Force ripple modeling and suppression in permanent magnet linear synchronous motors

A force ripple based on velocity and position was developed to study how to suppress force ripples in iron-core linear motors to improve the dynamic and static performance of ultra-precision stages. The harmonic components contained in the force ripple were calculated based on the relationship between the force ripple and trajectory tracking error. A force ripple model was then developed with a feedforward compensator. Tests indicate that this method efficiently reduces force ripples at various velocities. The moving standard deviation of tracking error is reduced to 40% and the steady-state tracking error of the ultra-precision stage is significantly improved.