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The operation of a brushless permanent-magnet machine requires rotor-position information, which is used to control the frequency and phase angle of the machine's winding currents. Sensorless techniques for estimating rotor position from measurements of voltage and current have been the subject of intensive research. This paper reviews the state of the art in these sensorless techniques, which are broadly classified into three types: motional electromotive force, inductance, and flux linkage. Index Terms--Brushless machines, estimation, permanent-magnet (PM) machines, position measurement, reviews.

Microscopic voids in the die attachment solder layers of power semiconductor devices degrade their overall thermal transfer performance. This paper presents analytical results of the effect of spherical and spheroidal void geometries on the thermal conductivity of bulk media. Analytical results are compared with axially symmetric and three-dimensional thermal simulations of single and multiple cavity defects in planar structures. The effective thermal conductivity of the die to case attachment solder layer of two commercial metal oxide semiconductor field effect transistor (MOSFET) devices is estimated using these results, with cavity dimensions and distributions obtained by electron microscopy. [ABSTRACT FROM AUTHOR]

Features a study which devised a strategy for device switching and voltage vector selection in direct torque control (DTC). Background of DTC; Leg-switching strategy in DTC; Inverter switching process; Experimental results.

Describes a novel algorithm for the estimation of rotor position in a switched reluctance motor based on recursive least-squares estimator. Capability of the algorithm to extract information about rotor position at very low speeds from voltage and current waveforms; Position estimation procedure.

Introduces a flywheel energy storage device capable of enhancing the fuel economy of a hybrid-type road vehicle. Speed range; Power requirements; Machine type; Rotor construction; Effect of pole number and core back depth upon iron loss.

Describes a modern solution to real-time rotor position estimation of brushless permanent magnet (PM) motor drives. Details on the two types of control used to drive brushless PM motors; What is the estimation scheme based on; Methodology used in the description process; Features of PM motors; Information on the conventional way of measuring rotor position in brushless PM motors.