Rejection of tangential vibrations of synchronous machine under speed control

Although fed by perfect sine currents, the tangential components of the forces developed between the stator and the rotor of synchronous machines include undesirable effects. They produce tangential vibrations and torque ripple containing especially harmonics at 6 k times the supply frequency. These harmonics can be particularly disturbing when their frequencies lie about mechanical resonances. This paper is about the interior permanent magnet synchronous machine (IPMSM) supplied by a current-controlled PWM inverter. The aim of this work is to show how, by suitable control of the inverter, it is possible to reject some of the undesirable effects. The main innovative contributions of this paper consist essentially in the IPMSM modelling, which leads to a variable saliency rotor model, and in a very simple inverter control implementation of the proposed procedure to reject some tangential vibrations. >