Theoretical and experimental analyses of a single phase permanent magnet generator (PMG) with multiple cores having axial and radial directed fluxes

A new single phase generator has been designed and preliminary experimental results have been reported. The effects of two types of alternator cores have been explored. The proposed generator has one stator and two rotors with rare-earth-element-made permanent magnets (PMs). The physical and electromagnetic features of this PM generator are presented. The electromagnetic analyses are realized by the finite element method (FEM). The proposed machine has a combined type of flux directing mechanism, namely with axial and radial directions. The flux orientations are provided by 12 cores at the double-sided stator. The design has 2 rotors with totally 24 permanent magnets, which are positioned at different radial distances. It has been found that this design reduces the cogging torque values compared to the simple axial flux machine with 2 rotors having cylindrical cores. Thus a new cogging torque reduction technique is also proposed beside the new design. The electromagnetic simulations have been realized at different rotor speeds. The analyses also include the waveforms of currents, voltages, magnetic fluxes and cogging torque calculations. The maintenance and control of the machine is easier in operation, since the output power increases smoothly and become nearly constant up to the rotor speeds 1000 rpm. Preliminary results indicate that peak-to-peak voltage Up = 34 V is generated at the rotor speed ω = 200 rpm and it increases linearly with ω. The rated speed is expected to be 1000 rpm and 95% of efficiency is measured in the preliminary tests.