Dynamic load management distributes the maximum available mains power evenly among the connected electric vehicles and thereby allows the operation of multiple charging points from a limited mains connection.
There are two main possibilities for supplying a charging infrastructure:
Optimum load management depends on the capacity of the network connection, use of the phase rotation when connecting the charging point and corresponding configuration of the charging network. Within a network one charging point always performs the coordination function. All other charging points communicate with the coordinator and regulate the power output accordingly. Communication takes place via Ethernet or WLAN.
All connected electric vehicles (EV) charge at full charging power until the rated current of the fuse (maximum supply line current) is reached. As soon as a another vehicle wants to charge, charging currents are distributed evenly among all vehicles. This prevents critical overloading of the supply line. Once it has been established that an EV has finished charging, the available power is then redistributed among the other vehicles that are still charging. The charging stations communicate with each other by cable over Ethernet or wirelessly over WLAN via a suitable access point.
Different DLM networks can also be set up which are in the same data network. This is useful, for example, if it is intended that only certain charging stations communicate with a common backend. The charging stations communicate with each other within their DLM network by cable over Ethernet or wirelessly over WLAN via a suitable access point. The IT network is identical for all DLM networks.
The load management ensures that sum of the charging currents in a charging network does not exceed the mains connection capacity. The present energy consumption of the external loads is captured by means of an additional external energy meter. The coordinator wall box uses Modbus TCP to communicate with the meter and regularly enquires about the present consumption. Accordingly, the meter must be provided with an Ethernet interface and be capable of TCP/IP communication. The coordinator subtracts the values sent by the meter from the mains connection current limitation value set and makes the resulting power evenly available to the charging network.
The total of all charging currents in a DLM network must not exceed the mains connection capacity. The present total load of a mains connection is captured by an additional external meter. The coordinator wall box uses Modbus TCP to communicate with the meter and regularly enquires about the total consumption. Accordingly, the meter must be provided with an Ethernet interface and be capable of TCP/IP communication. The coordinator regulates the individual charging currents in such a way that the total consumption does not exceed the mains connection current limit.
In this case, the wallboxes in the charging group have communication interfaces allowing connection to an intelligent energy management system. This controls all system inflows and outflows and directs the group. Accordingly, either each charging station individually or the charging group as a whole can be control by the EMS.
