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In wind energy systems, it is necessary to have a good knowledge of the used generator and its parameters. Despite the motor manufacturer's specifications, accurately estimating the machine parameter reference values is critical for the perfect control system. In this context, off-line identification tests of a 3 kW permanent magnet synchronous machine were conducted to determine the mechanical and electrical parameters. In addition, this research exploits a meta-heuristic optimization technic dubbed grey wolf optimizer in the on-line parameter's identification field. The estimate method is focused on the parameter's estimation linked to a reference model. The rule is based on the cancelation of the current error among the measured and the associated estimated current. For each measurement, the grey wolf estimator adapts the reference model parameters until the model response and the accurate response be similar. All were implemented using the real-time interface of the DSpace DS1104 Controller card while using the ControlDesk graphical user interface and the Simulink/MATLAB environments. Results from hardware simulation confirm the efficacy and benefits of the suggested strategy. [ABSTRACT FROM AUTHOR]

Synchronous Reluctance Motors (SynRMs) have become very attractive alternatives to induction motors which have been widely used in industry in recent years. Axial-flux motor (AFM) structures have been studied in the literature as a new field. However, studies on axial-flux synchronous reluctance motors (AF-SynRMs) are very limited. In this study, optimization of an AF-SynRM has been performed to achieve optimal motor performance. In addition, the effects of the permanent magnets (PMs) have been investigated. In this design, PMs have been placed in the barriers using eight different ways, and motor performance has been examined. The placement of magnets on the barriers that are close to the air gap has an increasing effect on the average torque. However, the distorting effect on the torque ripple is seen to be quite high. In particular, the placement of magnet on all barriers improves the machine performance significantly. The negative impact on torque ripple is also low. Therefore, this study aims to provide guidance to researchers working on the design of AF-SynRMs, especially with PMs. [ABSTRACT FROM AUTHOR]

In this study, a high-power synchronous reluctance motor (SynRM) was designed for the traction motor of electric vehicle (EV) and its double-stage optimization was performed. Genetic algorithm and sensitivity analysis methods were used to obtain the best design parameters. Double-stage optimization was carried out to minimize the torque ripple and obtain the targeted torque, speed, and power values of the SynRM. In the first stage, the genetic algorithm method was used to improve the design parameters of the stator and rotor. With the improved design parameters, it was observed that the torque ripple decreased. In the second stage, the sensitivity analysis method was used. In this method, the effect of changing the skew angle of the stator on the torque ripple was investigated. The performance of the designed motor was examined in the optimization process. It was observed that the targeted torque, power, speed, efficiency, and torque ripple minimization values are successfully achieved with the best stator and rotor parameters. The results showed that SynRM produces high torque and high power with high efficiency and low torque ripple over wide speed range. It is quite proper to use the designed SynRM as a traction motor of new generation electric vehicles. [ABSTRACT FROM AUTHOR]

Energy resources are decreasing in the world and the use of electrical machines is increasing. Motor design and development studies are carried out to reduce the losses and increase the efficiency of motors, which are widely used especially in industry. In this study, Line Start Synchronous Reluctance Motor (LS-SynRM) was designed by taking an induction motor, one of the most widely used motors in the industrial field, as a reference. With its rotor cage structure feature, it can be line-start without the need of a driver. The rotor has a lot of design variables due to slots and barriers. Sensitivity analysis was used to determine the effect of design variables on performance criteria such as power factor, efficiency and torque ripple. Subsequently, Multi-Objective Genetic Algorithm (MOGA) optimization was used to find the values of the design variables that bring the motor performance closer to the optimum result. The results of the reference induction motor, initial LS-SynRM, and the optimized LS-SynRM are compared. It has been taken care to preserve the synchronization feature of the LS-SynRM and the related results are given in the analyses. It is shown that the optimized motor is in IE4 efficiency class and operates with low torque ripple. [ABSTRACT FROM AUTHOR]

Variable reluctance motor is becoming a competitive candidate among all other machines available due to its added features. The development of variable reluctance motor is simple due to the simple construction of rotor without any permanent magnets. Reduced complexity in structure paves the way for low-cost motor and it also leads to the application of SRM in a wide manner. In order that the machine could be used in various applications, it is much necessary to have a suitable driving system (converter configuration). The best choice of converter for SRM would pave the way for desirable control of the machine. The proposed work includes the design and analyses of an appropriate driver configuration for SRM and interface it with the motor which is already designed and analyzed using ANSYS Maxwell. The design and analysis of the converter are carried out using the ANSYS Simplorer tool box. [ABSTRACT FROM AUTHOR]

—In this study, the design and analysis of multi-layer fully pitched winding switched reluctance motor (MFP-SRM) for general use (submersible pump, electric vehicles, etc.) have been performed. It is seen that the multi-layer switched reluctance motor (SRM) has higher output power when compared to the single-layer SRM. In multi-layer SRM, the motors in the layers are electromagnetically independent of each other although they are identically the same motors with the same characteristics in terms of performance and geometry. Each layer of the MFP-SRM which is designed in this study consists of a 6/4 pole fully pitched SRM (FP-SRM) and these motors are magnetically independent of each other. In the MFP-SRM, which is designed as a double layer, there is a 15° phase difference between the rotor position angles and torque profile curves of each layer. With the phase difference that changes depending on the number of layers, each layer contributes to the total torque production of the profile, ensuring a smooth profile. According to the results of the 3D FEM analysis, it is seen that the proposed multi-layer motor structure has high starting torque and low torque ripple properties. In the analysis carried out in the range of 3–15 Amperes, the torque ripple of the traditional FP-SRM varies between 31.99% and 38.19%, while the torque ripple of the proposed MFP-SRM only varies between 3.23% and 7.11%. [ABSTRACT FROM AUTHOR]

This study presents an enhanced AC drive for the SynRMs coupled with a circulation pump (CP) and an improved control system based on the field orientation. A grid-fed 900 W motor driver consisting of an electromagnetic interference filter (EMI), power factor correction (PFC), and three-phase inverter is designed to drive 0.75 kW SynRM. A boost PFC converter is designed as an interface between the AC power line and the motor drive. PFC is used to recover the bad power factor performance of the SynRM. In addition, the boosted and well-regulated DC-link voltage improves the motor driving performance. Control strategies and practical implementation based on the field-oriented control of synchronous reluctance motors are presented. Dynamic and steady-state responses of the CP SynRM drive in various conditions are verified experimentally. Low current and voltage ripples, unity power factor, maximum torque per ampere with low fluctuation and low EMI noise are achieved with the low cost efficiently. All of the improvements are obtained by fewer circuit elements and higher energy conversion efficiency. The advantages of using SynRMs in dry-rotor circulation pumps for heating applications have been demonstrated experimentally. [ABSTRACT FROM AUTHOR]

SRMs have high torque ripples. Modifying the stator and rotor shape of SRMs is one of their methods to remove torque ripples. In this study, new rotor and stator geometries have been proposed for SRM. Performance characteristics are obtained and dynamic analyses are carried out for both novel and classical 6/4 SRMs. FFT analyses of the torque characteristics are also performed for the both SRMs. The changes in performance and the FFT results of torque characteristics are determined for both the current-controlled and uncontrolled operations in both SRMs. 23.60% and 15.20% improvements in torque ripples are achieved for the uncontrolled and current-controlled operations in SRMs respectively. When the FFT analyses are applied to the torque characteristics, the THD values are obtained as 21.19% and 8.31% in the uncontrolled and controlled motor current operations respectively. A 122 W three-phase 6/4 SRM simulation based on the MATLAB–SIMULINK environment is performed to validate the improvement of the torque ripple of the proposed model. [ABSTRACT FROM AUTHOR]

In this paper, two different strategies are combined to optimize the phase current control for switched reluctance motor (SRM). Firstly, considering the sampling and computation delay, a current prediction chopping control method is proposed to alleviate the current ripple during the entire excitation phase chopping process. Secondly, in order to cut down the large current ripple in the initial stage of phase current establishment and the excessive output current of the battery, a partitioned current control method is proposed to control the phase current with different control logic at different rotor zones. Finally, the two control strategies are combined to further optimize the phase current. In order to verify the proposed combined control strategy, a three-phase 12/8 poles SRM simulation model and experimental platform are built. The simulations and experiments are carried out to verify the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper describes a sensorless control technique Based on current waveform detection for Switched Reluctance Motor (SRM) over full speed-range. For conventional sensorless method, the resistive drop and the back- EMF are always neglected, which may cause some errors in position determination and restrict the rotor speed-range. To overcome this problem, an improved current-slope-difference based approach is presented for sensorless starting and continuous low-speed sensorless operation. For medium and higher speeds, a current-gradient method is used for sensorless operation. Based on the proposed sensorless method, the position sensorless operation within the whole speed range of the SRM can be easily implemented. Finally, the experimental results demonstrate the validity of the hybrid sensorless approach in the full speed region. [ABSTRACT FROM AUTHOR]

In this paper, a novel linear switched reluctance motor (LSRM) is introduced in which the total electromagnetic losses and dimensions are significantly reduced compared to the conventional LSRMs. The LSRM's stator has a segmental structure, while its rotor possesses a seven pole configuration with three rotor poles equipped with the winding sets to generate the magnetic flux. The other remaining four rotor poles, i.e., auxiliary poles, are responsible for closing the magnetic flux path loop. In the proposed LSRM-auxiliary mover poles (LSRM-AMP), the flux path length is effectively reduced using the optimized provided auxiliary poles. Therefore, the required magnetomotive force (MMF) is reduced compared to the conventional LSRMs. In addition, as only half of the generated flux passes the stator segments, the dimensions of the stator segments and their corresponding weights are significantly reduced without any saturation issue. In order to verify the finite element (FE)-based performance prediction of the proposed structure, the electromagnetic operating principles and the design rules of the LSRM-AMP are separately investigated. A sensitivity analysis and comparative study for the proposed LSRM-AMP and conventional LSRM topologies are presented to show the performance and characteristics superiority of the optimized LSRM-AMP structure. [ABSTRACT FROM AUTHOR]

Abstract—This article presents a novel torque ripple minimization approach based on the genetic algorithm (GA) for the switched reluctance motor (SRM) drives. The fitness function of the GA is designed on the basis of two main optimization criteria. The first optimization criteria; three objectives are defined to optimize commutation angles minimizing torque ripple and copper loss. The second optimization criteria; an objective is defined to eliminate the negative torque which decreases the average torque in SRM drives. The achievement of all objectives depends on the adjusting appropriate the commutation angles of the torque sharing functions (TSF) during the commutation period. All of conventional TSFs are dependent on three different commutation angles, namely turn-on, turn-off, and overlapping. Due to the nonlinear phase inductances of SRM, the delay of current rising and falling time are not unity in overlapping commutation region. To overcome the separation of the incoming and outgoing phase currents during the commutation region, rise angle, and fall angle are used instead of overlapping angle. GA is used to optimize the commutation angles of conventional (sinusoidal) TSF and improved (sinusoidal) TSF. At the same time, the elimination negative torque effects on torque ripple, average torque, and copper loss is investigated. [ABSTRACT FROM AUTHOR]

This paper proposes a straightforward second-order sliding mode control (SMC) approach to minimize current distortions and torque ripples of a switched reluctance motor (SRM). In the first step, conventional SMC is briefly recalled and detailed. Then, a special attention is paid to the synthesis and the implementation of a second-order (SM2) approach. Stability analysis of these two approaches is ensured. It will be shown that the proposed second-order SM approach offers a lower harmonic distortion of the motor currents, a reduction of the torque ripples, and the elimination of chattering phenomena. The effectiveness of the proposed SM2 is verified by simulation results then validated by experiments. [ABSTRACT FROM AUTHOR]

Aiming at the problem of severe unbalanced magnetic force (UMF) of the switched reluctance motors (SRMs) caused by eccentricity, this paper analyses the radial electromagnetic force's spatial distribution and frequencies under eccentricity and conduct a compensation method for the UMF. Firstly, the expression of the radial electromagnetic force under eccentricity is derived by using the method of magnetomotive force multiplying permeance, combining with the modification of the permeance. Secondly, the UMF is reduced by applying compensation current to the two stator poles of the permeance-descending phase. The selection of the stator poles and the calculation of the compensation current are decided according to the direction and the value of the unbalanced flux density. Dynamic eccentricity (DE) will produce new frequencies and spatial orders of the radial electromagnetic force, and the static eccentricity (SE) only produces the new spatial orders. The results obtained by the finite element model prove that this method can effectively reduce the UMF without sacrificing the output torque performance. [ABSTRACT FROM AUTHOR]

This paper presents four-quadrant sensorless control in switched reluctance machine (SRM) over the wide speed range. The proposed sensorless control technique could be employed not only at low speed with current chopping control (CCC) but also at high speed with angle position control (APC). At startup and low speed, the narrow voltage pulse is injected into the idle phases and the rotor position zone is determined by comparing the measured flux linkage with four flux linkage-current curves. The same flux linkage-current curves also can be adopted for rotor positions estimation at medium and high speeds. Two flux linkage-current characteristic curves in the inductance rising zone are employed to estimate the rotor position for motoring mode and the other two curves in the inductance falling zone are used to estimate the rotor position for braking mode. The experiments on a three-phase 12/8 pole SRM drive platform are carried out to verify the effectiveness of the proposed sensorless control technique. [ABSTRACT FROM AUTHOR]

This work investigates the application of the adjoint variable method (AVM) to switched reluctance motors (SRMs). A MATLAB toolbox developed by the authors estimates the sensitivities of the required objective function with respect to different geometric design parameters using at most one adjoint simulation. In this work, the AVM evaluates the sensitivities of the x and y components of the magnetic flux density, the phase flux linkage, and the electromagnetic torque of switched reluctance motors with respect to teeth height, yoke thickness, teeth pole arc angle, and teeth taper angle of both stator and rotor. The nonlinearity of the motor magnetic material is taken into consideration. The estimated sensitivities using AVM are compared with those obtained using the more accurate but time intensive central finite differences (CFD). An interior-point optimization algorithm utilizes the sensitivities of the electromagnetic torque of an SRM to maximize the motor static torque profile. Structural mapping technique is used to control the geometric design parameters through the optimization process. [ABSTRACT FROM AUTHOR]

Synchronous Reluctance Machines (SynRMs) are facing a revamped industrial interest. A comparison between SynRMs and other types of electric machines allow listing the advantages and proving the choice of such machines. This paper presents a review of SynRMs, regarding particularly their thermal analysis. First of all, a description of the basic principles of SynRM is illustrated. The thermal analysis is based mainly on the study of the heat sources and the heat extraction mechanisms which are listed and described. Nevertheless, the coupling effects between the thermal field and the magnetic material parameters are discussed. Then, the three heat extraction phenomena (conduction, convection and radiation) are analyzed. Along the work, important facts about the thermal analysis are discussed. A comparison between the different approaches used for the thermal analysis is highlighted, and new developments and perspectives are identified. [ABSTRACT FROM AUTHOR]

Here we present a comprehensive analysis of structural performance of Induction Machine (IM) and Switched Reluctance Machine (SRM) rotors under different operational conditions. Electric machines are susceptible to forces of diverse origins. In addition to traditionally considered magnetic and centrifugal forces, this article discusses independent and inclusive effects of thermal expansion and shaft attachment techniques on structural integrity of the machines. A comparative analysis of structural performance of IMs and SRMs has also been performed, under a range of scenarios, to facilitate application-specific machine selection from a structural perspective. [ABSTRACT FROM AUTHOR]

In this work, we report on the application of the adjoint variable method (AVM) to sensitivity analysis of switched reluctance motors (SRMs). Using at most one adjoint simulation, the sensitivities of the desired response with respect to all geometrical and material parameters are estimated. In this work, the AVM evaluates the sensitivities of the air region magnetic energy and the electromagnetic torque of a SRM with respect to all parameters. Good match is achieved between the AVM sensitivities and those estimated using the more accurate but computationally expensive central finite differences (CFD). [ABSTRACT FROM AUTHOR]

Although synchronous reluctance machine (SynRM) like other electrical machine has a non-linear magnetic field, the complicated structure is mathematically analyzed by analytical equations and then finite element method (FEM) simulation is utilized to validate the design. One of the well-known drawbacks of SynRM is that it has poor power factor. SynRM machine rotor design is revisited in this paper using analytical and finite element methodologies. The study focuses on highly efficient SynRM with improved power factor and excellent saturation and torque ripple effects. The rotor is designed with optimum shapes of flux barriers and then concentrates on the flux barrier dimensions, the number of flux barriers, and optimum placement of flux barriers to improving the performance parameters of SynRM. Finally, the power factor and saturation effect on SynRM are also included. This paper investigates all possible methods to improve the power factor without affecting its torque density. The best design with high performance is used for final current control optimization simulation. [ABSTRACT FROM AUTHOR]

Different MRAS based approaches are gaining ample importance for the speed estimation of AC machine drives because of their simplicity and direct physical interpretation. In this work, MRAS is introduced for the sensorless control of promising low-cost brushless doubly-fed reluctance motor drive under primary field orientation and maximum torque per inverter ampere (MTPIA) conditions. In this regard, secondary flux vectors are employed as the control quantity in the formulation of the proposed MRAS. All the analytical studies, in this context, are carried out in MATLAB/Simulink. The scheme is further validated by a real-time experimentation using dSPACE-1103 based brushless doubly-fed reluctance machine (BDFRM) prototype. The simulation study and test results confirm the robust performance of the proposed controller around the synchronous speed. The investigation decisively affirms the feasibility of MRAS based approach for sensorless speed control of BDFRM drive as well. [ABSTRACT FROM AUTHOR]

The accurate prediction of temperature rise in various parts of a machine plays a significant role in ensuring that the machine delivers the required performance avoiding failures that arise due to high temperatures. In this paper, a lumped parameter thermal model is presented for exterior-rotor axial flux switched reluctance motors. Depending on its geometry, each part of the motor is modeled as a thermal equivalent circuit based on general cylindrical or cuboidal components. A total thermal network is obtained by proper connection of these sub-circuits. The model was calibrated by a stationary test; then, running conditions were applied to the model. The sensitivity of the model to the heat transfer coefficients was investigated by considering the effect of the coefficient variation on the estimated steady-state temperatures. Results show that the winding temperature, as the hottest part of the motor, is the most sensitive to the frame-to-ambient heat transfer coefficients. [ABSTRACT FROM AUTHOR]

In the new generation of “Stop & Start” starters, a DC series motor with high power density is used. In this application, non-symmetrical machines are used due to the single wave winding in brushed motors. The saturation of the iron core in this application reaches a really high level. Moreover, armature reaction in DC machine with a large stator pole spans makes this phenomenon even more enhanced. All these criteria lead to model the whole machine in highly saturated conditions which is time consuming. In this paper, a fast reluctance network (RN) model for an equivalent machine is proposed. It takes into account the armature reaction in high saturation conditions. It also allows a good accuracy and permits us to show the relevance of taking into account this phenomenon in torque calculation. This model is validated by a finite element (FE) method in many operating points, and by a statistical approach. It shows high robustness and low computation time. Finally, an optimization procedure using this reluctance network model and FE is presented in order to show the accuracy of the RN compared to FE model. [ABSTRACT FROM PUBLISHER]

This paper presents an application of direct torque and flux control (DTFC) for a four-switch three-phase inverter (FSTPI)-fed synchronous reluctance motor (SynRM) in which the saturation and iron losses' effects are involved in the machine control modeling. The DTFC switching technique for the SynRM fed by FSTPI in low-power and low-cost applications is implemented by imitating the six-switch three-phase inverter (SSTPI). By considering equal effective vectors depicted in SSTPI, theαβstationary reference frame is represented by using six sectors. Similarly, the voltage space vector formation is constructed in FSTPI. Accordingly the SynRM performance under DTFC is precisely analyzed by considering the saturation and iron losses' effects. The DTFC behavior based on SSTPI- and FSTPI-fed SynRM is evaluated using Simulink benchmark. At different operating conditions, further simulation and experimental results of DTFC based on FSTPI dynamically confirm the effectiveness of the proposed control application on the SynRM. [ABSTRACT FROM PUBLISHER]

Torque ripple is a major problem for switched reluctance motors, which may cause undesirable vibration and acoustic noise, especially at low speed. This paper presents an optimal topology structure of rotor for 8/6 pole switched reluctance motor by using the level set method. The nonlinear ferromagnetic material boundary of rotor pole is implicitly represented through an embedded level set function. This method is applied to obtaining the optimal distributions of material in the design domain for minimizing torque ripple and maximizing average torque. In the optimization objective function, the reluctivity of ferromagnetic material is selected as the design variable. The normal velocity is derived from sensitivity analysis, where the adjoint variable method is utilized. Two-dimensional finite element method is employed to calculate the electromagnetic parameters of this electric machine. Analysis results obtained from the transient simulation of electromagnetic field coupled with control circuit show that the torque ripple is reduced effectively by using the optimized rotor structure. [ABSTRACT FROM AUTHOR]

Double-rotor switched reluctance machine (DRSRM) integrates two switched reluctance machines (SRMs) into one housing, providing a compact solution for hybrid power trains so that one DRSRM can replace two electric machines. This paper presents a new DRSRM design in which the stator flux barriers are removed and the flux lines in the interior and exterior machines are more evenly distributed. The effects of stator flux barriers are investigated, the loss mechanism in the DRSRM is analyzed, and finally, various winding configurations are compared. It is concluded that flux lines are more evenly distributed in the stator, reducing iron saturation and losses, while the interior and exterior machines can be independently controlled without sacrificing performance. Moreover, winding polarity in DRSRM is critical to reduce stator iron saturation and thereby losses. [ABSTRACT FROM PUBLISHER]

The rotor radial force is changed by adjusting the windings current value to control rotor suspension for various kinds of bearingless switched reluctance motor (BSRM). To accomplish the BSRM's suspension control, the radial force analytical model is necessary. Currently the mathematic relationship among radial force, winding currents, and rotor rotation angle has been built for double-winding BSRM, but the rotor eccentricity displacement has not been considered. That is, the existing radial force analytical model only can be used to analyze rotor radial force when rotor shaft is located in the central position. Actually, the rotor radial force is significantly affected by the rotor shaft eccentricity displacement. It is difficult for the bearingless motor to keep the rotor shaft staying in the central position, and the rotor shaft always runs around the central position with an eccentricity displacement. The rotor eccentricity caused by the radial force is considered in the paper to obtain the air-gap permeance and the windings inductances. Furthermore, the radial forces analytical model considering the rotor eccentricity displacement is derived. Finally, the finite-element method (FEM)-based results are applied and the dynamics simulation using the proposed model is accomplished to verify the correctness of the model. [ABSTRACT FROM AUTHOR]

The single-winding bearingless switched reluctance motor has a simple structure of windings in which the winding current produces the magnetic torque and levitation forces simultaneously. In the proposed control strategy, the average torque and average levitation force are regulated simultaneously to ease the current calculation and reduce the processing time of the digital signal processor. Moreover, to simplify the algorithm and investigate the relationship between the two kinds of bearingless switched reluctance motors, the equivalent transformation between single-winding and dual-winding bearingless switched reluctance motors is developed. After that, the average levitation-force control strategy is developed to regulate the torque and the radial force simultaneously. Accordingly, the system control block is established to achieve the closed-loop control, and experimental results verify that the proposed control strategy is effective for a stable levitation. [ABSTRACT FROM AUTHOR]

A variable structure robust position controller is presented for a three-phase synchronous reluctance motor. Linear control and variable structure control and pulse-width modulation generation are combined. These provide robust, fast, and accurate position control without the penalty of high chattering. Schemes, including conventional sliding-mode control and the proposed scheme, are tested under parameter variations, and sudden perturbations are applied to the system at a specific time, then compared. This scheme uses both advantages of traditional variable structure control methods and linear methods. The disadvantages of each method, such as chattering and parameter sensitivity, are minimized. Results demonstrate that the proposed technique preserves the classical linear position control merits, while both the steady-state and transient behavior are significantly improved in terms of robustness, accuracy, and low ripple. The results also prove that the position reference command is perfectly tracked in spite of motor parameter uncertainties and load torque disturbance in control of the system that uses the new schemes. [ABSTRACT FROM AUTHOR]

Abstract—In this research, torque ripple is analyzed, considering both slot opening and distributed winding effects for a 4-pole 60-slot synchronous reluctance machine under healthy and eccentricity fault conditions. Mathematical-based models and numerical methods are used to study the behavior of the machine, especially when it is supplied with a voltage source. For this purpose, the parameters of the machine are computed in both healthy and eccentricity fault conditions using the winding function theory. This article proposes a method that deals with both dynamic and static eccentricity fault diagnosis using a vibration signature; consequently, the results demonstrate that the eccentricity fault has no significant effect on the machine's current signature. Moreover, unbalanced magnetic pull is computed considering eccentricity fault, and then mechanical instability is proven to occur under such circumstances. It should be noted that previous works were generally based on the finite-element method, and current sources were used as suppliers; in this article, a mathematical-based model is utilized and voltage sources are considered as suppliers, which are two main advantages of this article over previous ones. Verification carried out by simulation via the finite-element method supports the effectiveness of the model and control approach. [ABSTRACT FROM PUBLISHER]

This article presents a reference adaptive Hermite fuzzy neural network controller for a synchronous reluctance motor. Although synchronous reluctance motors are mathematically and structurally simple, they perform poorly under dynamic modes of operation because certain parameters, such as the external load and non-linear friction, are difficult to control. The proposed adaptive Hermite fuzzy neural network controller overcomes this problem, as using the Hermite function instead of the conventional Gaussian function shortens the training time. Furthermore, the proposed adaptive Hermite fuzzy neural network controller uses an online self-tuning fuzzy neural network to estimate the system's lumped uncertainty. The estimation method involves a fuzzy controller with expert knowledge of the initial weight of the neural network. Finally, the Lyapunov stability theory and adaptive update law were applied to guarantee system convergence. In this article, the responsiveness of the adaptive Hermite fuzzy neural network controller and an adaptive reference sliding-mode controller is compared. The experimental results show that the adaptive Hermite fuzzy neural network controller markedly improved the system's lumped uncertainty and external load response. [ABSTRACT FROM PUBLISHER]

This article presents an exhaustive study about the influence of some design parameters, such as the number of phases, pole stroke, and current density, in the behavior of a linear switched reluctance motor. The linear switched reluctance motor's performance is assessed, taking into account a set of quality indices, which are the energy conversion loop quality factor, propulsion force per unit of primary steel volume, per unit of copper mass, per unit of air-gap surface, and force ripple factor. The study is carried out by means of two-dimensional finite-element analysis. Finally, the results are discussed, and as a consequence, a set of linear switched reluctance motor configurations with optimal performance according to the quality indices is defined. [ABSTRACT FROM PUBLISHER]

Abstract—In this work, an electromagnetic design procedure for a line-start synchronous reluctance motor is presented, and the main considerations are highlighted. To improve the steady-state performance of this motor, the geometry of the flux barriers as well as their number are optimized using an automatic optimization algorithm. For this purpose, two types of flux barriers, arc shaped and trapezoidal shaped, are formulated and studied by finite-element analysis. Analyzing the average cage torque during synchronization, effectiveness of the dq-axis rotor resistances on successful synchronization is discussed. To validate the results of this analysis, dynamic simulations are used, and the impact of the dq-axis rotor resistances on synchronization is investigated. In addition, the effect of the rotor bar position on the value of the dq-axis rotor resistances is discussed and analyzed by finite-element analysis. Finally, the impact of small pieces of permanent magnet in the flux barriers is studied. It is shown that against the permanent magnet-assisted motor, permanent magnets always enhance the motor performance; the steady-state characteristic of the line-start permanent magnet assisted motor could be deteriorated by permanent magnet. [ABSTRACT FROM PUBLISHER]

Abstract—In this article, a comprehensive method is introduced to redress eccentricity fault consequences. Two main effects of eccentricity faults include considerable increase in unbalanced magnetic force and torque ripple. Dependency of unbalanced magnetic force and torque ripple on eccentricity fault level is shown, and the possibility of compensating them via controlling currents in facing poles is proved. These objectives are accomplished through a novel converter that controls currents in poles of every phase such that one pole is responsible for nullifying unbalanced magnetic force and the facing pole is in charge of torque ripple reducing. The control algorithm is analyzed in details and through finite-element method and MATLAB/Simulink (The MathWorks, Natick, Massachusetts, USA) is implemented on a 6/4 switched reluctance motor with 30% eccentricity fault level. The proposed strategy samples the flux leakage as the index both for occurrence and criterion for compensation of unbalanced magnetic force. The suggested method is designed such that there is no need to detect eccentricity fault direction, location, and type, which makes it cost effective and practical for a wide range of switched reluctance motors and applications. [ABSTRACT FROM PUBLISHER]

This article deals with a 12-pulse AC/DC converter for improving power quality in a midpoint converter based switched reluctance motor drive at AC mains. The conventional six-pulse AC/DC converter fed midpoint converter based switched reluctance motor drive injects high content of current harmonics into AC mains. The proposed 12-pulse AC/DC converter with a small rating passive filter is capable of eliminating harmonic currents from light load to full load with a high power factor. The proposed switched reluctance motor drive system is designed, modeled and simulated in Matlab/Simulink environment and its performance is compared with a conventional six-pulse AC/DC converter fed switched reluctance motor to demonstrate the power quality at AC mains. The simulated performance of the proposed 12-pulse AC/DC converter fed switched reluctance motor drive is experimentally validated for power quality improvement. [ABSTRACT FROM AUTHOR]

This article describes the control optimization of a slotted switched reluctance generator for low-speed applications. The machine is simulated with the finite-element method. The turn-off and turn-on angles are optimized by means of a genetic algorithm to maximize the output power and minimize the torque ripple. First, these two criteria are optimized separately with a mono-objective genetic algorithm, and then a multi-objective Pareto genetic algorithm is used. An analysis of optimized parameters and resulting current waveforms is also performed. Experimental results based on a 6/4 switched reluctance generator are also presented. [ABSTRACT FROM AUTHOR]

Abstract—Analytic modeling of radial forces is proposed for the novel bearingless switched reluctance motor, where the rotor eccentricity is taken into account. The novel bearingless switched reluctance motor's model is never disclosed, even though there are many advantages, such as fewer suspension windings and simpler control circuit and algorithm, when compared to the conventional bearingless switched reluctance motor. The analytic model of radial forces is very important to achieve this new bearingless switched reluctance motor's suspension control. The rotor eccentricity is a key cause to affect the radial forces. This article calculates the air-gap permeances through considering rotor eccentricity. The self-inductance and mutual-inductance expressions of the motor torque windings and the suspension windings are derived by using the magnetic equivalent circuit method. The derived radial force model discloses the effects of winding currents, rotor position angle, and rotor eccentricity displacement. The finite-element analysis based results verify the built model. [ABSTRACT FROM PUBLISHER]

A switching flux reference estimation based method for sensorless control of switched reluctance motors is proposed in this article. The basic idea of the method is to estimate switching-on and switching-off flux linkage references from the giving switching angles range and measured phase current. Real-time comparing the estimated flux linkage with estimated switching flux references, the driving signals can be obtained for sensorless control and rotor speed estimation. For closed-loop control, switching-off angle is fixed for speed estimation, and switching-on angle is regulated by the speed deviation proportional-integrator controller. The process to estimate the switching flux references is greatly simplified compared with conventional flux/current methods; it is easily implemented and is suitable for low-cost industry applications. To verify the proposed method, experiments were conducted on a 1-kW, 3-phase 12/8 switched reluctance motor. Experimental results show that speed variable performance of the sensorless drive is comparable with that of position sensors. [ABSTRACT FROM AUTHOR]

This article presents a simple control strategy to improve the performance of a synchronous reluctance motor drive system fed by a photovoltaic source. The photovoltaic generator parameters are selected based on maintaining the system operating point at the maximum output power of the photovoltaic generator at an average insolation level of 0.5 kW/m2. The proposed control strategy has three main functions; ensuring successful motor starting, maintaining the motor voltage within a permissible range, and forcing the photovoltaic array to operate at the maximum power point possible. Two modes of operation are studied for the proposed system depending upon the level of insolation compared with a critical value, which is the level below which the synchronous reluctance motor cannot work synchronously under the given pumping load. A sample of simulation results is introduced to confirm the effectiveness of the suggested strategy. It has been found that, using the proposed control strategy, the pump flow rate has been increased compared with an uncontrolled system. [ABSTRACT FROM AUTHOR]

A new sensorless control scheme for switched reluctance motor drives is presented in this article. This scheme is based on the basic characteristics that the phase inductance changes periodically with the rotor position. First, according to the inductance characteristics, the inductance model can be constructed. Based on the inductance model, the phase inductance at the turn-off angle of the active phase and the turn-on angle of the next phase can be calculated as the two dynamic thresholds. The real inductance is estimated using the terminal measurements of the active phases. By comparing the estimated phase inductance of the active phase with the dynamic thresholds, the drive signals of each phase can be obtained for controlling the switched reluctance motor directly without rotor position information. This sensorless method is quite easy for implementation and possesses good speed-regulating performance. Besides, in order to start the switched reluctance motor from standstill or start those with initial rotor speed conditions without any hesitation, a full-cycle phase inductance subregion method is utilized. Simulation and experimental results are presented and compared for verification. [ABSTRACT FROM PUBLISHER]

This article presents a new comprehensive design procedure for longitudinal flux flat linear switched reluctance motors. The design process comprises all the steps from detailing the specifications to sizing the prototype to validating the design, and it can be applied to three types of flux flat linear switched reluctance motors: single sided, double sided, and modified double sided. The design is based on an analytical formulation of the average translation force determined using a simplified non-linear energy conversion loop. Special emphasis is devoted to the calculation of the number of turns per phase. A two-dimensional finite-element analysis, corrected to take into account end effects, and a lumped parameter thermal analysis were used to refine and/or validate the design. Finally, a linear switched reluctance motor prototype was built following the proposed design and was verified by experimental measurements. [ABSTRACT FROM PUBLISHER]

This article proposes a new method to reduce the vibration and acoustic noise in a sensorless reluctance drive system applied in a washing machine. By using the proposed fuzzy controller, the DC-bus voltage of the power converter can be suitably adjusted; then the rate of the current pulsations of the switched reluctance motor is obviously reduced. The vibration and acoustic noise of the washing machine, therefore, can be effectively reduced. In addition, some applications use a power factor correction stage to improve the input power factor. As a result, the washing machine has good performance, including a satisfactory power factor in the AC input side, reduced vibration, reduced acoustic noise, large torque, and good reliability. By using a 16-bit digital signal processor, a fully digital drive system, including a digital speed-loop controller and a digital current-loop controller, is implemented here. The hardware circuit of the drive system is very simple. The proposed system can start from a standstill. The adjustable speed range of the system is from 30 r/min to 1800 r/min. The details are discussed in this article, and several experimental results are presented to validate the theoretical analysis. [ABSTRACT FROM AUTHOR]

This article presents a sliding mode control using a Gaussian radial basis function neural network speed control design for robust stabilization and disturbance rejection of the synchronous reluctance motor. In the conventional sliding mode control design, it is assumed that the upper boundary of parameter variations and external disturbances is known and the sign function is used. This causes high-frequency chattering and high gain. A new sliding mode controller using a Gaussian radial basis function neural network estimator is proposed for the synchronous reluctance motor. The proposed method utilizes the Lyapunov function candidate to guarantee convergence and to track the speed command of the synchronous reluctance motor asymptotically. The estimator of parameter variations and external disturbances is designed to estimate the lump unknown uncertainty value in real time. Experiments were conducted to validate the proposed method. [ABSTRACT FROM AUTHOR]

The switched reluctance motor has many benefits owing to its low cost, simple and rugged construction, and comparatively high torque-to-mass ratio. The main disadvantage of the motor is that it produces high torque ripples. Torque control is a difficult task since the switched reluctance motor is intentionally operated in deep magnetic saturation to increase the output power density. A new method, called the fuzzy iterative technique, is introduced in this work to modulate the phase current profile to minimize the torque ripples. The experimental results indicate that the torque ripple is reduced to lie within 5% of the desired steady torque even in dynamic operating conditions. [ABSTRACT FROM AUTHOR]

A switched reluctance motor (SRM) is suitable for many variable-speed and servo-type applications, and is getting increasing attention in the motor drive industry. However, the SRM has highly nonlinear characteristics since the developed torque of the SRM is a nonlinear function of both phase current and rotor position, and the SRM always operates with magnetic saturation to maximize torque/mass ratio. These nonlinearities of the SRM drives make the conventional PI (proportional + integral) controller a poor choice for application where high dynamic performance is desired under all motor operating conditions. The genetic algorithm (GA) can give robust adaptive response of a drive with nonlinearity, parameter variation and load disturbance effect. In this article, the genetic PI speed controller was applied to the speed loop of the SRM by replacing the conventional PI speed controller. The genetic PI controller software was implemented using C+ + Builder on a PC. Both the conventional and the genetic PI controller for the SRM are implemented by using a TMS320F240 digital signal processor. The results show that the genetic PI controller is less sensitive to the parameter variations and disturbances. [ABSTRACT FROM AUTHOR]

In this article, the authors present a simulation model of multiphase switched reluctance motor based on a combination of circuit-oriented and signal-oriented approaches under MATLAB/SimPowerSystems environment. It is shown that the proposed model combines the advantages of both circuit- and signal-oriented approaches. The nonlinear magnetic characteristics of both self- and mutual-couplings are taken into account by means of look-up tables. Contributions of the instantaneous electromagnetic torque from the self- and mutual-couplings are derived. Simulation and experimental results are reported and compared to verify the simulation model. [ABSTRACT FROM AUTHOR]

This article describes the design of a low speed slotted switched reluctance machine (SSRM) for wind turbine applications. The modeling and the dimensioning of the machine structure are investigated. Teeth shapes are studied by maximizing the produced torque, and then the global design is analyzed by optimizing the mass to torque ratio. The influence of the number of poles per phase is investigated, and finally a comparison with other high torque machines is carried out. Dimensions are obtained thanks to a genetic algorithm (GA) associated to the finite element method for the resolution of the electromagnetic equations. [ABSTRACT FROM AUTHOR]

The single-phase switched reluctance machine has a simple and robust construction and is suitable for high-speed operation. Torque production is a function of the difference between the aligned and unaligned inductance, and increasing this difference theoretically will increase the torque. In this article, conducting screens are incorporated into the rotor of a prototype 2/2 single-phase switched reluctance motor. The effect of the conducting screens on current response, flux linkage, and output torque is evaluated using finite element analysis and validated experimentally. At fixed current conduction angles, conducting screens improve the rate of change of inductance at low speed, and enhance performance at high speed when the machine operates in the single voltage pulse mode. The conducting screens have a negative effect on the output torque when using optimal commutation angles. Reasons for this phenomenon are given. [ABSTRACT FROM AUTHOR]

This article presents a novel method for the production of smooth torque as well as high performance speed controller for 6/4 switched reluctance motor (SRM) drives. The proposed method is based on direct torque control (DTC) technique. According to the sign of the error between the command and actual motor torque in addition to the rotor angle, the inverter output voltages are determined. Instead of current controllers, the DTC directly turns the power electronic switches on and off and, hence. fast response is achieved. The nonlinear SRM model is considered and simulation results are obtained to validate the proposed controller. [ABSTRACT FROM AUTHOR]

The knowledge of air velocity inside all the air regions in any electric machine is essential in performing various air velocity-dependent analyses such as calculation of windage loss, thermal analysis, determination of effectiveness of cooling, and estimation of life of insulators. This article, in this context, introduces computational fluid dynamics (CFD) procedure for the evaluation of air velocity distribution inside electric machines. One of the today's most experimented machine, the switched reluctance motor (SRM), is considered for the illustration. A two-dimensional finite element approach (FEA) for CFD is described and results are discussed. [ABSTRACT FROM AUTHOR]