Torque ripple minimization in permanent magnet synchronous servodrive

In this paper the electromagnetic torque developed in Permanent Magnet Sync hronous Motors is analyzed. Two strategies are discussed for torque ripple minimization. The first is based on numerical predetermination of the curre nt waveform which is imposed by the control in machine phases to obtain a c onstant torque. The second is a torque regulation based on its on-line inst antaneous estimation. To optimize the current waveform and minimize copper losses, two methods for current modulus minimization are compared. One is r elative to the optimal current which leads to a perfect constant instantane ous torque with minimum instantaneous current modulus, and the second conce rns only the mean current modulus. Relation between current components and torque reference can be expressed by functions after normalization These fu nctions optimizing the mean torque are easy to implement and can be used fo r torque ripple minimization.