The charging pile is fixed on the ground, uses a special charging interface, and adopts the conduction method to provide AC power for electric vehicles with on-board chargers, and has corresponding communication, billing and safety protection functions. Citizens only need to buy an IC card and recharge, and then they can use the charging pile to charge the car.
1. Charging principle of charging pile
The charging pile is fixed on the ground, uses a special charging interface, and adopts the conduction method to provide AC power for electric vehicles with on-board chargers, and has corresponding communication, billing and safety protection functions. Citizens only need to buy an IC card and recharge, and then they can use the charging pile to charge the car.
After the battery of the electric vehicle is discharged, direct current is used to pass through the battery in the opposite direction to 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 to the positive pole of the power supply, and the negative pole of the battery is connected to the negative pole of the power supply. The charging power supply voltage must be higher than the total electromotive force of the battery.
2. There are two charging modes: constant current charging and constant voltage charging.
Constant current charging method：
The constant current charging method is a charging method that keeps the charging current intensity unchanged by adjusting the output voltage of the charging device or changing the resistance in series with the battery. The control method is simple, but because the acceptable current capacity of the battery gradually decreases with the charging process, in the later stage of charging, the charging current is mostly used for electrolyzing water, generating gas, and making the gas out too much. Therefore, the stage charging method is often used.
Constant voltage charging method：
The voltage of the charging power supply maintains a constant value throughout the charging time, and as the battery terminal voltage gradually increases, the current gradually decreases. Compared with the constant current charging method, the charging process is closer to the optimal charging curve. For fast charging with constant voltage, since the electromotive force of the battery is low in the early stage of charging, the charging current is very large, and the current will gradually decrease as the charging progresses, so only a simple control system is required.
3. The difference between DC charging piles and AC charging piles
DC charging pile:
The DC electric vehicle charging station, commonly known as "fast charge", is a power supply device that is fixedly installed outside the electric vehicle and connected to the AC power grid to provide DC power for the off-board electric vehicle power battery. The input voltage of the DC charging pile adopts three-phase four-wire AC380V±15%, the frequency is 50Hz, and the output is adjustable direct current, which directly charges the power battery of the electric vehicle. Since the DC charging pile adopts a three-phase four-wire system for power supply, it can provide sufficient power, and the output voltage and current adjustment range is large, which can meet the requirements of fast charging.
AC charging pile:
AC electric vehicle charging pile, commonly known as "slow charge", is a power supply device that is fixedly installed outside the electric vehicle and connected to the AC power grid to provide the AC power supply for the electric vehicle on-board charger (that is, the charger that is fixedly installed on the electric vehicle). The AC charging pile only provides power output and has no charging function. It needs to be connected to the on-board charger to charge the electric vehicle. It is equivalent to just playing the role of a control power supply.
The difference between the two: In simple terms, the AC charging pile needs to be charged with the help of an on-board charger, and the DC fast charging pile does not need this equipment. The charging speed of the two is quite different. It takes 8 hours for a pure electric vehicle (ordinary battery capacity) to be fully discharged through an AC charging pile, while it only takes 2 to 3 hours to pass through a DC fast charging pile. The AC charging pile provides power input to the charger of the electric vehicle. Since the power of the on-board charger is not large, fast charging cannot be achieved. The DC fast charging pile is a power supply device that is fixedly installed outside the electric vehicle and connected to the AC power grid, and can provide DC power for the power battery of the non-vehicle electric vehicle. The DC charging pile can provide sufficient power, and the output voltage and current can be adjusted in a wide range. , can meet the requirements of fast charging.
