Active filtering of torque ripples in double stator synchronous machines

A current inverter fed synchronous motor is affected by torque ripple and suffers damping losses. These limitations can be overcome either by increasing the number of phases or by fitting several shifted armatures to the synchronous machine. This results in the reduction of the torque ripple which does not, however, vanish totally. A further enhancement is achieved by adding an active filter in parallel with the machine [B. Davat, P. Letellier, D. Poupard, Active filtering of torque ripples in high power electrical machines, PESC95, vol. 2, 1995, pp. 1133–1336]. This paper proposes an extension of the active filtering principle to deal with double stator synchronous machine (DSSM) as well. The authors, after presenting the method for calculating the current command, compared the filtering of torque ripples of a simple stator synchronous machine with that of a double stator synchronous machine and examined the impact of the filter voltage source on the functioning of the current inverter.