EV Chargers Charging Methods
A distinction is made between four charging modes where the term ‘mode’ refers to the charging technology (power, communication and safety).
Mode 1 is unlimited charging via a standard 230V AC outlet. The maximum charging current is 10A, depending on the region. This charging method works without a current limiter and is therefore rarely used for larger vehicles for safety reasons. This charging method is more suitable for e-bikes.
No test equipment is needed for this charging mode as this is basically just a cable connected to a standard wall socket.
Mode 2 is a safer way to charge via a standard 230V AC outlet. This uses a charging cable with a built-in current limiter. The electronics in the charging cable communicate with the car to start or stop the charging process. As in Mode 1, the charging current is 10A, or 2.3kW. Fully charging a 100kW battery, such as in the Tesla X, takes several days. In practical terms, this method is therefore only suitable for hybrid vehicles equipped with batteries smaller than 20kW.
No test equipment is needed for this charging mode as this is basically just a cable connected to a standard wall socket.
Mode 3 is metered charging, whereby communication takes place between the charging point and the vehicle regarding the correct power output. A separate circuit is provided to which the AC charging point is connected. This allows for higher power outputs of up to 7.4 kW single-phase, 22 kW (32 A x 3) three-phase, and even 43 kW (63 A x 3) three-phase. This charging method is the only one that is standardized and must comply with the IEC 61851 standard. To charge the battery, in Modes 1 to 3, the alternating current is converted to direct current by the inverter in the car.
Mode 4 is charging with direct current, also known as fast charging. The conversion from alternating current to direct current takes place at the charging point itself. This means that no converters are used in the electric vehicle. The charging point also controls the charging process and monitors the safety limits. Because the limits of the converter in the car do not have to be taken into account, much higher power levels can be used. This mode is used for fast charging with power levels from 50kW to >1MW. An example of this is the recently launched Tesla V3 DC supercharger, a charging station with four 250kW charging points and a total power output of 1MW.
Automated loading
In addition to connecting manually to charge the battery, there are also ways of automated charging, or Automated Connect Device (ACD).
Charging with a pantograph. This charging method delivers high conductive energy transfer from the charging infrastructure in a very short time. This charging method is mainly used for charging large electric vehicles such as buses, but also for other applications such as E-trucks and port and airport vehicles. Currently, two variants of these ACD systems are already widely used in buses, namely the top-down pantograph (built into the charging structure) and the roof-top pantograph (built into the roof). These systems are available in both AC and DC versions and can generate power up to +600kW. Developments are already underway for 900kW and 1200kW chargers. Communication to position the vehicle and connect to the charging point is wireless or via PLC.
Pantograph charging is mainly used for brief, very quick recharging of buses, for example at the terminus of a journey or at interchanges. In this way, city buses can be recharged in minutes for the next trip. In this method, the pantograph is built into the charging infrastructure. The roof top method is the most commonly used ACD charging variant. The pantograph is located on the roof of the bus and makes mechanical contact with the overhead charging infrastructure for charging.
Wireless induction charging. With this type of charging, charging takes place without the use of cables. Energy is transferred via a magnetic field. This field is created between two magnetic coils. One of these coils is located in the car and the other in the charging platform. Energy is transferred via a magnetic field between the two coils. Induction charging uses alternating current, which is converted to direct current in the vehicle. Efficiency is still an area that needs improvement. Power losses during induction charging can be as high as 25%. This charging method is still under development and is currently only used for lower power ratings. No standards have been established yet.
