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In this paper, the core losses that occur in a 4-kVA flux-modulating synchronous machine (SM) (FMSM) are investigated using 2-D finite-element analysis, and the results are supported by experiments. A method for reducing the core losses is also presented. The FMSM is a new type of multipole SM in which the stator field magnetomotive force is modulated by the air-gap permeance to generate the rotating field. A 2pa-pole three-phase armature winding and a 2pf-pole field winding are centrally wound around individual stator teeth, and a reluctance rotor with 2pr\ (= pa + pf) saliencies is used to provide a magnetic coupling between these windings. As a result of the investigation, it was found that, although the core losses occur in the rotor as well as in the stator, the rotor core loss can be effectively reduced by decreasing the height of the rotor poles. [ABSTRACT FROM AUTHOR]

In permanent-magnet (PM) synchronous machines, when using integral-slot windings, the torque computed by using the d–q-axis theory is almost independent of the variation of the flux linkage with the rotor position. This is not verified when fractional-slot PM motors are used. The iron saturation greatly affects the torque behavior, increasing the torque ripple significantly. Particular care is necessary to determine the average torque and the torque ripple when dealing with fractional-slot PM motors. The analysis is carried out by means of a finite-element (FE) model. Since, in synchronous PM machines, the current control imposes constant d- and q-axis currents, the FE solutions are strictly related to the classical d– q-axis theory. The impact of iron saturation is taken into account, comparing a 24-slot 4-pole integral-slot machine and a 24-slot 20-pole fractional-slot-winding machine. Particular attention is given to the interior PM machines. [ABSTRACT FROM PUBLISHER]

This paper presents a closed-loop vector control of an interior permanent magnet synchronous motor (IPMSM) drive incorporating two separate fuzzy logic controllers (FLCs). The first one is a Mamdani-type FLC which minimizes the developed torque ripple by varying online the hysteresis band of the PWM current controller. The second one is an FLC-based tuned proportional-integral (PI) controller where the PI controller actually serves as the primary speed controller and its gains are tuned by a novel Sugeno-type FLC. Thus, the limitations of traditional PI controllers are avoided, and the performance of the drive system is improved. A flux controller is also incorporated in such a way that both torque and flux of the motor can be controlled while maintaining current and voltage constraints. Thus, the proposed drive extends the operating speed limits for the motor and enables the appropriate use of the reluctance torque. The proposed IPMSM drive is also implemented in real time using DSP board DS1104 for a laboratory 5 HP motor. A performance comparison of the proposed IPMSM drive with conventional PI controller-based drive is provided. Simulation and experimental results demonstrate the better dynamic response in torque and speed for the proposed drive over a wide speed range. [ABSTRACT FROM AUTHOR]

A closed-form approximate formulation is proposed to establish a relationship between the uncontrolled generator (UCG) operation of interior permanent-magnet (IPM) motors at high speed and the constant power speed range (CPSR) and drive current capabilities. High-saliency IPM motors of the PM-assisted synchronous reluctance type are mainly considered in the analysis, since they are proved to have the most favorable ratio between flux weakening capability and UCG voltage. The results of the analysis show the tight relationship between the uncontrolled overvoltage and the CPSR of the drive. Moreover, where the uncontrolled voltage is higher, the relationship between the CPSR and the motor current amplitude becomes stiffer: For small current variations, a large reduction of the speed range can occur. The analysis is validated experimentally on two motors of very different size (500 W and 1 MW). [ABSTRACT FROM AUTHOR]

This paper presents a methodology for feature extraction of a new fault indicator focused on detecting demagnetization faults in a surface-mounted permanent-magnet synchronous motors operating under nonstationary conditions. Preprocessing of transient-current signals is performed by applying Choi–Williams distribution to highlight the salient features of this demagnetization fault. In this paper, fractal dimension calculation based on the computation of the box-counting method is performed to extract the optimal features for diagnosis purposes. It must be noted that the applied feature-extraction process is autotuned, so it does not depend on the severity of the fault and is applicable to a wide range of operating conditions of the motor. The performance of the proposed system is validated experimentally. According to the obtained results, the proposed methodology is reliable and feasible for diagnosing demagnetization faults in industrial applications. [ABSTRACT FROM AUTHOR]

The permanent-magnet (PM) synchronous motor (PMSM) takes advantages of small capacity, high efficiency, and high power density and have become commonplace in electric-vehicle driving systems. However, the excitation of PMSM cannot be adjusted, which restrains the PMSM from widening the speed range above its base speed. A PMSM with a variable magnetic reluctance field adjustment is presented in this paper. A new structure of the rotor is introduced, and flux-weakening (FW) principle is formulated. Analysis is discussed, including the force on the main PM, the movement process of the PM in the PM slot, the characteristics of the movement of the PM, and the FW performance of the new PMSM used for electric vehicles. The emulation analysis coincides with the test result, which verifies the availability and feasibility of the FW method for this kind of PMSM used for electric vehicles. [ABSTRACT FROM PUBLISHER]

As the exploitation of astrospace deepens, many new types of space-based electromagnetic launchers (EMLs) have aroused wide attention and discussions. Compared with traditional slotted electromagnetic linear launchers, a slotless-plate permanent-magnet linear synchronous motor can easily meet demands such as flexible structure, light weight, and high control precision for space use. This paper analyzes the magnetic field of the slotless inverted- U structure based on the equivalent-magnetizing-current method. The validity of this technique for integral-slot configuration is confirmed with finite-element analysis. Then, the influence of the main design parameters is investigated, and design optimization guides are established for the selection of the key design parameters. To reach the suitable air-gap flux density here, some new constructional optimization details are discussed. Design optimization is also performed to fulfill enough thrust for the EML system. [ABSTRACT FROM AUTHOR]

A three-phase, segmental-rotor, flux-switching synchronous motor is presented for the first time, with both field and armature windings placed on the stator. Mutual coupling of the circuits is through segments whose motion causes switching of flux in the armature circuit. The magnetic geometry is substantially different to that of other flux-switching machines (FSMs), and may offer advantages in terms of torque density and controllability. This paper describes the principles and the evaluation of a three-phase design, based on a 12-tooth stator with an eight-segment rotor, before introducing a prototype machine and test results. The prototype has been found to have torque density and profile comparable to that of a switched reluctance motor (SRM) of the same size. [ABSTRACT FROM PUBLISHER]

In this paper, a novel frequency pattern and competent criterion are introduced for short-circuit-fault recognition in permanent-magnet synchronous motors (PMSMs). The frequency pattern is extracted from the monitored stator current analytically and the amplitude of sideband components at these frequencies is introduced as a proper criterion to determine the number of short-circuited turns. Impacts of the load variation on the proposed criterion are investigated in the faulty PMSM. In order to demonstrate the aptitude of the proposed criterion for precise short-circuit fault detection, the relation between the nominated criterion and the number of short-circuited turns is specified by the mutual information index. Therefore, a white Gaussian noise is added to the simulated stator current and robustness of the criterion is analyzed with respect to the noise variance. The occurrence and the number of short-circuited turns are predicted using support-vector machine as a classifier. The classification results indicate that the introduced criterion can detect the short-circuit fault incisively. Simulation results are verified by the experimental results. [ABSTRACT FROM PUBLISHER]

This paper presents analytical and numerical conformal mapping (CM) to analyze magnetic fields originating from permanent magnets and armature winding currents in a slotted air-gap of a surface mounted radial permanent-magnet synchronous motor (SPM), taking into account the effect of arbitrarily curved motor surfaces. We also studied the slotless configuration of the external rotor permanent- magnet motor for the purpose of calculating the complex relative air-gap permeance. The model is able to predict the air gap field and torque with high accuracy, which cannot be achieved using the previously available analytical methods in both cases: internal and external rotor permanent-magnet motor. We obtained one of the conformal mappings used in this study, the numerical solution of the Schwarz-Christoffel (SC) integral, by using the Matlab SC Toolbox. We used this field solution to calculate cogging torque and electromagnetic torque by integrating the Maxwell stress tensor inside the air gap. We verified the accuracy of the developed method by comparing its results with those obtained from the developed numerical finite-element (FE) model. [ABSTRACT FROM AUTHOR]

Switched reluctance machines (SRMs) are normally designed and applied as 6/4 or 8/6 single-channel SRMs. However, recent efforts with 12/8 dual-channel SRMs (DCSRMs) have spurred interest. The 12/8 DCSRM is driven by two independent sets of power electronic circuits with dual control channels, and the two channels would have strong interactions between each other due to the magnetic mutual coupling for each channel. We propose a dynamic modeling strategy that accounts for the effect of mutual coupling of a DCSRM. First, we illustrate the flux patterns of a DCSRM under different operation modes. Then, we use an indirect experimental procedure to measure the static self and mutual flux linkages for the DCSRM. By using the measured flux linkage data, we describe a simulation model for a DCSRM operating in single-channel mode and dual-channel mode in which the mutual coupling is considered. We predict and compare the dynamic performance characteristics such as phase currents, flux linkages, energy conversion, and static torque under different operation modes and excitation conditions. Finally, we compare the simulation and experimental results for four operating conditions in DCSRM systems in single-channel mode and dual-channel mode. The proposed modeling strategy for the DCSRM is quite accurate. [ABSTRACT FROM PUBLISHER]

A switched reluctance (SR) motor has a doubly salient pole structure. A stator has concentrated windings on each pole, while a rotor is only made of iron core. Therefore, the SR motor is expected as a low cost, extremely robust, variable speed motor. The performance of the SR motor greatly depends on magnetic properties of core material since it consists of only laminated-core and windings. This paper investigates the performance of an SR motor made of permendur which has extremely high saturation flux density and very low core loss. Motor torque, iron loss, and efficiency of the SR motor are estimated by finite element method (FEM). Furthermore, a suitable structure for the SR motor made of permendur is examined based on the design of experiments. [ABSTRACT FROM AUTHOR]

This paper deals with the characteristics analysis and optimum design of Synchronous Reluctance Motor (SynRM) with anisotropy rotor using a coupled Finite Element Method (FEM) and Response Surface Methodology (RSM). The focus of this paper is the characteristics analysis and optimum design relative to the output power on the basis of rotor materials of a SynRM. The coupled Finite Elements Analysis (FEA) and Preisach model have been used to evaluate nonlinear solutions. Comparisons are given with characteristics of normal synchronous reluctance motor and those of anisotropy rotor SynRM (ANISO-SynRM), respectively. The feasibility of using RSM with FEM in practical engineering problem is investigated with computational examples and comparison between the fitted response and the results obtained from an analytical solution according to the design variables of rotor in anisotropy rotor SynRM. [ABSTRACT FROM AUTHOR]

We present a finite-element analysis of the temperature rise of switched reluctance motors (SRM) due to electromagnetic losses. We estimate the various components of electromagnetic losses, including core loss in the lamination as well as copper and eddy-current losses in windings, and then predict the temperature rise within the motor due to these losses. We present simulation results for an 8/6 SRM and discuss various aspects of thermal design of SRMs. To validate the procedure for the estimation of electromagnetic losses, we compare predicted and measured losses. [ABSTRACT FROM AUTHOR]

This paper investigated rotor eccentricity effects on switched reluctance motor (SRM) and reduction of these effects by winding method. The motor was simulated by using 2-D transient magnetic finite-element (FE) analysis coupled with external circuits. The main exciting force of the vibration is the electromagnetic force in the stator that is calculated using Maxwell stress method. Serial connection and various parallel connections of windings were modeled in the external circuit. It was found from the simulation results that the currents could be adjusted in parallel paths and unbalanced magnetic forces (UMFs) could be reduced. Experiment results also revealed that the acceleration of stator surface was minimized with the proposed method. [ABSTRACT FROM AUTHOR]

This paper presents the novel method inductance calculation of a synchronous reluctance motor (SynRM). Synchronous inductances (Ld and Lq) are exceedingly important factor of SynRM to drive. Because of self axis current as well as the other axis current, inductances of d-axis and q-axis of SynRM are varied. Using an equivalent circuit model for expressing d-axis and q-axis inductance variation, the authors elicit suitable equation considering iron loss and cross magnetic saturation. Parameters of motor Lo use calculation are gained by AC signal test. [ABSTRACT FROM AUTHOR]

The torque produced by a synchronous reluctance machine (including the permanent-magnet-assisted machine) is studied analytically, with the aim of pointing out the effect of the position of the flux barriers on the torque ripple. It is verified that the position of the flux-barrier ends highly influences the torque waveform. With the aim of reducing torque harmonic contents, a new strategy is proposed based on the choice of couples of flux barriers of different shapes. The flux-barrier geometry is chosen so as to obtain a compensation between the torque harmonics produced by each couple. Experimental results on two prototypes confirm the analytical prediction. [ABSTRACT FROM AUTHOR]

Particle swarm optimization (PSO) algorithm is applied to the design optimization problem of axially laminated anisotropic (ALA) rotor synchronous reluctance motor (SynRM) drive. The objective of the optimization is to maximize the developed torque while minimizing the torque ripple as well as the Ohmic and core losses for traction applications. The number of flux paths, stator tooth width, and rotor flux path width define the 3-D search space for the optimization problem. An artificial intelligence modeling approach utilizing PSO and finite element-state space (FE-SS) models is used for the characterization and design optimization of a prototype ALA rotor SynRM drive for traction applications. [ABSTRACT FROM AUTHOR]

Compared to the traditional steam catapult systems, the electromagnetic launch (EML) system with the permanent magnetic linear synchronous motor (PMLSM) has the features such as high efficiency, high power density and controllability, thus PMLSM is used in the EML system. In this paper, the long primary short secondary PMLSM used in electromagnetic launch system is designed, whose winding in the primary is divided into two sections. The control system employs two inverters and two current trackers, and the latter are adopted to track the 3-phase currents in the other section when the mover is in the cross section, so as to make the magnetic traveling field excited by the two windings move forward smoothly, and the thrust stable. With regard to the system nonlinearity and model variation, the fuzzy PI regulator is designed to adjust the mover velocity. In contrast to the conventional PI regulator, the simulation results show that the thrust is stable at section transition and the velocity reaction is quick without overshoot. The scheme proposed here is validated by the simulation results. [ABSTRACT FROM AUTHOR]

We present a nonlinear reluctance network approach for the computation of the electromotive force (EMF) waveforms of synchronous reluctance motors (SynRM) with a massive rotor or a flux barrier rotor. We model all ferromagnetic parts of the machine by nonlinear reluctances in order to take the saturation into account. The model of the motor consists of three reluctance networks: of the stator, of the rotor, and of the air gap. The originality of the work lies in the automatic computation of the topology and of the reluctance values of the reluctance network. The computation models the air gap for any relative position of the rotor and the stator; thus, the movement of the rotor can be taken into account. For any saturation level, a comparison with time-stepping finite-element results shows good agreement for the EMF fundamental, the mean torque, and the EMF and torque harmonics of order lower than the slotting ones. For a normal saturation level, the reluctance network models also accurately compute the slotting harmonics. [ABSTRACT FROM AUTHOR]

This paper deals with an automatic rotor optimum design strategy based on torque/volume for a synchronous reluctance motor (SynRM). The focus of this paper is the design relative to the torque/volume on the basis of each rated watt according to the rotor diameters of an SynRM. The coupled finite elements analysis and sequential unconstrained minimization technique have been used to evaluate design solutions. The proposed procedure allows us to define the rotor geometric design function according to the rotor diameter and rated watt starting from an existing motor or a preliminary design. [ABSTRACT FROM AUTHOR]

This study deals with the dynamic characteristics analysis of synchronous reluctance motor (SynRM) using finite element method in which the moving mesh technique is considered. The focus of this paper is to show the appropriate of online observer system for position sensorless control of a SynRM under saturation and iron loss. Comparisons are given with angle of the observer and that of proposed FEM and Preisach model of synchronous reluctance motor, respectively. The position sensorless control system is realized, and the effectiveness of the observer system is verified by experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes a hybrid observer for sensorless control of permanent-magnet synchronous motor drives equipped with an inverter output LC filter. An adaptive full-order observer is augmented with a high-frequency signal injection method at low speeds. The only measured quantities are the inverter phase currents and the dc-link voltage. The effects of the LC filter on the signal injection are investigated, and it is shown that the filter is not an obstacle to using signal injection methods. The proposed method allows sensorless operation in a wide speed range down to zero speed. Experimental results are given to confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

For the coupled electromagnetic and structure-dynamic simulation of electrical machines, various 2-D and 3-D techniques are available. This paper reviews and compares them. The strength as well as the weaknesses of these methods are pointed out. Numerical results for the analysis of a switched reluctance machine (SRM) as an example evaluate accuracy and computational effort. It shows that the 2-D simulation gives quite accurate results, as long as the axial effects and 3-D mode shapes are not relevant. [ABSTRACT FROM AUTHOR]

The torque behavior of a synchronous reluctance motor [including the permanent magnet (PM) assisted configuration] is deeply analyzed. An analytical model is developed, showing the dependence of the torque ripple on the rotor geometry. The results of this model allow to individuate the position of the flux-barrier ends so as to minimize the torque ripple. In addition, the proposed strategy to minimize the ripple is not only based on a suitable choice of the flux-barrier ends, but this choice is combined with the adoption of a rotor formed by two different laminations. This strategy allows an optimal compensation of the torque harmonics so that a smooth torque is achieved. Some motor prototypes have been manufactured and tested in a suitable testing bench. The torque versus position characteristics have been measured at very low speed, to avoid a reduction of the high-order torque harmonics. The experimental results confirm the effectiveness of the proposed strategy. [ABSTRACT FROM AUTHOR]

The article analyzes the performance of such motors under abnormal operating conditions and compares it under normal conditions by means of motor current signature analysis. The influence of the supply time harmonics and constructional asymmetries of the machine is also considered in order to permit an objective comparison of the simulation and experimental results.

Linear switched reluctance motors (LSRMs) for the primary propulsion of a ship elevator is proposed and investigated for the first time in this paper. To achieve the stated objective, a new type of LSRM is proposed with twin stators and a translator between them with no back iron in the translator. The proposed configuration of the LSRM is designed, simulated, analyzed, compared with traditional LSRMs, and verified by experimental measurements. The number of LSRM propulsion subsystems required is studied with a view to minimize their weights and an optimization study for that purpose is developed. Unique placement of the LSRM propulsion systems on the elevator is presented. The propulsion force is generated using one phase or multiphase excitation. To reduce propulsion force pulsations, a major requirement in elevators, controlled multiphase excitation using one of the known force distribution functions (FDF) is an acceptable solution. In this paper, it is proved that the currently available FDFs are able to reduce the force pulsations but are not able to meet the peak force command for the system. Consequently, the velocity and position control do not meet even the elementary performance requirements any more. A new FDF is proposed in this paper and presented to overcome the problem caused by a conventional FDF. The control system with the proposed FDF is derived and integrated into velocity and position controllers. Extensive dynamic simulation and experimental verification of the proposed LSRM with the novel FDF is proved to give superior performance in this paper. Such high performance capable of meeting vertical elevator applications is demonstrated. [ABSTRACT FROM AUTHOR]

The switched reluctance motor (SRM) has received considerable attention from researchers for its many inherent advantages, and thus, it has become a popular research topic in the field of variable-speed drives as well as servo drives. Research on SRMs mainly includes their design, modeling and performance analysis, control, as well as applications. However, for verification of design, performance prediction, as well as development of a high-performance sensorless control algorithm, accurate measurement of the magnetic characteristics of the SRM is most critical. Hence, one of the most important problems in the field of SRMs is a practical and accurate instrumentation system for the measurement of the SRM magnetic characteristics. This paper first describes an accurate and fully automated digital method for the measurement of the magnetic characteristic of SRMs, which includes online offset-error removal and winding resistance estimation. In this method, a digital-signal-processor-based virtual instrumentation for measurement of flux linkage is developed. Then, the results of the measurement conducted on a four-phase SRM are presented. The accuracy of the measurement system is verified by comparing with that found via a magnetic analyzer. Finally, the various sources of errors and their contributions to the errors are discussed. The scheme can also be used, in general, for transformers or inductors. [ABSTRACT FROM AUTHOR]

This paper presents a novel numerical method, which will be referred as the position stepping method (PSM), to predict the performances of switched reluctance motor (SRM) drives. The 2-D bicubic spline is employed to generate the finite rectangular elements. The 2-D bilinear spline is used to model the nonlinear magnetic characteristics in SRMs. Consequently, the conventional nonlinear first-order differential voltage equation for describing the performances of SRM drives can be simplified into an analytical expression in terms of the current with respect to the rotor position. Furthermore, the position stepping algorithm is developed according to the boundary and continuity conditions, to accurately and rapidly compute the current from the proposed current expression. Simulated and measured current waveforms are reported to validate the developed PSM. The CPU execution time required by the PSM compares very favorably with that of the analytical method. Overall, this paper provides an accurate and speedy approach to predict the currents and torques of SRM drives. [ABSTRACT FROM AUTHOR]

A new torque estimator for switched reluctance motor (SRM) drives based on 2-D rotary regression analysis is presented in this paper. The proposed torque estimator is composed of a bicubic regressive polynomial as a function of rotor position and input current. The regressive coefficients can be computed offline or online from the torque characteristics acquired either experimentally or from numerical computation. Furthermore, a torque estimation method by taking mutual coupling into consideration is proposed. It can be seen that the estimated and experimentally obtained self-coupling and mutual-coupling torque characteristics are in good agreement with each other. In addition, the dynamic torque waveforms with and without the mutual coupling, estimated by the proposed estimator, are found to be virtually the same as those obtained from the bicubic spline interpolation for SRM drives with single-pulse voltage, hysteresis current chopping, as well as with voltage pulse width modulation control. The success of all the case studies being reported is a good validation of the usefulness and accuracy of the proposed real-time torque estimator that, as described in this paper, can be used to quickly estimate the instantaneous output torque of SRM drives. [ABSTRACT FROM AUTHOR]

A novel online-modeling scheme for the switched reluctance motor (SRM) using a B-spline neural network (BSNN) is proposed in this paper. A 2-D BSNN is designed to learn the nonlinear-flux-linkage characteristic of an SRM online and in real-time. Torque, incremental inductance, and back-emf estimates can be derived from the BSNN after training. The scheme does not require a priori knowledge of the SRM electromagnetic characteristics. Simulation and experimental results show that the scheme has a good estimation performance and robustness at low to medium motor speed. [ABSTRACT FROM AUTHOR]

In a single-phase switched reluctance motor (SRM) drive, the dc voltage source is generally supplied by a circuit consisting of a bridge rectifier and a filter capacitor connected to an ac line. The charging time of the capacitor is shorter from the ac source as capacity increases. The bridge rectifier draws pulsating current from the ac source, which results in a degraded power factor (PF) and lower system efficiency. A single-phase SRM drive system is presented in this paper, which includes the realization of a drive circuit for the reduction of torque ripple and PF improvement with a novel switching topology. The proposed drive circuit adds one switch and one diode, which can separate the output of the ac/dc rectifier from the large capacitor and supply power to the SRM alternately. This allows the drive system to realize torque ripple reduction and PF improvement through the switching scheme. The validity of the proposed method is analyzed by mathematical modeling and tested by simulations and experiments. [ABSTRACT FROM AUTHOR]

In the high-technology mass manufacturing industry, high-speed and high-precision motion is an indispensable element in the automated production machines. In recent years, there has been a growing tendency to employ direct drive permanent magnet linear synchronous motors in demanding motion applications. Although the overall performance is good, its implementation cost remains high. This is mostly due to the cost of the Neodymium-Boron magnets, the manufacturing of the magnetic rails, and the precision of the overall mechanics. In this paper, a much cheaper alternative is proposed-to use a low-cost linear switched reluctance motor (LSRM) and an adaptive control strategy to overcome the tolerances and difficult control characteristics inherent in the motor. The LSRM has simple and robust structure, and it does not contain any magnets. However, its force is solely drawn from the reluctance change between the coil and the steel plates. Variations on the behavior of these two elements due to different operating conditions will change the motion behavior of the motor. Also, to keep the overall cost low, the LSRM sets a marginal mechanical tolerance during its mass production. This leads to characteristic variations in the final product. Finally, since the LSRM is a direct drive motor, any variations on the motor characteristics will directly reflect on the control system and the motion output. In this paper, a self-tuning regulator (STR) is proposed to combat the difficulties and uncertain control behaviors of the LSRM. This paper first introduces the motor winding excitation scheme, the model of the LSRM, and the current control method. The LSRM system is modeled as a single-input single-output discrete model with its parameters estimated by the recursive least square (RLS) algorithm. Then, an STR based on the pole placement algorithm is applied to the LSRM for high-performance position tracking. Both the simulation investigation and the experimental verification were conducted. In both cases, the results verified that the proposed RLS algorithm can estimate the parameters with fast convergence. The STR can provide quick response and high precision which is robust to the change of system parameters. Combined with SIR control, the LSRM is a low-cost solution to fast, accurate, and reliable position tracking for many demanding motion control applications. [ABSTRACT FROM AUTHOR]

In this paper, the rotor position of a synchronous reluctance motor is estimated exploiting the natural saliency of the machine through an addition of a small high-frequency sinusoidal voltage to the stator voltage reference. Due to rotor saliency, a stator voltage component is generated orthogonal to the added signal, whose amplitude depends on the phase displacement between the d-axis and the direction of the injected signal. A robust rotor position tracking can be accomplished by adjusting the direction of the carrier voltage in order to minimize the amplitude of the generated orthogonal voltage. The proposed technique allows zero-speed operation, does not require additional voltage or current sensors, and can easily correct the influence of the armature reaction. Experimental results confirm the validity of the proposed sensorless technique. [ABSTRACT FROM AUTHOR]

In this paper, we analyze mutual coupling of switched reluctance (SR) motors with even and odd numbers of phases. We illustrate that SR motors with an even number of phases produce asymmetric mutual flux in different phases. On the other hand, an SR motor with an odd number of phases produces symmetric mutual coupling in all the phases. Then, we explain a practical way of measuring the mutual flux in SR motors and present the test results for an 8/6 pole, four-phase 4 kW motor. We simulated the performance of the SR motor with and without mutual flux, thereby demonstrating the effect of mutual flux on phase current, flux, and average torque. We verified the effect of mutual flux on position estimation by simulation and experiment. We show that appropriate correction for mutual flux may improve the accuracy of estimated position by 3°, which will give better performance of the drive while driven without any shaft sensors. We also show that an SR motor with an odd number of phases is a better choice than one with an even number of phases because of its symmetric mutual coupling, its ability to utilize short flux paths, and the fact that it does not require costly bipolar excitation. [ABSTRACT FROM AUTHOR]

In this paper, a control strategy for reduced acoustic noise and sensorless operation of a switched reluctance (SR) motor is proposed for heating, ventilation, and air conditioning (HVAC) application, where the magnitude of the dc-bus voltage is controlled as a function of speed and the motor is operated in a single-pulse mode for all speed range. The dc-bus voltage is controlled by incorporating a dc chopper between the three-phase line rectifier and a split dc-link capacitor-type four-switch power converter. Such controller reduces the acoustic noise, provides more accurate position estimation for sensorless operation, and improves the life expectancy of the motor. The algorithm is first simulated through MATLAB/SIMULINK and then tested on a four-phase 8/6-pole 4-kW SR motor. The test results of achieved acoustic noise and improved sensorless operation are presented. Through the proposed method, the acoustic noise is reduced by almost 15 dB compared to the conventional scheme at low-speed regime. The proposed method is intended to drive a fan type of load in HVAC applications, where the dynamic performance requirement is not a stringent criterion. [ABSTRACT FROM AUTHOR]

A novel invertible generalized flux/current switched reluctance machine (SRM) model based on the Fourier series expansion is presented. This model, which is derived from machine geometry and materials properties, is accurate enough to be used for actual machine representation and can also be simplified for real-time controller applications. Simulation and experimental results illustrate that the proposed modeling approach provides better representation of the SRM than other existing techniques. [ABSTRACT FROM AUTHOR]

Based on two-dimensional (2-D) trigonometry, a new numerical method is presented to compute the nonlinear magnetic and electromagnetic torque characteristics in switched reluctance motors (SRMs). In the proposed method, the mathematical model is composed of the 2-D truncated Fourier series. The coefficients can be determined from a small amount of given magnetic or torque data acquired by experiment or finite-element (FE) analysis. The computed and experimental results demonstrate that the proposed method can be used to precisely compute the nonlinear magnetic and torque characteristics in SRMs. Hence, this paper provides a valuable approach for performance prediction, design, simulation, and control of SRMs. [ABSTRACT FROM AUTHOR]

Switched-reluctance motors produce acoustic noise and vibration caused by torque ripple. Applications of these motors where silent operation is desirable, such as in home appliances, has, thus, been limited. This paper describes a proposal for a new stator pole face having a nonuniform air-gap and a pole shoe attached to the lateral face of the rotor pole. These additions minimize the undesired torque ripple. The effects of each design parameter were investigated using a time-stepping finite-element method. The parameters were optimized by utilizing response surface method (RSM) combined with (1 + 1) evolution strategy. It has been shown, through numerical tests, that the optimized shape gives higher average torque and drastically reduced torque ripple. [ABSTRACT FROM AUTHOR]

This paper presents a method to calculate the transient characteristics of synchronous reluctance motor (SynRM). Using an approximate equation suitable for expressing d- and q-axes inductance variation, the authors derive a nonlinear state equation considering both iron loss and cross-magnetic saturation. All electrical motor parameters used for the calculation are measured from tests. Calculation results on transient and steady-state characteristics of a vector-controlled flux-barrier-type 1.1-kW SynRM are verified with experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a novel low-speed and high- torque motor, self-commutating low-speed reluctance motor (SCLRM), for direct-drive applications. With six diodes connected to the stator windings, it is capable of self-commutating when working on normal three-phase ac source for constant-speed operation. It provides an uncomplicated and low-cost method to increase the torque capability of the traditional vernier-type motors without the requirement of permanent magnets and inverter drive. In this paper, the basic theory of SCLRM is presented, including the operation principle and the mathematical models from which the calculation equations of the inductance parameters as well as the electromagnetic torque are deduced. Besides, the simulation and implemental results are shown, and the reasons of the improvement of the torque capability are analyzed. Moreover, an inverter drive system for SCLRM whose topology is different from that of the standard three-phase inverter is proposed for variable-speed applications. [ABSTRACT FROM AUTHOR]

This article presents a technique that uses rotor shorting rings to start the single-phase switched reluctance (SR) machine, from any rotor position, in a specified direction. It also outlines how the shorting rings enable starting of the machine. Transient finite-element analysis is used to illustrate the torque-producing mechanism from the aligned position using the rotor-mounted shorting rings. It is also used to determine the optimal stator and rotor pole arcs and shorting ring design for a 200-W prototype machine. An SR drive system incorporating rotor shorting rings is evaluated, and experimental results show the effectiveness of the technique. [ABSTRACT FROM AUTHOR]

Permanent-magnet-assisted synchronous reluctance motors are well suited to zero-speed sensorless control because of their inherently salient behavior. However, the cross-saturation effect can lead to large errors on the position estimate, which is based on the differential anisotropy. These errors are quantified in this paper as a function of the working point. The errors that are calculated are then found to be in good accordance with the purposely obtained experimental measurements. [ABSTRACT FROM AUTHOR]

Dynamic modeling of switched reluctance motors (SRMs) is usually done on a per-phase basis. However, in most applications, SRMs are used with simultaneous excitation of more than one phase. Thus, a model accounting for mutual coupling in the presence of magnetic saturation is needed to predict and optimize their performance in terms of efficiency and torque ripple. This paper presents a dynamic two-phase excitation model of the SRM. Motor symmetry is used to reduce the amount of flux linkage data needed for the model. An experimental procedure to obtain the flux linkage data is described. Measured flux linkage data for the 8/6 SRM are also included. Details of the simulation model and comparison with experimental waveforms along with their implications for performance prediction are presented. [ABSTRACT FROM AUTHOR]

A control system for power smoothing using a switched reluctance machine (SRM) driving a flywheel is presented in this paper. Power smoothing is achieved by controlling the SRM to operate as a motor/generator, storing or retrieving energy from a rotating flywheel. In order to increase the rotational energy stored in the flywheel, the SRM operates at high rotational speed, and the machine phase current is controlled using single-pulse mode. To control the SRM output power, a two-dimensional lookup table is used to store the switching angles. The control strategies proposed in this paper have been experimentally implemented in a 2.5-kW prototype based on an 8/6 SRM. Experimental results are presented and discussed. [ABSTRACT FROM AUTHOR]

This paper presents some design considerations for synchronous machines characterized by a fractional number of slots per pole per phase. The main advantage of this configuration is a smooth torque, which is due to the elimination of periodicity between slots and poles. A second advantage is a higher fault-tolerant capability, making the machine able to work even in faulty conditions. However, the fractional-slot configuration presents a high content of MMF harmonics that may cause an unbalanced saturation and thus an unbearable torque ripple. A method to design fractional-slot machines is illustrated in this paper, including double-layer and single-layer windings. The analytical computation is extended to determine the harmonics of MMF distribution. Their effect is highlighted in isotropic as well as anisotropic machines. Finally, some considerations are reported to avoid unsuitable configurations. [ABSTRACT FROM AUTHOR]

Although air-core linear permanent-magnet (PM) synchronous motors are widely used in precision applications because of their advantages such as fast dynamics, lack of detent force, and negligible iron loss, they basically suffer from low developed thrust, thrust ripple, and excessive use of permanent-magnet materials, all of which lead to undesirable performance and high production cost. In this paper, we analyze performance characteristics of an air-core linear PM synchronous motor by varying motor design parameters in a layer model and a d-q model of the machine. We propose a multiobjective design optimization to improve thrust, thrust ripple, and consumed magnet volume independently and simultaneously by defining a flexible objective function. A genetic algorithm is employed to search for optimal designs. The results confirm that desirable thrust mean and substantial reduction in magnet volume and thrust ripple can be achieved. We draw several design conclusions from the motor analysis and design optimization. Finally, we carry out a time-stepping finite-element analysis to evaluate the effectiveness of the machine models and the optimization method. [ABSTRACT FROM AUTHOR]

Dynamic hysteretic effects of magnetic materials are usually neglected in actuators modeling. In order to take into account these effects, we coupled a two-dimensional finite-element (FE) model in an original way with a magnetic equivalent circuit by using dynamic hysteretic flux tubes (DHFT). As an example of an application, we present the model of an ultrafast switched reluctance motor, in which the control of the power converter is of major importance, and where iron losses can reach critical values. [ABSTRACT FROM AUTHOR]

The switched reluctance (SR) drive is known to be fault tolerant, but it is not fault free. The goals of this study are the systematic classification of all electrical faults, for short and open circuits, in the SR drive (excluding the controller itself) and the investigation of fault patterns and possible remediation. Each situation is analyzed via finite-element analysis and/or experiments. The transient effects during the faults are described. Possible remediation schemes other than disabling the faulted phase are explored. There is a particular focus on the switch short circuit for which new results are presented. [ABSTRACT FROM AUTHOR]

This paper presents the use of Taguchi methods in optimizing a switched reluctance motor (SRM) for applications requiring fast actuation. In these applications, the SRM is designed to provide a high electromagnetic torque-to-inertia ratio required for high rates of mechanical acceleration. This is accomplished using two simultaneous robust optimizations of an SRM, namely: 1) an optimization of the motor torque and 2) an optimization of the torque per inertia (mechanical acceleration). The Taguchi two-step optimization method and the zero-point-proportional dynamic response were used successfully in the double optimization. Two orthogonal arrays were used to lead the design of experiments (DOE). Finite-element analysis was used to compute the performance of the motor designs generated by the Taguchi DOE. [ABSTRACT FROM AUTHOR]