The basic working principle of electric vehicle charging pile sharing

The basic configuration of an electric vehicle charging pile is a power unit, a control unit, a metering unit, a charging interface, a power supply interface, and a man-machine interface. The power unit refers to the DC charging module, and the control unit refers to the charging pile controller. The DC charging pile itself is a system integration product. In addition to the two major components of the "DC charging module" and "charging pile controller" that constitute the core of the technology, the structural design is also one of the keys to the overall reliability design. "Charging pile controller" belongs to the field of embedded software and hardware technology, and "DC charging module" represents the high achievement of power electronics technology in the field of AC/DC. So, let's take a look at the basic working principle of electric vehicle charging piles!

The basic process of charging is to apply a DC voltage across the battery to charge the battery with a certain large current. The battery voltage rises slowly. When it reaches a certain level, the battery voltage reaches the nominal value, and the SoC reaches more than 95% (depending on the battery), continue to charge with constant voltage and small current. In order to realize the charging process, the charging pile needs a "DC charging module" to provide DC power; a "charging pile controller" is needed to control the "power on, power off, output voltage, output current" of the charging module; it needs a "touch screen" As the man-machine interface, the controller sends instructions such as "power on, shutdown, voltage output, current output" to the charging module. The simple charging pile learned from the electrical aspect only needs a charging module, a control panel and a touch screen. Only a few keyboards are needed to input commands such as startup, shutdown, output voltage, output current, etc. on the charging module, and one charging module can charge the battery. Charges.

The electrical part of the electric vehicle charging pile is composed of the main circuit and the secondary circuit. The input of the main circuit is three-phase alternating current. The three-phase alternating current is converted into direct current received by the battery through the input circuit breaker, AC smart energy meter, and charging module (rectifier module), and the fuse and charging gun are connected to charge the electric vehicle. The secondary circuit consists of a charging pile controller, a card reader, a display, and a DC meter. The secondary circuit also provides "start-stop" control and "emergency stop" operation; the signal provides "standby", "charging" and "full charge" status indications, and the display screen serves as an interactive device to provide kanban, charging mode settings and start-stop control operations.

The electrical principle of electric vehicle charging pile is summarized as follows:

A single charging module is currently only 15kW, which cannot meet the power demand. Multiple charging modules are required to work in parallel, and a bus is required to realize the flow sharing of multiple modules;

2. The input of the charging module comes from the power grid and is a high-power power supply. It is related to the power grid and personal safety, especially when it comes to personal safety. An air switch shall be installed at the input end, and the lightning protection switch is a leakage switch.

3. The output is high voltage and high current, and the battery is an electrochemical substance, which is explosive. In order to prevent safety problems caused by misoperation, the output end needs to be fused;

4. Security is a top priority. In addition to the input side measures, mechanical locks and electronic locks, insulation checks, discharge resistors;

Whether the battery can be charged depends on the battery's brain and BMS, not the charging pile. The BMS sends an instruction to the controller "whether to allow charging, whether to suspend charging, and how high voltage and current can be charged", and the controller sends it to the charging module.

6. Monitoring and management. The background of the controller shall be connected with network communication modules such as WiFi or 3G/4G;

7. The electricity bill is not free, you need to install an electric meter, and the card reader needs to realize the billing function;

8. The shell should have clear indicator lights, generally three indicator lights, which indicate charging, fault and power supply respectively;

9. The air duct design of electric vehicle charging pile is the key. In addition to the structural knowledge of the air duct design, it is also necessary to install a fan in the charging pile, and each charging module has a fan.