Minimization of force ripples in coreless linear actuators

This paper concerns permanent magnet and coil geometries of coreless linear actuators which minimize the force ripples and power dissipation. One or more spatial harmonics of the force ripples are reduced for suitable magnet and coil geometries. Equations for parameter values of these geometries are given, and minima of force ripples and dissipation are determined by evaluating all combinations of the magnet and coil geometries. In theory, an rms force ripple as low as 0.002% can be achieved. The effect of manufacturing tolerances on the lower bound of the force ripples is shown by Monte Carlo simulations. It is shown that the minimization of the force ripples is mainly limited by variation in remanence of the permanent magnets.