The inverter drive output board is the place where the inverter is prone to failure, so today I want to talk about the maintenance of the inverter output board.

To repair the output board of the drive of the frequency converter, first observe whether the components on the PCB board are burnt out. If so, replace them first, and then analyze the cause of the burnt out place and solve the fault.

Then measure the IGBT module to confirm whether there is a short-circuit fault when the module is not powered on, and whether the voltage drop of 0V and + voltage (voltage drop measured by diode gear) from the three-phase input and output to the output of the rectifier bridge is basically equal. If the voltage drop difference is too large, check the corresponding circuit.

After the above operations, next, the frequency converter is unloaded, and a 60W bulb in the isolated power string is used to connect the power supply to check the working state:

When there is no load, the bulb should be off when it flashes once when the power is turned on. If it is always on, it indicates that there are components damaged in the circuit, and this fault should be eliminated first;

If the bulb does not flash, it means that the circuit is blocked. Check whether the starting resistance is burned out, and the switching power supply may not work.

If the starting resistance and switching power supply are normal, what we need to do is to measure whether the DC voltage on the filter capacitor is normal.

If the voltage is too low, check the filter capacitor, test the output voltage of a group of switching power supply, and make sure that the switching power supply works normally, otherwise, repair the switching power supply.

These can be tested under the working state of the frequency converter if they are normal. Adjust the frequency of the frequency converter from 0 to the maximum value of 50Hz, and measure whether the three-phase output no-load voltage can rise to the maximum value at a constant speed from 0V (the maximum output voltage of 200V should reach AC 200V 50Hz, and the maximum output voltage of 380V should reach 380 50Hz).

If it is too low, check the filter capacitance and whether the three phases have equal voltage at the same time point (three-phase balance);

If it is unbalanced, check the optocoupler of the corresponding upper tube and lower tube and its power supply and drive circuit.

Be sure to check these steps, and finally load the machine for a few minutes to confirm that the three-phase output current is balanced, whether the output voltage is equal (within 1V difference) and there is no alarm code. Only in this way can the maintenance be completely completed.