Title :
Drag loss in retaining rings of permanent magnet motors
Author :
Kirtley, James L., Jr. ; Lovelace, Edward C.
Abstract :
Slot openings modulate the magnetic field present in the air-gap of permanent magnet motors. If the magnets are conductive or if there is present a conductive magnet retention cylinder, losses will be present. This is no-load loss which appears as a drag on the rotor. It is difficult to distinguish from core loss, at least from terminal measurements, but in some cases can cause severe rotor heating. In this paper we present a simple method for estimating this drag loss, which is easily mitigated by proper selection of air-gap dimensions and slot openings.
Keywords :
air gaps; eddy currents; losses; parameter estimation; permanent magnet motors; rotors; air-gap; air-gap dimensions; conductive magnet retention cylinder; core loss; drag loss; eddy current model; field disturbance; losses; magnetic field; no-load loss; permanent magnet motors; retaining rings; rotor; rotor heating; slot openings; terminal measurements; Air gaps; Core loss; Engine cylinders; Heating; Loss measurement; Magnetic fields; Magnetic losses; Magnetic modulators; Permanent magnet motors; Rotors;
Conference_Titel :
Electric Machines and Drives Conference, 2003. IEMDC'03. IEEE International
Print_ISBN :
0-7803-7817-2
DOI :
10.1109/IEMDC.2003.1210367
