Investigation of the electromechanical variables of the spindle motor and the actuator of a HDD due to positioning and free fall

Abstract

This research investigates the electromechanical variables of a spindle motor and an actuator of an operating hard disk drive (HDD) due to the positioning and the free-fall of a HDD. Magnetic fields of a brushless DC motor and a voice coil motor are determined by the time-stepping finite element equation of the Maxwell equation and the driving circuit equation. The pressure of the fluid dynamic bearings (FDBs) is determined by solving the finite element equation of the Reynolds equation to calculate the reaction force and the friction torque. Dynamic equations of the rotating disk-spindle, actuator, and stationary bodies of a HDD are derived from the Newton-Euler's equation. The speed control of the rotating disk-spindle and the servo control of the actuator are included to describe the head positioning between the rotating disk and the head. The simulation is performed to investigate the electromechanical variables of the spindle motor and the actuator due to the positioning and the free-fall of a HDD. This research shows that the positioning and the free-fall of a HDD change the electromechanical variables of the spindle motor and the actuator of an operating HDD, and that monitoring their electromechanical variables may identify the positioning and the free-fall of a HDD without using extra sensors.

Investigation of the position error signal of an operating hard disk drive due to varying temperature conditions

“…The tracks on the disk were determined by the radius from the center of the disk and it was assumed to be a true circle. The PES can be represented by the displacement difference between the disk track and the read/write head (Jang et al 2007). …”

“…The magnetic field of the VCM is also derived by the Maxwell equation in terms of cylindrical coordinates. It is coupled with the electrical equation of the VCM using the linear current control (Jang et al 2007). …”

“…Subscripts R and A represent the rotating disk-spindle and the actuator of an HDD, respectively. Magnetic and torque are calculated from the finite element analysis of the electromagnetic field, the FDB reaction force and friction finite element analysis of FDBs (Jang et al 2007). The tracks on the disk were determined by the radius from the center of the disk and it was assumed to be a true circle.…”

“…The magnetic force and torque of a BLDC motor are calculated by using the Maxwell stress tensor and the magnetic torque of a VCM is calculated by using the Lorentz's force (Jang et al 2002(Jang et al , 2007.…”

A miniature spindle motor with fluid dynamic bearings for portable storage device applications

“…Many researchers have investigated the performance of the FDB in the spindle motors of data storage drives (Osman et al 2003;Chao and Huang 2005;Feng and Kenjo 2007;Jang et al 2007;Nada and Osman 2007). None of the aforementioned works, however, put effort toward the case of the FDB designed for miniature spindle motor.…”