Publisher: omega34 Latest update time: 2024-12-20 Source: elecfans Reading articles on mobile phones Scan QR code
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As the use of pure electric vehicles becomes more and more widespread, the demand for charging is increasing, and the market has placed higher and higher requirements on the safety and convenience of vehicle charging. Convenient, safe and fast charging is a consistent demand of the market for vehicles.
This article mainly introduces the composition, electrical principle and control strategy of the charging system of pure electric vehicles. There are two main charging system methods for pure electric vehicles, one is AC charging method, which is slow charging, and the other is DC charging method, which is fast charging. The composition, electrical principle and control method of the two charging methods are different.
AC charging means that the voltage input from the power grid to the vehicle is AC power, which can be 220V AC one-way power or 380V AC three-phase power. The AC power enters the on-board charger through the standard charging plug and charging socket, and the on-board charger converts the AC power into DC power to charge the power battery, completing the basic AC charging.
The components of AC charging mainly include on-board charger, AC charging socket (AC charging socket wiring harness), charging cable, AC charging pile or 220V AC power supply and vehicle controller (VCU, BMS), etc., as shown in Figure 1.
Figure 1 Composition of AC charging
The AC charging socket and on-board charger are fixed on the vehicle, the charging cable is delivered with the vehicle, and the AC charging pile is fixed in the parking lot. The functions of each component are as follows:
There are three AC charging modes, namely Mode 1, Mode 2 and Mode 3. According to national standards and charging safety, Mode 1 is strictly prohibited, and Mode 3 generally uses the connection mode C. The AC charging of Mode 2 and Mode 3 with connection mode C Working principle The electrical diagram is shown in Figures 2 and 3.
Figure 2 Electrical schematic diagram of Mode 2 charging
AC charging is a national standard charging method, and its electrical schematics, detection and control must meet the requirements of the standard GB/T 18487.1-2015 "Electric Vehicle Conductive Charging System Part 1: General Requirements", as shown in Figure 2 and Figure 3. In addition to meeting national standard requirements, different automobile manufacturers will add charging reminders or display functions according to project requirements to facilitate customers to check the charging status.
According to the standard requirements, the CC signal is a judgment signal for whether the charging plug and the charging socket are connected. At the same time, the vehicle determines the RC resistance value and the capacity of the wiring harness based on the CC signal value. The CP signal is used to determine the power supply capacity of the power supply device, which is determined by the PWM value. The resistance values and PWM values in the electrical schematic must meet the standard requirements, and the controller must make judgments according to the standard to meet the charging needs of the vehicle in the market.
Figure 3 Electrical schematic diagram of Mode 3 charging
As shown in Figure 2 and Figure 3, whether it is mode 2 or mode 3, the schematic diagram is basically the same, except that the AC power supply method of the power grid is different. Taking a certain project as an example, its control strategy is briefly described. Its electrical schematic diagram, detection and control meet the standard requirements. At the same time, for the convenience of customers, the control strategy and sequence of AC charging are as follows:
The above is a brief description of the control of the charging process. At the beginning of the entire charging process, the vehicle and the AC charging pile (or charging cable) will first determine whether the charging interface is connected intact, and the vehicle will determine whether to start charging, so the customer must plug the charger in place, which is also to ensure charging safety. In use, the customer only needs to plug the charger, and no other operations are required. The vehicle will then enter the charging mode and start charging, which improves the convenience of customer use. In actual use, if the vehicle is in the charging process, when there is no electricity in the power grid, the vehicle will automatically go to sleep to reduce its own energy consumption; when there is another call, the vehicle will automatically wake up and detect the vehicle status. If the vehicle is not fully charged, it will continue to charge. If it is fully charged, it will stop charging and go to sleep to reduce energy consumption. For example, the voltage change of mode 3 charging process is shown in Figure 4.
Figure 4 AC charging process view
DC charging means that the voltage input from the external power grid to the vehicle is DC power, that is, the DC charging pile converts 380V AC three-phase power into DC power, transmits it to the vehicle through a standard DC charging plug and charging socket, directly charges the power battery, and completes basic DC charging.
The components of DC charging mainly include DC charging socket (DC charging socket wiring harness), vehicle controller (VCU, BMS) and DC charging pile, as shown in Figure 5.
Figure 5 Composition of DC charging
The DC charging socket is fixed on the vehicle and directly connected to the power battery, and the DC charging pile is fixed in the parking lot. The functions of each component are as follows:
