Abstract: A fault condition is diagnosed in an electric machine that includes a rotor and a plurality of permanent magnets. To do so, the rotor is rotated so that each of the plurality of permanent magnets passes a magnetic flux density sensor, and the values of magnetic flux density are measured using the magnetic flux density sensor at a plurality of positions of the rotor. The measured values of magnetic flux density are analyzed and a magnitude of a peak amplitude is compared in a time or frequency domain with a reference value. If the peak amplitude is below the reference value, the electric machine is determined to have a fault condition.

Abstract: There is disclosed a method for diagnosing a fault condition in an electric machine 4, the electric machine 4 comprising a rotor 10 having an axis of rotation 14 and comprising a plurality of permanent magnets M1-M8. The method comprises: rotating the rotor 10 so that each of the plurality of permanent magnets M1-M8 passes a magnetic flux density sensor 6; measuring values of magnetic flux density using the magnetic flux density sensor 6 at a plurality of positions of the rotor 10; analysing the measured values of magnetic flux density and comparing a magnitude of a peak amplitude in a time or frequency domain with a reference value; and if the peak amplitude is below the reference value, determining that the electric machine 4 has a fault condition.

Abstract: A low profile spindle motor for supporting and rotating media disk or disks of a hard disk drive includes a plurality of stator teeth, a winding layer which may be formed by printed circuit board or the like, and a rotor. The plurality of stator teeth are disposed in an annular region surrounding an axis of rotation of the motor, and have projected ends for increasing the tooth area facing a magnet ring of the rotor. The winding layer has a plurality of windings disposed surrounding the axis of rotation. Each winding is coupled to one of the plurality of stator teeth. The magnet ring is positioned radially spaced apart and coplanar with the annular region. The magnet ring has magnetic poles annularly distributed to generate magnetic fluxes along radial direction. Spindle motor formed according to the invention has a low profile, improved performance and manufacturability.

Abstract: A low profile permanent magnet synchronous motor with segment structure. In accordance with this invention, a stator assembly for an electromagnetic motor is provided. The stator assembly has a first stator core and a second stator core that couple windings. Teeth extend outward from each stator core and through the windings to contact the other stator core.

Abstract: A low profile permanent magnet synchronous motor with segment structure. In accordance with this invention, a stator assembly for an electromagnetic motor is provided. The stator assembly has a first stator core and a second stator core that couple windings. Teeth extend outward from each stator core and through the windings to contact the other stator core.

Abstract: A low profile spindle motor for supporting and rotating media disk or disks of a hard disk drive includes a plurality of stator teeth, a winding layer which may be formed by printed circuit board or the like, and a rotor. The plurality of stator teeth are disposed in an annular region surrounding an axis of rotation of the motor, and have projected ends for increasing the tooth area facing a magnet ring of the rotor. The winding layer has a plurality of windings disposed surrounding the axis of rotation. Each winding is coupled to one of the plurality of stator teeth. The magnet ring is positioned radially spaced apart and coplanar with the annular region. The magnet ring has magnetic poles annularly distributed to generate magnetic fluxes along radial direction. Spindle motor formed according to the invention has a low profile, improved performance and manufacturability.