Eddy current is generated by time-varying current in the armature and the back EMF causing by moving magnets in the cooling plate. It produces a damping force influencing the motor’s dynamic characteristic. In this paper, a new method is introduced to suppress eddy current by offsetting back EMF. The correction of the method and effect of eddy current suppression is proved by simulation: 95% reduction in the damping force significantly help with reducing the thrust fluctuation. The new cooling plate is designed into a unit module, and it can combine with others to make cooling plates of different lengths.

Eddy current， Long primary， cooling plate