Torque Ripple Minimization Using Stator Tooth Shaping in A Triple Rotor Architecture

Improving power density of electric machines is one of the primary goals in aerospace industry. A novel triple rotor architecture has been proposed here targeting to push the state-of-the-art power density limit. The proposed concept has three rotors to produce useful torque and undesirable torque ripple. The torque ripple can be substantial for the triple rotor architecture since it has three rotors. High torque ripple can lead to rotor vibration, mechanical structure instability, and rotor bearing related issues. To reduce the torque ripple, a novel tooth shaping technique is proposed to reduce the level of tooth saturation and the stator field harmonics. A notch cut is introduced at the center of each tooth mainly to increase manufacturability during stator coil integration. Moreover, the rotor is beneficial from the proposed technique as it reduces rotor eddy current loss and its temperature. Based on the finite element results, the proposed teeth shaping technique demonstrated effective torque ripple reduction in the triple rotor architecture electric machines.