How does a DC charging station work?

How does a DC charging station work?

The DC EV charging system consists of three parts: charging station, charging gun, and electric vehicle, as shown in the following figure.

1.The three-phase AC power of the main circuit is connected to the rectifier module of the charging station through the AC switch k0. After rectification, it outputs DC power, which is then connected to the charging gun through the DC switches K1 and K2. Finally, it is connected to the vehicle socket through the charging gun to supply power to the power battery pack.

2.The control circuit is mainly used to complete control functions such as confirming the connection between the vehicle and the pile, exchanging data, and output auxiliary power supply.

DC charger working principle

1. Charging station power on stage: K0 is engaged, and three-phase AC power is connected to the input terminal of the

rectifier module; At the same time, switch K is closed, and the auxiliary power supply obtains 220V AC power and outputs 24V/12V DC power to supply power to the internal controller, detection circuit, and other components of the charging pile. Charging gun connection and auxiliary power supply stage: After the charging gun is inserted into the vehicle socket, the electronic lock of the gun head automatically locks to ensure safe connection; The auxiliary contacts K3 and K4 are closed accordingly, and the auxiliary power supply supplies power to the vehicle end through the A+/A - line, providing working power for the vehicle controller.

2. The vehicle pile starts message interaction through the CAN bus.

3. The charging module starts boosting, the DC contactors K1 and K2 are closed, and the system enters the insulation detection process;

4. The insulation detection is completed, the DC contactors K1 and K2 are disconnected, the discharge circuit is conductive, and the residual voltage detected is below 60V before proceeding to the next step.

5. K5 and K6 at the vehicle end are closed, and the voltage of the power battery pack is sent in reverse to the outside of K1 and K2; The charging module immediately starts boosting for pre charging to avoid direct impact on the charging station caused by closing the switch. When the voltage difference between the inner and outer sides of K1 and K2 is detected to be stable within the range of 1-10V, K1 and K2 are engaged, the main charging circuit is turned on, and the system enters the normal charging stage.

During the charging process, the voltage and current output by the charging station will dynamically respond to the instructions of the vehicle BMS for real-time adjustment.

6. Stop charging initiated by the pile or vehicle end, disconnect K1, K2, K5, K6 to start discharging, disconnect auxiliary power relays K3, K4, press the electronic lock of the charging gun, pull out the gun and return it to its original position.