These 5 common inverter failure analysis You need to know!
Release Date: 2018-04-20 Source: China Air Compressor Network View: 22398
Core Tip: Frequency converter as an automated factory production exchanger, the role of the production operation is indisputable, today, I will be the frequency converter common failure analysis to do simple and complex organization.
▌▌Failure one
Frequency converter charging starting circuit failure, general-purpose frequency converter is generally used for the voltage type frequency converter, using the alternating - direct - alternating mode of operation. When the inverter is just powered on, due to the DC side of the flat wave capacitor capacity is very large, the charging current is very large, usually using a starting resistor to limit the charging current.
After the charging is completed, the control circuit short-circuits the resistor through the contacts of a relay or a changer. The starting circuit failure is generally manifested as a burned out starting resistor, and the inverter alarm shows a DC line line voltage failure. In general, the design of the frequency converter, in order to reduce the size of the frequency converter and choose a smaller starting resistor, the value of more than 10-50Ω, the power of 10-50W; when the frequency converter's AC input power supply is frequently switched on, or the bypass contacts of the contact contact is not good, will lead to the starting resistor burned out. Therefore, while replacing the resistor, the cause must be found out. If the fault is caused by the frequency start of the power supply on the input side, this phenomenon must be eliminated before the inverter is put into use, and if the fault is caused only by the bypass contact elements, these devices must be replaced.
▌▌Fault two
Frequency converter without fault display, but can not run at high speed, after checking the frequency converter parameters are set correctly, the speed control input signal is normal, after powering up and running test, the frequency converter DC bus voltage is only about 450V (normal should be in 580V-600V), and then test the input side, found that a phase is missing. The cause of the failure is caused by the poor contact of one phase of an air switch on the input side. Caused by the inverter input missing phase does not alarm, can still work in the low-frequency band, because most of the inverter bus voltage lower limit of 400V, only when the bus voltage drops below 400V, the inverter only report faults.
And when two-phase input, DC bus voltage is 380V×1.2=452V>400V.When the inverter is not running, DC voltage can also reach normal value due to the role of the flat wave capacitor.The new inverters are using PWM control technology, the work of regulating the voltage and frequency is completed in the inverter bridge, so it can still work normally when the input is out of phase in the low-frequency band.However, due to the input voltage, the output voltage is low, which causes the Asynchronous motor speed low frequency does not go up.
▌▌ Failure three
The frequency converter displays overcurrent, when this kind of display appears, first check whether the acceleration time parameter is too short, whether the torque boost parameter is too big, and then check whether the load is too heavy. If there are no such phenomena, you can disconnect the current transformer on the output side and the Hall current detection point on the DC side, run after reset, and see whether the overcurrent phenomenon occurs. If so, it is likely that the IPM module is faulty, because the IPM module contains over-voltage and over-current, under-voltage, overload, overheating, phase loss, short-circuit and other protection functions, and these fault signals are transmitted to the controller via the output Fn pin of the module control pins. After receiving the fault information, the microcontroller blocks the pulse output on one hand and displays the fault information on the panel on the other hand. The IPM module should be replaced.
▌▌Fault four
The frequency converter shows over-voltage fault, the frequency converter has over-voltage fault, generally thunderstorm, due to lightning strung into the power supply of the frequency converter, so that the voltage detector on the DC side of the frequency converter operates and trips, in this case, usually only need to disconnect the power supply of the frequency converter for about 1 minute and then power up again, and the other case is that the frequency converter drives a large inertia load and over-voltage phenomenon occurs. In this case, one is to lengthen the deceleration time parameter or increase the braking resistance (braking unit); the second is to set the stopping mode of the frequency converter to free stopping mode.
▌▌ Failure five
Motor heating, inverter display overload, for the inverter has been put into operation, must check the load condition, for the new installation of the inverter this kind of failure, it is likely that the V / F curve is not set properly or the motor parameter setting problems, at this time must be correctly set up a variety of parameters, in addition, the motor in the low-frequency work of the heat dissipation performance deterioration, will also appear in this case, then need to be added to the heat dissipation device.
The use of frequency converter as an asynchronous motor drive, despite its high reliability, but if the use of improper or accidental events, can also cause damage to the frequency converter, in order to be in the production process, the use of good frequency converter, familiar with the structural principle of the frequency converter, to understand the common failures, for the technicians is particularly important.
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