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Inverter output side of the PWM voltage waveform, after the motor winding, the output current is approximately sinusoidal, and behind a voltage phase angle, the angle determined by the motor power factor. 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, when the output current is higher than a certain threshold, the inverter will report a fault. The inverter will block the pulse output immediately. This is an important and necessary way to protect the inverter from damage. This fault can not be shielded.
This paper introduces several methods to deal with the inverter overcurrent fault
There are many reasons for the over-current fault of the inverter, which should be analyzed according to the actual situation. If you find the root cause, and then the right medicine, generally can be resolved.
The motor cable is connected to the inverter and the motor. It is from the inverter side and the motor side were analyzed.
1, first of all from the inverter side of the impact
Inverter side may cause the inverter overcurrent common causes are:
Acceleration time is too short: the greater the torque required at this time, the torque is proportional to the current, so the current is also great. Can be appropriate to extend the acceleration time.
Lifting function: If the V / f control, the start process, the voltage rise is too high, may also cause over-current. The voltage rise value can be appropriately reduced.
PID parameter is not appropriate: too high dynamic response, may cause over-current. Should extend the filtering time, minus P plus I.
2, followed by the influence from the motor side
The common causes of the motor side may cause the inverter to overcurrent are:
Motor cable to ground short circuit: cable insulation is not good, there are broken skin. The cable insulation can be tested with a shaking table to verify the cable quality.
Motor stall: At this time the inverter will attempt to use the greater torque to rotate the motor, which may cause overcurrent fault.
3, and finally the hardware problem
If the inverter within the current detection mechanism is not working properly, or CPU processing mechanism out of the problem, these are not set parameters can be resolved, need to repair.
If the inverter does not match the motor current, it may cause overcurrent fault. Such as small inverter with a large motor, or nameplate parameters are wrong, may cause over-current failure.
