1. Charging principle of charging pile
As is known to all, the charging pile is a charging facility for "refueling" electric vehicles.
The charging pile is fixed on the ground, and the special charging interface and conduction mode are used to provide ac and dc power for ev with on-board charger, with corresponding communication, billing and safety protection functions. Citizens only need to scan the code to pay or IC card recharge to pay, can use the charging pile to charge the car.
After the discharge of the battery of an electric car, direct current is used to pass through the battery in the opposite direction from the discharge current to restore its working capacity. This process is called battery charging. When the battery is charged, the positive electrode of the battery is connected with the positive electrode of the power supply, while the negative electrode of the battery is connected with the negative electrode of the power supply. The voltage of the charging power supply must be higher than the total electromotive force of the battery.
2. Charging principle of charging pile
There are two charging modes: constant current charging and constant voltage charging.
1) constant current charging method
Constant current charging method is a charging method that keeps the strength of charging current unchanged by adjusting the output voltage of the charging device or changing the series resistance with the power battery. The control method is simple, but the acceptable current capacity of the battery decreases gradually with the progress of the charging process. In the later stage of charging, the charging current is mostly used for electrolysis of water to produce gas, which leads to excessive gas output. Therefore, the stage charging method is often used.
2) constant voltage charging method
The voltage of the charging power supply keeps a constant value during the whole charging time. With the gradual increase of the terminal voltage of the battery, 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, due to the low electromotive force of the battery at the beginning of charging, the charging current is very large, as the charging goes on, the current will gradually reduce, therefore, only a simple control system.
3. Difference between dc charging pile and ac charging pile
1) dc charging pile
Dc ev charging station, commonly known as "quick charging", is a power supply device that is fixed on the outside of the ev and connected to the ac grid, and can provide dc power to the power batteries of non-vehicle-mounted ev.
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, directly charging the power battery of the ev. Because the dc charging pile adopts three-phase four-wire power supply, it can provide enough power, and the output voltage and current are adjusted in a wide range, which can realize the requirement of quick charging.
2) ac charging pile
Ac ev charging pile, commonly known as "slow charging", is a power supply device that is fixed outside the ev and connected to the ac power grid to provide ac power to the ev on-board charger (namely the charger fixed on the ev).
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 ev. It just ACTS as a power source.
3) the difference
To put it simply, ac charging pile needs to be charged by vehicle charger, while dc quick charging pile does not need this device.
There is a big difference in charging speed between the two. It takes 8 hours for a pure electric vehicle (ordinary battery capacity) to be fully charged through an ac charging pile after full discharge, while it only takes 2 to 3 hours for a dc quick charging pile.
The ac charging pile provides power input to the charging machine of electric vehicles. Since the power of the on-board charging machine is not large, it cannot realize fast charging.
The dc quick charging pile is a power supply device that is fixed outside the electric vehicle and connected to the ac power grid, and can provide dc power for the power batteries of non-vehicle-mounted electric vehicles. The dc charging pile can provide enough power, and the output voltage and current are adjusted in a wide range, which can meet the requirements of quick charging.
