Inverter switching power supply common troubleshooting solutions - Database & Sql Blog Articles
This article lists the problems and solutions encountered by the inverter maintenance engineer in the actual maintenance of the inverter switching power supply, for your reference.
[Case 1]: The inverter (fault phenomenon: no display after power-on) detected that the main circuit of the power supply, the charging resistor, and the main circuit contactor were all normal, so it was determined that the switching power supply board was faulty. Follow the repair procedure above to measure the switching power supply board. During the first measurement, it was found that the 330KΩ/2W step-down resistor between the DC bus 560V and the PWM modulation chip was damaged, and the nominal 330KΩ/2W resistor was actually measured at 2MΩ or more. Therefore, the PWM modulation chip is not obtained. It is not possible to start the work until the power is turned on. For the sake of caution, the key components such as the switch tube, transformer, rectifier diode and filter capacitor were detected. After confirming that there is no problem, the power-on test is OK! The switching power supply starts to oscillate, and the output voltage of each group is normal. After the inverter is installed, the startup test is normal. The inverter is repaired. (Note: Maintenance personnel must develop habits during maintenance: do not rush to replace the test machine after discovering bad components. Be sure to test the components with high power and easy to be bad, and then try to test the machine after no problem, so it is safe and safe).
[Case 2]: The inverter (fault phenomenon: no display after power-on) detected that the main circuit of the power supply, the charging resistor, and the main circuit contactor are all normal, and the fault is determined on the power board. Follow the repair procedure to measure the switching power supply board. The first step is to pass the measurement. In the second step, the switch tube ce junction is broken down, and it is removed. Then, the transformer, the rectifier diode, the filter capacitor and other key components are detected. After the problem is confirmed, the power-on test is performed, and the groups are output. The voltage is normal, the installation test is normal, and the fault is eliminated.
[Case 3]: The inverter (fault phenomenon: no display after power-on) has found that the main circuit of the power supply, the charging resistor and the main circuit contactor are all normal, and the fault is determined on the power board. Follow the repair procedure to measure the switching power supply board. The first step is measured, the second step is passed, the third step is passed, the fourth step is passed, and then the power board is powered separately. The power supply of the PWM modulation chip has a voltage of about 12.5V to the ground, indicating that the power supply is normal. . Looking at the PWM output of the chip with an oscilloscope, I found that there is no PWM modulation waveform. After replacing the PWM modulation chip, the power-on test is normal and the fault is eliminated.
[Case 4]: Inverter (Fault phenomenon: No display after power-on) The burnt-out switch tube has been tested and found that the main circuit of the power supply, the charging resistor and the main circuit contactor are all normal, and the fault is determined on the power board. Follow the repair procedure to measure the switching power supply board. The first step is measured, the second step is to find the switch tube breakdown, the third step is passed, the fourth step is passed, the new switch tube is replaced, the power board is powered separately, and the tube is burned again. After the switch tube is removed, the tube is not installed, and the power is tested. It is normal to measure the voltage of the PWM modulation chip to the ground with a voltage of about 12V. Look at the PWM output of the chip with an oscilloscope and find that the PWM wave is only about 5-6 KHZ. After the power is turned off, the timing component is removed and measured. It is found that the resistance of the timing resistor becomes larger. After replacing the timing resistor and the switch, the power is normal. Burn the power tube and troubleshoot.
[Case 5]: Lenze frequency converter (fault phenomenon: no display after power-on) Repeated burning switch tube measures the switching power supply board according to the maintenance procedure. The first step of measurement is passed. In the second step, the switch tube ce junction breakdown is found, and the third, fourth, fifth, sixth, and seventh steps are measured. Install a new switch tube power-on test. As the voltage of the regulator rises, you can hear the click of the start-up, which is a little loud. After adjusting the voltage to the rated voltage, the measured output voltage is lower than the normal value. 2 minutes, suddenly smelled a burning smell, the fuse was broken, and quickly cut off the power and found that the switch tube is very hot, the measurement found that it has broken down. Remove the switch tube power-on test, measure the voltage of the PWM modulation chip to the ground with a voltage of about 12V, use the oscilloscope to see the PWM output of the chip, and find that there is a PWM wave output and the frequency is around 30 KHZ, which is also normal. Therefore, it is suspected that the quality of the switch tube that has just been replaced is not good, and it is replaced with a power-on test. The result is that the tube is burnt. After the power is turned off, the components of the absorption circuit are inadvertently encountered. It is found to be hot, but it is normal during the measurement. Ah, so I measured it again and it was normal. Simply remove the absorption circuit first, and then put on a tube to conduct the test. It is found that the noise of the transformer is small, and the output voltage of each group is also normal. After running for 20 minutes, the switch tube is not burned again. After the power is turned off, the touch switch tube is slightly heated, which is a normal heating state. Therefore, it is judged that the fault is in the absorption circuit, the absorption circuit component is replaced, and the fault is eliminated.
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