The electrical machines can be characterized by a global scale relative to the inducted coil, and a local one relative to the teeth dimensions. In the case of synchronous structures with centralized coil, excited by split magnets, the characterized ratio of the two previous scales is largely higher than one. The complete parametrical study of the machine that uses a large torque is particularly weighty and complex. In this paper, we propose a simple and fast pre-designing methodology. It considers different limitations and constraints such as demagnetization, overheating, dimensions,... This methodology is based on an elementary pattern and is limited to the linear regime. It combines a numerical calculation of the magnetic field -using a 2D finite elements methodology-, and a semi-analytical approximation of the constraints. We first present the performances' intrinsic formalism, and the models relative to the constraints. Then, we analyze the influence of some parameters on the limit and optimal machine's performances. Finally, we compare the obtained results to the tests we have done on a cylindrical machine with ferrite magnets.
