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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]

A hybrid ferrite‐Al‐Ni‐Co permanent magnet assisted synchronous reluctance motor (PMa‐SyRM) for an air‐conditioner compressor is proposed. Al‐Ni‐Co PMs have high residual flux density similar to rare‐earth PMs such as Nd‐Fe‐B and Sm‐Co. Therefore, the performance parameters of the PMa‐SyRM such as power factor, efficiency etc., with Al‐Ni‐Co PMs can be improved without significantly increasing the cost of the motor. However, Al‐Ni‐Co PMs have a steep IInd‐quadrant B‐H curve, and the challenge lies in addressing their demagnetisation issues. In the proposed hybrid PMa‐SyRM, the rotor geometry is suitably optimised for placing the Al‐Ni‐Co PMs in the centre flux barriers to address the demagnetisation issues. Further, an analytical magnetic circuit is presented to design the proposed PMa‐SyRM. Later, 2‐D finite element analysis of the proposed motor including the demagnetisation analysis of PMs and stress analysis of the rotor is carried out and presented. A prototype is fabricated, experimental validation is carried out, and the results of the performance and cost are compared with that of ferrite and hybrid ferrite‐Nd‐Fe‐B PMa‐SyRM. [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]

This paper proposes a new design for line-start operation of synchronous reluctance motors. In the past years, synchronous reluctance motors have been studied by many researchers. Due to high efficiency, they have gained increasing interest because in the synchronous operation, there is limited losses in the rotor. On the other hand, line-start operation of the synchronous reluctance motors is an important challenge that can make this type of the motors popular in many applications. However, line-start operation techniques should not considerably affect the steady-state characteristics of the motor. In the proposed design, the arrangement, size and shape of the rotor conductor bars are designed based on the rotor magnetic circuit difference between induction and reluctance synchronous motors. Complete assessment of the motor parameters are examined using finite element analysis. The proposed structure improves the starting characteristics of the motor. Moreover, power factor of the proposed motor is slightly increased in comparison to that of conventional line-start synchronous reluctance motors. The results obviously show effectiveness of the proposed line-start operation strategy for the synchronous reluctance motors. Finally, experimental verification are also included to confirm the finite element analysis results. [ABSTRACT FROM AUTHOR]

This paper contains research on the development of a fault-tolerant six-phase synchronous reluctance motor (SynRM) based on the stator adopted from a general-purpose three-phase induction motor. In the design and calculation process, an extended Clarke transformation was developed for a six-phase asymmetrical system. To verify the proposed design approach, a field–circuit model of electromagnetic phenomena in the studied motor was developed and used to study the motor performance. The increased torque value and reduction in torque ripples were confirmed by comparison to the classical three-phase SynRM design. To illustrate fault tolerance capabilities, the operation of the studied three- and six-phase synchronous reluctance motors under inverter-fault conditions was examined. The conducted analysis shows, among other things, that from the electromagnetic performance point of view, only the proposed six-phase machine is able to properly operate under inverter-fault conditions. The results of the winding design calculations, the performed simulations of six-phase motor operation, and the preliminary tests of the prototype motor are presented and discussed. [ABSTRACT FROM AUTHOR]

Aiming at the influence of eccentric faults on the performance of synchronous reluctance motor (SynRM), the distribution characteristics and change rules of dynamic electromagnetic stress before and after eccentric faults of SynRM were studied. A dynamic electromagnetic stress calculation model combining eccentric fault finite element method and Maxwell tensor method is established under the influence of magnetic saturation. The dynamic electromagnetic stress before and after the eccentric fault of the rotor surface, rotor magnetic ribs, and stator tooth wall are calculated, and the differences in the electromagnetic stress distribution are analyzed in detail. The analysis methods and results of electromagnetic stress provide a reference for the design and structure optimization of SynRM, and it also presents a theoretical guarantee for the smooth and orderly operation of SynRM. [ABSTRACT FROM AUTHOR]

This paper introduces a novel index for static eccentricity (SE) fault diagnosis in synchronous reluctance motors (SynRMs). Although SynRMs with rotor barriers under SE have been modeled in a few papers, any indices for the fault detection have not yet been reported. The proposed index is a specific frequency pattern in the motor current, which can also determine the fault severity. A novel analytical magnetic field investigation is applied to ascertain the proposed index. An accurate nonlinear numerical method is proposed for the motor inductances calculation. The model considers the rotor flux barriers, magnetic saturation, and the stator slots effect. The air gap flux density and the motor current are then achieved. The fast Fourier transform is exploited as a signal-processing tool to calculate motor current spectra. Then, a two-dimension time-stepping finite element method is used to attest of the proposed numerical model. Effectiveness of the proposed index is verified by simulation and experimental tests. [ABSTRACT FROM AUTHOR]

The inverter dead time effect is non-negligible for the control performance of sensorless synchronous reluctance motor (SynRM) drives at low speeds. In this paper, a reduced-order observer-based sensorless control method for SynRM drives combined with the adaptive linear neurons (ADALINE)-based dead-time compensation is proposed. The reduced-order observer-based sensorless control method is presented, for which is parameter tuning is easy. On this basis, the dead-time compensation strategy using ADALINE filters is proposed to reduce the voltage harmonics effect on the estimation performance of the reduced-order observer. With ADALINE filters, the sixth current harmonic can be successfully filtered out by compensating the voltage directly or fitting the current to compensate the voltage. In this way, the low-speed estimation performance of the reduced-order observer is improved. The effectiveness of the proposed method is verified on a 3 kW SynRM experimental platform. [ABSTRACT FROM AUTHOR]

As rare-earth permanent magnet prices continue to fluctuate, interest in non-rare-earth permanent magnet-assisted synchronous reluctance motors (PMa-SynRMs) is increasing. However, non-rare-earth PMa-SynRMs have a multi-layer structure with interior permanent magnets to compensate for the low magnetic fields. Therefore, the rotor has several design parameters, and electromagnetic analysis is time-consuming. To overcome these challenges, magnetic equivalent circuit analysis was used to perform fast electromagnetic analysis of non-rare-earth PMa-SynRMs. In addition, the validity of the proposed method was confirmed through a comparison of the obtained results with those of finite element analysis. [ABSTRACT FROM AUTHOR]

There are usually noise problems when the position sensorless control of a synchronous reluctance motor (SynRM) is carried out by high-frequency (HF) signal injection method. Due to the special structure, the cross-saturation effect of the SynRM is particularly serious, resulting in reduced position observation accuracy. In this paper, a variable-angle random HF voltage injection strategy with cross-saturation effect compensation is proposed for position sensorless SynRM drives. Random number generation based on the chaotic mapping method is used to generate random HF voltage signals with different frequencies for injection; the current power spectral density (PSD) distribution is extended and the HF noise can be reduced. A control strategy based on variable-angle square-wave injection is proposed to suppress the cross-saturation effect. By measuring the position error curves of different loads off-line and polynomial fitting the curves, the position error is achieved by combining with the corresponding signal demodulation algorithm. The proposed method does not require additional hardware resources and can maintain high control accuracy and robustness. Finally, the effectiveness of the proposed sensorless control strategy is verified on a 3 kW SynRM experimental platform. [ABSTRACT FROM AUTHOR]

Synchronous reluctance machines are considered a cost-effective solution for several industrial applications and present potential efficiency benefits compared to induction motors. In industrial applications, power supply oscillations can lead to short-term disturbances that can affect the drive operation; therefore, the control must be robust to guarantee high efficiency and service continuity. The focus of this study was to identify the speed boundaries considering different values of applied DC-link voltage, taking into account the highly nonlinear magnetic behavior of the machine and its cross-coupling characteristics. In addition, a comprehensive carrier-based implementation of a pulse width modulation strategy was proposed to achieve optimal efficiency in both the machine and converter, which is essential in the presence of "weak" grids. The proposed technique was demonstrated to meet the desired reference torque and rated speed, even during DC-link voltage drops (up to 7.4% of the rated voltage). The proposed methodology was experimentally validated on a 90 kW SynRM drive with a broader modulation range and higher efficiency. This work considered several different supply voltage levels to assess the stability and continuity of torque output and further proved the proposed method. [ABSTRACT FROM AUTHOR]

The authors present a new design of a PM‐assisted synchronous reluctance motor (PM‐SynRM) with uneven air‐gap length to improve the power factor and enhance the torque production capability. The rotor structure is modified to properly shift rotor magnetic poles and therefore (i) increases the back‐EMF and the electromagnetic torque, (ii) allows electromagnetic torque and reluctance torque components peak near the same current phase angle. The proposed solution is simple, does not require changing the arrangement of magnets and/or flux barriers and is applicable to all types of PM‐SynRMs. Sensitivity analysis is carried out to determine the extent of which the proposed magnetic pole shifting may impact the resultant torque profile. To assess the level of success, the electromagnetic characteristics of the proposed design (e.g. torque, power factor, and back‐EMF) are compared against the baseline structure under the same operating conditions. For verification purposes, Finite Element simulation results are validated via a series of analytical calculations and experimental measurements, and supported with detailed theoretical discussion. [ABSTRACT FROM AUTHOR]

Purpose: Industrial drives require appropriate control systems for reliable and efficient performance. With synchronous reluctance machines (SynRMs) slowly replacing the most commonly used induction, switched reluctance and permanent magnet machines, it is essential that the drive and its control be properly selected for enhanced performance. But the major drawback of synchronous reluctance motor is the presence of high torque ripple as its design is characterized by large number of variables. The solutions to reduce torque ripple include design modifications, choice of proper power electronic inverter and PWM strategy. But little has been explored about the power electronic inverters suited for synchronous reluctance motor drive to minimize torque ripple inherently by obtaining a more sinusoidal voltage. The purpose of this paper is to elaborate on the potential multilevel inverter topologies applicable to SynRM drives used in solar pumping applications. Design/methodology/approach: The most significant field-oriented control using maximum torque per ampere algorithm for maximizing the torque production is used for the control of SynRM. Simulation results carried out using Matlab/Simulink are presented to justify the choice of inverter and its control technique for SynRM. Findings: The five-level inverter drive gives lesser core or iron losses in the SynRMin comparison to the three- and two-level inverters due to lower Id current ripple. The five-level inverter reduces the torque ripple of the SynRM significantly in comparison to the three- and two-level inverter fed SynRM drives. The phase disposition-PWM control method used for the inverter shows the least total harmonic distortion (THD) levels in output voltage compared with the other level shifted PWM techniques. Originality/value: Among the available topologies, a fitting topology is proposed for use for the SynRM drive to have minimal THD, minimal current and torque ripple. Additionally, this paper presents various modulation techniques available for the selected drive system and reports on a suitable technique based on minimal THD of output voltage and hence minimal torque ripple. [ABSTRACT FROM AUTHOR]

The effect of winding chording on five-phase synchronous reluctance motor (SRM) modelled in phase variables is presented. The stator winding configuration is shifted a pole pitch from a fullpitch configuration to a 54 degrees over-full-pitched configuration incorporating the effect of 3rd harmonic of the air-gap magneto-motive force in the inductance equations. The models are monitored on starting, synchronism, loading, faults and loss of synchronism. These are considered simultaneously with vector potential, rotor speed, air-gap flux linkage and winding current. The phase variable (analytical) models have been simulated by using MATLAB/Simulink software while ANSYS Maxwell software has been used to simulate the finite element model (FEM) of the motor for corresponding chording ranges for comparison on direct online starting (DOL). Under all conditions considered in the work, the detailed results are presented and very close similarity is observed between the analytical and the nearly ideal FEM model for all chording ranges and the similarity is enhanced with increase in chording angle. [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]

In this study, a generalized torque estimation method is proposed for synchronous motors, including surface permanent magnet synchronous motors (SPMSMs), synchronous reluctance motors (SynRMs), and interior permanent magnet synchronous motors (IPMSMs) for building the analytical motor model. The average motor torque is estimated using the Lorentz force by the generated flux density in the air gap to determine the relationships among torque, flux density, and injected current. In the proposed method, the generated flux density is derived step by step by considering the effects of magnetic flux saturation, the stator slot, the rotor barrier, and permanent magnets (PMs) to ensure that the generated average torque complies with the operating condition of the motor. To verify the proposed method, the output torque of finite element analysis (FEA), Maxwell 2D, is compared to the proposed method in a SPMSM. Moreover, a phasor diagram is plotted to determine the mechanism through which torque is generated in SynRMs and IPMSMs. A SynRM and an IPMSM with ferrites PMs are analyzed using the proposed method, FEA, and the experimental results of this study indicate the effectiveness. [ABSTRACT FROM AUTHOR]

This paper discusses the selection of an interior permanent magnet synchronous machine and converter for a 100V-200V DC, 100-400 Hz, 150-175 Nm, 30kW-100kW, 1550-4100 rpm electrical vehicle engine alternator. The electrical vehicle engine application requirements are outlined including the engine coupling configuration. Then the characteristics of different machines and their converters are compared through a competitive trade-off study framed by the alternator requirements; direct-drive induction, variable-reluctance, surface permanent magnet synchronous machine, and interior permanent magnet synchronous machine are all considered. The results of the study indicate that the interior permanent magnet synchronous machine is a potentially superior candidate, and so this machine is selected for further investigation. The preliminary findings are described, and the paper concludes with a discussion of current work addressing analytic design. [ABSTRACT FROM AUTHOR]

Recently, synchronous reluctance motors have had a resurgence of benefit for many applications in the industry because of their simple framework, high effectiveness, low manufacturing cost, and high robustness. This research presents two inverter neutral-point-clamped topologies to improve the vector-controlled SynRM; these topologies offer interesting characteristics compared to the conventional structure-based two-level inverter. To get an inverter smooth switch command sequence, pulse width modulation has been modified to be adapted to the new topologies. The goal is to produce an output voltage vector which approaches the reference voltage vector as closely as possible. As a result, and contrary to the two-level inverter, that can only supply eight voltage vectors, the seven-level inverter can produce one 127 voltage vectors, and the nine-level inverter can produce 255 voltage vectors. Besides, an anti-windup structure is used in the speed loop regulation to ensure robust control with less static error. A comparison is done between the proposed techniques-based multilevel inverters and the conventional technique-based two-level inverter. Satisfactory results have been got by numerical simulation using MATLAB/Simulink. [ABSTRACT FROM AUTHOR]

The rotating high-frequency (RHF) signal injection method is widely adopted for the initial position estimation in sensorless permanent magnet-assisted synchronous reluctance motor (PMa-SynRM) drives due to its simple implementation. However, the position estimation accuracy of the conventional method may be seriously deteriorated by the dead-zone effects of the inverter and the cross-saturation effects of the machine. Thus, to improve initial position estimation accuracy, a strategy to apply dual RHF signals is proposed in this paper. Different from the traditional solution, the proposed method sequentially injects dual RHF carrier voltages with the same frequencies but different amplitudes into the machine. Objective equations that consider the dead-zone and cross-coupling effects can be extracted from high-frequency response currents in turn. After the simple calculation, the initial position can be obtained directly and accurately, which effectively minimizes the influences of machine cross-saturation and inverter nonlinearities. The influence of the system delay on the rotor position estimation is also analyzed and deduced in detail. Finally, experimental results on a 5.5-kW PMa-SynRM indicate that the proposed method can achieve precise initial position estimation under any rotation position. [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]

This paper investigates an optimal model-free control design for a synchronous reluctance motor (Syn-RM) with unknown nonlinear dynamic functions, parameter variations, and disturbances. The idea is to combine a predictive control with a time-delay estimation technique (TDE) in order to successfully deal with the system's uncertainties and make the Syn-RM control scheme easy to implement in real-time. This model-free control strategy comprises two cascade control loops namely outer and inner loops. The outer loop is designed for the mechanical part of Syn-RM to ensure the convergence of the speed dynamics by using a proportional-integral controller while the inner loop is developed to control the uncertain dynamics of currents via an optimal robust controller. In the proposed current loop, the predictive control is enhanced by the inclusion of ultra-local model theory where dynamic functions and disturbances are estimated by instantaneous input-output measurements of the Syn-RM using the TDE approach. Moreover, a particle swarm optimization (PSO) algorithm is also proposed to find the optimal design parameters to improve the dynamic performances of the closed-loop control system. Numerical validation tests of the proposed TDE-based model-free predictive current control (TDE-MFPCC) method are performed in the simulation environment of the Syn-RM system, and the results show the robustness and the effectiveness of the proposed TDE-MFPCC compared to the conventional model-based PCC. [ABSTRACT FROM AUTHOR]

This paper presents research on an unconventional electric machine. It is a hybrid excited machine which includes the features of three types of machines: the Permanent Magnet Synchronous Machine, the Synchronous Machine, and the Synchronous Reluctance Machine. Therefore, a broad literature review related to the above-mentioned types of machines was constructed. The well-known Permanent Magnet assisted Synchronous Reluctance Machine joins features of Permanent Magnet Synchronous Machine and Synchronous Reluctance Machine topologies. This paper shows the results of the innovative design of the Hybrid Excited Permanent Magnet assisted Synchronous Reluctance Machine, which additionally has advantages of the Synchronous Machine. In the article the basic methods of electromagnetic flux control and the designs using them are also presented. Finally, the results of simulation studies of the effect of the stator skew on the machine performance are described. [ABSTRACT FROM AUTHOR]

In recent years, there has been a significant focus on synchronous reluctance motors (SynRM) owing to their impressive efficiency and absence of magnetic material. Although the SynRM shows great potential for use in electric vehicles, its widespread adoption is limited by unmodeled dynamics and external disturbances. Moreover, the uncertainty factor significantly restricts SynRM's peak efficiency and superior control performance, leading to an unjustifiable current loop reference command. To address these issues, this work presents various new research contributions which focus on the robust control of SynRM to optimize performance through the novel reaching law-based sliding mode control. Initially, a novel advanced sliding mode control reaching law (ASMCRL) with adaptive gain is proposed, to enhance the acceleration of the system state reaching the sliding surface. After that, an extended state observer (ESO) is designed to estimate and compensate for the overall disturbances of the system. Finally, the ASMCRL and ESO are integrated to design two nonlinear controllers namely, the disturbance-rejection sliding mode controller (DRSMC) and the disturbance-rejection sliding mode speed regulator (DRSMSR) for SynRM. The proposed DRSMSR eliminates the steady-state error and eradicates inherent chattering in DRSMC. Moreover, this yields a system trajectory that converges to a predetermined proximity of the sliding surface, irrespective of any lumped disturbances. The steady-state error of DRSMSR is less as compared to DRSMC. Furthermore, the speed response of this technique is 22.62% faster as compared to the state-of-the-art finite-time adaptive terminal sliding mode control. Additionally, the asymptotic stability of the proposed system is validated using Lyapunov's theorem. Thus the experimental results demonstrate the effectiveness and robustness of the proposed approach. [ABSTRACT FROM AUTHOR]

Synchronous reluctance motor drives (SynRMs) are the best promising machines utilized in modern industries and electric vehicles, according to the current study. Research on new SynRMs drive systems has increased as a result. This review article disseminates the most recent developments in these technologies' design, modeling, and controlling. First, a simple comparison between the main motor technologies and SynRMs is made. To aid researchers in selecting the appropriate motor controller for their motor drive systems, the most common motor control approaches are examined and classed. [ABSTRACT FROM AUTHOR]

An intelligent servo drive system for a permanent magnet-assisted synchronous reluctance motor (PMASynRM) that can adapt to the control requirements considering the motor's nonlinear and time-varying natures is developed in this study. A recurrent wavelet fuzzy neural network (RWFNN) with intelligent backstepping control is proposed to achieve this. In this study, first, a maximum torque per ampere (MTPA) controlled PMASynRM servo drive is introduced. A lookup table (LUT) is created, which is based on finite element analysis (FEA) results by using ANSYS Maxwell-2D dynamic model to determine the current angle command of the MTPA. Next, a backstepping control (BSC) system is created to accurately follow the desired position in the PMASynRM servo drive system while maintaining robust control characteristics. However, designing an efficient BSC for practical applications becomes challenging due to the lack of prior uncertainty information. To overcome this challenge, this study introduces an RWFNN as an approximation for the BSC, aiming to alleviate the limitations of the traditional BSC approach. An enhanced adaptive compensator is also incorporated into the RWFNN to handle potential approximation errors effectively. In addition, to ensure the stability of the RWFNN, the Lyapunov stability method is employed to develop online learning algorithms for the RWFNN and to guarantee its asymptotic stability. The proposed intelligent backstepping control with recurrent wavelet fuzzy neural network (IBSCRWFNN) demonstrates remarkable effectiveness and robustness in controlling the PMASynRM servo drive, as evidenced by the experimental results. [ABSTRACT FROM AUTHOR]

Fault diagnosis and condition monitoring of synchronous machines running under load is a key determinant of their lifespan and performance. Faults such as broken rotor bars, bent shafts and bearing issues lead to eccentricity faults. These faults if not monitored may lead to repair, replacement and unforeseen loss of income. Researchers who attempted to investigate this kind of machine stopped at characterizing and deduced ways, types and effects of rotor eccentricity fault on the machine inductances using the winding function method. A modified closed-form analytical model of an eccentric synchronus reluctance motor (SynRM) is developed here taking into cognizance the machine dimensions and winding distribution for the cases of a healthy and unhealthy SynRM. This paper reports the study the SynRM under static rotor eccentricity using the developed analytical model and firming up the model with finite element method (FEM) solutions. These methods are beneficial as they investigated and presented the influence of the degrees of static eccentricity on the machine performance indicators such as speed, torque and the stator current and assess the extent to which the machine performance will deteriorate when running with and without load. The results show that static eccentricity significantly affects the machine's performance as the degree of eccentricity increases. [ABSTRACT FROM AUTHOR]

Currently, applications of the algorithms based on artificial intelligence (AI) principles can be observed in various fields. This can be also noticed in the wide area of electrical drives. Consideration has been limited to neural networks; however, the tasks for the models can be defined as follows: control, state variable estimation, and diagnostics. In the subsequent sections of this paper, electrical machines, as well as power electronic devices, are assumed as the main objects. This paper describes the basics, issues, and possibilities related to the used tools and explains the growing popularity of neural network applications in automatic systems with electrical drives. The paper begins with the overall considerations; following that, the content proceeds with the details, and two specific examples are shown. The first example deals with a neural network-based speed controller tested in a structure with a synchronous reluctance motor. Then, the implementation of recurrent neural networks as state variable estimators is analyzed. The achieved results present a precise estimation of the load speed and the shaft torque signals from a two-mass system. All descriptions in the article are considered in the context of the trends and perspectives in modern algorithm applications for electrical drives. [ABSTRACT FROM AUTHOR]

The modern era of green transportation based on Industry 4.0 is leading the automotive industry to focus on the electrification of all vehicles. This trend is affected by the massive advantages offered by electric vehicles (EV), such as pollution-free, economical and low-maintenance cost operation. The heart of this system is the electric motor powered by lithium-ion batteries; however, due to their many limitations, a hybrid energy storage system (HESS) consisting of batteries and ultracapacitors is currently gaining increased attention. This paper aims to review the distinct motor technologies such as brushless motors, synchronous reluctance and induction motors currently used in EVs. Additionally, through eleven selected criteria, such as regenerative braking efficiency and power density at different load ranges, the motors are classified in terms of their combined ability to operate with a HESS in order to maximize efficiency and sizing. The results show that permanent magnet and induction motors are the best options when all criteria are considered, while synchronous reluctance motor outperforms the induction motor regarding only the main factors affecting the performance of the hybrid storage system. [ABSTRACT FROM AUTHOR]

This article proposes a novel method to reduce rotor movement when estimating magnetic flux models for interior permanent magnet synchronous motors (IPMSMs) and synchronous reluctance motors (SynRMs). A rotation reduction technique that considers the flux saturation effect is proposed. A hysteresis controller is used to inject voltages only into the q-axis and simultaneously into the dq-axes. The rotation of the IPMSM is reduced by calculating the current at the point where the integral of the q-axis current over time becomes zero. In the case of SynRM, the rotation is reduced by calculating the injection voltage magnitudes such that the oscillation frequency of the q-axis current is higher than that of the d-axis current. The effectiveness of the proposed method was experimentally demonstrated using an 11-kW IPMSM and 1.5-kW SynRM. The proposed technique can be used for the self-commissioning of IPMSMs and SynRMs at a standstill, without rotor locking, or position sensors. [ABSTRACT FROM AUTHOR]

Due to their robustness and adaptability, position estimators based on the extended Kalman filter have been used in permanent magnet synchronous motors for decades. The time has come to extend their use to reluctance motors as well and this work focuses on the elements that hinder the transition. All passes through the availability of an accurate and analytical magnetic model, which is obtained by Artificial Intelligence tools. It is proved that the sensorless control of synchronous reluctance motors using the extended Kalman filter is possible over broad speed and torque ranges. The experimental session compares different implementation possibilities, concluding with the proposal of a new hybrid algorithm that greatly reduces the computational load. [ABSTRACT FROM AUTHOR]

This paper presents an evolutional topology optimization of electric machines, which works like gradient‐based local search methods, based on the covariance matrix adaptation evolution strategy (CMA‐ES). The present method enables to improve the performance of initial machine shapes without computing the deviation of the objectives. Moreover, for the resultant shapes obtained by the present topology optimization method, this paper also presents a sensitivity analysis method based on the normal distribution which is used to seek for solutions in CMA‐ES. Using the present sensitivity analysis method, important parts which contribute to improve a machine characteristic can be visualized. The two present methods are applied to the optimization problem of a synchronous reluctance motor. It is shown that initial rotor shapes defined by designers can effectively be modified using the present optimization method. Moreover, it is also shown that the sensitivity distributions with respect to some machine characteristics are visualized by the present method. In addition, each machine characteristic is respectively improved by modifying the machine shape according to the respective sensitivities. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a new three-layer, five-phase winding configuration theory of unconventional slot-pole combinations by each layer of winding for a phase vector correction, three layers of winding superimposed together to achieve the results of three-phase symmetry. Since the single-layer unconventional winding has to have an empty slot to meet its symmetry, based on the characteristics of single-layer winding, the unconventional winding design is carried out. Based on the simulation comparison between the single-layer unconventional winding and double-layer unconventional winding, a three-layer, nine-phase unconventional winding is proposed, which is based on the theory of single-layer unconventional winding, and three layers are staggered and stacked to realize nine-phase winding, which not only increases the utilization rate of the winding slot but also improves the fault tolerance performance. In addition, a 105-slot, 20-pole, three-layer, five-phase motor is proposed for a winding configuration and performance analysis to achieve both low torque pulsation and high fault tolerance. [ABSTRACT FROM AUTHOR]

Fractional‐slot concentrated‐windings are appreciated for their simple construction, short end‐winding length, high copper fill factor, low cogging torque, good field‐weakening capability and fault‐tolerant ability. However, in comparison to the conventional distributed windings, the fractional‐slot concentrated‐windings are characterised with high space magnetomotive force (MMF) harmonics, which results in undesirable effects on the machine performance, such as localised core saturation, eddy current loss in the rotor and noise and vibration. In order to improve winding characteristics, several techniques have been developed recently. This manuscript introduces the 5 new winding topologies by using the general concept of stator slot shifting. It means that, in order to cancel undesirable MMF harmonics, by doubling (or tripling or even multiplying) the slot number and dividing the winding and then relatively shifting the winding by one (or more) slots, the undesirable harmonics have been eliminated effectively. The best choice is chosen according to the lowest amount of the MMF harmonic, highest value of winding factor and torque desirable characteristics. At the end, comprehensive comparisons for the designed synchronous reluctance motor (SynRel) equipped with proposed windings and also distributed winding are presented. The analytical study and 2D FEM analysis results show that it is possible to get an ideal low space‐harmonic winding topology, and consequently, a low torque ripple for these motors. [ABSTRACT FROM AUTHOR]

The goal of this article is to develop a new topology optimization framework that can secure the manufacturability of the synchronous reluctance motors (SynRMs) with multiple iron webs and bridges while satisfying the required electromagnetic and mechanical performances. In the SynRM, multiple iron webs and bridges are crucial to achieve a higher torque and a structural safety. A minimum thickness of the web and bridge should also be guaranteed to achieve manufacturability. To acquire the optimal SynRM that can satisfy the above characteristics, a two-stage topology optimization framework is proposed with an individual filtering-and-penalization scheme. This proposed scheme can individually control the number and thickness of multiple iron webs and bridges in the rotor to obtain the manufacturable and structurally safe SynRMs. For the abovementioned purpose, topology optimization is formulated to minimize a torque ripple while satisfying the desired average torque, structural compliance, and a rotational moment of inertia. Average torque and structural compliance are evaluated by performing the electromagnetic and structural finite element analyses, respectively, at each iteration of topology optimization. Here, design-dependent loads are considered in the radial and circumferential directions to reflect a high-speed rotation. Through investigating the optimized SynRM designs with various filter radii, the relationship among the torque, structural pattern, and stress distribution is examined. Finally, the experimental results with the manufactured prototypes validate the feasibility and potential of the proposed design method. [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel multi‐objective topology optimization with response surface approximation interpolating various topologies, which is derived by deep learning with training data in the actual design space. The response surface is constructed by means of autoencoder with the training data of geometrically diverse shapes of targeted devices, which can express the interpolations that combine the multiple characteristic structures. The global topology search is performed based on the gradient information of the response surface, by which we can obtain the initial shapes for level set optimization to efficiently obtain easily manufactured and excellent Pareto optimal solutions. The effectiveness of the proposed method is demonstrated by optimizing multi‐flux barriers in a synchronous reluctance motor for the objective functions of average torque and torque ripple. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Sensorless control based on high-frequency square-wave voltage injection (HFSVI) is one of the most common sensorless control methods for synchronous reluctance motors (SynRMs). However, the injection frequency for SynRMs cannot be too high due to various factors. As the injection frequency decreases, the dead-time harmonic current will greatly affect the separation of high frequency signals. This paper analyzes the effect of dead-time harmonic current on the HFSVI-based sensorless control performance of SynRMs and proposes a source of position estimation error. Then, a dead-time compensation method suitable for filter-free HFSVI is proposed. It can estimate current vector spatial orientation without any low-pass filters (LPFs) and effectively compensate the impact of dead-time setting. The correctness of the theoretical analysis and the feasibility of the proposed methods in this paper are verified by experiments. [ABSTRACT FROM AUTHOR]

A novel position estimation strategy based on lag compensation-assisted adaptive quasi-fading Kalman filter (LC-AQFKF) is proposed for synchronous reluctance motor (SynRM) sensorless drive in this article. In LC-QFKF, the quasi-fading factor is derived to avoid the harsh assumptions of conventional adaptive fading Kalman filter, and accessibility of the method is improved while ensuring the estimation accuracy. The computational efficiency of LC-AQFKF is promoted by introducing the quasi-fading factor into the prediction error covariance matrix. Moreover, the frequency characteristic of AQFKF-based active back electromotive force observer is analyzed, and the phase lag problem in high-speed situations caused by the low-pass filtering property of AQFKF is overcome. In this way, the estimation accuracy of the rotor position is significantly enhanced. Besides, the double dynamic position compensation method is put forward to strengthen the position estimation performance of sensorless SynRM drive under dynamic conditions. The effectiveness of the proposed scheme is validated at a 1.5 kW SynRM drive. [ABSTRACT FROM AUTHOR]

This article presents a structural strength analysis and noise reduction method for high-speed long primary moving-magnet-type linear synchronous motors (MMT-LSMs) applied to electromagnetic launch systems under high acceleration. The stresses and deformations of the mover and frame at different mover offset distances are analyzed and calculated to reveal that the permanent magnets (PMs) placed ectally on both sides of the mover core are easily damaged and need to be protected by sleeves. Then, the mover stresses with different sleeve materials and varied PM-sleeve interference values are compared for subsequent optimization. Furthermore, tooth harmonic is the main cause of vibration and noise when electromagnetic force waves are exerted on this MMT-LSM. Three improved methods are discussed comprehensively to reduce vibration and noise, including pole/slot combination, slot width, and pole arc coefficient. Finally, the experiment platform is built with the implementation of the modal and vibration acceleration experiments to verify the proposed analysis method. [ABSTRACT FROM AUTHOR]

Recently, model-based predictive current control (MB-PCC) has been presented as a good alternative to classical control algorithms in terms of simplicity and performance reliability. However, MB-PCC suffers from the high dependence on system parameters, which may deteriorate its performance under parameters variations. On the other hand, synchronous reluctance motors (SynRMs) are susceptible to suffer from inductances variations due to the magnetic saturation. Accordingly, in this article a new model-free predictive current control of SynRMs based on a recurrent neural network (RNN-PCC) is developed and proposed. The proposed RNN-PCC relies on the identification of the SynRM currents without considering any parameters. Simulation and experimental results show that both RNN-PCC and MB-PCC have similarly excellent dynamics, while better control performance and tracking errors can be achieved thanks to the proposed RNN-PCC. [ABSTRACT FROM AUTHOR]

Due to the significant advantages of a high torque density, better fault tolerance and high efficiency, the combined star–pentagon winding has recently gained researchers' interest. In this paper, a simple method to identify the sequence of phases of a five-phase machine with combined star–pentagon winding was proposed. This was accomplished using resistance measurements between adjacent and non-adjacent phases. The analysis was conducted to clarify the phase sequence identification method. A case study of a 5.5 kW five-phase synchronous reluctance motor with combined star–pentagon winding was considered to simply apply the proposed method using an LCR meter for resistance measurements. The parasitic and wire resistances are dominant in the studied case, and this did not influence the accuracy of this method. [ABSTRACT FROM AUTHOR]

Power generation for renewable energy sources increased rapidly during last few years. Similarly, the high gain dc–dc boost choppers are taking place of conventional power converters used for photovoltaic (PV) appliances. Researchers are developing different methods in order to provide high voltage gain, low ripple, reduced switch stress, low converter costs, and minimized variations of PV operating points. This study proposes a two-stage converter for a freestanding water pumping motor drive power by solar PV system. According to the proposed system, at first, a high gain (HG) cell and a DC-to-DC boost converter are combined to increase the PV voltage to high levels. Later on, the resulting dc voltage feds a three-phase synchronous reluctance motor drive that operates centrifugal pump load. The perturb and observe approach is utilized to get the maximum power out of the solar PV module. Moreover, indirect field-oriented control is implemented to accomplish smooth starting of synchronous reluctance motor. In order to validate the effectiveness of proposed technique, a MATLAB/Simulink environment-based simulation setup along with an experimental prototype is developed. Additionally, various cases are considered based on different operating conditions and irradiance levels to collect and analyse the results. [ABSTRACT FROM AUTHOR]

This article presents the control of solar photovoltaic (PV) battery-fed reluctance synchronous motor drive for light electric vehicle. The system performance is evaluated based on the Indian driving cycle (IDC). This system uses a bidirectional dc–dc converter for regulating battery power for different operating conditions as per IDC. For augmenting the performance of the battery, a rooftop solar-PV panel is installed with a dc–dc boost converter for maximum power point tracking. The reluctance synchronous motor drive is operated using three-phase voltage inverter with hysteresis current control and energy regeneration of the stored kinetic energy of the system. The speed and position of the reluctance synchronous motor drive are also estimated using flux linkages, which makes this system cost effective. The reluctance synchronous motor drive is simulated in MATLAB/Simulink for dynamic and steady-state conditions of the vehicle. The system's applicability and performance are validated by test results recorded on a laboratory-developed experimental setup in detail. [ABSTRACT FROM AUTHOR]

In this article, a method for topology optimization (TO) of a synchronous reluctance motor (SynRM) is proposed using deep reinforcement learning (RL). Due to the need for simulating a large number of finite-element models in a traditional TO task, incorporating a study involving a different problem formulation (such as a varying design domain) can be an overwhelming task. A neural network (NN)-based agent trained using an RL formulation is able to extend the knowledge from one TO design problem to other similar TO tasks. The applicability of such learning is performed using a sequence-based TO environment. It is observed that such an approach not only reduces the computation required for TO, but also introduces the capability to generalize RL to unseen TO scenarios. The proposed optimization method reduces computation time by 70%–90% when compared to a genetic algorithm-based implementation. [ABSTRACT FROM AUTHOR]

This article proposes a hybrid analytical modeling procedure for the performance parameter estimation of synchronous reluctance machine, including its operation in the region of magnetic saturation. The proposed model better estimated the torque profile through improved translation and stepped transition of rotor flux barriers. The non-linear operation is simulated by considering the global saturation and estimating the machine’s operating point on the magnetization curve of the core material. The procedure formulation focuses on improving the accuracy and rapidness of the iterative design process. The obtained results are validated against an already established design analysis technique, finite-element analysis, and the frequency spectrum analysis of practical machine results. With the improved accuracy and the least requirement of simulation runtime and computational resources, the modeling procedure can be utilized as an initial design iteration tool. [ABSTRACT FROM AUTHOR]

The transient and dynamic performance analysis of a proposed line-start, three-phase concentrated dual-winding synchronous reluctance motor (cDWSynRM) in comparison with the conventional concentrated winding synchronous reluctance motor (cSynRM) was presented. Both windings are overlapping windings. The cDWSynRM consist of main and auxiliary windings with capacitive assistance for power factor improvement. The modelling of the synchronous reluctance motors (SynRM) was done in direct-phase variables considering only the fundamental magneto-motive force (MMF). The machine inductances of both machine models were determined using winding function theory (WFT). These derived inductances were used to determine machine performance characteristics such as Torque, Speed, Phase currents etc. The performance characteristics of both motors were monitored using MATLAB/Simulink, and the proposed line-start cDWSynRM with capacitive assistance was observed to have improved performance characteristics when compared to the cSynRM [ABSTRACT FROM AUTHOR]

To meet the new international efficiency (IE) standards, line-start (LS) synchronous reluctance motors (SyRMs) are now being considered. Conventional star and delta windings are usually employed in LS SyRMs. However, combined star-delta winding has higher winding factor and lower magneto-motive force (mmf) harmonics compared to conventional star and delta windings. Hence, in this paper, LS SyRM and LS ferrite assisted SyRM with star and star-delta winding are analyzed and their performance indices are compared. A winding function analysis is used for the design of star and star-delta windings. Further, the effect of zero sequence current on the performance of the motors under comparison is presented in detail. Star and star-delta winding prototype LS SyRMs with and without ferrite magnets in the rotor are fabricated. Experimental studies are carried-out on these prototypes and the results are presented which are in close agreement with the simulation results. [ABSTRACT FROM AUTHOR]

Synchronous reluctance motors (SynRMs) with four layers of flux barriers are currently in practical use as high-efficiency motors for industrial applications. While SynRMs have higher efficiency than induction motors, they have a high torque ripple. In this study, an asymmetric rotor structure was designed to reduce the torque ripple of the four-layer SynRM, considering the mechanical strength. Two rotor structures with different flux barrier angles were combined in the stacking direction, and the ratio of the combination was optimized by finite element analysis. In addition, prototypes of the initial structure and proposed asymmetric structure were manufactured, and their torque and efficiency characteristics were measured. The experimental results show that the proposed asymmetric structure can reduce the torque ripple while maintaining the basic characteristics such as average torque and efficiency. [ABSTRACT FROM AUTHOR]

This article reviews the state-of-the-art back electromotive force (EMF) based sensorless schemes for synchronous machines. Field-oriented control (FOC) of a synchronous machine requires real-time rotor position for decoupled torque and flux control. Extraction of rotor position without a sensor or sensorless control has been an enabling technology for the past few decades. Sensorless control using back EMF voltage induced by rotor movement is the most widely used method. However, the connections and differences between different methods have not been thoroughly investigated and documented. This article first reviews basic sensorless methods. The two implementation forms of an observer are examined to facilitate analysis. A detailed analysis puts in evidence the connections behind different methods in both stationary and synchronous reference frames. A summary is drawn that is meant to offer a few key points regarding different sensorless methods. Finally, a conclusion is given to summarize the major contributions of this article. [ABSTRACT FROM AUTHOR]

Dual three–phase synchronous reluctance motors (DTP–SynRM) have the advantages of simple structure, high power density, fast dynamic response, and small torque ripple, and have broad application prospects in flywheel batteries. However, the synchronous reluctance motor has no permanent magnet, and the inductance value will change with the current change in actual operation. Direct torque control (DTC) is more suitable for the control strategy of dual three–phase synchronous reluctance motors because of its low dependence on motor parameters. However, traditional direct torque control uses a large vector control motor within one control period, which can not suppress the inherent 5th and 7th current harmonics in the motor. A new harmonic suppression method is proposed in this paper: that is, using a low harmonic vector to replace a large vector in traditional direct torque control, which can be synthesized by adjusting the action time and order of three adjacent large vectors within one control period. Through this improvement, torque control can have a harmonic suppression effect. The three vector synthesis method can make full use of the existing space voltage vector, and to adapt to different working conditions, two synthesis methods of switching frequency reduction and constant torque response are proposed. An improved direct torque control strategy is obtained by optimizing the design of the switch table using a new vector synthesis method. Finally, the suppression effect of traditional DTC and improved DTC on current harmonics is compared and analyzed. The results show that the direct torque control with low harmonic vector can suppress the harmonic current in x–y subspace, and the current harmonic content is greatly reduced. [ABSTRACT FROM AUTHOR]