Introduction of AC charging interface and related interface technology

This article will introduce two national standard charging pile interfaces – AC charging pile interface and DC charging pile interface, and introduce the related interface technology around the commonly used AC charging interface. Friends who want to know don’t miss it~

This article will introduce two national standard charging pile interfaces – AC charging pile interface and DC charging pile interface, and introduce the related interface technology around the commonly used AC charging interface. Friends who want to know don’t miss it~

1. Basic introduction of charging pile interface

Compared with traditional gasoline vehicles, pure electric vehicles have many advantages, and I will not list them all here, but a troublesome place for pure electric vehicles is the need to consider the length of charging time and battery life. There are many compromise solutions in the hybrid field, such as plug-in, extended range, etc., which do not require a large battery capacity, shorten the charging waiting time compared to pure electric vehicles (and use gasoline/diesel to increase the cruising range) .

In the field of pure electric vehicles, it is difficult to unilaterally optimize the charging time or battery life. You cannot have both, because the life of the battery is related to the charging rate. In general, the larger the charging and discharging rate, the more cycles you use. smaller.

In order to ensure that the cycle charging times of the battery can be between 800 and 1000, usually the charging rate should be between 0.5C and 0.25C. The national grid is used for power supply, and the on-board charger is used to charge the power battery. This is a slow charging solution. Public facilities are AC charging piles.

AC charging pile interface

In order to cope with emergencies, it is hoped that the battery can be fully charged to 80% of the maximum capacity within 15~30 minutes, and the corresponding charging rate should be between 2C~4C. This is a fast charging solution, and the supporting public facilities are DC charging piles. The DC charging pile is relatively harmful to the battery, and the cost of replacing the battery will increase for the owner. Therefore, if it is not a very urgent situation, the use of the DC charging pile should be minimized (local tyrants are free).

DC charging pile interface

The principles of charging piles at home and abroad are similar, but the 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 low cost, simple structure, and is more friendly to the battery. It is suitable for popularization and promotion in a large area. Interface technology of charging piles.

The main function of the AC charging pile (including national standard and non-national standard) is to draw out single-phase electricity or three-phase electricity. The charging pile only acts as a current transfer station. The subsequent rectification + DC/DC conversion is performed by the on-board charger. Finish.

The national standard AC charging pile is based on the original AC charging pile shown in the figure above, adding some commercial modules (such as man-machine interface, billing module, alarm module, etc.) and control guide circuit, the control guide circuit is AC charging The core content of stub interface technology. And in order to be compatible with single-phase power and three-phase power, the 7-terminal structure finally adopted for the national standard AC charging pile interface, the terminal distribution is shown in the following figure:

Function definition of each terminal:

Typical control steering 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 perform periodic detection during the charging process to determine whether to continue charging or stop charging.

The working principle of the control steering circuit is described in detail below:

1. Connection confirmation

(1) The vehicle control device confirms whether the vehicle plug and the 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 determines whether the power supply plug and the power supply socket are connected by detecting the voltage value of the monitoring point 4 or the monitoring point 1.

2. Charging starts

When both the vehicle interface and the power supply interface are confirmed to be connected, 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 detection point 1 is 9V, and the CP terminal 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 to be charged, and the voltage peak value of the detection point 1 is 6V. After confirming that the vehicle is ready, the charging pile closes the contactors K1 and K2 to make the AC circuit conduct, and charging starts. The voltage state of detection point 1 in the whole process is as follows:

3. Cycle detection during charging process

During the charging process, the charging pile periodically detects the detection point to confirm the connection status of the charging connection device and whether the vehicle is in a rechargeable state. The detection period is not more than 50ms.

(1) During the charging process, the charging control device continuously detects the detection point 4 and the detection point 1. If it is detected that the power supply interface is disconnected, the power supply control device switch S1 is switched to 12V and the AC power supply circuit is disconnected;

(2) During the charging process, the vehicle control device continuously detects the detection point 2 and the detection point 3. If it is determined that the vehicle interface is disconnected, the vehicle control device controls the vehicle-mounted charger to stop charging and turns off the switch S2.

4. End of charging

The general principle is as described above, the control guide circuit is the soul of the charging pile interface technology, which is very important for electric vehicle designers and users. For more details, please refer to the national standard GBT 20234-2011.

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