New energy electric vehicle charging pile fault diagnosis and detection!

The charging pile is a charging device for electric vehicles. If a fault occurs, the electric vehicle will be unable to replenish energy. This article analyzes the two common faults of electric vehicle AC charging piles, and specifically discusses the causes of the faults and how to eliminate them.

The charging pile is a device for charging electric vehicles. The input end is connected to the AC power grid, and the output end is connected to the electric vehicle through a charging plug. As shown in Figure 1, the charging pile provides a human-computer interactive operation interface. People can use a specific charging card to perform corresponding charging methods, charging time, and cost data printing through the input module. The charging pile display module can display data such as charging amount, cost, and charging time. Failure of the charging pile will cause the electric vehicle to be unable to recharge energy.

Classification and working principle of charging piles

According to the charging method of electric vehicles, charging piles can be divided into AC charging piles and DC charging piles. AC charging piles provide electric vehicles with a single-phase 220V AC power supply. The AC power of the power grid is converted into DC power through the on-board charger to charge the battery of the electric vehicle, which plays the role of controlling the power supply. The power is generally within 7KW. Since the output current of the AC charging pile is small and the charging speed is slow, it is also called "slow charging". The input voltage of the DC charging pile is three-phase four-wire 380VAC ±15%, the frequency is about 50Hz, and the output is an adjustable DC voltage, which directly charges the electric vehicle. Since the input voltage of the DC charging pile is three-phase four-wire, the power provided is large enough, the output voltage and current adjustable range is large, and fast charging can be achieved, so it is called "fast charging".

Common faults of AC charging piles

During the use of AC charging piles, the main circuit is directly affected by current and voltage stress, which becomes the main cause of AC charging pile failure. Therefore, charging piles are divided into two categories according to the fault state: the first category is that the power indicator light of the charging pile is not on and charging cannot be performed; the second category is that the physical connection has been completed and charging has been started, but charging cannot be performed.

Fault diagnosis and troubleshooting

The first type of fault diagnosis and troubleshooting

cause of issue:

1. The charging power connection is abnormal;

2. The AC charging connection device is not connected correctly;

3. The charging pile circuit is faulty.

Troubleshooting Flowchart

Perform specific diagnosis based on the possible causes of the first type of fault phenomenon.

First, check the main switch of the power distribution cabinet according to the fault phenomenon. When working normally, the main switch is closed. If it is disconnected, turn off the main switch.

Second, check the output voltage of the main switch, the voltage between the live wire (L wire) and the neutral wire (N wire), and the voltage between the live wire (L wire) and the ground wire (PE wire). If it is abnormal, it means that the line is disconnected, poorly connected or damaged, and you need to recheck and reconnect the line or replace the switch;

Third, check the input voltage of the charging pile, the voltage between the live wire (L wire) and the neutral wire (N wire), and the voltage between the live wire (L wire) and the ground wire (PE wire). If it is abnormal, it means that the line is disconnected or damaged, and the line needs to be reconnected or the switch needs to be replaced.

The second type of fault diagnosis and troubleshooting

The second type of fault is when the power supply is normal, before charging, the charging plug is correctly connected to the vehicle battery interface and the equipment is in the shutdown state. There are mainly 7 types of faults.

First, in normal charging state, the monitoring system displays data as 0, which may be caused by a failure in the data communication between the charging pile and the monitoring system;

Second, under normal charging conditions, the charging current is less than 20A, because the charging pile display screen and charging program are faulty;

Third, the charging cannot be done normally or the charging operation interface cannot be entered. The reason is that the data communication between the charging pile and the monitoring system may fail.

Fourth, after restarting the charging program of the charging pile display, the BMS has no communication because the data communication between the charging pile and the monitoring system may fail;

Fifth, if the BMS status is normal, the charging voltage is normal and the charging current is 0, it may be that the charging emergency stop button was pressed by mistake;

Sixth, if the BMS status is normal and there is no charging voltage, it may be that the charging emergency stop button is pressed by mistake;

Seventh, the BMS status is normal, the charging voltage changes, and the charging current is 0. The possible reason is that the charging module is faulty.

For the above seven fault phenomena, the following solutions are given: