Patent ID: 7969106

Claim:
A vector controller for a permanent-magnet synchronous electric motor that controls an alternating current from an inverter that drives the permanent-magnet synchronous electric motor so as to come into coincidence with a current command, comprising: a reference phase-angle calculation unit for generating a reference phase angle of the permanent-magnet synchronous electric motor; a current command generation unit for generating the current command using a given torque command; a current control unit for making a control calculation of a current error between the current command and a current through the permanent-magnet synchronous electric motor, to output the calculated current error; a decoupling voltage calculation unit for calculating a feed-forward voltage using motor parameters of the permanent-magnet synchronous electric motor and the current command; a modulation index calculation unit for outputting a modulation index for the inverter by receiving a direct-current voltage to the inverter and a voltage command that is the sum of the current error and the feed-forward voltage; a control phase-angle calculation unit for outputting a control phase angle for the inverter by receiving the voltage command and the reference phase angle; a pulse-width-modulation signal generation unit for generating pulse-width-modulation signals for the inverter using the modulation index and the control phase angle; and a current command compensator for correcting the current command using a corrected current command calculated based on the modulation index; wherein the current command compensator sets the corrected current command to a value obtained by processing through a time delay element and by multiplying by a predetermined constant the difference between the modulation index and a predetermined modulation index set value.