light industry

  In the inverter daily maintenance process, often encounter a variety of problems, such as the periphery of the line problem, parameter setting bad or mechanical failure and a series of problems, but also may be the inverter fault. If the drive fails, how to determine which part of the problem, introduced a here.

一、Static test
1 test rectifier circuit
Find inside the inverter DC power P end and the N end and find million table transferred to resistance X10 file, the red bar received P, the black bar are respectively connected to the R, s, t should about dozens of European values, and basic balance. The opposite will be the black bar to the P side, the red bar in R, S, T received, there is a close to the infinite resistance. Red table stick to N end, repeat the above steps, should go to the same results. If the results are as follows: decidable circuit has been abnormal, the resistance of unbalanced three-phase bridge rectifier fault, can explain. When the red table rod is connected with the P end, the resistance is infinite, and the fault of the rectifier bridge or the starting resistance can be judged.
2 test inverter circuit
The red bar received P end, and the black bar are respectively connected with the U, V, W, should have dozens of European resistance and the phase resistance is basically the same. Instead, we should to infinity. The black table stick to the N side, repeat the above steps should get the same results, or you can determine the inverter module.
二、dynamic test
After the static test results are normal, the dynamic test can be carried out, that is, on the electric test machine. Before and after the power must pay attention to the following points.
1 before the power, the input voltage is required to confirm whether there is a mistake, the 380V power will be connected to the 220V inverter will be the emergence of deep fried machine (deep fried capacitors, voltage sensitive resistors, modules, etc.).
2 check the inverter is connected to the correct connection, the connection is loose, the connection is sometimes caused by the abnormal frequency of the inverter failure, serious will appear, such as blasting machine.
3 after power on the detection of fault display content, and initially determine the cause of failure.
4. If no fault display, first examine whether the parameters are abnormal and parameters after the reversion of no-load (not connected to a motor) starting with frequency converter, and the U, V, w three-phase output voltage values are measured. If there is lack of phase, three-phase output voltage value. If there is lack of phase, three-phase imbalance and other conditions, the module or the driver board and so on.
5 in the case of the normal output voltage (no phase, three-phase unbalance), with load test. When tested, it is best to be full load test.
三、Fault judgement
1, rectifier module damage
Is generally caused by the two power grid voltage or internal short circuit, in the case of the exclusion of internal short circuit, the replacement of the rectifier bridge. When dealing with faults in the field, we should focus on the user's power grid, such as the power grid voltage, the electric welding machine and so on.
2, inverter module damage
Generally due to motor or cable damage and drive failure caused by. After repairing the driving circuit, the test drive waveform is in good condition, and the module is replaced. After changing the drive board in the field service, we must pay attention to the motor and the connecting cable. In the determination of no fault, the operation of the inverter.
3, no display on the power
Is generally due to the switching power supply damage or soft charging circuit damage caused by DC circuit without DC power, such as the starting resistance damage, it is also possible that the panel is damaged.
4, after the power is displayed over voltage or under voltage
Generally due to the lack of input phase, circuit aging and circuit board caused by damp. Find out the voltage detection circuit and the detection point, the replacement of damaged devices.
5, after the power of the current or grounding short circuit
Is generally on the current detection circuit damage. As Holzer element, operational amplifier.
6, start to display the current
Generally due to damage caused by the driver circuit or the reverse flow module.
7, the no-load output voltage is normal, after the load shows the overload or over current
This kind of circumstance is caused by the improper parameter setting or the aging of the driving circuit.