Finite-element analysis of electromechanical field of a HDB spindle motor at elevated temperature

This research presents a finite element method to analyze the electromechanical field of a hydrodynamic-bearing (HDB) spindle motor of computer hard disk drives at elevated temperature. Magnetic field is analyzed by the nonlinear time-stepping finite element method considering the switching action of PWM inverter, and magnetic force and torque are calculated by the Maxwell stress tensor. Mechanical motion of a rotor is determined by Newton´s equation of motion, in which the hydrodynamic bearing force and friction torque are calculated by solving the Reynolds equation. Both the analyses of magnetic and mechanical field are combined in a closed loop to control the speed using PWM. Simulation results are verified by the experiments. This research also investigates the electromechanical performance of a HDB spindle motor at elevated operating temperature.