Reduction of Torque Ripple and Radial Force Harmonics in Consequent-Pole Permanent Magnet Motor for Electric Power Steering Applications

This paper focuses on the reduction of torque ripple and radial-force harmonics of a consequent-pole permanent magnet (CPM) motor by harmonic current injection based on dq-axis frame without skewing the rotor or stator so that the CPM motor can be applied to electric power steering (EPS) applications. In the proposed method, the 6
^th
and 12
^th
radial-force components are reduced by the 6
^th
and 12
^th
d-axis current harmonics, respectively, whereas the 6
^th
and 12
^th
torque components are reduced by the 6
^th
and 12
^th
q-axis current harmonics, respectively. Finite element analysis (FEA) results demonstrated that the electromagnetic and acoustic noise performances of the CPM motor with harmonic current injection were significantly improved and were competitive with those of the surface permanent magnet motor.