A method of modeling and numerical simulation of a brushless permanent-magnet dc motor using time-stepping finite-element technique is presented. In the proposed model, the electromagnetic field equations, the stator circuit equation, and the motion equation are solved simultaneously at each time step; thus, the eddy-current effect, the saturation effect, the rotor movement, and the nonsinusoidal quantities can all be taken into account directly in the system of equations. Dynamic conditions of the motor at starting, step voltage variation, and load torque changes are investigated using the proposed dynamic model.
Index Terms-Brushless permanent-magnet dc (BLDC) motor, dynamic analysis, time-stepping finite-element method (FEM).
Spin torque oscillator frequency versus magnetic field angle: The prospect of operation beyond 65 GHz Applied Physics Letters 94, 102507 (2009) We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs) consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.