This paper will introduce two national standard charging pile interfaces – AC charging pile interface and DC charging pile interface, and introduce the relevant interface technology around the common AC charging interfaces. Friends who want to know, don’t miss it~
1、 Basic introduction to charging pile interface
Compared with traditional oil vehicles, pure electric vehicles have many advantages, which are not listed here, but one trouble of pure electric vehicles is that they need to consider the length of charging time and battery life. There are many compromise schemes in the field of hybrid power, such as plug-in, add-on program, etc., which does not require large battery capacity. Compared with pure electric vehicles, it shortens the charging waiting time (and uses gasoline / diesel to improve the mileage).
In the field of pure electric vehicles, it is difficult to unilaterally optimize the charging time or battery service life. You can’t have both fish and bear’s paw, because the battery life is related to the charging rate. Generally, the larger the charging and discharging rate, the smaller the number of cycles.
In order to ensure that the cycle charging times of the battery can be between 800 ~ 1000, the charging rate should usually be between 0.5c ~ 0.25c. The State Grid is used to supply power and the on-board charger is used to charge the power battery. This belongs to the slow charging scheme, and the supporting public facilities are AC charging piles.
AC charging pile interface
In response to an emergency, it is hoped that the battery can be fully charged to 80% of the maximum capacity within 15 ~ 30min, and the corresponding charging rate should be between 2C ~ 4C, which belongs to the fast charging scheme, and the supporting public facilities are DC charging piles. The DC charging pile will cause great damage to the battery, and the cost for car owners to replace the battery will increase. Therefore, if it is not a very urgent situation, the use of DC charging pile should be reduced as much as possible (at the discretion of local tyrants).
DC charging pile interface
The principles of charging piles at home and abroad are similar, but their shapes are slightly different, as follows:
2、 Explain the interface technology of AC charging pile in detail
The AC charging pile charges the battery through the on-board charger. Compared with the DC charging pile, the AC charging pile has the advantages of low cost, simple structure, more friendly to the battery and is suitable for popularization and promotion in a large area. Next, the interface technology of the AC charging pile will be introduced from simple to deep.
The national standard AC charging pile adds some commercial modules (such as human-computer interaction interface, billing module, alarm module, etc.) and control guidance circuit on the basis of the original AC charging pile shown in the above figure. The control guidance circuit is the core content of the AC charging pile interface technology. In addition, in order to be compatible with single-phase electricity and three-phase electricity, the 7-terminal structure is finally adopted for the interface of national standard AC charging pile, and its terminal distribution mode is shown in the following figure:
Function definition of each terminal:
Typical control and guidance circuit diagram of charging mode 3 connection mode B:
The main function of the control guide circuit is to confirm whether the charging interface and the charging socket are connected, and then conduct periodic detection during the charging process to judge whether to continue charging or stop charging.
The working principle of the control pilot circuit is described in detail below:
1. Connection confirmation
(1) The vehicle control device confirms whether the vehicle plug and vehicle socket are connected by detecting the resistance value between PE and monitoring point 3;
(2) The power supply control device on the charging pile side judges whether the power supply plug and the power supply socket are connected by detecting the voltage value of monitoring point 4 or detection point 1.
2. Start charging
When both the vehicle interface and the power supply interface confirm the connection, the charging pile switches the switch S1 from the 12V connection state to the PWM state, and waits for the vehicle control device to close the switch S2. At this time, the peak voltage of the test point 1 is 9V, and the CP end generates a 1kHz PWM wave, and its duty cycle represents the rated current of the charging pile. When the vehicle side switch S2 is closed, it means that the vehicle is ready for charging. At this time, the peak voltage of detection point 1 is 6V. After confirming that the vehicle is ready, the charging pile closes contactors K1 and K2 to turn on the AC circuit and start charging. During the whole process, the voltage state of detection point 1 is as follows:
3. Cycle detection during charging
During the charging process, the charging pile shall periodically detect the detection points to confirm the connection state of the charging connection device and whether the vehicle is in the rechargeable state. The detection period shall not be greater than 50ms.
(1) During charging, the charging control device continuously detects detection point 4 and detection point 1. If the power supply interface is detected to be disconnected, the power supply control device switch S1 is switched to 12V and the AC power supply circuit is disconnected;
(2) During charging, the vehicle control device continuously detects detection point 2 and detection point 3. If it is judged that the vehicle interface is disconnected, the vehicle control device controls the on-board charger to stop charging and disconnect switch S2.
4. End of charging
The general principle is as described above. The control guidance circuit is the soul of the charging pile interface technology, which is very important for electric vehicle designers and users,