Charging principles of EV charging station
The EV charging station is fixed to the ground, uses special charging interface and adopts conduction mode to provide AC power for the electric vehicle with on-board charger. It has corresponding communication, billing and safety protection functions. Citizens only need to buy the IC card and top it up to charge their cars with high power EV charger.
After discharging the battery of electric vehicles, the direct current is used to pass the battery in the opposite direction from the discharge current to restore its working capacity. This process is called battery charging. When charging the battery, the positive pole of the battery is connected with the positive pole of the power supply, the negative pole of the battery is connected with the negative pole of the power supply. The voltage of the charging power supply must be higher than the total electromotive force of the battery.
Charging methods of EV charging pile
1. Constant current charging method
The constant current charging method is to adjust the output voltage of the charging device or change the series resistance of the battery to keep the charging current intensity unchanged.
The method is simple. However, due to the acceptable current capacity of the battery decreases gradually along with the electric vehicle charging process, in the late charging period, the charging current is mostly used for brine electrolysis to generate redundant gas. Therefore, the stage charging method is often used.
2. Constant voltage charging method
The voltage of the charging power supply remains constant value throughout the charging time, the electric current decreases gradually as the terminal voltage of the battery increases gradually. Compared with the constant current charging method, the electric vehicle charging process is closer to the optimal charging curve.
Because the battery electromotive force is low at the beginning of charging and the charging current is very large, quick charging with constant voltage will lead to the gradual current being reduced with the charging, therefore, it only requires a simple control system.
Requirements of the construction of EV charging pile
The special structure of EV charging pile determines its wide use and it can solve charging problem.
1. Communication reliability: The communication system should withstand the test under a harsh environment and strong electromagnetic or noise interference for a long time, but still maintain smooth communication.
2. Construction cost: On the premise of satisfying reliability, comprehensive consideration is given to the construction cost of automobile charging pile and the cost of long-term maintenance.
3. Two-way communication: It can both upload information and publish control.
4. Multi-service data transmission rate: With the continuous growth of terminal traffic in the future, the communication between the primary station and the sub-station of EV charging pile and the sub-station and the terminal will have more requirements for multi-service data transmission rate.
5. Communication flexibility and expansibility: Because the EV charging pile (bolt) has the characteristics of multiple control points, wide area and scattered, it requires the standard communication protocol.
With the development of “ALLIP” network technology and the continuous growth of power operation business, we need to consider the IP-based service carrying, at the same time, make EV charging piles easier to install, construct, debug, operate, and maintain.