The difference between DC charging pile and AC charging pile
1. Charging principle of charging pile
The charging pile is fixed on the ground, uses a dedicated charging interface, and adopts a conductive 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 it, and then they can use the charging pile to charge the car.
After the electric vehicle battery is discharged, direct current is used to pass the battery in the opposite direction to the discharge current to restore its working ability. This process is called battery charging. When the battery is charged, the positive electrode of the battery is connected to the positive electrode of the power source, and the negative electrode of the battery is connected to the negative electrode of the power source. The voltage of the charging power source must be higher than the total electromotive force of the battery.
2. Charging method of charging pile
There are two charging methods: constant current charging and constant voltage charging.
Constant current charging method
The constant current charging method is a method of adjusting the output voltage of the charging device or changing the resistance in series with the battery to keep the charging current intensity constant. The control method is simple, but because the acceptable current capacity of the battery gradually decreases with the progress of the charging process, in the later stage of the charging, the charging current is mostly used to electrolyze water to generate gas and cause excessive gas out. Therefore, the stage charging method is often used.
Constant voltage charging method
The voltage of the charging power supply maintains a constant value during the entire charging time. 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. Fast charging with constant voltage, because the battery electromotive force is low at the beginning of charging, the charging current is large, and the current will gradually decrease as the charging progresses. Therefore, only a simple control system is required.
3. The difference between DC charging pile and AC charging pile
DC charging pile: DC electric vehicle charging station, commonly known as "fast charging", 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 non-vehicle electric vehicle power batteries. 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 can be adjusted in a wide range, which can meet the requirements of fast charging.
AC charging pile: AC electric vehicle charging pile, commonly known as "slow charging", is fixedly installed outside the electric vehicle and connected to the AC grid to provide AC power for the on-board charger of the electric vehicle (that is, the charger that is fixedly installed on the electric vehicle) Power supply device. 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 a role in controlling the power supply.
The difference between the two: Simply put, the AC charging pile needs to be charged with the help of an on-board charger, while the DC fast charging pile does not require this device. There is a big difference in the charging speed between the two. It takes 8 hours to fully charge a pure electric vehicle (normal battery capacity) through the AC charging pile, while it only takes 2 to 3 hours to pass through the 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 realized. 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. It 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 realize the requirement of fast charge.