COMPENSATION OF PERMANENT-MAGNET MOTORS TORQUE RIPPLE BY MEANS OF CURRENT SUPPLY WAVESHAPES CONTROL DETERMINED BY FINITE-ELEMENT METHOD

A method to determine the supply current waveshapes for torque ripple compensation in permanent magnet motors without saliency and damping bars, by means of a finite element code, is presented. First, a theoretical analysis shows that current waveshapes producing constant torque can be determined. This analysis leads us to an expression for the current as a function of the motor emf and cogging torque. Several methods, based on finite element computation of the magnetic field, for computing the cogging torque and emf are proposed and compared. A special experimental bench for motor torque measurement is used to validate the theoretical results.