What is a charging pile? How do charging piles charge?

What is a charging pile?

Charging piles, as the name implies, are used to charge our electric vehicles. It acts like a tanker that fuels fuel cars at gas stations. The charging pile can be fixed to the ground or fixed on the wall, installed in various public spaces, residential areas and charging stations, and then charged for various types of electric vehicles according to different voltage levels. People can use a specific charging card to swipe the card on the human-computer interaction interface provided by the charging post, and perform the corresponding charging mode, charging time, cost data printing, etc. The charging pile display can display the charging amount, cost, charging time, etc. data.

How to charge the charging pile?

Charging an electric car with a charging post actually charges the battery in the electric car. The charging principle is that after the battery is discharged, the battery is returned to the working capacity by direct current in the opposite direction to the discharge current, and this process is called battery charging. When the battery is charged, 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, and the voltage of the charging power supply must be higher than the total electromotive force of the battery. In general, charging piles have two charging methods, namely constant current charging and constant voltage charging. In the new version of the electric vehicle terminology implemented on May 1st, the two charging modes were defined: constant current charging, charging the battery with a controlled constant current; constant voltage charging, with a controlled the constant voltage is used to charge the battery. So what is the constant current charging and constant voltage charging? The following is a more detailed explanation of the two charging methods.

Constant current charging method

The constant current charging method is a charging method in which the output voltage of the charging device is adjusted or the resistance in series with the battery is changed to maintain the charging current intensity. The control method is simple, but since the acceptable current capability of the battery is gradually decreased as the charging process progresses, the charging current is mostly used to electrolyze water and generate gas to make the gas out too late. Therefore, the stage charging method is often used.

Constant voltage charging method

The voltage of the charging power source maintains a constant value throughout the charging time and the current gradually decreases as the voltage at the battery terminal gradually increases. Compared with the constant current charging method, the charging process is closer to the optimal charging curve. Fast charging with a constant voltage since the battery electromotive force is low at the initial stage of charging, the charging current is large, and as the charging progresses, the current will gradually decrease, so that a simple control system is required.

What type of charging pile?

At present, there are two types of charging piles commonly available on the market, one is a DC charging pile, and the other is an AC charging pile.

DC charging pile

DC charging piles are fixedly installed in some public places outside electric vehicles, such as residential quarters, residential parking lots, commercial areas, service areas, outdoor parking lots, electric vehicle charging stations and other places. It is a charging device that supplies DC power to an off-board electric vehicle battery by accessing the public power grid. Because the DC charging pile can directly charge the battery of the electric vehicle, generally adopts three-phase four-wire system or three-phase three-wire system power supply, and the output voltage and current can be adjusted in a wide range, so that the electric vehicle can be quickly charged, and the DC charging pile is also used. It is called fast charge. Due to the large output power, DC charging piles are available in general specifications of 30 kW, 60 kW, 80 kW, 120 kW, 150 kW, and 180 kW.

AC charging pile

The AC charging pile is also fixedly installed in some public places outside the electric vehicle, and provides a controllable one-way AC power supply or a three-phase AC power supply device for the electric vehicle's on-board charger. It should be noted that the AC charging post itself does not have a charging function. It simply provides power output, and the battery of the electric vehicle can be charged by connecting an electric vehicle in-vehicle charger. Since the power of the electric vehicle on-board charger is generally small, the AC charging pile cannot be quickly charged, and the AC charging pile is also called slow charging. AC charging pile output power will not be very large, generally 3.5kW, 7kW, 15kW and so on.

DC charging pile and AC charging pile difference

There are two differences between DC charging piles and AC charging piles. First, when charging, the DC charging pile can directly charge the battery of the electric vehicle, so no car charger is needed, and the AC charging pile cannot directly charge the electric vehicle battery, so the car charger is needed. The second is the difference in charging time. The charging speed of the DC charging pile is relatively fast. Generally, the electric vehicle battery is fully charged and only takes several tens of minutes to two or three hours. The AC charging pile is the time for the electric vehicle battery to be fully charged. It takes a lot longer and usually takes about eight hours.

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