Study of magnetic vibrations in hydrogen electric vehicles

The transport sector is responsible for generating approximately 30% of the total emissions, with 20% of all carbon dioxide emissions coming from road transport. Transitioning to electric transport can help reduce emissions from road traffic in urban areas. Hydrogen is one of the few energy carriers that practically does not emit carbon dioxide , and it can satisfy a significant portion of the world's transportation energy needs. Synchronous machines with permanent magnet excitation and fractional slot concentrated windings can be highlighted as promising traction motor for electric transport. These machines compared to conventional electric machines have the following advantages: increased energy efficiency, less active material consumption, and improved mass-dimension indicators. However, some machine sizes have highter noise and vibration levels due to radial forces acting between the stator and rotor. The paper presents a methodology for calculating the radial forces using the harmonic components method. The design of the magnetic system with permanent magnets placed on the surface of the cylindrical rotor is considered. The radial force generation conditions with a smooth non-magnetic gap are described. The obtained results show that in electric machines with fractional slot concentrated windings with six phase zones radial forces causing bending deformations of the stator ring and distorting the stator to an elliptical shape are predominated. In machines with fractional slot concentrated windings with three phase zones, radial forces causing one-sided attraction of the rotor to the stator are predominated. The formation of these radial forces is due to the presence of two main harmonics with high amplitude in the magnetomotive force harmonic content created by the winding. Therefore, the use of a design solution that allows reducing one of the main harmonics of the winding magnetomotive force will lead to reduction of magnetic vibrations. The obtained results can be used in the design of the considered class traction motors for hydrogen transport.