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As the area density of hard disk drives (HDD) increases, the speed of spinning media disks should be very stable. Now each HDD employs a sensorless brushless DC (BLDC) motor to spin the media platters at a constant speed. However, the drag torque of the spinning disk varies as the slider with writer and reader heads moves in or out to seek the targeted tracks, which will cause the spinning speed fluctuation...
The leading wires of the armature winding may conduce the windings be asymmetric in permanent magnet synchronous motor (PMSM), and finally induce an additional unbalanced magnetic pull (UMP) in the motor operation. The influence of the UMP could be serious, especially in the operation of high speed PMSMs. The paper analyzes the reason inducing this special UMP, and effects of UMP to the motor operation...
The electromagnetic (EM) sources of the acoustic noise are very concerned in the spindle motor used in the hard disk drives (HDDs). Identifying the effects of these sources is important for high performance hard disk drive products. The electromagnetic analysis results in this paper show that, when the spindle motor is driven by brushless DC (BLDC) mode, the EM torque ripples can be categorized as...
In the applications of high performance permanent-magnetic brushless DC (PM-BLDC) motor, the effects of unbalanced-magnetic-pull (UMP) is very concerned. Besides the intrinsic and extrinsic reasons, the motor drive current may also be an UMP source if the armature winding design is not reasonable. This paper presents an analytic model for analyzing the UMP induced by electromagnetic (EM) structure...
Both symmetric and asymmetric armature windings are applied in the spindle motors used in hard disk drives. Consider the influence of the drive current in the windings, the analysis to the unbalanced-magnetic-pull (UMP) generated in the motor becomes more difficult. Besides the intrinsic and extrinsic components, the additional UMP can also induced by the current, and the UMP could thus be serious...
The performance of two-phase spindle motor is analyzed, which is driven by constant voltage sensorless BLDC mode. In the motoring operation, the rotor positions are estimated by back EMF detecting and a digital filter is used to realize BLDC sensorless control. The two-phase BLDC motor is more robust in the starting and low speed operation, and can realize accurate speed control. Both the simulations...
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