How to slove over current problem of VFD

frequency inverter for Lifting


General treatment method of inverter overcurrent problem:

The output side of the inverter is a PWM voltage waveform. After passing through the motor winding, the output current is approximately a sine wave and lags behind the voltage by a phase angle. This angle is determined by the power factor of the motor. The output current of the inverter is detected by a precision resistor or current transformer, and the current signal is processed by the CPU.

In order to protect the inverter, the inverter will report an overcurrent fault when the output current is above a certain threshold. The inverter will also immediately block the pulse output. This is an important and necessary method to protect the inverter components from damage. This fault cannot be masked.

There are many reasons for the inverter overcurrent fault, which should be analyzed according to the actual situation. If you find the right source, then you can solve the problem.

The motor cable connects the inverter and the motor. Then analyze from the inverter side and the motor side.

1. The first is the influence from the inverter.

Common causes of inverter overcurrent that may occur on the inverter side are:

The acceleration time is too short. At this time, the larger the motor torque is, the torque is proportional to the current, so the current is also large. Properly extend the acceleration time.

Improved functions. If the voltage rises too high during V / f control during startup, it may also cause overcurrent. Reduce the voltage boost value appropriately.

PID parameters are inappropriate. Excessive dynamic response may cause overcurrent. Extend the filtering time by subtracting P and I.

2. The second is the influence from the motor side.

Common reasons that may cause inverter overcurrent on the motor side are:

The motor cable is shorted to ground. The cable is not well insulated and has broken skin. You can use a shaker to test the cable insulation to confirm the quality of the cable.

Motor stalled. At this time, the inverter will try to use a larger torque to rotate the motor, which may cause overcurrent failure.

3. Finally, there is the hardware problem.

If the current detection mechanism inside the inverter does not work properly or there is a problem with the CPU processing mechanism, these cannot be solved by setting parameters and need to be repaired.

If the inverter does not match the motor current, it may cause an overcurrent fault. For example, a small inverter with a large motor, or a wrong nameplate parameter may cause an overcurrent fault.



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