This paper reminds the drawbacks of classical voice-coil motors and presents a way to improve them. Two ironless and leakage free structures are presented, one using traditional sintered magnets and the other one using bonded magnets, giving the pros and cons of each solution. A 2D analytical model using the Coulombian approach is used to calculate and compare the performances of both structures. Then, in order to evaluate the relevance of the 2D model for magnet rings, a comparison is done with a 3D analytical model for several radii of rings.