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The segmental translator linear switched reluctance motor (STLSRM) is a special type of linear switched reluctance motor (LSRM) that has more output power than its conventional type. Therefore, it can be a good choice for certain applications. Heat is one of the factors limiting the output in machines. Therefore, predicting the thermal distribution of machine is as important as the magnetic design. A comprehensive thermal model is presented based on the lumped parameter approach for STLSRM, which predicts temperature distribution in different parts of this motor, including slot winding, end‐winding, stator pole, stator yoke, and the moving part. Considering that the proposed thermal model depends on dimensions and materials used in machine, it can be used for other designs of the STLSRM. The presented thermal model is applied to a typical STLSRM and temperature is determined in its different parts. The simulation results are then compared with the results of 3‐D thermal modelling based on the finite element method (FEM) for validation. [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 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]

This study elaborates upon a new modular split‐tooth permanent magnet‐assisted switched reluctance motor (MSTPM‐SRM). In the proposed topology, the stator comprises six modular E‐cores in which the middle poles are split into two teeth. Two permanent magnets (PMs) are placed between each module's middle and side poles. Primarily, the proposed topology is introduced. Next, the principle of operation of the proposed topology are elucidated, and the magnetic equivalent circuit analysis is adopted in order to validate the operational basics. It is proved that the embedded PMs significantly increase the air‐gap's flux density and adjusts the poles' flux density. The flux density distributions, static, and steady‐state characteristics of the proposed MSTPM‐SRM motor and its PMless counterpart are extracted by utilising 2‐D finite element analysis. It is illustrated that the average torque of the proposed MSTPM‐SRM is dramatically increased compared to its PMless counterpart, especially at high excitation currents. Furthermore, the cogging torque analysis is done and it is shown that the proposed structure has approximately zero cogging torque. Finally, a prototyping version of the proposed motor is fabricated, and the experimental results are elicited. It is shown that the experimental results endorse the simulation results. [ABSTRACT FROM AUTHOR]

Purpose: More electric aircraft (MEA) is defined as the extensive usage of electric power in aircraft. The demand for electric power in new generation aircraft rises due to environmental and economic considerations. Hence, efficient and reliable starter/generators (SGs) are trending nowadays. The conventional main engine starting system and power generation system can be replaced with an individual SG. The constraints of the SG should be investigated to handle the aviation requirements. Even though the SG is basically an electric machine, it requires a multidisciplinary study consisting of electromagnetic, thermal and mechanical works to cope with aviation demands. This study aims to review conventional and new-generation aircraft SGs from the perspective of electric drive applications. Design/methodology/approach: First of all, the importance of the MEA concept has been briefly explained. Also, the historical development and the need for higher electrical power in aircraft have been indicated quantitatively. Considering aviation requirements, the candidate electrical machines for aircraft SG have been determined by the method of scoring. Those machines are compared over 14 criteria, and the most predominant of them are specified as efficiency, power density, rotor thermal tolerance, high-speed capability and machine complexity. The features of the most suitable electrical machine are pointed out with data gathered from empirical studies. Finally, the trending technologies related to efficient SG design have been explained with numeric datasets. Findings: The induction motor, switched reluctance motor and permanent magnet synchronous motor (PMSM) are selected as the candidate machines for SGs. It has been seen that the PMSM is the most preferable machine type due to its efficient operation in a wide range of constant power and speed. It is computationally proven that the using amorphous magnetic alloys in SG cores increases the machine efficiency more. Also, the benefits of high voltage direct current (HVDC) use in aircraft have been explained by a comparison of different aircraft power generation standards. It is concluded that the HVDC use in aircraft decreases total cable weight and increases aircraft operation efficiency. The thermal and mechanical tolerance of the SG is also vital. It has been stated that the liquid cooling techniques are suitable for SGs. Originality/value: The demand for electrical power in new generation aircraft is increasing. The SG can be used effectively and efficiently instead of conventional systems. To define requirements, constraints and suggestions, this study investigates the SGs from the perspective of electric drive applications. [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]

The development of dual phase soft magnetic laminate for advanced electric machines at General Electric is summarized, including alloy development, properties, manufacturing trials, prototype experience, potential applications, and future material development. Dual phase soft magnetic laminates provide the flexibility to tune magnetic/non-magnetic state at the desired locations, using solution nitriding treatment with protective mask/coating. This enabling material technology benefits electric machine performance by reducing flux leakage in the laminates. It also decouples the electromagnetic and mechanical design, which opens up the design space for advanced electric machines. Magnetic and mechanical properties of dual phase laminates were compared to commercial FeSi and FeCo soft magnetic laminates. Driven by the market needs for high power density and high-speed electric machines, a synchronous reluctance (SynRel) machine without PMs using dual phase soft magnetic laminates was assessed in machine electromagnetic performance as well as rotor stress analysis by finite element simulation. Successful prototype build and testing further retired manufacturing risks and advanced the technology maturity level. Future material development with higher mechanical strength, higher saturation magnetization, higher permeability, and lower loss are highly desired for ground and air transportation electrification. [ABSTRACT FROM AUTHOR]

In this paper, an analysis of the properties of a switched reluctance motor (SRM) 8/6 in an extended constant power range is presented. The typical constant power range to constant torque range ratio is between 2 and 3. In the case of machines designed as an electric vehicle drive, it is important to maximize this ratio. In the case of an SRM, it is possible to achieve this by applying an appropriate control strategy. An analysis of the SRM operation utilizing a modified control algorithm allows control of the maximum value of the motor phase current. As a consequence, using the so-called nonzero initial conditions for the current and flux allows the output power to be maintained in a wide speed range. For the improvement of drive system efficiency, the work of the phase current regulator should be limited to a minimum. The most advantageous work conditions we obtain with single-time current regulator work. Laboratory verification has been performed for selected states of motor work. [ABSTRACT FROM AUTHOR]

In this article, we deal with design considerations of a new ac hybrid-excitation permanent-magnet machine with axial stator. Due to the presence of an axial stator, the machine features a typical three-dimensional geometric structure and field distribution. A simplified reluctance-based network is developed to capture the main design features of the machine. The analytical equations are deduced relating the main geometric dimensions to the machine design criteria: speed, power, and flux regulation capability. The influence of key machine geometric parameters, i.e., radial/axial air-gap length, stack length, and bore diameter, on output power, flux density, and flux regulation capability is investigated. It is found that there is a design tradeoff between the machine power density and flux regulation capability. The d/q-axis inductance and its ratio, which has an influence on flux weakening capability and operation performance, is examined. Finally, a 6-pole/36-slot prototype is built. Intensive experimental tests are carried out to verify the machine characteristics. [ABSTRACT FROM AUTHOR]

Summary: Predictive control of stator currents is a model‐based technique needing an estimation of rotor currents, which are normally not measured. These currents affect the evolution of the stator currents and, therefore, also affect the predictions used by the controller. The usual procedure consists in correcting their effect by a simple feedback technique. In this article, the estimation of rotor currents is tackled based in the induction machine equivalent circuit. The proposed estimation procedure aims at improving the predictions with respect to the usual procedure. Simulation and experimental results are provided for the particularly demanding case of a multi‐phase induction machine, showing the superiority of the proposal. [ABSTRACT FROM AUTHOR]

Slotting effect in electric machines reduces flux per pole that effect magnetic flux density distribution in the air gap which induces harmonics in magnetic flux density causing flux pulsation, that in turn generates dominant torque pulsation in the form of cogging torque and torque ripples. To overcome the abovesaid demerits, a novel outer rotor field-excited flux-switching machine (OR-FSFSM) with a combined semi-closed and open slots stator is proposed in this study. The developed OR-FEFSM offers a high-power factor, due to the utilization of the semi-closed slot for armature coils. The open slot stator structure was chosen for the field excitation coil, which effectively suppresses leakage reluctance that causes flux pulsation. Thus, the influence of torque ripples is reduced, and the average torque is improved. In order to investigate the effectiveness of the proposed OR-FEFSM, a detailed study of stator slot and rotor pole combinations are performed. Based on simplified mathematical formulation, 12S/7P (stator slot/rotor poles), 12S/11P, 12S/13P, and 12S/17P are the most feasible combinations. Finite Element Analysis (FEA) based on comprehensive electromagnetic performance is performed on each combination, and found that 12S/13P offers the highest average torque of 4.62 Nm, whereas 3.72 Nm, 2.72Nm, and 1.68 Nm average torque is offered by 12S/17P, 12S/7P, and 12S/11P, respectively. Based on the initial analysis, 12S/13P was considered for further analysis and optimized using JMAG built-in Genetic Algorithm (GA). Moreover, thermal analysis was performed, and the proposed design was compared with the conventional design. [ABSTRACT FROM AUTHOR]

The energy-efficiency indicators of a direct-on-line synchronous reluctance motor with a power rating of 4 kW are compared with a motor with rare-earth permanent magnets on the rotor, as well as with an IE3 energy efficiency class induction motor. The permanent magnet motor provides slightly greater energy savings; however, unlike the synchronous reluctance motor, it has a long payback period due to its high cost associated with the use of expensive rare earth magnets. In [[10]], for electric vehicles, a novel design of an SRM with twelve stator teeth and eight rotor teeth without permanent magnets is proposed. [Extracted from the article]

This article illustrates a method for sensorless control of a switched reluctance motor. The detection of the time instants for switching between the working phases is determined based on the evaluation of the switching frequency of the hysteresis current controllers for appropriately selected sensing phases. This enables a simple and cost efficient implementation. The method is compared with a pulse injection method in terms of efficiency and resolution. [ABSTRACT FROM AUTHOR]

Asymmetric interior permanent magnet (AIPM) rotor topologies can achieve torque enhancement in IPM synchronous machines without the increase of PM usage due to utilizing magnetic-field-shifting (MFS) effect by reducing the current angle difference between maximum PM and reluctance torque components. This paper investigates the influence of armature reaction on MFS effect in AIPM machines. A general model of IPM machines considering MFS effect is analytically developed and the AIPM and IPM machines using the same stator, rotor diameter and total PM amount are comparatively studied. It shows that the armature reaction affects the MFS effect in both AIPM and IPM machines and the influence is more significant in AIPM machine. The relationships between MFS effects in PM flux-linkage and inductance characteristics and current angles for maximum PM and reluctance torque components are revealed. It confirms that the change of current angles of torque components is due to the MFS effect in PM flux-linkage and inductance characteristics in both AIPM and IPM machines. Besides, the developed machine model considering MFS effect is verified by finite element analysis. Finally, a small-scale AIPM machine prototype is fabricated and measured to validate the finite element analysis. [ABSTRACT FROM AUTHOR]

The torque ripple of a switched reluctance motor (SRM) should be taken into account, as it can have negative effects on a connected gearbox and/or load. In this paper a concept and two realization methods for the reduction of the torque ripple are presented. An optimized alignment of the active elements of the stator leads to a reduction of this torque ripple. The first method proposed here is a four-fold segmented motor, which can reduce the torque ripple by 37.3 %. This can be achieved by segmentation in combination with a clever arrangement of active elements. However, this increases the number of necessary inverters, which increases redundancy and therefore leads to more security. A second method of achieving an equal reduction can be obtained by using a “double stator” motor. In this configuration both stators can be powered together. With this concept, the number of converters is halved compared to the first mentioned solution. This saves electronic components and thus reduces the effort. All results referred to in this article are obtained by simulation, or measured on a prototype. [ABSTRACT FROM AUTHOR]

This article presents the application of model predictive control (MPC) in high-performance drives. A wide variety of machines have been considered: Induction machines, synchronous machines, linear motors, switched reluctance motors, and multiphase machines. The control of these machines has been done by introducing minor and easy-to-understand modifications to the basic predictive control concept, showing the high flexibility and simplicity of the strategy. The second part of the article is dedicated to the performance comparison of MPC with classical control techniques such as field-oriented control and direct torque control. The comparison considers the dynamic behavior of the drive and steady-state performance metrics, such as inverter losses, current distortion in the motor, and acoustic noise. The main conclusion is that MPC is very competitive concerning classic control methods by reducing the inverter losses and the current distortion with comparable acoustic noise. [ABSTRACT FROM AUTHOR]

In this paper, an analysis of noise and vibration of a synchronous reluctance machine for EV applications is performed. The analyzed machine was designed for electric vehicle application. The noise and vibration of a synchronous reluctance machine were first estimated during simulations; next, the obtained results were validated during laboratory tests. The analyzed model of the machine was simplified and included only stator core as it was assumed to be the main source of the machine vibration and generated noise. To simulate the noise and vibration of the machine, multiphysics modeling of the machine was performed. Laboratory tests proved the correctness of performed simulations. The obtained results allowed us to investigate the influence of the machine's operating point on the generated noise and vibration. The frequency of the magnetic radial forces were proven to be the dominant factor in noise generation. The influence of the load and current angle on the machine's noise and vibration was proven to be negligible. It was also proven that considering only the stator structure in numerical analysis of the noise and vibration of the machine leads to valuable results. [ABSTRACT FROM AUTHOR]

SRM is one of the most attractive electric machines to be used as a S/G in the future MEA thanks to its special physical characteristics that facilitate its direct coupling to the propulsive unit; however, the controllability of the SRG at different operational points, imposed by the specific application, is critical. In this article, a novel active power control scheme which uses a vector-controlled SAF is proposed, in order to efficiently drive the SRG in a wide set point range. Considering the highly non-linearity of the SRM operational behavior, an adaptive phases’ magnetization regulation is applied, aiming at taking full advantage of the SRG's energy production capability, in compliance with the MEA power system specifications and limitations. The mathematical analysis is verified through simulation results, while the SRG concept under study is validated via a RT CHIL implementation. [ABSTRACT FROM AUTHOR]

Characterization modules in electric machines and drives design optimization environments typically involve the use of electromagnetic finite element-state space models that require large number of iterations and computational time. It is shown in this work that the utilization of a Taguchi orthogonal arrays method in conjunction with a particle swarm optimization (PSO), search algorithm in a design optimization case study of a synchronous reluctance motor (SynRM) drive, resulted in about 80% reduction of computational time. [ABSTRACT FROM AUTHOR]

Many electric traction drive systems (ETDSs) are driven by electric motors primarily composed of high-energy rare-earth (RE) permanent magnets (PMs), such as neodymium–iron–boron (NdFeB) and samarium–cobalt (SmCo). Given the high cost of RE materials, there is a great interest among various industry sectors in searching for breakthrough technologies that reduce the consumption of high-energy RE magnets in their electromechanical energy conversion systems. The reduction of the magnetic volume is typically realized either by replacing a portion of the high-energy RE magnet with the low-energy ferrite magnet (knows as hybrid structure) or by modifying the magnetic arrangement of the machine itself, where a portion of the physical RE magnets is removed and replaced by induced magnets (known as consequent-magnetic pole structure). For this purpose, this article presents a review of the current state-of-the-art motor typologies with less-RE PMs and their key design challenges, followed up by a series of recommended guidelines to overcome related design challenges. [ABSTRACT FROM AUTHOR]

The belt-driven starter/generator (BSG), as a cost-effective solution, has been widely employed in hybrid electric vehicles (HEVs) to improve the stability and reduce the fuel consumption of the vehicles. It can provide more than 10% reduction in CO2. Electrical machine is the heart of the BSG system, which is functioned both as motor and generator. In order to optimize both aspects of motor and generator simultaneously, this paper presents a new multimode optimization method for the switched reluctance machines. First, the general multimode concept and optimization method are presented. The switched reluctance motor and the switched reluctance generator are the two operation modes. The optimization models are established based on motor and generator functions. Sensitivity analysis, surrogate models and genetic algorithms are employed to improve the efficiency of the multimode optimization. Then, a design example of a segmented-rotor switched reluctance machine (SSRM) is investigated. Seven design variables and four driving modes are considered in the multiobjective optimization model. The Kriging model is employed to approximate the finite element model (FEM) in the optimization. Finally, the optimization results are depicted, and an optimal solution is selected. The comparison between the initial and optimal designs shows that the proposed method can improve the foremost performance of the SSRM under all driving modes. [ABSTRACT FROM AUTHOR]

A variable reluctance electric machine with a two-degree of freedom rotor motion characterized by rotation around the center of the rotor and orbiting around the center of the stator is studied. One motivation for adopting such rotor motion would be to allow torque generation through both the radial and tangential components of the electromagnetic forces created in the airgap, as opposed to common rotary machines in which torque is a byproduct of only the tangential component of the airgap electromagnetic forces. Furthermore, the rotor motion provides a built-in gearing action similar to that of a cycloidal drive, which allows natural torque multiplication and the tight integration of the electromagnetic and mechanical systems. The two-degree of freedom rotor motion also results in a counter-intuitive inertia characteristic of this machine concept which is elaborated in this paper for the first time. Due to the reluctance nature of the torque, and because of the distinctive rotor motion profile which resembles the motion of a cycloid, the studied machine is called a cycloidal reluctance (CR) electric machine (CRM). In this paper, the principle of operation of the CRM is explained, and its performance is compared to a counterpart switched reluctance machine (SRM). A prototype is built, and the theoretical torque calculations are validated by experimental measurements. [ABSTRACT FROM AUTHOR]

Five-phase machine employment in electric drive system is expanding rapidly in many applications due to several advantages that they present when compared with their three-phase complements. Synchronous reluctance machines(SynRM) are considered as a proposed alternative to permanent magnet machine in the automotive industry because the volatilities in the permanent magnet price, and a proposed alternative for induction motor because they have no field excitation windings in the rotor, SyRM rely on high reluctance torque thus no needing for magnetic material in the structure of rotor. This paper presents dynamic simulation of five phase synchronous reluctance motor fed by five phase voltage source inverter based on mathematical modeling. Sinusoidal pulse width modulation (SPWM) technique is used to generate the pulses for inverter. The theory of reference frame has been used to transform five-phase SynRM voltage equations for simplicity and in order to eliminate the angular dependency of the inductances. The torque in terms of phase currents is then attained using the known magnetic co-energy method, then the results obtained are typical. [ABSTRACT FROM AUTHOR]

With growing interest in electrification in automotive industries, the selection of suitable electric machine types based on application requirements is most important. In this article, three electric machine types, axial flux machine, interior permanent magnet (IPM) machine, and switched reluctance machine, are compared systematically to find the best candidate to drive engine accessories in a hybrid truck. These machine types are designed and optimized to meet the application-oriented design requirements and constraints. An extensive Pugh matrix is created where each machine type is scored based on efficiency range, cost, volumetric power density, gravimetric power density, acoustic noise and stress on the rotor, fault tolerance, heat rejection, and manufacturability. Each Pugh matrix component is assigned to a priority-based weighting, based on the application demand, to determine an accumulated score for each machine topology. A full-scale prototype of the best performing machine type is built and tested. Experimental results validate the multiphysics conclusions drawn in the work. [ABSTRACT FROM AUTHOR]

Multiobjective and multiload point design optimization of an interior permanent magnet (IPM) synchronous machine using a global response surface method to achieve low torque ripple with high average torque over the entire speed range is presented in this article. The approach consisting of a set of design steps and multiobjective optimization to obtain high-performance electric machines with optimum usage of rare-earth materials for mass production is presented. The design optimization has been applied to a 12-slot eight-pole IPM machine with two different rotor structures to arrive at the optimized design for a variable-speed high-performance application. Motor parameters are extracted under different load conditions to predict the torque/speed performance of the motors. The proposed design approach provides a machine design with maximized output torque, improved torque density, lower torque ripple, and optimum usage of rare-earth materials. Finally, the finite-element-based modeling results are validated with the experimental results. [ABSTRACT FROM AUTHOR]

Interturn short-circuit fault, also known as turn fault, is a common fault in electric machines, which can cause severe damages if no prompt detection and mitigation are conducted. This article proposes a turn fault detection method for permanent magnet machines based on current residual. After the impact of the turn fault is first analyzed on a simplified mathematical machine model to assess the fault signature, a finite-element model is developed to obtain healthy machine behavior. The residual between the measured and estimated currents by the model with the same applied voltages contains mainly the fault features. The quality of the fault detection can be improved because the fault signatures are enhanced, and the impact of the current controller bandwidth on fault signature is minimized. The dc components in the negative-sequence current residuals are extracted through angular integration, and their magnitude is defined as the fault indicator. The robustness of the fault detection against transient states is achieved. The effectiveness of the proposed method is validated on a triple redundant fault-tolerant permanent-magnet-assisted synchronous reluctance machine. [ABSTRACT FROM AUTHOR]

An interturn short-circuit fault in the stator winding of an electric machine, denoted as turn fault, has been recognized as one of the most severe faults in permanent magnet machines, which require a swift and reliable detection, in order to implement appropriate mitigations. The asymmetry brought by a turn fault is widely used for fault detection. However, similar features also emerge in a less severe high-resistance connection (HRC) fault, which may lead to an incorrect fault identification. In this article, a more exclusive turn fault detection method with the ability to differentiate from the HRC fault is proposed. It injects high-frequency square-wave voltage signals and makes use of the difference in the high-frequency impedance under the two fault conditions. The sensitivity to the HRC fault is largely reduced. The proposed turn fault indicator is independent of the operating conditions and robust with respect to state transients. This method is validated in a fault-tolerant permanent magnet assisted synchronous reluctance machine drive. [ABSTRACT FROM AUTHOR]

Limitation in manufacturing tolerances and assembly imperfections are the source of asymmetrical stator axes (ASA) defect, in particular, in a vacuum dry pumps (VDP) where the canned permanent magnet machines (CPMMs) are with fractional slot concentrated winding (FSCW). The performance and multi-physical field of CPMM in the vacuum environment is vulnerable to ASA. This work provides comprehensive research on the influence of ASA on the performance and multi-physical field of CPMM for VDP. This article establishes a mathematical model and Park transformation of a 1.6kW 6-pole/9-slot CPMM under the ASA condition. With the universality of ASA and not so strictly symmetrical stator axes as commonly expected, the experimental results demonstrated the significant impacts of ASA on the drive performance and multi-physical field, especially the inductance characteristics, the symmetry degree of stator current and flux linkage, rotor electromagnetic force and stator electromagnetic vibration of CPMM. The obtained conclusions can act as a significant reference for robust design and analysis of electric machines and drives. [ABSTRACT FROM AUTHOR]

Optimal design of electric machines, having complex 3-D magnetic flux path, such as transverse flux or axial flux motors, is computationally demanding owing to the unavailability of a fast 2-D finite-element method (FEM), which leads to the indispensable use of costly 3-D FEM models. With multiobjectives and large design parameter vector, this task is further exacerbated. To accelerate the design procedure, unlike conventional methods, this article proposes the use of two information sources, an expensive but accurate high-fidelity 3-D-FEM model and a fast but inaccurate low-fidelity 2-D-equivalent FEM model to exploit corresponding opposite merits of each and construct a multifidelity surrogate model (response surface) with minimum number of expensive 3-D-FEM simulations. The low-fidelity 2-D model, which intrinsically does not exist for such machines, is generated by ensuring equal magnetic reluctance along main magnetic path despite deformation of model's geometry. The proposed methodology is applied to optimize a novel magnetically levitated transverse flux permanent magnet linear synchronous motor, considering suspension characteristics (lateral and normal stiffnesses) along with thrust as objectives and a seven parameter design vector. Results show significant design time-saving without compromising surrogate accuracy. The optimized design is fabricated and relevant experimental measurements are taken. [ABSTRACT FROM AUTHOR]

In this article, a simplified 3D magneto-thermal model to study the temperature distribution over the housing of a Switched Reluctance Machine (SRM) is proposed. The main objective of such model is to study the temperature distribution profile on the body of the machine under various working conditions in order to introduce a temperature based signature to develop condition monitoring procedures. The analysis of fluid flow and heat transfer inside the SRM supports the hypothesis that the effect of turbulent flow of the fluid and the complex heat transfer phenomenon of the rotating parts can be simplified to a heat flux boundary condition representation of the heat loss. The accuracy of the model is validated through simulation and experimental results on a prototype SRM. The developed simplified model can be used as for prediction of temperature profile on SRM surface, well suited for fault diagnosis in SRM. The proposed methodology can be modified applied in developing a thermal model for other types of electric machines. [ABSTRACT FROM AUTHOR]

A parametric analysis is carried out to investigate the dependence of the rotor iron losses on the stator and rotor geometry of several synchronous reluctance machines. Six four-pole rotors have been designed with different flux barriers per pole through a multiobjective differential evolution algorithm coupled to a finite-element analysis (FEA). Two different stators with 24 and 36 slots are considered. During the optimizations, a rapid finite-element evaluation has been used to predict the performance of the motors. After that, an accurate time stepping FEA is used for computation of the rotor iron losses. Finally, the interaction between the rotor iron losses and several rotor and stator geometrical parameters is highlighted. The effect of the current time harmonics have also been taken into account, weighting its impact on the rotor losses. [ABSTRACT FROM AUTHOR]

The growth of electric and hybrid electric vehicles has drawn more attention toward the development of high power density electrical machines. The materials used in the fabrication of electrical machines play a crucial role in enhancing their power density. In this paper, the significance of advanced magnetic materials for lamination, nano-material based conducting materials, and high energy product permanent magnets (PMs) is discussed in detail. Finally, a case study has been presented with a 5 kW PM synchronous machine in order to understand the advantages of the discussed materials. [ABSTRACT FROM AUTHOR]

The Double-sided Linear Switched Reluctance Machine (DLSRM) suffers from complex eccentricities in practical operations. A novel sensorless control method for a DLSRM with eccentricities is developed in this paper. The influences of eccentricities on the machine inductance characteristics and the estimated positions in sensorless control systems are discussed. A new position index, which is independent of eccentricities, is proposed according to an analysis of a DLSRM equivalent magnetic circuit. On the basis of this position index, the starting and low-velocity operation of eccentric DLSRMs are achieved. Experimental results obtained in the laboratory validate the proposed method. [ABSTRACT FROM AUTHOR]

Momentary power disruptions commonly occur in many industrial settings, and can trip large electric machines, which must then be brought to zero speed before the machine can be restarted. The resulting frequent interruptions in industrial processes can have negative effects on productivity. A restart algorithm brings the machine back to the original speed as soon as power is restored, without waiting for the machine to reach zero speed. This paper proposes an approach for implementing a restart algorithm for synchronous reluctance machines (SynRMs) that use a simple identification algorithm to determine the speed and position of the machine so that the appropriate voltage vector can be applied, thus minimizing the inrush current during the restart. The proposed method only requires nameplate machine parameters and needs no machine-specific tuning, making the approach suitable for implementation with both high-inertia vector and scalar-controlled SynRM. [ABSTRACT FROM AUTHOR]

A novel 8/10 two-phase switched reluctance motor is proposed. Thanks to this unique design, the flux paths are shortened, resulting in lower magnetomotive force requirements. There is no negative torque, bringing a higher total torque. The space is more effectively utilized to provide a higher torque density. Flux reversals in the iron cores are reduced, causing a significantly lower loss. The associated conceptual diagrams, optimized design procedures, detailed flux study, and loss analysis are presented. The proposed motor is compared with two existing 9/12 and 6/10 switched reluctance motor in terms of topology advantages, peak and average torques, torque density, core losses, etc. Moreover, a new efficiency index is introduced to more reasonably perform comparisons. Furthermore, finite element method is employed in the investigations. Finally, the motor is prototyped whose experimental results including torque-angle measurements and open-loop control confirm the novelty and superiorities of the proposed motor over the existing ones. [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]

Proliferation of electronics is a major breakthrough in the industrial sector as these play a promising role in the functioning of electric machines and together described as an electric drive. In this regard, the important factor is the efficiency of the electric drive. Based on this aspect, many electric machines have been invented and among all those machines switched reluctance motor (SRM) has found to be more beneficial because of its reduced losses. This paper presents different unconventional converters which are helpful for the functioning of low power SRM drives. Three different converters along with simulation results are presented and based upon the results of the three converters, the efficient converter for low power SRM drives is chosen for the hardware development. Experimental tests and simulations have shown the proposed converter results are closely correlated with the simulated results. [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]

Synchronous reluctance machines are very appealing for high-speed traction applications due to their robustness, simple structure, absence of magnets, and simple control. The absence of magnets means that synchronous reluctance machines are not susceptible to price variability and sustainability of rare-earth materials. Also, there are no concerns about demagnetization or uncontrolled generation mode. However, the challenge of achieving a good constant power to speed ratio is dependent on the mechanical aspects of the design. Conventional synchronous reluctance designs perform poorly compared to permanent magnet machines due to the presence of bridges and/or center posts that provide a path for performance-robbing leakage flux and the absence of permanent magnets that help saturate the bridges and/or center posts. Elimination or reduction of these features presents a challenge for rotor mechanical retention due to the reduction in radial stiffness that these members provide mainly for high-speed applications. A carbon-fiber sleeve on the rotor will provide the needed mechanical strength to enable a reduction of bridges and/or center posts. This paper will present the design details, analysis, manufacturing, and test results of a proof-of-concept carbon-fiber-wrapped synchronous reluctance machine targeting traction applications. [ABSTRACT FROM AUTHOR]

Estimation of dimension parameters for an electric machine has great importance before assembling on production line. As a matter of fact, researchers should find optimum solution once they decide to perform analytical design of an electric machine. In this study, we have tried to find dimensional and electrical parameters via derived mathematical equations for in-wheel switched reluctance motor (IW-SRM), and the motor has been manufactured. Moreover, an experimental setup is designed, and the speed and torque control of IW-SRM is carried out. The motor tests including both standstill and running test are performed by using the experimental setup. Initial size parameters are intuitively provided as motor analysis is conducted by software package. Then, numerous trials are examined to get optimum results. In fact, this motor is employed by an electric vehicle whose design is ongoing. Therefore, optimum motor parameters for required base speed and torque have been estimated by solving generated equations for IW-SRM with 18/12 poles via MATLAB. Considering parameters estimated, analysis of IW-SRM has been performed by Ansoft Maxwell 15.0 Software Package based on 3D finite element method (3D-FEM). Consequently, the estimated parameters have been validated by the results of Maxwell 3D FEM. Experimental results of the motor manufactured are obtained via the motor driver designed; also have been validated by Maxwell 3D. [ABSTRACT FROM AUTHOR]

This paper presents a nonlinear analytical model of a multi-V-shape interior permanent magnet (IPM) motor with nonoverlapping concentrated winding. The model relies on Ampere's theorem and the flux conservation law in order to compute the flux density in the different parts of the motor. This article proposes a saturated analytical model of the stator and the rotor. The analytical model is used to calculate the average torque, the power factor, and the voltage of the motor. It is five times faster than the 2-D finite element analysis (FEA). The results are compared with 2-D FEA simulations and experimentally validated using a prototype motor. [ABSTRACT FROM PUBLISHER]

A concept of general flux-modulated electric machines is introduced in this paper, which is based on a proposed unified theory for such types of machines. It can explain the operating principles of a basic flux-modulated motor, a flux-switching motor, a vernier motor, and a dual-permanent-magnet (PM)-excited motor with PMs on both rotor and stator. Based on the proposed theory, a novel doubly-fed dual-stator (DFDS) motor is presented. Finite-element method of magnetic field with mechanical motion coupled computation is employed to evaluate the performances of the machines. Its design method using an optimization algorithm is also presented. Experiment results of a prototype are presented to showcase the performance of the proposed novel DFDS motor. [ABSTRACT FROM AUTHOR]

This paper deals with replacement of an existing DC motor by an optimized switched reluctance motor (SRM) for an automotive application, especially for electrical vehicles. The SRM was designed by means of 2D and 3D software based on finite element method and independently designed by a new optimization procedure. The input parameters were taken into account on requirements for a real electrical vehicle, e.g., maximum torque, acceleration and power at different speeds. The designed and subsequently optimized motor was constructed, and the static nonlinear and dynamic performances and parameters were measured and compared with the calculated ones. [ABSTRACT FROM AUTHOR]

This paper proposes a novel dc-excited flux-modulated linear machine with a new primary structure for utilizing amorphous core. Although amorphous core is regarded as a good candidate in highly efficient electric machines, and is being investigated for decades, it has not been widely used in electric machines yet. The key challenge is the difficulty in slotting. For the new structure, the difficulty in slotting is avoided. Furthermore, the proposed machine is economical and has a robust double salient structure without any permanent magnets, and both single-toothed field and armature windings are located together in the primary core. By regulating the field excitation, the machine can operate at a wide speed range. Due to the low loss of amorphous core, this machine shows high efficiency at high speed. [ABSTRACT FROM AUTHOR]

Switched-reluctance motors (SRM) present major acoustic drawbacks that hinder their use for electric vehicles in spite of widely-acknowledged robustness and low manufacturing costs. Unlike other types of electric machines, a SRM stator is completely encapsulated/potted with a viscoelastic resin. By taking advantage of the high damping capacity that a viscoelastic material has in certain temperature and frequency ranges, this article proposes a tuning methodology for reducing the noise emitted by a SRM in operation. After introducing the aspects the tuning process will focus on, the article details a concrete application consisting in computing representative electromagnetic excitations and then the structural response of the stator including equivalent radiated power levels. An optimised viscoelastic material is determined, with which the peak radiated levels are reduced up to 10 dB in comparison to the initial state. This methodology is implementable for concrete industrial applications as it only relies on common commercial finite-element solvers. [ABSTRACT FROM AUTHOR]

Direct-on-line synchronous reluctance machines combine the characteristics of induction machines and synchronous reluctance machines. Saturation of core materials, the eddy currents, and the asymmetry of the rotor core and cage make it difficult to predict which kind of loads a machine can synchronize. In this paper, the start-up of a direct-on-line synchronous reluctance machine is analyzed with a magnetic field decomposition that makes it possible to quantify and isolate forces between any two distinct parts of an electric machine using a transient time-stepping finite element field solution. The results show explicitly which portion of the torque is produced by the rotor core and which by the rotor cage. Compared with conventional average torque analyses (also known as pseudo-constant-speed or quasi-steady-state analyses) used to distinguish between the torque on the rotor core and cage, the proposed method makes no assumptions on the state of the machine. This results in a more detailed view of the starting transient. [ABSTRACT FROM PUBLISHER]

This paper deals with the results of measurements, calculations, and computer simulations, leading to the determination of the stator core's building factor (BF) of the fractional power synchronous reluctance motor (350 W). In the process of calculation, the authors indicated the part of the BF factor resulting from the punching process, the geometry of the stator core, and the fabrication process carried out during manufacture of the core. The obtained results indicate that for the analyzed core, the BF factor component resulting from the punching is greater than the sum of the components coming from clamping and pressing the core into the housing. The factor component dependent on geometry is less important. The data necessary for the finite-element method modeling were obtained from the modified SST system, whose idea has been described in detail. [ABSTRACT FROM PUBLISHER]

The design of electric machines is a hot topic in the syllabuses of several undergraduate and graduate courses. With the development of hybrid and electrical vehicles, this subject is gaining more popularity, especially in electrical engineering courses. This paper presents a computer-aided educational tool to guide engineering students in the design process of a switched reluctance machine. A step-by-step design procedure is detailed and a user guide interface programmed in the Matlab® environment developed for this purpose is shown. This user guide interface has been proved a useful tool to help the students to validate the results obtained in their lecture assignments, while aiding to achieve a better understanding of the design process of electric machines. A validation of the educational tool is done by means of finite element method simulations. [ABSTRACT FROM AUTHOR]