When afrequency converter's fast fuse after the large capacitor opens, or when the IGBT inverter module is damaged, the drive circuit basically cannot be intact. Do not simply replace with a good fast fuse or IGBT inverter module, as this can easily cause the newly replaced good components to be damaged again. At this time, you should focus on checking whether there are burn marks on the drive circuit. Here, you can first unplug the drive pin connections of the IGBT inverter module, and use a multimeter's resistance range to measure whether the resistance values of the six drive circuits are the same (but for a very fewfrequency converters, the six drive circuits do not have the same resistance values: such as Mitsubishi, Fuji, etc.frequency converters),
Generally speaking, the problems that occur are nothing more than no output on U, V, W three phases, or unbalanced output, or balanced output but jitter at low frequencies, and also startup alarms, etc.
If the six resistance values are basically the same, it still cannot fully prove that the drive circuit is intact. Next, you need to use an electronic oscilloscope to measure whether the voltages on the six drive circuits are the same. When a start signal is given, whether the waveforms of the six drive circuits are consistent; if you do not have an electronic oscilloscope, you can also try using a digital electronic multimeter to measure the DC voltage of the six drive circuits. Generally, the DC voltage on each drive circuit before startup is about 10V, and after startup it is about 2-3V. If the measurement results are all normal, it can basically be judged that thisfrequency converter's drive circuit is good. Then connect the IGBT inverter module to the drive circuit, but remember that without 100% certainty, the safest method is to disconnect the P of the IGBT inverter module from the DC bus, and connect a series of incandescent bulbs or a resistor with a larger power rating in between. This can protect the IGBT inverter module from being burned by the discharge current of the large capacitor in the event of a large current in the circuit.
