Share the basic working principle of electric vehicle charging pile

The basic configuration of electric vehicle charging pile is power unit, control unit, metering unit, charging interface, power supply interface and human-machine interface, etc., of which the power unit refers to DC charging module and the control unit refers to charging pile controller. DC charging pile itself is a system integration product. In addition to the “DC charging module” and “charging pile controller” which constitute the core of the technology, the structural design is also one of the keys to the overall reliability design. The “charging pile controller” belongs to the field of embedded hardware and software technology, and the “DC charging module” represents the high achievement of power electronics technology in the field of AC/DC. So, let’s understand the basic working principle of electric vehicle charging pile!

The basic process of charging is to apply DC voltage to both ends of the battery and charge the battery with a certain high current. The battery voltage rises slowly, and when it reaches a certain level, the battery voltage reaches the nominal value, the SoC reaches more than 95% (varies from battery to battery), and continues to charge the current with a small constant voltage. In order to realize the charging process, the charging pile needs a “DC charging module” to provide DC power; it needs a “charging pile controller” to control the charging module’s “power on, power off, output voltage, output current “It needs a ‘touch screen’ as the human-machine interface, through the controller to the charging module to send ‘power on, power off, voltage output, current output’ and other commands. The simple charging pile learned from the electrical side only needs charging module, control panel and touch screen; only a few keyboards are needed to input the commands of power on, power off, output voltage, output current, etc. on the charging module, and a charging module can charge the battery.

The electrical part of the electric vehicle charging pile consists of the main circuit and the sub-circuit. The input of the main circuit is three-phase AC power, which is converted into DC power received by the battery through the input circuit breaker, AC smart energy meter, and charging module (rectifier module), and connects the fuse and charging gun to charge the electric vehicle. The secondary circuit consists of charging pile controller, card reader, display, DC meter and so on. The secondary circuit also provides “start-stop” control and “emergency stop” operation; the signaling machine provides “standby”, “charge The signaling machine provides “standby”, “charging” and “fully charged” status indication, and the display acts as an interactive device to provide signage, charging mode setting and start/stop control operation.

The electrical principle of electric vehicle charging pile is summarized as follows:
1, a single charging module is currently only 15kW, can not meet the power requirements. Multiple charging modules need to work in parallel, and a bus is needed to realize the equalization of multiple modules;
2, charging module input from the grid, for high-power power. It is related to the power grid and personal safety, especially when it involves personal safety. The air switch should be installed at the input side, and the lightning protection switch is a leakage switch.
The output is high voltage and high current, and the battery is electrochemical and explosive. In order to prevent safety problems caused by misoperation, the output terminal should be fused;
4. Safety is the most important issue. In addition to the measures of the input side, mechanical and electronic locks, insulation check, discharge resistance;
5. Whether the battery can be charged or not depends on the brain of the battery and the BMS, not the charging post. the BMS sends commands to the controller “whether to allow charging, whether to pause charging, how high the voltage and current can be charged”, and the controller sends them to the charging module.
6, monitoring and management. The background of the controller should be connected to WiFi or 3G/4G network communication module;
7、Electricity is not free, need to install the meter, the card reader needs to realize the billing function;
8, the shell should have clear indicators, generally three indicators, respectively, indicating charging, fault and power supply;
9, the air duct design of electric vehicle charging pile is key. In addition to the structural knowledge of air duct design, a fan needs to be installed in the charging pile, and there is a fan in each charging module.