As the supporting infrastructure of electric vehicles, charging piles are indispensable to provide charging services for electric vehicles. Today's article will give you the basic knowledge and working principle of the new energy charging pile for science popularization. Let's learn it together!

Classification of Charge Point

The charging pile is the charging facility of electric vehicles, and its function is similar to the fuel dispenser in the gas station.

1) According to different power supply modes, it can be divided into AC charging pile and DC charging pile.

The AC charging pile is generally of small current, small pile body and flexible installation; The DC charging pile is generally characterized by high current, larger charging capacity in a short time, larger pile body, and large occupation area (heat dissipation).

2) According to different installation methods, it is mainly divided into vertical charging piles and wall mounted charging piles. The vertical charging pile does not need to lean against the wall, and is suitable for outdoor parking spaces and residential parking spaces; The wall mounted charging pile must be fixed by the wall, which is suitable for indoor and underground parking spaces.

3) According to different installation scenarios, it is mainly divided into public charging piles, special charging piles and self use charging piles.

Public charging pile is a charging pile built in public parking lot (garage) combined with parking space to provide public charging service for social vehicles.

The special charging pile is the self owned parking lot (garage) of the construction unit (enterprise), which is used by the internal personnel of the unit (enterprise).

Self use charging pile is a charging pile built in the private parking space (garage) to provide charging for private users. The charging pile is generally combined with the parking space construction of the parking lot (garage). The protection level of charging piles installed outdoors shall not be lower than IP54. The protection level of charging piles installed indoors shall not be lower than IP32.

4) According to different charging interfaces, it is mainly divided into one pile one charging and one pile multiple charging.

One charge per pile means that one charging pile has only one charging interface. At present, one charging pile is the main charging pile in the market.

Multi charging in one pile, namely group charging, means that one charging pile has multiple charging interfaces. In large parking lots such as bus parking lots, group charging piles are needed to synchronously support the charging of multiple electric vehicles, which not only speeds up the charging efficiency, but also saves labor costs.

Operating principle of charging post

The general structure block diagram of pure electric vehicle charging is shown in the figure below. The working principle is: AC power is input from the three-phase power grid, and it is converted into DC power through the bridge uncontrolled rectifier circuit. After filtering by the LCR circuit, it is sent to the high-frequency DC-DC power converter. The power converter outputs the required DC voltage through the direct to direct conversion, and after output filtering, it charges the electric vehicle battery. Four modes of charging can be selected, namely, fixed power, fixed time, fixed amount and automatic (until full).

▲ Electric vehicle charging structure diagram

To sum up, the working principle of the charging pile can be summarized as combining the power supply, converter and output device, so as to change the voltage from low to high, convert the high voltage into a state that can provide power supply, and finally realize charging the electric vehicle.

Composition and structure of charging post

The main structure of the charging pile includes the pile body, charging module, display screen, connecting cable, accounting management module, safety protection device, etc. The structural design and quality of these parts directly affect the service life and safety of the charging pile.

1) Piles

The pile structure of charging pile is usually made of steel, aluminum alloy and other materials, with strong durability and stability.

2) Charging module

Charging module is the core part of charging pile, including charger, controller, power supply and other components. The charger is the main component of the charging pile, which is responsible for converting the electric energy into the electric energy required by the electric vehicle. The controller is responsible for controlling the working state of the charger and various parameters during the charging process to ensure the safety and stability of the charging process. The power supply provides power for the charging module.

3) Display screen

The display screen of the charging pile is usually used to display the status, charging progress, charging cost and other information of the charging pile. The types and sizes of display screens are different. Some charging piles are also equipped with touch screens, which are convenient for users to use, realize human-computer interaction, and meet the personalized needs of different types of users.

4) Accounting management module

The accounting management module calculates the current consumption amount, collects fees and prints bills according to the current real-time electricity price and consumed electricity and other data. To complete the accounting management task, the controller and embedded printer need to work together. The charging pile adopts the trapezoidal electricity price policy. The controller calculates the consumption amount and completes the charging. The printer communicates with the controller, and the controller sends the consumption information to the printer to print the bill details of this charging.

5) Connecting cable

The connecting cable is the bridge between the charging pile and the electric vehicle, which is responsible for transmitting electric energy and data. The quality and length of the connecting cable directly affect the charging efficiency and safety. Some high-end charging piles are also equipped with an automatic wire winder, which is convenient for users.

6) Safety protection device

The safety protection devices of charging piles include leakage protection, overcurrent protection, overvoltage protection, etc. These devices can effectively protect the safety of charging piles and electric vehicles.

▲ Schematic diagram of AC contactor circuit

The design and manufacturing quality of the above six major parts directly affect the service life and safety of the charging pile. Therefore, attention should be paid to these aspects when purchasing the charging pile.

Charging mode of charging post

There are three main charging modes for charging piles, namely fast charging, slow charging and wireless charging.

1) Slow charging

Slow charging is a commonly used charging method. For new energy Electric vehicle charging pile For example, it is connected to the on-board charger, which mainly converts low power AC to DC, that is, the AC-DC conversion. The charging power is generally 3kw or 7kw. The reason is that the power battery can only be charged by DC. In addition, the slow charging interface of the new energy electric vehicle charging pile is generally 5 holes.

2) Quick charge

Fast charging is a popular charging method, which saves time after all. Fast charging is to connect the AC-DC converter to the charging pile of the new energy electric vehicle, and the output of the charging gun is high power DC. In addition, the charging current of the interface is generally very large, the cell is much thicker than the slow charging, and the number of holes of the cell is also much larger. The fast charging interface of the charging pile of new energy electric vehicles is generally 7 holes.

3) Wireless charging

Officially, the wireless charging of new energy vehicles refers to the high-power charging mode for supplementing the high-voltage power battery. It is similar to the wireless charging of smart phones. Put the phone on the wireless charging panel, and you can charge the phone battery without connecting the charging cable. At present,

3) Wireless charging

Officially, the wireless charging of new energy vehicles refers to the high-power charging mode for supplementing the high-voltage power battery. It is similar to the wireless charging of smart phones. Put the phone on the wireless charging panel, and you can charge the phone battery without connecting the charging cable. At present, the technology of electric vehicle wireless charging is mainly divided into four types: "electromagnetic induction, magnetic resonance, electric field coupling and radio waves". At the same time, due to the low transmission power of electric field coupling and radio wave, electromagnetic induction and magnetic resonance are mainly used at present.

In addition to the above three charging methods, electric vehicles can also realize energy supplement by changing electricity.

Have you mastered the structure and working principle of the charging post? What other questions do you want to know about the Charge Point? Comment and discuss in the comment area.

 Reference data:

[1] Duan Xiwen, Yu Shijun Research on fixed charging piles for electric vehicles [J] Hebei Agricultural Machinery, 2020 (7): 42-43. [2] Zhao Lili Research and design of electric vehicle AC charging pile [D]. Chang'an University, 2017 [3] Sang Lei, Yang Yujun Working principle and charging parameter analysis of electric vehicle charging pile [C]//Jiangsu Measurement and Testing Society, Jiangsu Measurement and Testing Academic Paper Collection, 2014