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

The switched reluctance motor (SRM) is a promising candidate for electric propulsion systems. In the design process of an SRM, the motor geometry needs to be determined. Using the finite element method (FEM) might be time-consuming for the sizing of the motor geometry. As an alternative, electromagnetic models based on a magnetic equivalent circuit (MEC) can be utilized for the sizing of an SRM. MEC models require fewer computational resources and can help determine the electromagnetic performance with reasonable accuracy. Using the conventional MEC method for SRM sizing might be challenging since the flux pattern inside the motor should be changed for different motor dimensions. In order to address this challenge, this paper applies a reluctance mesh-based MEC technique to determine the geometry of a three-phase 12/16 SRM for a high-lift motor in the NASA Maxwell X-57 electric aircraft. A comprehensive reluctance mesh-based MEC model is developed for this purpose. Both the static and dynamic characteristics of the SRM geometry are evaluated using the reluctance mesh-based MEC method. The determined geometry is verified using the results computed from FEM. [ABSTRACT FROM AUTHOR]

In this article, a switched reluctance machine (SRM) with six phases and a misaligned segmental rotor is proposed. The segmental rotor has an internal 15-degree misalignment, allowing the SRM structure to be a one-layer 2D structure with a short flux path structure. The proposed SRM produces a relatively low torque ripple by exciting two phases simultaneously. Additionally, an optimization method is applied, allowing for the maximum torque position of one phase to be aligned with the zero-torque position of the adjacent phase. The finite element method (FEM) is used to analyze and design the proposed SRM and to simulate the proposed liquid cooling system. The static torque waveforms are analyzed, and the dynamic torque waveforms are simulated with a drive using SiC MOSFETs. Finally, a prototype is manufactured, and the experiment is performed to validate the design and simulation results. [ABSTRACT FROM AUTHOR]

In this paper, a finite element analysis (FEA) based fast optimization method to optimize a lightweight in-wheel switched reluctance machine is presented. This method speeds up the switched reluctance machine optimization procedure by running the FEA simulations with single-phase constant current excitations for half electrical cycle and estimating the machine performance metrics using the gathered FEA data. Hence, the machine's dynamic performance estimation process takes shorter for each design candidate. The optimization algorithm employs designs of experiments (DOE), response surface (RS) analysis method, and differential evolution algorithm (DE). Here, the DOE method is used to reduce the search space by narrowing down the upper and lower boundaries of each design variable based on the RS analysis. Although this process does not guarantee getting the Pareto front, it places the search space close to the actual one. Hence, the multi-objective DE optimization finds the Pareto optimal solution set without requiring a large number of iterations as well as a large number of candidate designs for each iteration. The method is applied to a 24/16 SRM that is intended to be used in a lightweight race car as a hub motor. Six dimensionless geometric variables are optimized to satisfy three objective functions, namely torque ripple, motor mass, and copper loss. While the conventional DE takes at least 3000 candidate designs, the proposed method considers only 559 designs to reach a similar Pareto front. It is observed that the proposed method takes about 6 h 30 min compared to the conventional method that takes 32 h 50 min using the same computer. Therefore, the computation time is reduced almost five times with the proposed method. [ABSTRACT FROM AUTHOR]

In this article, a switched reluctance machine (SRM) with six phases and a misaligned segmental rotor is proposed. The segmental rotor has an internal 15-degree misalignment, allowing the SRM structure to be a one-layer 2D structure with a short flux path structure. The proposed SRM produces a relatively low torque ripple by exciting two phases simultaneously. Additionally, an optimization method is applied, allowing for the maximum torque position of one phase to be aligned with the zero-torque position of the adjacent phase. The finite element method (FEM) is used to analyze and design the proposed SRM and to simulate the proposed liquid cooling system. The static torque waveforms are analyzed, and the dynamic torque waveforms are simulated with a drive using SiC MOSFETs. Finally, a prototype is manufactured, and the experiment is performed to validate the design and simulation results.

In the present paper, a simple model based on magnetic equivalent circuit (MEC) method is introduced for the switched reluctance machine to predict the phase flux linkage characteristic. All equations required to build up the model are given, and therefore, someone can use it easily for different types of the switched reluctance machines. Because of large speed of the suggested model, it can be utilized properly for quick prediction of machine performance. The suggested MEC model is applied to a typical 8/6 switched reluctance motor (SRM), and simulation results including flux linked by a phase, phase current and instantaneous torque are presented. In order to validate the suggested MEC model, the obtained simulation results are compared to those derived from finite element method (FEM) and experimental results. [ABSTRACT FROM AUTHOR]

The torque production mechanism of switched reluctance machines (SRMs) is investigated from the perspective of air-gap field modulation principle. The unipolar stator current excitations can be divided into DC and AC components and they induce the air-gap magneto-motive force (MMF) respectively. Meanwhile, thanks to the salient structure in SRMs, the air-gap MMFs induced by the two sources above can be modulated to obtain the synchronized air-gap fields for torque production. It is revealed that a multitude of field harmonics contribute to the torque together. The MMF-permeance model is built and the analytical deduction of the field modulation effect is provided, with which the orders of the field harmonics contributing to the torque output can be identified. Moreover, finite element method is employed to verify the predictions on various SRM topologies. Finally, aprototype machine is fabricated and measuredfor validation. [ABSTRACT FROM AUTHOR]

In the design processes of Switched Reluctance (SR) Machines that operate in wide constant power speed ranges, the maximum power available at maximum speed must be evaluated for every machine candidate. This is critical to ensure compliance with the power requirement. Important parameters to include in the design routine are the duration of the energizing period and the advance of the turn-on instant, i.e., advance angle. The latter is highly related to the machine geometry and is usually evaluated through time-consuming finite-element-based iterative methods. In this article, a simple, yet novel analytical model is proposed to cater for the torque-maximising advance angle in a closed-form analytical expression, directly from the machine geometry. The goal is to provide a non-iterative design tool that speeds up the design process. Successful validations against finite element analyses and experimental results on an SR machine prototype are reported. The main outcome of this article is shown by the improvement in computation time, without any significant loss of accuracy. [ABSTRACT FROM AUTHOR]

Phase inductance is a key parameter in the design of switched reluctance machines (SRMs) because the torque, torque ripple, losses, and the dynamics of phase voltages and currents are related to the phase inductance. Therefore, accurate calculation of the inductance profile of an SRM is important in determining the SRM behavior. Instead of using the time-consuming finite element analyses (FEAs), or the analytical methods that require prior knowledge of flux linkage from either an FEA simulation or an experimental test such as the curve fitting and flux path based methods, this paper proposes a fast and accurate analytical approach to determine the phase inductance of an SRM with any common topologies, dimensions, and phase currents at any rotor position. In the proposed approach, the magnetic field distribution and the permeance parameters in the air region are first determined by solving the partial differential equations of magnetic potentials based on Maxwell's equations. The air-region permeance parameters are then substituted into a magnetic circuit network to include the impact of the saturation effects of steel on the phase inductance profile. The agreement between the results of the proposed analytical method and two/three-dimensional FEAs and experimental results validates the analysis. [ABSTRACT FROM AUTHOR]

To effectively find a valid solution in the development process of electrical machines, it is essential to predict machine iron loss in the pre-design stage. In guidance on the choice of the most suitable configuration of the switched reluctance machine (SRM) is given, but iron loss prediction is neglected. Based on the study of Burkhart et al., this study proposes a simplified model to efficiently calculate iron loss in the design procedure of SRMs. For this purpose, a maximum co-energy loop control method is implemented to facilitate the estimation of flux waveform and machine torque. Three different iron loss calculation methods are compared in terms of accuracy and time. The accuracy of the simplified model is verified by comparison with finite element simulation results. Furthermore, the impact of different parameters on the iron loss is discussed, and the iron loss of various machine geometries is comparatively analysed. [ABSTRACT FROM AUTHOR]

This paper investigates the performance improvement of a segmented-rotor switched reluctance machine (SSRM) with 16/10 stator/rotor poles. First, the application area, prototype and operation principle of the SSRM are introduced. Second, some important parameters are analyzed to get the optimal values. Then, the simulation results are proposed to show the improvement of the SSRM after optimization, and the improved fault-tolerant characteristic is presented by using finite element method (FEM). It is found that the SSRM after optimization can greatly improve the ability of fault-tolerant, reduce the torque ripple, and continuously operate when two phases of the SSRM have failure. Finally, the predicted static performance and the operation under the current chopper control system of the SSRM are verified by experiments. [ABSTRACT FROM AUTHOR]

In this study, a high-speed switched reluctance machine (HS-SRM) with cobalt-iron lamination material is proposed for spindle motors, which are used in computer numerical control machines. Wide torque-speed range, high power density, high efficiency, and low cost are the crucial issues in spindle applications. Three types of electric machine candidates, the permanent magnet synchronous machine (PMSM), induction machine (IM), and switched reluctance machine (SRM), are compared with their outstanding features. The SRM spindle motor will offer a more robust, reliable, compact, and cost-effective solution compared to the IM or PMSM spindle applications. Moreover, advancement on cobalt-iron laminations gives a chance to the SRM for competing with the PMSM and IM in terms of power density and efficiency. In this study, a high-speed SRM is designed, optimized, and analyzed. Its performance metrics are obtained based on torque-speed range and efficiency over a wide speed range. The proposed SRM is compared with existing industrial products in terms of power densities. Then the design is verified via experimental study. The results show that the HS-SRM with cobalt-iron lamination material offers ultimate power density and efficiency in wide operating conditions. [ABSTRACT FROM AUTHOR]

This paper proposes an advanced dynamic modelling approach of the mutually coupled switched reluctance motor (MCSRM) in the $dq$ reference system that can consider saturation, cross-coupling, and spatial harmonics. Different topologies and their operating principles are investigated and an idealized $dq$-model considering the inductance harmonics is derived. A dynamic model is built based on flux-current lookup tables (LUTs) obtained from finite element analysis (FEA). A simplified method to inverse the two-dimensional LUTs is proposed. A fast computation approach is used to reduce the number of FEA simulations and calculation time to obtain the LUTs. Motor dynamic performances at different speeds are simulated by using the proposed dynamic model and the results are investigated and verified by FEA. The motor dynamic behavior can be accurately obtained in a short simulation time by using the proposed approach. Experiments are carried out on a 12/8 MCSRM, showing good accuracy of the proposed model. [ABSTRACT FROM AUTHOR]

In this study, an analytical model is proposed for natural frequency calculation and acoustic noise prediction for high speed switched reluctance machines. The developed natural frequency model results are compared with the mechanical finite element analysis results in terms of 6 different mode shapes that cause the majority of the acoustic noise in switched reluctance machines. The results show that the analytical results are consistent with the numerical method results with minimum 90% matching. Based on the natural frequency calculation model, a new acoustic noise prediction method is developed that only needs a radial force waveform as an input emerging on stator pole surfaces. The comparison of the developed and the numerical results clearly indicates that the acoustic noise level of the switched reluctance machine can be effectively found during the design process without using time-consuming numerical methods. [ABSTRACT FROM AUTHOR]

In this paper, power losses in high-speed switched reluctance machine (HS-SRM) is studied considering the copper loss, including skin and proximity effect, iron loss in machine side; switching and conduction losses in the drive circuit side using interactive coupled simulation methods. In high frequency fed electric machines, copper losses are increased due to the skin and proximity effects. Moreover, iron losses play a significant role in total electrical losses. Nevertheless, its computation is not straight. In addition, power electronics switching devices cause both conduction and switching losses in the SRM drive circuit. Switching loss may reach excessive levels with the high-frequency switching. In this study, the losses are calculated detailed though coupled simulation method. Different wire constructions in the bundle are analyzed and compared. Finally, circuit simulation is performed on different switching devices. The results prove that high-speed switched reluctance machine driving and operating efficiency is really sensible to design methodology with suitable material and device selection. [ABSTRACT FROM AUTHOR]

Double Stator Switched Reluctance Machine (DSSRM) is a novel switched reluctance machine with limited information about its heat distribution and dissipation. This paper presents a two dimensional (2-D) thermal analysis of Double Stator Switched Reluctance Machine (DSSRM) to observe actual heat distribution in the parts of the machine, using Finite Element Method (FEM). Two topologies for the rotor of DSSRM are considered, Non-Squirrel Cage Double Stator Switched Reluctance Machine (NSCDSSRM) and Squirrel Cage Double Stator Switched Reluctance Machine (SC-DSSRM). The heat distribution of these two topologies is analyzed, using Computational Fluid Dynamics (CFD). Finally the results are presented and compared. [ABSTRACT FROM AUTHOR]

The half-teeth-wound switched reluctance machines (HT-SRMs) having single-layer concentrated windings, feature simpler structures since the coil number is half, and phase-to-phase insulations in slot are eliminated. To evaluate the effects of winding configurations, the electromagnetic performances of HT-SRMs and conventional full-teeth-wound SRMs (FT-SRMs), including air-gap flux density, coil and phase flux linkage, inductance, torque, volt–ampere, and radial magnetic force (RMF), are comprehensively compared. The results based on theoretical analysis and finite-element (FE) method reveal that HT-SRMs would exhibit higher torque per ampere when the magnetic saturations are not too severe, whereas require higher voltage supply and generate more significant RMF. Further, it is found that the fault-tolerant capabilities of HT-SRMs are superior to FT-SRMs. A pair of prototypes with identical laminations but different winding configurations are manufactured and the experimental results confirm the predictions. [ABSTRACT FROM PUBLISHER]

In this work, 4 structural configurations are proposed, and analysed, to be used as a tubular linear switched reluctance generators with tubular topology (TLSRG). For the 4 models under assessment, inductance change with the mover part position is assessed to quantify the machine capabilities as generator for an wave energy converter (WEC), namely a point absorber device. This evaluation is supported by a 2D FEM analysis based software through which are determined the inductance values at different alignment conditions as well as the magnetic flux densities for the referred alignment conditions. An analytic design procedure is presented for one structural model and the same procedure is used to size the generator for given nominal power and based velocity, derived from an ocean wave energy assessment based on meteorological data. [ABSTRACT FROM AUTHOR]

In this paper a novel modular switched reluctance machine (SRM) with E-core stators and segmental rotors is presented. Unlike the conventional SRMs, there are hybrid radial and axial magnetic paths in the E-core stators due to the particular construction. An approximate and simplified 2D finite-element analysis (FEA) model is proposed to calculate its magnetic characteristics and compared with 3D FEA model results. A comparison of the static magnetic characteristic and dynamic performance between the modular SRM and a conventional SRM is made to emphasize the superiority of this novel SRM. Furthermore, the fault tolerant performance of this modular SRM under open-circuit faults is also presented. Finally, a prototype machine is built and tested in the laboratory. The flux linkage characteristics are experimentally obtained by indirect method and are compared with FEA results. Other experimental results such as single-pulse operation, closed-loop control operation, fault-tolerant operation at open-circuits and sudden change in load torque operation are also presented to validate the analytical and simulation results of the modular SRM and its performance. [ABSTRACT FROM AUTHOR]

Switched reluctance machines (SRMs) suffer from ultra-low-frequency torque ripple in single pulse mode. This ripple is the result of an imbalance in phase currents, when multiphase excitation occurs. This paper investigates the origin of this imbalance and identifies the imbalanced phase. Excitation shifting strategy, which delays excitation of the imbalanced phase, is then proposed. The delay angle adjusts current amplitude in the imbalanced phase to attain a perfect balance between all phases. The excitation shifting strategy is a general solution, which is applicable to both three-phase and four-phase machines. In addition, the proposed method can be implemented by a much simpler drive structure, when compared to the existing balancing methods. Hardware measurements are provided to verify superior performance of the proposed current balancing technique. [ABSTRACT FROM PUBLISHER]

This paper presents a novel strategy of switched reluctance motor optimal design. The strategy is based on the so called flux linkage characteristic. The flux linkage characteristic contains most of the information of the machine and thus could be regarded as the “footprint” of the machine performance. In this work, first the desired flux linkage characteristic is identified, and then the optimal design parameters are sought after starting form this “idealized characteristic”. This could be regarded as an inverse problem. In this paper, neural networks are proposed to identify the mapping between the design variables and the flux linkage curve of the machine, and thus overcoming the nonlinearities that are inherent to this type of problems. Finite elements analysis is used to validate this approach. [ABSTRACT FROM AUTHOR]

A 5 phase SRM used for electrical vehicle propulsion is proposed in this paper. Starting from the output equation the machine main dimensions are obtained based on an exhaustive search algorithm in order to obtain a high efficiency and power factor. The overall performance of the motor is estimated using parametric finite element models. [ABSTRACT FROM AUTHOR]

This paper proposes two distinct numerical simulation methods using finite-element time-step analysis for predicting the current wave-form of a switched reluctance machine drive and explains them in detail. It evaluates and compares the methods in terms of waveform results and simulation time, with the focus on only single pulse mode operation. The paper also reviews important factors that affect the simulated current waveforms. It presents and compares measured and simulated multi-phase current waveforms of a 49 kW switched reluctance machine drive under single pulse mode operation. [ABSTRACT FROM AUTHOR]

Abstract: The dynamical behavior of switched reluctance machines is mainly governed by the stator leakage inductance. A comparison of machine parameters, such as the ratio between the self and the leakage inductance, for constructions based on two different axial lengths are suitable for a deeper knowledge about the influence of the non-linear iron saturation effects within higher electrical currents. Therefore, 3D non-linear numerical field calculations are carried out in order to obtain the self and leakage inductances from a magnetic energy approach. [Copyright &y& Elsevier]

Minimizing torque ripple in electrical machines for a given application is not a straightforward task, especially when the application imposes certain constraints. There are many techniques to improve torque ripple, either design-based or control-based. In this paper, a new geometry for switched reluctance machines based on rotor poles skewing is proposed to minimize torque ripple. This paper describes a methodology to design an asymmetrical skew rotor—switched reluctance machine using a multi-objective differential evolutionary algorithm. The main parameters of the optimization process are defined, as is the optimization methodology to obtain an improved design with less torque ripple than a conventional one. Moreover, the analytical formulas used in the optimization method, as well as the optimization technique, are deduced and explained in detail. The mathematical model used to simulate the electrical machine and the power converter are also described. Two-dimensional and three-dimensional finite element analyses were also conducted to assess whether 3D effects (end-effect and axial fringing field) affected the results. Finally, a particular case of a high-voltage direct current-controlled generator in the base of the More Electric Aircraft (MEA) concept or an energy storage system as an electrical machine was analyzed, and the results for the improved configuration were compared with those for the conventional one. [ABSTRACT FROM AUTHOR]

The design of switched reluctance motor (SRM) is considered a complex problem to be solved using conventional design techniques. This is due to the large number of design parameters that should be considered during the design process. Therefore, optimization techniques are necessary to obtain an optimal design of SRM. This paper presents an optimal design methodology for SRM using the non-dominated sorting genetic algorithm (NSGA-II) optimization technique. Several dimensions of SRM are considered in the proposed design procedure including stator diameter, bore diameter, axial length, pole arcs and pole lengths, back iron length, shaft diameter as well as the air gap length. The multi-objective design scheme includes three objective functions to be achieved, that is, maximum average torque, maximum efficiency and minimum iron weight of the machine. Meanwhile, finite element analysis (FEA) is used during the optimization process to calculate the values of the objective functions. In this paper, two designs for SRMs with 8/6 and 6/4 configurations are presented. Simulation results show that the obtained SRM design parameters allow better average torque and efficiency with lower iron weight. Eventually, the integration of NSGA-II and FEA provides an effective approach to obtain the optimal design of SRM. [ABSTRACT FROM AUTHOR]

• A new method to design a tubular linear switched reluctance generator. • The new method is based on a minimization process. • The design procedure is supported by the finite element method (FEM). • The design allows to maximize the machine conversion efficiency. The tubular linear switched reluctance machine (TLSRM) has shown potential for applications as generator in direct drive conversion of ocean wave energy devices. However, the design of this type of machine is a difficult task and there is no methodology to provide an explicit solution. This work aims to contribute for the solution of this problem with the proposal of a new procedure to design tubular linear switched reluctance generators (TLSRG). With the proposed procedure the TLSRG can be designed to develop a given linear force and to achieve better generation efficiency. The design is defined as a minimization problem where an optimization process is used to find the optimal solution for the dimensional parameters. Finite element method (FEM) analysis is applied to compute the relevant electromagnetic characteristics. The mathematical model of the generator conversion system is formulated to evaluate its dynamic performance. An H-Bridge asymmetric converter is adopted to control the energy flow in the generator. The electric currents in the generator phases are adjusted with a hysteresis controller. A TLSRG with a maximum mean force of 120 kN is designed by applying the proposed procedure, implemented in Matlab ® and combined with MagNet ® (FEM commercial software) to compute the electromagnetic characteristics of the machine. The system mathematical model is solved in Simulink ®. The dynamic simulations are performed for a constant velocity of 1.3 m/s. For these operating conditions, the generator is characterised with an output power of 126.2 kW and an efficiency of 82.1%. The control proposed to drive the TLSRG is experimentally tested on a small-scale prototype. The experimental results show the effectiveness of the controller in keeping the phase current near the reference value. [ABSTRACT FROM AUTHOR]