Hybridization ratio alpha is an additional degree of freedom offered by the hybrid excitation principle in the design of synchronous electrical machines. The first goal of this contribution is to present the tool developed for analysing the effect of the hybridization ratio. This software tool is based on the electrical circuits modelling of hybrid excitation synchronous machines. This tool can also be advantageously used for the pre-optimization of this parameter. The used model and the optimization algorithm are first thoroughly detailed. Finally, a parametric study intended to investigate the effect of some design specifications and parameters on this optimal value is presented. (C) 2020 International Association for Mathematics and Computers in Simulation (IMACS). Published by Elsevier B.V. All rights reserved.