Control and dynamics of constant-power-loss-based operation ofpermanent-magnet synchronous motor drive system

The operational envelope of electrical machines is limited by the maximum permissible power loss of the machine at any given speed. The control and dynamics of the permanent-magnet synchronous motor (PMSM) drive operating with a maximum power loss versus speed profile is proposed in this paper. The proposed operational strategy is modeled and analyzed. Its comparison to the conventional strategy of limiting current and power to rated values demonstrates the superiority of the proposed scheme. The implementation of the proposed strategy is developed. It is achieved with an outer power loss feedback control loop. This has the advantage of retrofitting the present PMSM drives with the least amount of software/hardware effort. The PMSM drives in this case then can use the existing controllers to implement any torque control criteria, such as constant torque angle, unity power factor, constant air-gap flux linkages, maximum torque per unit current, or maximum-efficiency operation. Experimental verification of the new operational strategy is provided. The concepts presented in this paper can be applied to all other types of motor drives     

Pawl latch mechanism design and control for load/unload technology

This paper summarizes functions and features of a new latch design, named as pawl latch from herein, for implementation on ramp loading disk drives, where a disk drive with a ramp would allow actuator to stay on the ramp outside the disk when not in use. The new latch system consists of two latch mechanisms: one is inertia latch and the other is magnetic latch. These two latches work together to obtain very reliable non-contact break free latch while maintaining high resistance during rotary shock condition. Simple control method is also presented to alleviate audible noise issue generated using the pawl latch mechanism.