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The charging principle of the charging pile mainly includes two modes: AC charging and DC charging, as follows:
AC charging
AC charging piles use alternating current to transmit electrical energy to the battery of electric vehicles. This charging method is slower because AC charging piles provide a lower current. AC charging piles are usually used in scenarios where long-time charging is required, such as parking lots or home charging equipment.
Direct Current Charging
DC fast chargers use direct current (DC) power to transmit energy directly into the battery of electric vehicles. This charging method can quickly charge electric vehicles because DC fast chargers can provide a higher current. DC fast chargers are typically used in scenarios that require rapid charging, such as charging stations on highways.
The specific working process of DC charging pile
Input Distribution: The input distribution section of a DC charging pile includes protective circuit breakers, lightning protection units, and input energy meters. These components serve protective functions such as lightning and short-circuit protection.
Main Circuit: The main circuit’s input is three-phase AC power, which after passing through the input circuit breaker and AC intelligent electric energy meter, is converted into DC current that the battery can accept by the charging module (rectifier module). It is then connected to a fuse and charging gun to charge the electric vehicle.
Secondary Circuit: The secondary circuit consists of a charging pile controller, card reader, display screen, DC electricity meter, etc. The secondary circuit provides start and stop control and emergency stop operation; signal lights provide standby, charging, and full state indications; the display screen, as a human-machine interaction device, provides card swiping, charging mode setting, and start and stop control operations.
Charging Process: Apply a direct current (DC) voltage to both ends of the battery, charging it with a constant large current. The battery’s voltage gradually and slowly increases until it reaches a certain level, at which point the battery voltage achieves its nominal value and the State of Charge (SoC) reaches above 95%. Charging then continues with a constant voltage and a small current. To implement this charging process, the charging pile needs to have a DC charging module to provide DC power; a charging pile controller to manage the startup, shutdown, output voltage, and output current of the charging module; and a touch screen as a human-machine interface to send commands, which are then transmitted by the controller to the charging module.
Communication and Monitoring: Whether it’s direct current (DC) charging or alternating current (AC) charging, the charging pile needs to communicate with electric vehicles to ensure the safety and effectiveness of the charging process. The charging pile needs to detect the battery status and charging requirements of the electric vehicle, and adjust the charging power and current based on this information. At the same time, the charging pile also needs to monitor the temperature and voltage during the charging process to ensure the stability and safety of the charging process.
Through the above steps, electric vehicle charging piles can effectively provide the required electricity for electric vehicles, supporting the popularization and development of electric vehicles.
