Method for frequency converter

Abstract

A method for a frequency converter, when the frequency converter controls a motor and operates torque-controlled partly or entirely in a field weakening region. The method comprises the steps of defining the direction of travel and sector of a stator flux vector ({overscore (ψ)}s) in the motor, predicting a torque estimate (Tpred) produced by a voltage vector of the output of the frequency converter at the end of the voltage vector when a voltage vector change occurs at the instant of prediction, comparing the predicted torque estimate (Tpred) with a reference torque (Tref) of the frequency converter, and implementing the voltage vector change when the predicted torque estimate (Tpred) is smaller than the reference torque (Tref) and the stator flux vector ({overscore (ψ)}s) is moving in a positive direction of travel or when the torque estimate (Tpred) is greater than the reference torque (Tref) and the stator flux vector ({overscore (ψ)}s) is moving in a negative direction of travel.

Dependencies are inferred from the claim text.