Functional requirements analysis of Separated DC fast charger


Electric vehicle Separated DC fast charger is a power supply device fixed on the outside of the electric vehicle to provide high power DC charging function for the electric vehicle power battery

The current national standards for charging facilities of electric vehicles specify the charging control guidance process and fault protection process handling of Separated DC fast charger.The functions of touch screen monitoring, charging and networking monitoring are explained in the general technical specifications of the State Grid.Based on the above two design standards, and taking into account the higher security and compatibility requirements of Separated DC fast charger due to the development of charging facilities, the functions of Separated DC fast charger are divided into the following four categories.

Charge control function is the most basic function of Separated DC fast charger, which is powered by AC and provides safe and reliable DC charging function for electric vehicle.Specifically, the Separated DC fast charger should provide low-voltage auxiliary power supply for EV to supply power for EV battery management system during charging, and the power supply voltage should be 12vdc.Separated DC fast charger should be compatible with old and new national standard protocols, connect automatically after inserting the gun and charge control, and disconnect automatically after charging is completed.During the charging process, Separated DC fast charger dynamically adjusts the charging parameters according to the data provided by the battery management system, performs the corresponding actions, and completes the charging process.

Failure protection is an important function of Separated DC fast charger. Separated DC fast charger is required to detect faults in time and handle the corresponding faults according to the fault level.Specifically, the monitoring unit should be able to detect and warn, including AC voltage failure, AC overvoltage, AC overcurrent, AC undervoltage, insulation monitoring failure, short circuit, charging overcurrent, charging connection failure, etc.It should have an emergency stop switch to stop charging urgently through manual or remote communication instructions.The system should have interlocking function to ensure that the vehicle cannot start until it is separated from the electric vehicle.

Human-computer interaction is a function related to the charging user of Separated DC fast charger. Users can control the charging process, view the charging status and charge measurement through the external device of Separated DC fast charger.These include: Separated DC fast charger needs to provide display function;Separated DC fast charger should have the function of detecting and measuring the output energy;Monitoring unit should be able to set parameters through foreground and background software.

Networking monitoring is a Separated DC fast charger function related to system monitoring and networking.Specifically, the monitoring unit should be able to upload related data through the communication interface with the background software communication group network, and accept the control of the background software to perform the corresponding operations.

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