As an energy-efficient motor speed control device, the frequency converter has been widely used in enterprises. High-power devices, auxiliary power supplies, and corresponding drive circuits that perform frequency conversion in the inverter have high damage rates.
When repairing the inverter, the customer indicates that the motor is running with jitter. At this time, the first reaction is that the inverter output voltage is unbalanced. After checking the main circuit power device, it was found that there was no damage. After the inverter was powered on, it showed normal. After running the inverter, the three-phase output voltage was indeed unbalanced. The 6-channel drive output waveform was tested. It was found that the V-phase bridge waveform was abnormal. Measuring the circuit resistance, diode, optocoupler and other electronic devices, it is found that a diode providing reverse voltage is broken down, and then re-powered after replacement, the three-phase output voltage is balanced, and the motor is operated without jitter.