Soft magnetic steel for the rotor of the Lundell alternator

Maybe the most common and widespread electrical machine. the Lundell machine is also one of the least known. The current material used for the claw poles rotor is a low carbon steel. The current state of the art of the production of such component will be illustrated and the focus of the analysis will be the soft magnetic materials used for the automotive application. The performance improvement of this soft magnetic material can contribute to tackle the always increasing restrictions in emissions in the automotive industry. An investigation on the current material and production process is therefore performed as a first step to know if the material is used at its full potential. To perform a complete analysis on the low carbon steel in curent use, an electrical and metallurgical study is carried on and the annealed component is compared with the as-forged one. To perform the metallographic analysis, a Python script has been used to perform efficiently the grain size measurements. Finally, the claw poles rotors have been machined into ring samples, that have been then used to perform magnetic measurements.