Abstract: A method for detecting abnormal direct current voltage measurement in a modular multilevel converter high voltage direct current transmission system is provided. In the method, a valve group voltage at a detection pole is obtained, voltages at voltage measurement points at the detection pole are collected, and comparison and determination are performed based on the actual arrangement of the voltage measurement points, and then whether an abnormal measurement occurs at each of the voltage measurement points is determined.

Abstract: An axial field motor and a method of assembling the motor are provided. The hard disk drive includes a spindle motor having a fluid dynamic bearing (FDB) motor hub, a hard disk drive housing and a base insert. The hard disk drive housing houses the spindle motor therewithin and has an upper housing and a base, the base including a first material. The base insert has ferromagnetic properties, includes a second material and has a flat circular bottom portion and an outer circumferential vertical portion. The flat circular bottom portion of the base insert is located between the FDB motor hub and the base to enhance yield strength therebetween and a bottom portion of the FDB motor hub is surrounded by the outer circumferential vertical portion of the base insert to generate preload for the FDB motor hub.

Abstract: A spindle motor for a hard disk drive includes a base and a bearing assembly coupled to the base. The bearing assembly includes a sleeve configured to rotatably support a shaft therein. A rotor hub is affixed to the shaft so as to be rotatable with the shaft about a rotational axis. A stator is arranged in between the rotor hub and the base. A first magnet is arranged over the stator and on a bottom surface of the rotor hub. In particular, the rotor hub includes a body portion, a peripheral wall portion extending from the body portion in a direction towards the base, and a flange portion having a disk seating surface configured for supporting one or more disks thereon. The peripheral wall portion is configured to at least partially surround the stator in a radial direction. There is also provided a method of fabricating the spindle motor and a hard disk drive incorporating the spindle motor.

Abstract: According to an embodiment of the present invention, a data storage device comprising a motor having a stator is disclosed. The stator may include a substrate having a first surface and a second surface opposite to the first surface; and a n-phase winding arrangement having n phase windings; wherein each phase winding comprises m flat fractional-pitch coils arranged on the first surface of the substrate such that the coils are spaced apart uniformly along a closed loop and connected in series; wherein each coil together with an angular section of the substrate between the coil and an adjacent coil of the same phase winding defines a stator pole-pair; and wherein m is an integer larger than 1.

Abstract: A spindle motor for a hard disk drive includes a base and a bearing assembly coupled to the base. The bearing assembly includes a sleeve configured to rotatably support a shaft therein. A rotor hub is affixed to the shaft so as to be rotatable with the shaft about a rotational axis. A stator is arranged in between the rotor hub and the base. A first magnet is arranged over the stator and on a bottom surface of the rotor hub. In particular, the rotor hub includes a body portion, a peripheral wall portion extending from the body portion in a direction towards the base, and a flange portion having a disk seating surface configured for supporting one or more disks thereon. The peripheral wall portion is configured to at least partially surround the stator in a radial direction. There is also provided a method of fabricating the spindle motor and a hard disk drive incorporating the spindle motor.

Abstract: An axial field motor and a method of assembling the motor are provided. The hard disk drive includes a spindle motor having a fluid dynamic bearing (FDB) motor hub, a hard disk drive housing and a base insert. The hard disk drive housing houses the spindle motor therewithin and has an upper housing and a base, the base including a first material. The base insert has ferromagnetic properties, includes a second material and has a flat circular bottom portion and an outer circumferential vertical portion. The flat circular bottom portion of the base insert is located between the FDB motor hub and the base to enhance yield strength therebetween and a bottom portion of the FDB motor hub is surrounded by the outer circumferential vertical portion of the base insert to generate preload for the FDB motor hub.

Abstract: According to an embodiment of the present invention, a data storage device comprising a motor having a stator is disclosed. The stator may include a substrate having a first surface and a second surface opposite to the first surface; and a n-phase winding arrangement having n phase windings; wherein each phase winding comprises m flat fractional-pitch coils arranged on the first surface of the substrate such that the coils are spaced apart uniformly along a closed loop and connected in series; wherein each coil together with an angular section of the substrate between the coil and an adjacent coil of the same phase winding defines a stator pole-pair; and wherein m is an integer larger than 1.