max 400 A) (Poly phase) |
From 120 kW up to 240 kW |
Approximately 30 Minutes |
A Level 1 EVSE uses commonly-available 120 VAC/230 VAC 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 VAC 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.
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.
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.
The power module in a DC charging station consists of AC/DC power stage and DC/DC power stage integrated into the charging station. Each converter is associated with its power stage comprises of power switches and gate driver, current and voltage sensing, and controller. Each of EV charging station power module subsystems are described in detail in the upcoming sections.