In order to develop the new generation of motor pump (water) for heating or for cooling applications, a structural motor study was made to determine the best motor corresponding to the specifications. Stator structures, winding, supplying mode, pole number, etc. are the parameters of this study. To analyse them, several software packages were developed in order to design each solution as best as possible. This paper first describes the differences between the choice of the motor based on the phase number and the supply (uni or bi-directional). Secondly, the influence and the choice of the back-EMF shape versus supplying mode is analysed. Finally, the motor design comparison is presented showing the advantages and disadvantages of each solution