Method for improving sensorless flow rate estimation accuracy of pump driven with frequency converter

摘要

A method in connection with a pump driven with a frequency converter. The method comprises measuring and storing the flow rate ( Q Mean ) when the pump is in operation, storing the used rotational speed ( n Mean ) and torque ( T Mean ) of the pump during the measuring of the flow rate ( Q Mean ), determining from the provided characteristic curve that is transformed into the stored rotational speed ( n Mean ), the torque ( T Manufacturer ) corresponding to the measured flow rate ( Q Mean ), calculating a bias value of the torque ( T Bias ) by comparing the torque determined from the characteristic curve ( T Manufacturer ) and the stored torque ( T Mean ) of the pump, and using the bias value of the torque ( T Bias ) in the determination of the operating point of the pump.