Mitigation of acoustic noise by minimize torque and radial force fluctuation in fault tolerant permanent magnet machines

A spoke-type fault tolerant permanent magnet (ST-FTPM) machines incorporate the merits of interior permanent magnet motors and in-wheel motors, but they still suffer from vibration and acoustic noise due to torque and radial force fluctuation. The distinctive winding distribution can offer more sinusoidal back electromotive force, but it brings unbalance radial force simultaneously. This paper analyzes its electro-magnetic force, and then an optimal control strategy is proposed to minimize the torque and radial force fluctuation as well as the unbalanced radial force, thus mitigating the vibration and acoustic noise level. In addition, the transient structural finite element analysis is adopted to verify the theoretical analysis.