What is the cause of the imbalance of U.V.W output in the maintenance of the inverter

- Jul 18, 2019-

In the actual inverter maintenance, U, V, W output imbalance can be divided into three cases:

(1) The drive display shows: output lack of phase fault code, in the repair to eliminate the detection circuit fault, then by direct inspection of the IGBT module and the drive circuit, the conclusion is that the IGBT module is damaged, while the drive circuit also has problems. By replacing the IGBT module and driving circuit components such as optocoupler, PNP, NPN a pair of drive crystal tube, electrolytic capacitor, regulator tube and other basic can solve the problem.

(2) the difference between the output of the inverter U, V, W about 100V, (output 380V for example) in the drive circuit S1 to S6 in the middle of a drive circuit without drive voltage and drive signal waveform, the drive repair can be measured output terminals U, V, W-P between the voltage to get results.

(3) U, V, W-N between the DC voltage, the drive repair can be done by looking for specific driving voltage is not normal or no driving signal waveform, it causes U, V, W in a phase failure caused by a phase difference. The solution is to check whether the driving circuit voltage is normal, optocoupled is broken, electrolytic capacitor is leaking, etc. The problem can be solved by measuring the 6-way waveform by the oscilloscope in accordance with the technical requirements. Another situation is the difference between the inverter U, V, W three-phase output AC voltage is greater than 3%, although it can be used normally, but can not be used for long-term use and large load. The main reason for this is that the main device between the drive circuit S1 to S6 is asymmetric, such as the technical parameters of the transistor, the parameters of the regulator tube, the fluid and leakage of capacitors, leakage and leakage, etc., the 6-way drive circuit on the device's wear and tear to make a certain difference in its parameters, resulting in the inverter output U, V, W between the production of a small potential difference. Although the above situation can be used, it is not technically permissible.