The high-voltage inverter has a highly intelligent computing level and a perfect fault detection circuit, and can provide accurate positioning of all faults, and make clear instructions on the main control interface. In practical application, we find that common faults can be divided into control channel abnormality, IGBT overcurrent, overvoltage fault and so on. Here is an analysis of common high-voltage inverter failures and their causes and high-voltage inverter maintenance methods.
First, the abnormal fault of the control pass
The abnormal fault of the control channel is usually caused by the optical fiber communication between the sub-PWM board and the power unit board, which is generally caused by the following situations:
1. Poor contact of the optical fiber connection part or falling off of the optical fiber head;
2. Ash accumulation inside the optical fiber signal transmitter/receiver;
3. Optical fiber breakage;
4. Optical fiber communication control vibration damage;
In the case of an optical fiber failure, it is first necessary to determine whether the power unit is faulty or the controller side is faulty, and the optical fiber can be adjusted by the method. The optical fiber corresponding to any power unit of the same phase on the optical fiber board in the controller is reversed with the optical fiber that reports the fault, and if the optical fiber fault located by the power-on monitoring interface is still in the original position, it means that the optical fiber board is damaged, on the contrary, the optical fiber fault displayed by the monitoring interface has been replaced, then it means that the power unit is faulty, and the faulty power unit can be considered to be replaced or repaired at this time.
2. Causes and solutions of IGBT overcurrent faults
IGBT is the most critical power device in high-voltage inverter, and as a high-power composite device, IGBT may be locked and damaged during overcurrent. In order to improve the reliability of the system charge, some measures have been taken to prevent damage due to overcurrent. There are several common causes of IGBT overcurrent faults:
1. The output of the inverter is short-circuited;
2. The IGBT in the power unit is broken down;
3. The drive detection circuit is damaged
4. The detection circuit is interfered with;
The detection method is to find the corresponding module according to the fault location displayed in the monitoring interface, disassemble and check whether the IGBT is damaged, and the method of judgment is to find the positive pole v+ and negative pole v- of the DC bus inside the power unit, connect the black gauge of the multimeter to v+, and the red gauge pen is connected to U, V respectively, with the second machine tube file, the value of about 0.4V should be displayed, and the inverted phase shows infinity;
3. Causes and solutions of overvoltage faults
The reason for overvoltage is generally the overvoltage from the input side of the power supply, and the passive power grid voltage is within -10%-+10% of the rated voltage under normal circumstances, but under special conditions. The voltage of the sub-DC bus rises with the power supply voltage, so when the voltage rises to the protection value, the inverter will trip due to overvoltage protection. In order to enter and exempt the input side overvoltage, the tap of the transformer can be changed for adjustment, this method is only suitable for the situation that the sub-field voltage has been high, and the absorption device can also be considered on the power input side to reduce the overvoltage factor on the input side of the inverter.
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