Solution of the over-voltage fault happens during constant speed

Fault Name:

Over-voltage fault happens during constant speed.

Fault Symptom:

AC200T-T3-22G frequency inverter is used for unwinding and E.oU3 would be reported when running for a period of time.

Causes:

Generally, when unwinding, in order to ensure tension from unwinding to traction, the unwinding motor is pulled or reversed by the winding motor, and the motor is in the power generation state, resulting in over-voltage.

Solutions:

The 22KW frequency inverter does not have a brake unit. You could instruct the customer to select the appropriate brake unit and braking resistor. No fault has occurred after installation.

Analysis:

When unwinding, the unwinding motor is actually pulled reversely, and the slip S of the motor must be negative at this time. The motor is in the state of power generation, and the generated energy is fed back to the frequency inverter bus side through the freewheeling diode of the circuit. Bus voltage increases and passes the current limiting and depressurization filter and then passes through the operational amplifier to obtain the VPN analog signal. The VPN obtains the VPN-IN analog signal through one operational amplifier on the control board. The VPN-IN is directly input to the DSP is used as the software voltage calculation signal. The software converts the bus voltage through the pin analog quantity. When the converted bus voltage exceeds the software setting value, an over-voltage fault will be reported.