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In this paper, the characteristics of brushless dc (BLDC) motors were compared and analyzed according to the types and control methods under the inter-turn fault (ITF) condition. The shorted windings produced by the ITF were modeled by the winding function theory (WFT) based on the distributed constant circuit method. We also introduced the inductance calculated by the WFT to the voltage equation and analyzed the effect of the ITF using the characteristics of the input and output parameters. The increase rate of torque ripple, increase rate of input current, and the circulating current of the surface permanent-magnet (PM) and interior PM motors under healthy and ITF conditions were compared to determine which motor type is more efficient in preventing the ITF. We also analyzed the fault characteristics by applying the advanced angle control. In this paper, the analysis results are validated by the finite-element method and experiments. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to discuss electrical machines building and computation while taking into account the change of reluctance network (RN) topology required in an optimization process. Indeed, as electrical machine RN changes during an electrical period, this model has to consider several rotor positions to analyze harmonic influence on machine performance (e.g., its torque and losses). Such a requirement can also be important in applications where machine geometry changes shortly during sizing process by optimization. These two cases are addressed in this paper. Using established independent meshes of the initial RN, this paper proposes an algorithm to deal with all topologies necessary for an optimization process. This aims to reduce the computation time, increase the model, and improve the solving stability. An output selectivity approach is also applied on the RN modeling to improve the computation time of the optimization process. The simulation results are compared to finite-element methods and the optimization performance is presented. [ABSTRACT FROM AUTHOR]

Core loss is one of the key factors for performance evaluation of switched reluctance machines. In this paper, core loss analysis of the planar switched reluctance motor (PSRM) is calculated based on the 3-D time-stepping finite element methods. The numerical analysis for the computation of the core loss is discussed, also its transient and average core loss in the mover and the stator are calculated. The corresponding experiments of measurement loss for a PSRM prototype are conducted and the results validate the accuracy from the numerical analysis. It can be concluded that core loss dominates around the corner of the mover and stator cores. [ABSTRACT FROM AUTHOR]

A switched reluctance motor (SRM) can be one of substitutes for interior permanent magnet synchronous motors used in many industrial applications because of their merits. This paper proposes an optimization method for an SRM fed by an asymmetric bridge converter. The converter is coupled with 2-D finite element method. We optimize five geometries of SRM shape and turnon and turnoff angles of the asymmetric bridge converter by using the experimental design method. The optimized SRM produces a larger torque than that of an initial motor in low speed range. [ABSTRACT FROM AUTHOR]

Vibration and acoustic noises are viewed as a drawback in switched reluctance machines (SRMs), which prohibit their widespread use in noise sensitive applications. Double-stator SRMs (DSSRMs) can be considered as a solution to this problem by incorporating an improved magnetic configuration, which reduces the radial forces in the machine. This paper compares structural behavior of a DSSRM and a conventional SRM using a multi-physic analysis. An electromagnetic finite-element (FE) method is used to calculate force density at various parts of the stator surface in both machines. These force densities are then used in a structural FE analysis to compute acceleration, deformation, and velocity of the vibrating surface at selected point on the outer surface of the machine. [ABSTRACT FROM AUTHOR]

This paper proposes a novel transverse flux type permanent magnet reluctance generator (TFPMRG), which contains a permanent magnet (PM) in its U-shaped salient stator pole. A U-shaped stator core is designed with the short flux path to reduce the mutual effect between phases. Moreover, the proposed TFPMRG shape is designed for using PM instead of an excitation circuit to provide the field excitation, which increases the output power and efficiency. Both the transverse flux type switched reluctance generator (TFSRG) and the TFPMRG are designed using 3-D finite-element analysis (FEA) and a torque equation called the D-2L method. Finally, the design results of the TFSRG and TFPMRG are confirmed with 3-D FEA. According to the results, the output power and efficiency of TFPMRG are higher than those of TFSRG. [ABSTRACT FROM AUTHOR]

An integrated rotary–linear machine based on switched reluctance principle is investigated. The characteristics of the motor are analyzed by finite-element methods, with particular emphasis on the coupled magnetic paths. Results from numerical calculation are verified by the hardware experiment. The simple yet effective decoupling algorithm for the independent position control of both rotary and linear axes is proposed. Implemented with the proportional–integral-differential algorithm, the motor is capable of high-precision rotary and linear position tracking with the steady error within 0.3^\circ and 10~\mum, respectively. [ABSTRACT FROM AUTHOR]

The switched reluctance machine (SRM) has certain advantages such as robustness and the absence of permanent magnets which have encouraged its use in recent years. One of its applications is as a self-excited generator. This behavior is produced when a capacitor is series or parallel connected to each single phase forming a nonlinear pseudoresonant circuit. This application can be used in isolated sites with a wind turbine for energy generation. This paper describes a novel method used for the specific design of a 1-kW self-excited SRM for wind power applications based on torque considerations. The machine volume, dimensions, finite-element analysis, model verification, simulations, and experimental results are all presented. [ABSTRACT FROM AUTHOR]

This paper deals with modeling and power control methods of a switched reluctance generator (SRG) driven from the wind power generation system. To consider electromagnetic nonlinear characteristics of SRG, the flux linkage and torque of the designed generator computed by a finite element method (FEM) are applied to the SRG model. And the SRG model is controlled with a required output curve depending on the speed of the generator using optimized switching angle which has been analyzed in advance to maximize its efficiency. The power control algorithm is applied to a manufactured 3 kW prototype SRG. The simulation results are compared with the experimental ones for validation. [ABSTRACT FROM PUBLISHER]

This paper presents a multiphysics modeling of a switched reluctance motor (SRM) to simulate the acoustic radiation of the electrical machine. The proposed method uses a 2-D finite-element model of the motor to simulate its magnetic properties and a multiphysics mechatronic model of the motor and controls to simulate operating conditions. Magnetic forces on the stator are calculated using finite-element analysis and are used as the excitation on a forced response analysis that contains a finite-element model of the motor stator structure. Finally, sound power levels are calculated using the boundary element method. Simulation results of the model are shown and compared with experimental measurements for a four-phase 8/6 SRM. [ABSTRACT FROM PUBLISHER]

There has always been a high demand for cost-efficient, reliable, low-noise, and durable low-maintenance motors, especially in high-quantity applications. A switched reluctance motor (SRM) can be a great candidate because of its rigid and simple construction. Among different SRMs, the two-phase type has the simple power converter, control unit, and geometry. In this paper, a short-flux two-phase SRM (2-phase SRM) known as E-Core 6/10 is modified to produce higher torque. The formulas for the number of rotor and stator poles have been amended, and in addition to alleviating some mechanical issues, the empty adjacent-pole spaces have been fully utilized. Comparisons are made based on simulations by 2-D finite-element analysis method and experimental results. It is obtained that for the same main dimensions, the average torque in the modified 6/10 two-phase SRM improves by about 35% that validates the new proposed motor. [ABSTRACT FROM PUBLISHER]

A novel rotor design of interior permanent-magnet synchronous motors (IPMSMs) has been developed in order to cope with both maximum torque and iron-loss reduction for wide-speed-range applications. First, the flux barrier and permanent-magnet shapes of an IPMSM are determined by using an automatic optimization method. In this optimization, the iron loss of the IPMSM under flux-weakening control at high speeds is minimized under the constrained condition of maximum torque at low speeds. As a result, a novel rotor, which has inner magnetic pole bodies, is obtained. The effectiveness of this design is discussed from both results of the finite-element analysis (FEA) and the measurement of a prototype motor. It is revealed that the iron loss of the proposed IPMSM at high speeds is significantly reduced, whereas the maximum torque decreases by only a few percent. [ABSTRACT FROM PUBLISHER]

The LU recombination method is applied within a dual-primal finite element tearing and interconnecting (FETI-DP) framework to solve low-frequency multiscale electromagnetic problems. The FETI-DP method, a robust domain decomposition method, is adopted to deal with the large-scale linear system resulting from finite element modeling of multiscale problems. When frequency decreases or a highly nonuniform mesh is used, the FETI-DP method encounters a low-frequency breakdown problem. The LU recombination method is adopted to identify and eliminate dependent degrees of freedom (DOFs), so that nearly singular finite element matrices are regularized. Since it deals with matrices directly, the LU recombination method is easily combined with different types and orders of basis functions. A nested scheme is adopted to apply LU recombination within the FETI-DP framework. The proposed algorithm is applied to large-scale eddy-current, switched reluctance motor, and logging-while-drilling tool problems. With the LU recombination method, the FETI-DP method is extended down to DC, making it possible to deal with a variety of problems of practical interest. [ABSTRACT FROM AUTHOR]

This paper presents a single-phase switched reluctance motor (SRM) with skewed stator and rotor so that the acoustic noise and vibration have been significantly reduced. The motor has the same skew angle for both stator and rotor laminations. The main source of acoustic noise and vibration is the rapid change of radial magnetic force along the air gap between the stator and rotor poles. Since the radial force (RF) is most intensified on the stator yoke near the salient poles, the abrupt change of the RF can be mitigated by skewing the stator and/or rotor laminations. Therefore, the RF can be more distributed throughout the stator core, and in turn, the peak value of the RF is reduced. In this paper, the distribution of the RF with respect to the skew angles is analyzed through the finite-element method simulation to design a single-phase SRM with the significantly reduced vibration and noise. Based on the simulation results, prototype motors with three different skew angles (0^\circ, 30^\circ, and 64 ^\circ) have been constructed and tested, validating that the proposed design is effective in mitigating acoustic noise and vibration. [ABSTRACT FROM PUBLISHER]

This paper proposes a nonlinear adaptive lumped parameter magnetic circuit (LPMC) model for a new spoke-type fault-tolerant permanent-magnet (ST-FTPM) brushless motor. The LPMC method, which reduces the total computational time greatly, can be used as a finite-element method (FEM) assistant design tool. Hence, it is used to calculate the flux linkage, back-electromotive force (back-EMF), inductance, and torque performance of the ST-FTPM motor. The novelty of this paper is to predict short-circuit current based on the developed LPMC model. Meanwhile, in order to ensure the analytical accuracy, the magnetic saturation is considered in the model design. The effectiveness of the presented LPMC model is verified by FEM and the experiments. [ABSTRACT FROM PUBLISHER]

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]

Zero-voltage loop (ZVL) commutation in switched reluctance (SR) motor operation can result in a significant improvement of their performance by lowering the flux-linkage peaks and harmonic magnitudes of the magnetic flux densities within the core of the SR motor. The efficiency enhancement provided by ZVL commutation, especially in high-speed SR motoring has not been thoroughly investigated to-date. This paper investigates the energy conversion efficiency of SR motors with ZVL current commutation. The lowering of core losses is investigated with finite element modeling of a 250 kW 12/8 SR motor. An enhancement of efficiency in the ranges of 0--3% and 0--5% is computed considering operation below base-speed and above base-speed respectively. The effect of core material on the ZVL commutation performance is also investigated for the 250 kW 12/8 SR motor. The increase of efficiency with ZVL is further validated with experimental results on a 300 W 6/4 SR motor which achieves an enhancement in the range of 2–6%. [ABSTRACT FROM AUTHOR]

This paper quantitatively compares three advanced magnetless machines, namely the switched reluctance (SR) machine, double-stator SR (DS-SR) machine and DS multitoothed SR (DS-MSR) machine. The DS-SR machine is particularly favorable for low-torque high-speed operation while the DS-MSR machine is desirable for high-torque low-speed operation. Because of more effective power transfer by using two stators, the two DS machines achieve better performances than the single-stator counterpart. All machine performances are analyzed by using the time-stepping finite element method. [ABSTRACT FROM AUTHOR]

The brushless doubly-fed reluctance machine has two sets of stator windings of different pole number linked by a reluctance type of rotor. The rotor modulates the stator MMF from one winding so that flux links the other winding creating mutual coupling. This is still a research machine and the design methodology is under development. Past works indicates that a ducted rotor with radial laminations is best suited to be the reluctance rotor. In this paper the geometry of the rotor is investigated. If the ducts are too thin then the reluctance ratio is low and the coupling is affected. If they are too wide then the reluctance path for the coupling flux is high and the machine will saturate quickly. It is found, using finite element analysis, that the duct ratio should be about 38% from the results in the paper. This is in line with previous work on synchronous reluctance machines that can also use ducted rotors (although they use axial lamination which are inappropriate for this application). [ABSTRACT FROM AUTHOR]

We investigated the torque characteristics and the motor efficiency of interior permanent magnet synchronous motors (IPMSM), in which a rotor core consists of high-strength nonoriented electrical steel, as-cold-rolled nonoriented electrical steel, and conventional nonoriented electrical steel with various bridge widths. Furthermore, we analyzed deformation behavior of the rotor core during operation by finite element method. The motor of the high-strength nonoriented electrical steel generated greater magnet torque than that of the conventional nonoriented electrical steel. Although the high-strength nonoriented electrical steel had much higher iron loss than the conventional nonoriented electrical steel, the motor efficiency decreased only slightly. A reduction in the bridge width of the rotor core significantly enhanced the torque characteristics and the motor efficiency of IPMSM. The high-strength nonoriented electrical steel effectively suppressed the deformation of the rotor core with its excellent mechanical properties, and the suppression enabled us to reduce the bridge width sufficiently. Accordingly, a magnetically optimum rotor core design will be realized with the high-strength nonoriented electrical steel, and the performance of IPMSM will be significantly enhanced, particularly in traction motors for electric vehicles and hybrid electric vehicles and compressor motors for energy-efficient air conditioners. [ABSTRACT FROM PUBLISHER]

The maximum torque values in computer analysis and experiment in the switched reluctance motor (SRM), having competitive torque density and efficiency with respect to the rare-earth permanent magnet motor employed in the 2009 Toyota Prius, have been compared. The SRM is highly saturated to provide the maximum torque for a short time; thus, the torque value tends to have considerable error of 15% even in the 3D FEM analysis with respect to experimental result because of the incomplete material setting. A comparison of the flux-linkage and current is also provided for consideration. The results of the 2D-FEM and 3D-FEM analysis as well as a test machine are presented. The maximum torque in the 3D-FEM analysis is shown to be within errors of 5.0% with respect to that in the test machine. [ABSTRACT FROM AUTHOR]

Switched reluctance motors (SRMs) show crucial attributes to applications where light weight, high-temperature adaptability, fault-tolerance capability, ruggedness, and simplicity are strongly required. The axial-flux configuration of SRM has additional features over the radial-flux configuration. This paper presents the design and analysis of a novel axial-flux SRM. Detailed procedures of deriving the output power equation as a function of the motor dimensions and parameters are provided. A modified phase winding design approach is thoroughly explained, a flowchart describing the design algorithm is presented, and the inductance determination by different methods is verified experimentally. The 3-D finite-element analysis (FEA) unveils the excessive end core and radial-flux fringing effects in the axial-flux configuration. An exclusive pole-shape design is also proposed. The operation of the motion model using 3-D dynamic FEA is analyzed, and its prototype development process and static testing are demonstrated. [ABSTRACT FROM PUBLISHER]

Linear flux-switching permanent magnet (LFSPM) motors with both permanent magnets and armature windings on the short primary mover have attracted considerable attention due to their simple and cheap stator which only consists of iron. Hence, this kind of liner motor is very suitable for long stator applications such as in urban rail transportations. However, the conventional LFSPM motors directly split from rotary FSPM motor suffer from drawbacks such as unbalanced magnetic circuit of end coil, heavy mover, and bigger cogging force and force ripple. Modular LFSPM (MLFSPM) motors can mitigate the problem of unbalanced magnetic circuit of end coil. But some MLFSPM motors with different stator/mover pole pitch \taus/\taum=12/14, 12/10 don't have complementary phase armature windings, which will lead to asymmetrical and non-sinusoidal back-electromotive force, bigger cogging force and thrust force ripple. The key of this paper is to propose, investigate, and compare four complementary and modular structures for the LFSPM motors with different \taus/\taum. The electromagnetic performance and dimensions of the proposed complementary MLFSPM motors with different \taus/\taum are investigated, compared and confirmed by the means of finite element analysis and experimental results. Based on the analysis results, two complementary MLFSPM motors with \taus/\taum=12/13 are chosen to be the two best motors, which can offer the biggest thrust force, relatively smaller cogging force and thrust force ripple, and shorter mover length. [ABSTRACT FROM AUTHOR]

In this paper, a bidirectional cross-linking transverse flux permanent magnet synchronous motor is presented, which has a larger space utilization ratio than the traditional transverse flux machine. The stator core unit can make full use of rotor permanent magnets, and effectively increases no-load back-electromotive force (back-EMF), with the features of easy manufacturing. The structure and the driving principle of this motor are introduced. The 3-D magnetic circuit model is established, and the analytical expression of the no-load back-EMF and the torque are derived. In addition, the magnetic field and torque are analyzed by the 3-D finite element method (FEM). A prototype was designed and manufactured. The back-EMF and static torque experiments were carried out. The theoretical analyses agreed with the experimental results well. That verified the validity of the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive method for eccentricity fault diagnosis in switched reluctance machine (SRM) during offline and standstill modes. In this method, the fault signature is achieved by processing the differential currents resulted from injected high-frequency diagnostic pulses to the motor windings. For feasibility assessment of the proposed method, the correlation between differential current and eccentricity occurrence is analytically demonstrated. A 3-D transient finite-element method is utilized to analyze the proposal, and its results are validated by experimental tests on a prototype machine in the laboratory. According to the obtained results by experimental as well as numerical analysis, a pattern is introduced in order to detect fault presence. In this stage, an algorithm with two methods is proposed for the detection of fault location or faulty phase. Furthermore, the direction of fault is recognized by a simple comparative technique. Next, a normalized indicator is proposed in order to estimate the eccentricity fault severity as well as its occurrence. This indicator is not dependent of the healthy motor information, which makes it reliable and applicable tool for all sizes of SRMs. Finally, a simple procedure based on achieved pattern and indicator is implemented to distinguish the static, dynamic, and mixed eccentricity in the SRM. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive method for eccentricity fault diagnosis in switched reluctance machines (SRMs) during offline and standstill modes is presented. This sensorless method is able to detect occurrence, location, direction, and severity of the eccentricity fault in SRM. First, the theory of the method is presented, and then its background formulation is explored and discussed. In order to model the eccentric SRM and apply the test method, a 3-D transient finite-element method (3-D TFEM) is employed, which takes into account all physical and geometrical characteristics of the motor components. Next, a test rig is established to carry out various measurements on a faulty motor with different degrees of eccentricity. Then, a procedure of diagnosis method with achieved data is described. In this regard, this method investigates how the fault location as well as the faulty phase in the SRM can be detected. Furthermore, the strategy of the fault direction detection based on induced voltage variations is stated. In addition, a proper index will be proposed in order to detect the fault severity. To demonstrate the merits of this indicator in the eccentricity detection and estimation of its severity, the correlation between the index and frequency and voltage variations are evaluated. [ABSTRACT FROM AUTHOR]

This paper describes the design of an axial-type switched reluctance motor (SRM) with the aim of improving the output torque characteristic. The axial-type structure has several advantages, including a large air-gap area due to the dependence on the radial length, whereas the air-gap area of the radial-type motor depends on the axial length. This advantage is expected to increase the inductance and the output torque. This paper shows a method to design an axial-type SRM and basic properties of the designed motor by comparing the results of the finite-element analysis with those obtained by experiments. [ABSTRACT FROM AUTHOR]

Brushless doubly fed reluctance machines (BDFRMs) are a class of machines that may be controlled using a power converter that has a rating lower than the total power rating of the machine. The attractive properties of these machines have, in the past, been offset by low power density and efficiency when compared to other types of machines. Recent advances have shown that, when well designed, these machines are, in fact, capable of operation at high torque density and efficiency. However, little guidance on how to design these machines is available in the literature. This paper presents analytical approaches to design a BDFRM with desirable qualities and the use of time-stepped finite-element analysis to validate the results of the design process. [ABSTRACT FROM AUTHOR]

This paper presents a technique to modify the rotor lamination of a permanent-magnet-assisted synchronous reluctance motor, in order to reduce the magnet volume with no side effect on performance. A closed-form analysis, which is based on a lumped parameter model, points out that the magnet quantity can be minimized with a significant saving of material volume and cost. At a second stage, the risk of demagnetization is evaluated since the minimized magnets are thinner than the starting ones and work on lower load lines in their respective B-H planes. A feasible drawing is analytically defined, which is robust against demagnetization at overload, showing that the saving of magnet quantity depends on the maximum current overload and can be significant. The theoretical formulation is validated with finite-element analysis and experiments on a prototype machine. [ABSTRACT FROM AUTHOR]

Reluctance machines (RM) have desirable features including low rotor and no-load rotational losses. In this paper, a new type of RM is introduced, namely the asymmetrical RM. This machine has higher torque density than a conventional RM and is useful in situations where low rotor and no-load rotational losses are desirable. A design model for the new type of machine is presented and validated using finite-element analysis. The machine is compared to other machine types by comparing Pareto-optimal fronts of loss versus electromagnetic mass for a given torque. [ABSTRACT FROM AUTHOR]

Motors for in-wheel electric vehicle application should have high specific torque. In addition, these motors should be rugged, insensitive to vibration, and temperature variation. Therefore, segmented rotor switched reluctance motor (SSRM) could be an attractive alternative to permanent magnet-based motors, which are being used for this application. A limitation of SSRM is that it requires full pitch winding for its operation. Since, in-wheel motors have high diameter to axial length (D/L) ratio, SSRM of these dimensions would be bulky and has high copper loss due to full pitch winding. Hence, in this paper, a novel SSRM with nonoverlapping winding is proposed. This motor is an axial flux SSRM (AFSSRM) with toroidal winding arrangement. It has single-stator, dual-rotor configuration with 12 stator poles and 16 rotor segments on each rotor disc. Design procedure for AFSSRM is developed and a flowchart describing the design algorithm is presented. A finite element method-based simulation is carried out to verify the performance of the proposed AFSSRM. In order to validate the performance of the motor, a prototype is fabricated and experimental results are presented. [ABSTRACT FROM AUTHOR]

Force ripple is the main disadvantage of conventional linear switched reluctance actuators/motors (LSRAs/LSRMs). Based on finite element analysis (FEA), a new method to minimize force ripple is proposed for multimodular LSRAs/LSRMs in this paper. First, the force distribution of an LSRA/LSRM module is computed by using FEA. Then, the scheme of the spatial distribution of modules is developed. Finally, the modular spatial displacement is optimized to minimize force ripple. The computed results based on the FEA demonstrate the proposed method. The proposed method does not require any change in both module design and motor control. Thus, it is simple, cost-low, feasible, and effective. [ABSTRACT FROM AUTHOR]

A permanent magnet reluctance generator (PMRG) has almost the same structure as a switched reluctance generator, but has permanent magnets in the stator yoke. Therefore, neither an exciting circuit nor a position sensor is required. This paper describes a super-multipolar PMRG for small-scale wind-turbine generation, which can be directly connected to the turbine without a gear box. The designed PMRG has two features for reducing torque ripple drastically; the first one is two-stacked structure that one rotor is shifted by 180^\circ in electrical angle from the other rotor; the second one is that the rotor pole-tips are cut off. To find the optimum shape of the rotor pole-tip efficiently, the coupled analysis of finite element method and a general purpose optimization program is employed. In addition, load characteristics of the PMRG are indicated. [ABSTRACT FROM AUTHOR]

This paper presents a novel switched reluctance (SR) motor that has auxiliary windings and permanent magnets on the stator yoke. It can be driven by an asymmetric half-bridge converter in the same manner as the conventional SR motor, and the performance is improved by the auxiliary windings and magnets. The characteristics of the proposed SR motor are demonstrated by finite element method (FEM) and experiment. In addition, operating principle and characteristics in the case of generating mode are indicated. [ABSTRACT FROM PUBLISHER]

A transverse-flux tubular linear machine with novel gear-shaped teeth for high force density is proposed. The teeth can be formed by silicon steel laminations or permanent magnets for a tubular linear switched reluctance or tubular linear hybrid motor. With the unique improved teeth structure and short magnetic circulation paths, larger propulsion force output can be obtained with reduced mover weight and volume. Simulation based on finite element method (FEM) verifies the validity of the proposed machine design. The proposed machines are compared with other transverse-flux linear machines. Results show that the proposed tubular motors exhibit better output performance with a higher force-to-volume ratio. [ABSTRACT FROM AUTHOR]

In safety-critical systems, faults can cause life losses, environmental degradation, or significant financial losses. In this paper, a segmental stator switched reluctance machine is proposed for such applications. A short overview of its design is given. Its fault tolerance is investigated by dynamic simulations and laboratory tests. It is demonstrated via both methods that the proposed machine is able to have a continuous operation despite five severe winding fault conditions. [ABSTRACT FROM AUTHOR]

Industry applications involving torque brushless dc motors require high efficiency over a large speed range. In order to achieve such specifications, flux weakening is necessary, which could lead to relative high electromagnetically induced vibrations and consequently to audible noises. Furthermore, in order to decrease cogging torque and to satisfy motor manufacturing constraints, concentric windings are usually considered. Such motor configurations lead to harmonics of the electromagnetic forces being the sources of mechanical vibrations. This paper focuses on the electromagnetic forces created in surface-mounted permanent magnet and internal permanent magnet motors for two concentric windings: one and two coil sides per slot. These forces are determined using both lumped magnetic scheme and two-dimensional finite-element (FE) simulations. Then, three-dimensional FE simulations enable to predict the mechanical modes and the acoustic radiated power. Finally, the authors propose a simple method to mitigate the magnetic forces and their variations. This method deals with skewing the stator. The skewing angle is optimized differently as in the usual case of decreasing the cogging torque. This method is really interesting for industry applications, because does not require any important change in the motor construction. The acoustic measurements confirm the analysis and the proposed improvement technique (stator skewing). [ABSTRACT FROM PUBLISHER]

This paper presents an operating strategy for high-speed switched reluctance (SR) generators employed in exhaust gas energy recovery systems. The machine is operated in “single pulse” mode, and a parametric study of the control angles is performed to analyze the machine operation. It is shown that, for given speed and power, optimum sets of control angles exist, which achieve maximum machine efficiency and minimum thermal stress. This study is undertaken using a coupled nonlinear modeling approach, combining magnetostatic finite-element analysis with time-domain circuit simulation. The results are compared with measurements performed on an SR generator designed for a prototype exhaust gas energy recovery system, showing overall good agreement. [ABSTRACT FROM PUBLISHER]

The multichannel generator is a kind of special generator, which is developed to enhance power reliability in safety critical applications. This paper compares the dynamic performance computation for a 12/8 dual-channel switched reluctance generator (DCSRG) under single- and dual-channel operation modes. First, the static phase self- and mutual inductances are numerically calculated through finite element analysis (FEA). Based on the magnetic characteristics, the mathematical and simulation models of DCSRG under different operation modes are presented. In the dual-channel model, the effect of mutual coupling between phases of each channel in the DCSRG is considered. By using these proposed dynamic models, the different performances for the DCSRG under single- and dual-channel operation modes, such as generating process under closed-loop control, steady-state performance at different conditions, sudden change in load operation, and the operating status when changing from motoring to generating, are predicted and compared. Finally, a 12/8 DCSRG system is built for experimentation. The simulation and experimental results are also compared in the DCSRG system under different operation modes to verify the proposed modeling and analysis. [ABSTRACT FROM AUTHOR]

This paper presents a new method to minimize the torque ripple of a 3-phase, 6-slot, and 4-pole mutually coupled switched reluctance motor (MCSRM 6/4). The difference between a MCSRM and a classical SRM is their winding configuration. In a MCSRM, the mutual inductances are no longer neglectable when compared to self inductance. On the contrary, due to mutual inductances, the MCSRM can produce higher average torque than a classical SRM. A literature review is firstly performed to identify the source of high torque ripple level of a MCSRM. Then, the method using punching holes in rotor poles to modify the waveforms of flux as well as derivatives of inductances with respect to rotor position (dL/d\theta and dM/d\theta) is proposed. Using the 2-D finite-element method (FEM), the influence of dimensions of punching hole on the electromagnetic performances (average torque and torque ripple) is analyzed. The two MCSRM are supplied by three-phase sine wave currents, and comparisons in terms of average torque and torque ripple versus RMS current density are also carried out. In order to make sure that the presence of punching holes does not cause mechanical problems, some mechanical studies are performed. Finally, experimental tests are also realized to validate numerical results obtained by 2-D FEM. [ABSTRACT FROM PUBLISHER]

This paper presents an advanced lumped parameter (LP) thermal model for a permanent-magnet assisted synchronous reluctance machine (PMaSRM) developed for propulsion in a hybrid electric vehicle. Particular focus is put on the stator winding and a thermal model is proposed that divides the stator slot into a number of elliptical copper and impregnation layers. The model is enabled by the derivation of an approximate analytical expression for the thermal resistance of an elliptical cylinder with constant thickness. The approach is attractive due to its simplicity and the fact that it closely models the actual temperature distribution for common slot geometries. Additionally, an analysis, using results from a proposed simplified thermal finite element model representing only one slot of the stator and its corresponding end winding, is presented in which the number of layers and the proper connection between the parts of the LP thermal model representing the end winding and the active part of winding is determined. The presented thermal model is evaluated experimentally on a PMaSRM equipped with a water cooling jacket, and a good correspondence between the predicted and measured temperatures is obtained. [ABSTRACT FROM PUBLISHER]

Switched-reluctance-machine (SRM) technology is a potential candidate for the propulsion systems of hybrid and plug-in hybrid electric vehicles. They are robust in harsh operational conditions and have a wide constant power speed range. Conventional SRM configurations have a higher number of stator poles than rotor poles. This paper presents the advantages of a novel SRM configuration with the number of rotor poles greater than the number of stator poles. It also investigates different design challenges toward the traction applications. The proposed SRM configuration is based on a pole-design formula. Geometrical design equations and related challenges are introduced, and their applicability has been verified on a three-phase 6/10 SRM using finite-element-analysis simulations. [ABSTRACT FROM PUBLISHER]

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

This paper presents an extended Field Reconstruction Method (FRM) to model a Switched Reluctance Machine (SRM), which is set apart from other electric machines by its double-saliency and magnetic saturation. Traditional magnetic models of SRM developed using Finite Element Analysis (FEA) are computationally inefficient. This, in turn, limits their application in simulation of SRM drive system especially under iterative optimization procedures. FRM can significantly reduce the computational time by utilizing a small number of static magnetic field snapshots to establish the basis functions which are then used to reconstruct the magnetic field with high accuracy. In this paper an extended version of FRM is introduced within which effects of magnetic saturation and double saliency are taken into account. Results from FRM, FEA and experiments are compared and good accuracy is observed. [ABSTRACT FROM PUBLISHER]

This paper presents a thermal model of power converter used in switched reluctance motor (SRM) drive under constant convective heat transfer. The distribution of the system temperature rise is derived based on the average heating power measured as SRM is running steadily, and the temperature rise is independent of ambient temperature which is proved in this paper. The accuracy of the thermal model is verified by comparing experimental data with the results derived from finite-element method (FEM) simulation. Furthermore, this study achieves optimization in heat sink geometry and the placement of power components with the present model. [ABSTRACT FROM PUBLISHER]

A novel method is developed to easily compute the complex series impedance matrix of a multi-conductor transmission line in a wide frequency range. It is based on a network of complex reluctances describing flux paths around the conductors. The network parameters are derived from the geometry of the conductor-insulator arrangement and from its material parameters. The method is best suited for situations where the typical gap width between conductors is much smaller than their thicknesses, where it provides an accurate treatment of both skin and proximity effects. Especially the proximity effect is hard to treat by other means in that limit. The method is demonstrated for an idealized example geometry, where its accuracy is verified with harmonic FEM field calculations. [ABSTRACT FROM PUBLISHER]

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

Electric vehicles make use of permanent-magnet (PM) synchronous traction motors for their high torque density and efficiency. A comparison between interior PM and surface-mounted PM (SPM) motors is carried out, in terms of performance at given inverter ratings. The results of the analysis, based on a simplified analytical model and confirmed by finite element (FE) analysis, show that the two motors have similar rated power but that the SPM motor has barely no overload capability, independently of the available inverter current. Moreover, the loss behavior of the two motors is rather different in the various operating ranges with the SPM one better at low speed due to short end connections but penalized at high speed by the need of a significant deexcitation current. The analysis is validated through FE simulation of two actual motor designs. [ABSTRACT FROM PUBLISHER]

A linear doubly salient permanent magnet (LDSPM) motor is particularly suitable for long stator applications due to its simple and low cost stator, which consists of only iron. This paper proposes a new LDSPM motor design with complementary and modular structure. The key of this structure is that the primary mover is composed of two modules whose positions are mutually four and one half of the stator pole pitch apart and there is a flux barrier between them. Hence, the back electromotive force (EMF) waveform and cogging force of the two modules have 180 electrical degree differences. This design results in the total cogging force being significantly reduced and the back-EMF of each phase becoming symmetrical because the even harmonics are canceled. For fair comparison, an existing linear LDSPM motor is designed based on the same electromagnetic parameters and compared by the means of finite element analysis (FEA). The results reveal that the proposed LDSPM motor can offer symmetrical back-EMF waveforms, smaller cogging force, lower force ripple, and higher magnet utilization factor than the existing one. [ABSTRACT FROM AUTHOR]

An accurate estimation of flux linkage characteristics is very important during the preliminary design stage and high-performance control of linear switched reluctance motor (LSRM). In this paper, longitudinal and transversal end-effects of a double-side LSRM are studied using analytical method and finite element analysis (FEA). The estimation discrepancy introduced by both end-effects is presented respectively by investigating their sensitivities to machine parameters, such as excitation level, translator position, and stack length. [ABSTRACT FROM AUTHOR]