Patent ID: 8141234

Claim:
A method for magnetizing a rotor of an electrical machine, the method comprising: assembling an array of non-magnetized anisotropic permanent magnet segments around a rotor spindle encased in a retaining ring; determining a plurality of optimal magnetization orientation directions of the non-magnetized anisotropic permanent magnet segments; positioning the assembled non-magnetized anisotropic permanent magnet segments around the rotor spindle such that the optimal magnetization orientation directions of the anisotropic permanent magnet segments are aligned with a plurality of flux lines produced by a magnetization fixture; and energizing the magnetization fixture for magnetizing the segments via a pulse direct current for an optimal duration of the pulse, wherein the optimal duration of the pulse is a function of thickness, magnetic permeability, and resistivity of the retaining ring, and the optimal duration is given by an expression of T RISE > 25 ⁢ ⁢ T R ⁢ ⁢ R 2 ⁢ πμ ρ , where T RISE is the time period for optimal duration, T RR is the retaining ring thickness, μ is the magnetic permeability and p is resistivity of the retaining ring.