How to deal with the crash of the inverter

- Dec 28, 2018-

When I work for a while, I will die. What is the reason? Does the frequency converter have a fault code? If there is, look at the manual, most of them are overcurrent and undervoltage. If the original is normal, the inverter equipment may be frictionally large, the resistance will be large, the overcurrent value will be increased, or the torque will be increased. Do not overshoot too much, depending on the rated current of the motor. Look at the high-power device startup when the inverter is stopped, resulting in undervoltage.

Solution and cause analysis:

First, the deceleration time of the inverter is set too short. When the inverter is dragging a large load and its deceleration time is set to a small value, the inverter output frequency drops too fast during the deceleration process, and the load inertia is large, so that the actual motor speed is higher. The speed corresponding to the output frequency of the inverter causes the motor to be in the power generation state, thus causing the intermediate DC link voltage of the inverter to be too high and reaching the limit trip. Therefore, the large inverter generally has an overvoltage word processing unit.

Second, when multiple motors are dragged by the same load, since there is no load distribution, when the actual speed of one motor exceeds the speed of the other motor, the high speed is equivalent to the prime mover, and the low speed is equivalent to generating electricity. The machine may also cause an overvoltage fault.

Third, due to the capacitor life problem of the intermediate DC link of the inverter, after many years of use, the capacity of the intermediate DC link to the DC voltage is reduced, and the probability of overvoltage tripping increases. In practical applications, the second factor is more. Take the inverter of the refining furnace ladle trolley as an example. It is the same load for the double motor. The overvoltage alarm fault often occurs during the operation, and the same inverter is often alarmed. After observation, the inverter is in operation. The intermediate DC link has a high voltage value at high frequency. After analysis, the actual speed of one motor is higher than the actual speed of the other motor, so that it works in the power generation state, and the intermediate DC link is well consumed. This part of the energy leads to the voltage of the intermediate DC link of the inverter is too high, and the voltage fault is reported.

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