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The benefits and drawbacks of a 5-hp reconfigurable induction motor, which was designed for experimental emulation of stator winding interturn and broken rotor bar faults, are presented in this paper. It was perceived that this motor had the potential of quick and easy reconfiguration to produce the desired stator and rotor faults in a variety of different fault combinations. Hence, this motor was anticipated to make a useful test bed for evaluation of the efficacy of existing and new motor fault diagnostics techniques and not the study of insulation failure mechanisms. Accordingly, it was anticipated that this reconfigurable motor would eliminate the need to permanently destroy machine components such as stator windings or rotor bars when acquiring data from a faulty machine for fault diagnostic purposes. Experimental results under healthy and various faulty conditions are presented in this paper, including issues associated with rotor bar-end ring contact resistances that showed the drawbacks of this motor in so far as emulation of rotor bar breakages. However, emulation of stator-turn fault scenarios was successfully accomplished. Index Terms--Condition monitoring, fault diagnostics, fault emulation, induction motors, reconfigurable motors, rotor broken bar faults, stator winding interturn faults.

Two new models for specific power losses in cold-rolled motor lamination steel are described together with procedures for coefficient identification from standard multifrequency Epstein or single sheet tests. The eddy-current and hysteresis loss coefficients of the improved models are dependent on induction (flux density) and/or frequency, and the errors are substantially lower than those of conventional models over a very wide range of sinusoidal excitation, from 20 Hz to 2 kHz and from 0.05 up to 2 T. The model that considers the coefficients to be variable, with the exception of the hysteresis loss power coefficient that has a constant value of 2, is superior in terms of applicability and phenomenological support. Also included are a comparative study of the material models on three samples of typical steel, mathematical formulations for the extension from the frequency to the time domain, and examples of validation from electrical machine studies. Index Terms--Brushless permanent-magnet (BLPM) motor, cold-rolled motor lamination steel, core loss, electric machine, Epstein test, finite-element analysis (FEA), interior permanent-magnet (IPM) motor, iron loss.

A procedure is described for identifying a mathematical model of core losses in ferromagnetic steel based on a minimal amount of experimental data. The new model has a hysteresis loss multiplicative coefficient variable only with frequency, a hysteresis loss power coefficient variable both with frequency and induction and a combined coefficient for eddy-current and excess losses that is, within a set frequency range, variable only with induction. Validation was successfully performed on a large number of different samples of nongrain oriented fully and semiprocessed steel alloys. Over a wide range of frequencies between 20 Hz and 2.1 kHz and inductions from 0.05 up to 2 T, the errors of the proposed model are substantially lower than those of a conventional model with fixed value coefficients. Index Terms--Core loss, eddy-current loss, electrical machine, Epstein test, ferromagnetic steel, hysteresis loss, iron loss.

For the calculation of torque in brushless (BL) alternating current motors a local method is proposed, based on the Maxwell stress theory and the filtered contributions due to the harmonics of the magnetic vector potential in the motor air gap. By considering the space fundamental field only, the method can efficiently estimate the average synchronous torque for a variety or motor topologies, including concentrated winding designs. For BL direct current motor analysis a global method is introduced, based on the virtual work principle expressed in terms of energy components in various motor regions. The method leads to simplifications in the average torque calculation and enables the direct identification of the cogging and ripple components. The mathematical procedures have been validated against experiments and other numerical techniques. Index Terms--Brushless (BL) permanent-magnet (PM) motor, cogging torque, electric machine simulation, finite-element analysis (FEA), ripple torque, synchronous machine.

The motor presented employs multiple independent windings for operation with two very different pole numbers. The 18-pole field is produced with a symmetrical three-phase winding connected in a Steinmetz arrangement to a single-phase supply. A unified analysis method has been developed and used to demonstrate the equivalence of a Steinmetz delta or star connection with a main and auxiliary winding of a single-phase motor. The method has been experimentally validated and also included are some specific motor design considerations. Index Terms--Asynchronous rotating machines, design methodology, machine windings, phase conversion, single-phase induction motors, squirrel cage motors.

This paper describes a general method for preliminary design of fast-acting solenoid actuators. Moving armature, drive circuit, and nonlinearities are modeled, as well as eddy currents for solid iron devices. The electromagnetic model is obtained by computing two magnetization characteristics corresponding to the extreme positions of the armature and a novel interpolation function for the intermediate positions. This function, characterizing the magnetic configuration of the actuator, is computed analytically and leads also to an analytical formulation of the magnetic force. In order to achieve extremely fast computation, eddy currents are modeled through a new type of electric equivalent network, derived directly from Maxwell's equations and taking into account the actual BH nonlinearities, moving armature, and device geometry. The method is demonstrated on a pot-core solenoid actuator and compares favorably with finite-element results and measurements. Index Terms: Dynamic design, eddy current, reluctance network, solenoid actuator.