Showing papers in "IEEE Transactions on Industry Applications in 2004"
TL;DR: The IEEE Standard 1459, Definitions for the Measurement of Electric Power Quantities Under Sinusoidal, Nonsinusoidal, Balanced or Unbalanced Conditions (1459) as mentioned in this paper, was proposed by Buchholz and Goodhue.
Abstract: This paper describes the new IEEE Standard 1459, Definitions for the Measurement of Electric Power Quantities Under Sinusoidal, Nonsinusoidal, Balanced or Unbalanced Conditions. The information is presented in the context of historical events that explain the reasons for new definitions. The new definitions originate from S/sub e/, the effective apparent power definition attributed to F. Buchholz and W. Goodhue. The resolution of S/sub e/ extends from well-established concepts. The need for the separation of 60/50-Hz powers from the non-60/50 Hz-powers is emphasized. The standard serves users who want to evaluate the performance of modern equipment or to design and build the new generation of instrumentation.
635 citations
TL;DR: A new, direct torque and flux control strategy based on variable-structure control and space-vector pulsewidth modulation is proposed for induction motor sensorless drives and very-low-speed sensorless operation (3 r/min) is demonstrated.
Abstract: Direct torque control (DTC) is known to produce fast response and robust control in ac adjustable-speed drives. However, in the steady-state operation, notable torque, flux, and current pulsations occur. A new, direct torque and flux control strategy based on variable-structure control and space-vector pulsewidth modulation is proposed for induction motor sensorless drives. The DTC transient merits and robustness are preserved and the steady-state behavior is improved by reducing the torque and flux pulsations. A sliding-mode observer using a dual reference frame motor model is introduced and tested. Simulations and comparative experimental results with the proposed control scheme, versus classic DTC, are presented. Very-low-speed sensorless operation (3 r/min) is demonstrated.
281 citations
TL;DR: In this paper, the authors introduced the notion of categorizing bearing faults as either single-point defects or generalized roughness, which separate bearing faults according to the fault signatures that are produced rather than by the physical location of the fault.
Abstract: Most condition monitoring techniques for rolling element bearings are designed to detect the four characteristic fault frequencies This has lead to the common practice of categorizing bearing faults according to fault location (ie, inner race, outer race, ball, or cage fault) While the ability to detect the four characteristic fault frequencies is necessary, this approach neglects another important class of faults that arise in many industrial settings This research introduces the notion of categorizing bearing faults as either single-point defects or generalized roughness These classes separate bearing faults according to the fault signatures that are produced rather than by the physical location of the fault Specifically, single-point defects produce the four predictable characteristic fault frequencies while faults categorized as generalized roughness produce unpredictable broadband changes in the machine vibration and stator current Experimental results are provided from bearings failed in situ via a shaft current These results illustrate the unpredictable and broadband nature of the effects produced by generalized roughness bearing faults This issue is significant because a successful bearing condition monitoring scheme must be able to reliably detect both classes of faults
272 citations
TL;DR: The impact study of connecting a 120-MW wind farm into the transmission system of a utility company within the southwest power pool discusses the impacts of a large-scale wind generation on the system operation, voltage profile, and system security.
Abstract: Following in the steps of the gas industry, the traditional paradigm of the vertically integrated electric utility structure has begun to change. In the United States, the Federal Energy Regulatory Commission (FERC) has issued several rules and Notices of Proposed Rulemaking (NOPR) to set the road map for the deregulated utility industry. The crisis in California has drawn great attention and sparked intense discussion within the utility industry. One general conclusion is to rejuvenate the idea of integrated resource planning and promote the distributed generation via traditional or renewable generation facilities for the deregulated utility systems. Wind generation is the most mature and cost effective resource among different renewable energy technologies. Recently, several large-scale wind generation projects have been implemented in the US and other parts of the world. Similar to other new generation facilities, the impacts of a large scale wind generation on the system operation, voltage profile, and system security have to be investigated and studied. Remedies for possible operation issues have to be evaluated and implemented. This paper discusses the impact study of connecting a 120 MW wind farm into the transmission system of a utility company within the Southwest Power Pool (SPP).
228 citations
TL;DR: Based upon results, an optimal common-mode voltage reduction PWM technique, which requires no extra voltage/current sensors and compensation mechanism while not being affected by the dead time, is recommended.
Abstract: The objective of this paper is to investigate the optimal common-mode voltage reduction pulsewidth modulation (PWM) technique when dead-time effect is taken into account. The effect of dead time on common-mode voltage for inverter control and the associated solution are discussed. Based upon these results, an optimal common-mode voltage reduction PWM technique, which requires no extra voltage/current sensors and compensation mechanism while not being affected by the dead time, is recommended. The common-mode voltage can be reduced to one-third for the inverter with diode front end, which is widely used in industry. Intensive measured results are presented to fully support the claims.
217 citations
TL;DR: In this article, a series and a parallel configuration of hybrid series and parallel hybrid electrical discharge (HED) this article was proposed, where the high voltage needle-point electrode is submerged and the ground electrode is placed in the gas phase above the water surface.
Abstract: Ozone in the gas phase and hydrogen peroxide in the liquid phase were simultaneously formed in hybrid electrical discharge reactors, known as the hybrid-series and hybrid-parallel reactors, which utilize both gas phase nonthermal plasma formed above the water surface and direct liquid phase corona-like discharge in the water. In the series configuration the high voltage needle-point electrode is submerged and the ground electrode is placed in the gas phase above the water surface. The parallel configuration employs a high voltage electrode in the gas phase and a high voltage needle-point electrode in the liquid phase with the ground electrode placed at the gas-liquid interface. In both hybrid reactors the gas phase concentration of ozone reached a power-dependent steady state, whereas the hybrid-parallel reactor produced a substantially larger amount of ozone than the hybrid series. Hydrogen peroxide was produced in both hybrid reactors at a similar rate to that of a single-phase liquid electrical discharge reactor. The resulting concentration of H/sub 2/O/sub 2/ in the hybrid reactors, however, depended on the pH of the solution and the gas phase ozone concentration since H/sub 2/O/sub 2/ was decomposed by dissolved ozone at high pH.
215 citations
TL;DR: In this article, an analytical design program that uses quasi-3D computation is developed to evaluate the performance of the surface-mounted axial flux PM machine with reasonable accuracy via an analytical model using quasi- 3D computation.
Abstract: In modeling axial field machines, three-dimensional (3-D) finite-element method (FEM) models are required in accurate computations. However, 3-D FEM analysis is generally too time consuming in industrial use. In order to evaluate the performance of the axial flux machine rapidly, an analytical design program that uses quasi-3-D computation is developed. In this paper the main features of the developed program are illustrated. Results given by the program are verified with two-dimensional and 3-D finite element computations and measurements. According to the results, it is possible to evaluate the performance of the surface-mounted axial flux PM machine with reasonable accuracy via an analytical model using quasi-3-D computation.
212 citations
TL;DR: In this article, a simple control method is proposed that will allow an induction machine to run a turbine at its maximum power coefficient, where the rotational speed is the controlled variable.
Abstract: To optimize the power produced in a wind turbine, the speed of the turbine should vary with the wind speed. A simple control method is proposed that will allow an induction machine to run a turbine at its maximum power coefficient. Various types of power control strategies have been suggested for application in variable speed wind turbines. The usual strategy is to control the power or the torque acting on the wind turbine shafts. This paper presents an alternative control strategy, where the rotational speed is the controlled variable. The paper describes a model, which is being developed to simulate the interaction between a wind turbine and the power system. The model is intended to simulate the behavior of the wind turbine using induction generators both during transient grid fault events and during normal operation. Sample simulation results for two induction generators (2/0.5 MW) validate the fundamental issues.
183 citations
TL;DR: In this article, a reference frame model for a dual-stator induction machine (DSIM), including mutual leakage coupling, is proposed, which allows us to highlight the previously mentioned circulating harmonic currents.
Abstract: The major drawback of usual dual-stator ac machines, when supplied by a voltage-source inverter (VSI), is the occurrence of extra harmonic currents. These extra currents circulate only in the stator windings and cause additional losses. This paper deals with the modeling and design of dual-stator winding ac machines for safe operation with a VSI. A new reference frame model for a dual-stator induction machine (DSIM), including mutual leakage coupling, is proposed. This model allows us to highlight the previously mentioned circulating harmonic currents. The leakage inductance associated with these harmonics is shown to have quite a small value, highly depending on the coil pitch. It is also shown that full pitch is required, and that special slot shape designs should be investigated, to limit the magnitude of circulating currents. Experimental results on a prototype of a DSIM are presented and they show a very good correlation with theoretical curves.
168 citations
TL;DR: In this paper, a three-phase self-excited induction generator (SEIG) with squirrel-cage rotor is presented along with its operating performance evaluations for small-scale clean renewable and alternative energy utilizations.
Abstract: In this paper, the practical impedance approach steady-state analysis in the frequency domain for the three-phase self-excited induction generator (SEIG) with squirrel-cage rotor is presented along with its operating performance evaluations. The three-phase SEIG is driven by a variable-speed prime mover(VSPM) in addition to a constant-speed prime mover (CSPM) such as a wind turbine and a micro gas turbine for clean alternative renewable energy in rural areas. The basic steady-state characteristics of the VSPM are considered in the three-phase SEIG approximate equivalent circuit and the operating performance of the three-phase SEIG coupled with a VSPM and/or a CSPM are evaluated and discussed online under the conditions related to the speed changes of the prime mover and the electrical inductive load power variations with simple computation processing procedures. A three-phase SEIG prototype setup with a VSPM is implemented for small-scale clean renewable and alternative energy utilizations. The experimental performance results give good agreement with those obtained from the simulation results. Furthermore, a proportional-integral (PI) closed-loop feedback voltage regulation of the three-phase SEIG driven by the VSPM on the basis of the static var compensator (SVC) composed of the thyristor phase-controlled reactor in parallel with the thyristor switched capacitor and the fixed-excitation capacitor bank is designed and considered for the wind generation as a renewable power conditioner. The simulation analysis and experimental results obtained from the three-phase SEIG with SVC for its voltage regulation prove the practical effectiveness of the additional SVC with the PI-controller-based feedback loop in steady-state operation in terms of high performance with low cost.
160 citations
TL;DR: In this article, a characterization of the current market of VSDs is presented, including the average prices, the installation costs, and the total sales in each EU country, per power range.
Abstract: In the European Union (EU), variable-speed drives (VSDs) were identified as the motor systems technology having the most significant electricity savings potential. In the EU, the identified economic electricity savings potential with the application of VSDs, by the year 2015, in industrial and tertiary sectors, are 39 and 8 TWh/year, respectively. However, only a small percentage of this potential is being used. In this paper the characterization of the current market of the VSDs is presented, including the average prices, the installation costs, and the total sales in each EU country, per power range. Selected VSD applications are presented. The key barriers to a wider application of VSDs are identified. In particular, the power quality and reliability problems associated with the use of VSDs are presented and possible technical solutions are discussed.
TL;DR: In this paper, the conceptual design and finite element method analysis of a permanent-magnet-assisted reluctance synchronous motor/generator for mild hybrid vehicles where a large constant power speed range (6:1) is required and machine volume, converter peak kVA, and battery size are the main constraints.
Abstract: This paper introduces the conceptual design and finite-element method analysis of a permanent-magnet-assisted reluctance synchronous motor/generator for mild hybrid vehicles where a large constant power speed range (6:1) is required and machine volume, converter peak kVA, and battery size are the main constraints. Careful flux-barrier and permanent-magnet sizing, high magnetic saturation, and current density are the main requirements for maximum torque production with constraint volume. A specific tangential force density of 4.33 N/cm/sup 2/ is obtained. Rated (continuous) power-battery limited is 2.5 kW at 42 V dc, from 1000 to 6000 r/min. The peak torque of 140 N/spl middot/m is obtained at 202 A (rms/phase) and can be secured up to 500 r/min. Peak power is still 7.85 kW at 6000 r/min at 42 V dc with an efficiency of 90%. Preliminary results on a prototype are also available.
TL;DR: In this paper, the magnetic characteristics of surface-mounted permanent magnet machines are analyzed and modeled in terms of the magnetic material properties and the motor dimensions, and the results show that the errors between the FEM results and analytical predictions are less than 7% for nonsaturated tooth flux and less than 17% for the saturated case.
Abstract: In this paper the magnetic characteristics of surface-mounted permanent-magnet machines are analyzed and modeled. The air-gap and zigzag leakage fluxes are analytically expressed in terms of the magnetic material properties and the motor dimensions. Both factors are essential quantities for the accurate prediction of the flux distribution within the machine and of the machine torque. Therefore, they are desired for the purpose of machine design and optimization. In order to evaluate the validity of the proposed models, the finite-element method (FEM) analysis is used. The results show that the errors between the FEM results and analytical predictions are less than 7% for the nonsaturated tooth flux and less than 17% for the saturated case. Finally, the models are applied to a novel permanent-magnet machine design.
TL;DR: In this paper, the authors used modulation of air-gap permeance in order to emulate saturation and used Modified winding function approach (MWFA) to model the induction machine with saturation.
Abstract: A review of the literature suggests that modeling of induction machines with saturation has received considerable attention Most of these models are very application specific None of them, however, seems to be completely adequate for the purpose of fault diagnosis This is because for a noninvasive detection technique such as Motor Current Signature Analysis (MCSA), one has to detect different frequency components in the line current of the machine Incorporation of saturation in the induction machine model will help in identifying and analyzing harmonics in the line current spectra that may arise due to the interaction of saturation with a specific fault The present paper attempts to create such a model The model uses modulation of air-gap permeance in order to emulate saturation Modified winding function approach (MWFA) has been used to model the induction machine with saturation To demonstrate the effectiveness of the model, certain high-frequency harmonics that can be predicted theoretically are shown to be present in the line current of the simulated machine Experimental results also confirm the presence of these harmonics The author plans to extend this model in the future for fault analysis
TL;DR: In this paper, a nonlinear control strategy is proposed, consisting of a proportional-integral-derivative (PID) controller and a feedback compensator for friction and limp-home effects.
Abstract: An electronic throttle is a low-power dc servo drive which positions the throttle plate. Its application in modern automotive engines leads to improvements in vehicle drivability, fuel economy, and emissions. Transmission friction and the return spring limp-home nonlinearity significantly affect the electronic throttle performance. The influence of these effects is analyzed by means of computer simulations, experiments, and analytical calculations. A dynamic friction model is developed in order to adequately capture the experimentally observed characteristics of the presliding-displacement and breakaway effects. The linear part of electronic throttle process model is also analyzed and experimentally identified. A nonlinear control strategy is proposed, consisting of a proportional-integral-derivative (PID) controller and a feedback compensator for friction and limp-home effects. The PID controller parameters are analytically optimized according to the damping optimum criterion. The proposed control strategy is verified by computer simulations and experiments.
TL;DR: In this paper, the authors discussed the approach to analytical calculation of the cogging torque in permanent magnet brushless motors and derived two equations with the PM circumferential width taken into account, and a simplified equation without the effect of the finite width of the PM.
Abstract: This paper discusses the approach to analytical calculation of the cogging torque in permanent-magnet (PM) brushless motors. Magnetic field energy in the air gap has been used to obtain the cogging torque equations. Two equations have been derived: with the PM circumferential width taken into account, and a simplified equation, i.e., without the effect of the finite width of the PM. The effect of eccentricity has also been included. Calculation results have been compared with laboratory test results.
TL;DR: In this paper, the amplitude of the fundamental harmonic of these discrete data serves as the imbalance indicator of the proposed scheme, therefore, overcomes small load and slip fluctuations, and the measured results of a mechanically unbalanced machine and a case of combined static and dynamic eccentricity are presented.
Abstract: Mechanical rotor imbalances and rotor eccentricities are reflected in electric, electromagnetic, and mechanical quantities. Therefore, many surveillance schemes determine the Fourier spectrum of a single line current in order to monitor the motor condition. Mechanical imbalances give rise to two first-order current harmonics. Due to the interaction of the currents and voltages, both these current harmonics are also reflected by a single harmonic component in the frequency spectrum of the electric power. This single component is easier to assess than both the current harmonics. The technique proposed in this contribution evaluates this imbalance-specific modulation of the electric power. The proposed approach does not determine the Fourier spectrum of a time-domain signal, though. First, the imbalance specific oscillation of the electric power is extracted by a bandpass filter. Then, the averaged pattern of this component is determined by means of an angular data clustering technique. In that way, the oscillation of the electric power in the time domain becomes mapped into a discrete waveform in an angular domain. The amplitude of the fundamental harmonic of these discrete data serves as the imbalance indicator of the proposed scheme. This technique, therefore, overcomes small load and slip fluctuations. Measured results of a mechanically unbalanced machine and a case of combined static and dynamic eccentricity are presented.
TL;DR: In this paper, the utility of the method for the sensorless control of both brushless dc and ac motors, including operation in the flux-weakening mode, is demonstrated.
Abstract: The sensorless control of brushless machines by detecting the third harmonic back electromotive force is a relatively simple and potentially low-cost technique. However, its application has been reported only for brushless dc motors operating under normal commutation. In this paper, the utility of the method for the sensorless control of both brushless dc and ac motors, including operation in the flux-weakening mode, is demonstrated.
TL;DR: In this article, the design of the lamination bridges, or ribs, at the rotor outer diameter is explained in terms of both material considerations and electromagnetic performance impact, and the tradeoff of complexity versus performance associated with using strengthening ribs in the magnet cavities is discussed.
Abstract: This paper discusses mechanical design considerations that are particular to conventionally (i.e., radially) laminated rotors of interior permanent-magnet synchronous machines. Focus is placed on applications where the radial forces due to high-speed operation are the major mechanically limiting design factor. Proper design of the lamination bridges, or ribs, at the rotor outer diameter is explained in terms of the both material considerations and electromagnetic performance impact. The tradeoff of complexity versus performance associated with using strengthening ribs in the magnet cavities is discussed. The sensitivity of the mechanical design limitations to the rotor-shaft mounting mechanism is also highlighted. These effects are then analyzed using finite-element analysis for a 150-N/spl middot/m/6-kW integrated starter/alternator designed for operation up to 6000 r/min with an annular rotor to accommodate a torque converter or clutch assembly. This example demonstrates that it is possible to significantly improve the rotor's structural integrity using the techniques described in this paper with only a very modest impact on the projected machine drive cost.
TL;DR: In this article, the authors demonstrate the applications of the newly developed common-mode voltage reduction pulsewidth-modulation (PWM) technique, which restricts the commonmode voltage to one-third of DC-link voltage, to vector-controlled induction motor drives.
Abstract: The main theme of this paper is to demonstrate the applications of the newly developed common-mode voltage reduction pulsewidth-modulation (PWM) technique, which restricts the common-mode voltage to one-third of DC-link voltage, to vector-controlled induction motor drives. As compared to previous common-mode voltage reduction techniques, the presented technique can be applied to the inverter with diode front end and has no adverse effect on the linear modulation range. Therefore, vector-controlled drives using the developed technique for inverter control have a wide speed range. Moreover, the effects of the common-mode voltage reduction PWM technique on speed response for vector-controlled induction motor drives will be fully investigated in this paper. It will be demonstrated by intensive experimental results that speed performance does not deteriorate significantly within the rated speed range.
TL;DR: In this paper, a rotor temperature estimation scheme for fan-cooled mains-fed squirrel-cage induction motors was proposed, which combines a rotor resistance estimation method with a thermal equivalent circuit.
Abstract: This paper deals with a rotor temperature estimation scheme for fan-cooled mains-fed squirrel-cage induction motors. The proposed technique combines a rotor resistance estimation method with a thermal equivalent circuit. Usually, rotor resistance estimation works quite well under rated load conditions. By contrast, if the motor is slightly loaded, rotor resistance estimation becomes inaccurate due to the small slip. Therefore, rotor temperature estimation under low-load conditions may be estimated by a thermal equivalent model. In order to determine the rotor resistance and, thus, rotor temperature accurately, several machine parameters have to be obtained in advance. Load tests provide the leakage reactance and the iron losses of the induct machine. The stator resistance has to be measured separately. The parameters of the thermal equivalent model are a thermal resistance and a thermal capacitance. These parameters are derived from a heating test, where the reference temperature is provided from the parameter model in the time domain. This lumped thermal parameter model is based on the assumption that the total rotor temperature increase is caused by the total sum of the losses in the induction machine. Measuring results of a 1.5-kW and an 18.5-kW four-pole low-voltage motor and a 210-kW four-pole high-voltage motor are presented and compared.
TL;DR: In this article, the sensorless control of PMASR motors is investigated, in order to conjugate the advantages of the sensor-less control with full exploitation of the allowed operating area, for a given inverter.
Abstract: The sensorless control of permanent-magnet-assisted synchronous reluctance (PMASR) motors is investigated, in order to conjugate the advantages of the sensorless control with full exploitation of the allowed operating area, for a given inverter. An additional pulsating flux is injected in the d-axis direction at low and zero speed, while it is dropped out, at large speed, to save voltage and additional loss. A flux-observer-based control scheme is used, which includes an accurate knowledge of the motor magnetic behavior. This leads, in general, to good robustness against load variations, by counteracting the magnetic cross saturation effect. Moreover, it allows an easy and effective correspondence between the wanted torque and flux and the set values of the chosen control variables, that is d-axis flux and q-axis current. Experimental verification of the proposed method is given, both steady-state and dynamic performance are outlined. A prototype PMASR motor will be used to this aim, as part of a purposely assembled prototype drive, for light traction application (electric scooter).
TL;DR: In this paper, a dual-rotor, radial-flux, toroidally wound, permanent-magnet (RFTPM) machine was proposed to improve the machine efficiency and boost the torque density.
Abstract: A novel machine family-the dual-rotor, radial-flux, toroidally wound, permanent-magnet (RFTPM) machine-has been proven in a previous paper to be able to improve the machine efficiency and boost the torque density. This paper will present the key design equations and design procedure of the RFTPM machines, analyze parameter effects on machine performance, and give design guidelines to achieve specific design objectives. In addition, finite-element analysis is employed to prove the effectiveness of the design equations and find the machine overload capability. Experimental measurements of a prototype, which match the design specifications well, verify the effectiveness of the design equations.
TL;DR: 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.
Abstract: 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.
TL;DR: In this paper, the analysis of a DC drive system with elastic joints and different speed controllers with one and two speed feedbacks was analyzed. And the simulation results for different parameters and operation modes of the drive system were demonstrated and compared.
Abstract: This paper deals with the analysis of a DC drive system with elastic joints and different speed controllers. The control structure with one and two speed feedbacks was analyzed. The dynamics of the drive system with classical proportional-integral (PI) and fuzzy-logic (FL) speed controllers was compared. Parameters of the classical PI and FL speed controllers were optimized using the same control indexes. Controllers were parameterised using the hybrid genetic-gradient algorithm. The simulation results for different parameters and operation modes of the drive system were demonstrated and compared.
TL;DR: In this paper, a sensorless vector control method for a salient-pole permanent-magnet synchronous motor (SP-PMSM) is proposed, which is directly based on a new principle called "mirror-phase characteristics".
Abstract: This paper proposes a new sensorless vector control method for a salient-pole permanent-magnet synchronous motor (SP-PMSM). The proposed method is directly based on a new principle called "mirror-phase characteristics" and has the following high-performance and attractive features: 1) it can allow 250% rated torque at standstill, under which strong flux saturation usually occurs; 2) it can allow ultralow-speed control (the observed minimum speed ratio to the rated speed under the rated motoring or regenerating load is 1/1800); 3) in spite of the ultralow-speed performance, it can operate up to the rated speed; 4) it accepts instant injection of the rated load even for zero-speed control; 5) it accommodates a load with huge moment of inertia.; 6) it is insensitive to all motor parameters; 7) it is also insensitive to saturation phenomena of stator flux; and 8) it is so simple that it can be implemented with no additional hardware. The high performance and usefulness of the new "mirror-phase vector control" method are verified through experiments.
TL;DR: In this article, a finite-element (FE) program was proposed to determine the resonant frequencies of SRM stator vibration, and the effects of mass density and Poisson's ratios were discussed.
Abstract: The switched reluctance motor (SRM) has a disadvantage of higher acoustic noise, caused by stator vibrations. Techniques for noise reduction require knowledge of the modal frequencies, which depend on mechanical shapes and dimensions as well as material properties, for example, Young's modulus, Poisson's ratio, mass density, etc. It is found that the generally accepted value of Young's modulus is not valid for a machine with laminations and no frame. This paper introduces a simple and nondestructive method for the measurement of Young's modulus; it is then used in a finite-element (FE) program to determine the resonant frequencies of SRM stator vibration. The effects of mass density and Poisson's ratios are also discussed. The FE results are validated by vibration tests, which show good accuracy.
TL;DR: In this article, a series of papers discussing the application and accuracy of different analysis techniques supporting the determination of industrial and commercial power system reliability and availability is presented. But the results of applying different reliability methodologies and tools varied significantly, and comparisons were difficult.
Abstract: This is one of a series of papers discussing the application and accuracy of different analysis techniques supporting the determination of industrial and commercial power system reliability and availability. There is a need recognized in the power industry to identify and utilize a standard tool, or a set of tools, to analyze the reliability of power systems. Historically, the results of applying different reliability methodologies and tools varied significantly, and comparisons were difficult. The Reliability Analysis Techniques Working Group of the Gold Book (IEEE Std. 493-1997) developed a standard network to enable comparison of analytical techniques. This paper describes the approach of simulations via reliability block diagrams as applied to the Gold Book standard network. Reliability indexes of the load points are presented, and are compared with ones obtained from other techniques in the series to determine the accuracy.
TL;DR: The design, material, and production techniques are evolving on AC induction motors leading to improved efficiencies over older designs as discussed by the authors, and IEEE 841 and even NEMA Premium efficiency levels are now quite easy to meet and exceed.
Abstract: Design, material, and production techniques are evolving on AC induction motors leading to improved efficiencies over older designs. IEEE 841 and even NEMA Premium efficiency levels are now quite easy to meet and exceed. New research and production techniques will allow construction of ac motors with die-cast copper rotors, allowing even higher efficiency levels and greater longevity.
TL;DR: In this article, the authors specify the main components of the stray load loss of induction motors from both results of measurement and analysis using the IEEE standard 112 Method B to the cage induction motor.
Abstract: The purpose of this paper is to specify the main components of the stray load loss of induction motors from both results of measurement and analysis The IEEE standard 112 Method B is applied to the cage induction motor for the measurement of the stray load loss On the other hand, the losses generated at the stator core, the rotor core, and the rotor cage are calculated directly by the finite-element method considering the magnetic saturation and the harmonic fields, which vary due to the load condition The measured and the calculated torque, losses, and efficiency agree well It is clarified that the main parts of the stray load loss in the case of the analyzed motor are the increase of harmonic losses due to load, which are the harmonic Joule losses of the rotor cage and the harmonic core losses of the stator and the rotor The relationships between the losses separated by the measurement and the losses calculated directly by the finite-element method are also clarified