An Analytical Approach to Design the PM in PMAREL Motors Robust Toward the Demagnetization
In the permanent magnet (PM) assisted reluctance motors, low energy PM, such as Ferrite PM, is used to get a cheap rotor. As far as the design choices are concerned, the PM width has to be selected so as to achieve the desired air gap flux density at no load condition and the PM thickness has to be selected to avoid the demagnetization of the PM under full load conditions. This paper presents a practical analytical approach to compute PM width and thickness according to a given air gap flux density and stress on the PM itself. Two approaches based on a complete model and a simplified model are considered and compared. As an example, a 36 slot 4 pole machine is designed. Finite element analysis confirms the results achieved by means of both analytical analyses.
IEEE Transactions on Energy Conversion