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Most of the existing diagnosis techniques for interturn short circuits (ITSCs) in switched reluctance motors (SRMs) suffer from three major issues. 1) The problem of lower sensitivity where the system cannot detect an ITSC if a lower number of turns are short-circuited; 2) Interference of load variation on the detection reliability in which the fault index might initiate false alarm without any fault; 3) The dependency of the diagnosis system on the control strategy on which the motor is operating. This article proposes a novel method to diagnose ITSCs in SRMs independent of control schemes with better sensitivity and reliability using the signal injection technique. In SRMs, not all the phases take part in the torque production at any instant. The idle or inactive phase is injected with a high-frequency (HF) voltage signal for a preselected injection ratio within an electrical cycle. Any change in the winding parameters owing to an ITSC fault is deciphered by monitoring the HF currents generated in the phase windings. The results are validated experimentally for a four-phase 8/6 SRM employing two control strategies: 1) chopped current control and 2) angle position control. [ABSTRACT FROM AUTHOR]

Thanks to the absence of rotor windings and permanent magnets, switched reluctance motors have a small weight construction. The integration of a modular power converter in a switched reluctance motor leads to a highly compact and fault-tolerant motor drive with small weight and high power density. In this article, a polygon-retrofitted integration topology is proposed for switched reluctance motors. Both the switched reluctance motor and the power converter are cooled with one shared cooling circuit. The power converter is designed and implemented using silicon carbide technology for its low losses and small thermal resistance. The proposed integration topology is extensively studied using multiphysics modeling and experimental measurements on a fully integrated rotating setup. A highly compact and power dense drive of 3.1 kW/L is obtained. [ABSTRACT FROM AUTHOR]

In this article, a low-ripple continuous control set (CCS) model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed. The inherent high nonlinearity of the SRMs makes it difficult to solve the optimization problem in the CCS MPTC algorithm analytically. To address this issue, an equivalent linear SRM model is adopted, and the cost function is also properly modified. Then, with the torque boundary values provided by executing the voltage vectors of an improved switching table, the optimization problem in the CCS MPTC method becomes simple and analytically solvable. The Lagrange multiplier method is employed to solve this optimization problem analytically and generate the optimum torque reference values for the active phases. Based on the estimated torque variation rates, the duty cycles for each phase are calculated. Extensive simulation and experimental tests are carried out in a four-phase 8/6 SRM setup. These testing results reveal that the proposed CCS MPTC method shows much lower torque ripples and current ripples in a wide speed range with a low computational burden than the existing finite control set MPTC methods. [ABSTRACT FROM AUTHOR]

Multiphysics analysis and experimental validation of acoustic noise reduction in a high pole count, high power, switched reluctance machine (SRM), through skewing are explored in detail in this work. An iterative optimization strategy covering electromagnetic, structural, and thermal domains is proposed to investigate the effect of different skewing methods and angles on a 24-stator slot/16-rotor pole (24/16) SRM rated at 100 kW. The contributions of this work are twofold. First, electromagnetic impact, considering average torque, torque ripple, radial and tangential air gap forces, of symmetric and asymmetric skewing on stator and rotor is studied in this work. Second, the impact of skewing methods on acoustic noise and vibration performance is studied and presented in detail. The study reveals that skewing both the stator and rotor by the same amount has superior electromagnetic performance over other types of skewing. Multiphysics simulations conducted, predict a 10.5 dBA reduction in the acoustic noise, compared to a baseline design with no skew, for an optimized rotor-stator skewing angle of 13.75°. Finally, 100 kW prototypes of the baseline and the optimized skewed SRM were constructed and subjected to wide speed range testing. Simulation and test results closely follow each other and validate the effectiveness of the proposed skew design in mitigating acoustic noise and vibration in high pole count SRMs. [ABSTRACT FROM AUTHOR]

In this article, a novel model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed based on the equivalent linear SRM model and the improved switching table. First, an improved switching table with only six switching states is developed based on the inductance characteristics. The adoption of this improved switching table not only reduces the computational burden by 25% but also improves the torque control performance and system efficiency at high-speed region. However, the look-up-table (LUT) based MPTC methods suffer from occupying numerous storage space. To ease this issue, the simple linear SRM model is utilized. The flux-linkage and torque equivalent transformations are introduced to address the difference between the linear and nonlinear SRM models. With these transformations, the MPTC realized on the linear SRM model is proposed. Compared to 1530 storage units consumption to store three two-dimensional (2-D) LUTs in the LUT-based MPTC methods, the proposed method only occupies 228 storage units. Experimental results on an 8/6 SRM setup verify that the proposed method effectively eliminates the commutation torque ripple with lower execution time, less storage space, and improves the torque control performance at a high-speed range compared with the conventional LUT-based method. [ABSTRACT FROM AUTHOR]

This article presents a method to reduce the torque ripple in an 8/6 four-phase switched reluctance motor (SRM). The proposed scheme introduces a nonlinear modulating factor dependent on the rotor position and magnitude of the phase currents. This factor manipulates the currents in two adjacent phases during commutation and reduces the torque ripple effectively. Unlike the conventionally available torque-sharing functions, the proposed method instantaneously modulates every phase current obtained mathematically based on the other phase current in order to maintain the net torque constant. The proposed method requires minimal offline analysis and offers maximum possible torque with a minimal ripple. The method is simple and easy to implement due to a low computational burden. The proposed algorithm is implemented using MATLAB/Simulink software and is also validated experimentally on a 0.6-hp 8/6 SRM using a field-programmable-gate-arrays-based hardware setup developed in the laboratory. Typical results are presented and compared with the existing techniques. A torque ripple of $\approx 8\%$ has been achieved. [ABSTRACT FROM AUTHOR]

This article investigates the design methods and performance optimization of segmented-double-stator switched reluctance machine (SDS-SRM). First, two segmented U-shaped single-stator SRMs are introduced, including inner-rotor and outer-rotor constructions. In order to enhance the torque and power density, these two kinds of single-stator SRMs are combined together to constitute an SDS-SRM. Then, the relationships of torque ripple coefficient with the mechanical offset angles of the inner and outer rotor teeth are investigated to obtain the optimal rotor structure, and the corresponding conduction phase sequences for double-stator excitation mode are also analyzed. Furthermore, the flux distributions of the inner and outer stators with different coil magnetic polarities configurations are researched, and it reveals that the phase windings both on inner and outer stators with NSSNNSSN polarities have better magnetic field decoupling characteristics. To evaluate the final topology of the proposed SDS-SRM, the static magnetic characteristics and dynamic performances are presented. Finally, the SDS-SRM prototype is manufactured and tested to validate the theory and simulation analyses. [ABSTRACT FROM AUTHOR]

In this paper, an analytical method (AM) based on the air-gap magnetomotive force (MMF) permeance model is proposed to predict the nonlinear instantaneous torque of switched reluctance machines (SRMs). The analytical expression of the air-gap MMF is first obtained from the winding function and current profile, while the air-gap magnetic permeance considering the double-sided slotting effects is also derived. Then, the nonsaturated field distribution along the air-gap circumference is presented based on which the instantaneous torque can be calculated from the Lorentz force law. Furthermore, the model is enhanced with a saturation distribution factor to include the nonlinear characteristics. The proposed method is free from preliminary data or empirical coefficient and benefits from the simplified model and solution. The AM will be validated by the two-dimensional finite-element method based on four SRMs with different structures. Moreover, an SRM prototype is manufactured for experimental verification. [ABSTRACT FROM AUTHOR]

Switched reluctance motors are frequently quoted for electric and hybrid electric vehicle traction. However, high torque ripple is a common restraining disadvantage. This article proposes a design method for model following sliding mode as cruise controller, considering a direct instantaneous torque controller as part of the controlled plant. In addition, a back-electromotive force cancelation is incorporated by modifying the torque reference using the developed model. A minimum torque ripple point tracking (MTRPT) that actuates over the turn-off angle is proposed through an adaptation from the steepest descent maximum power point tracking algorithm. The turn-on angle is also controlled, aiming for enhanced torque regulation. The cruise controller is Lyapunov stable, robust to parameter variations, and is capable of rejecting load disturbances. Experimental results show that the MTRPT convergence time is around $\text{2.5 s}$ for a load step and around $\text{1.625 s}$ for a speed step. Besides, the speed tracking capability of the proposed system returns an MAE of 0.9223% and 1.0884% for the ECE-R15 and for the EUDC driving schedules, respectively. The MTRPT is capable of reducing the torque ripple by 14.6% in low speeds (ECE-R15) and by 10.1% at high speeds (EUDC). The results show that the proposed system is well founded for electric and hybrid electric vehicles applications. [ABSTRACT FROM AUTHOR]

For a permanent magnet synchronous machine (PMSM), torque ripple is a critical issue, especially under low speeds. Torque ripple minimization (TRM) control aims to find the optimal currents to be injected to cancel the existing torque ripple. In this article, we propose an optimal current modeling technique for the TRM control. In the proposed technique, torque harmonics are modeled by using a set of polynomials in which their degree parameters are determined by the theoretical torque model and their coefficients are determined by the experimental torque model. The optimal current model is derived from the identified polynomials to minimize the torque harmonics and machine loss in which there is no need of machine parameters. The proposed approach is both computation and memory efficient as the optimal currents are calculated from equations, which eliminates the need for the time-consuming optimization procedure and memory-consuming lookup table. The proposed approach is fast and efficient for the TRM control, which is critical to practical applications with fast-changing loads. Extensive experiments and comparisons are conducted on a laboratory PMSM to validate the proposed modeling technique under various operating conditions. [ABSTRACT FROM AUTHOR]

For traditional 12/8 bearingless switched reluctance motors (BSRMs), the coupling between torque and levitation increases the complexity of control. For the turbomachinery application, 2 degrees of freedom (DOF) BSRMs stabilized by extra 3-DOF active magnetic bearings are required. In this article, an improved BSRM with 4 rotor poles and 12 stator poles is proposed to realize 4-DOF radial levitation, and the torque dead zone is compensated because that two rotors and these poles are assemble with 15 mechanical degree shifted. The decoupling of torque and radial levitation is realized simultaneously. Moreover, the operation principle of axial reluctance force is analyzed for passive levitation in the axial direction. Various experiments were completed to verify the performance of the proposed BSRM, and the prototype achieved stable levitation of the rotor in 10 000 r/min. [ABSTRACT FROM AUTHOR]

This article proposes an online torque ripple minimization (TRM) technique using a fuzzy system (FS)-based d-axis current design for interior permanent magnet synchronous motor (IPMSM) drives. Existing control-based TRM techniques generally employ optimization algorithms to design the dq-axis currents that attenuate the torque ripples. However, complex iterations applied for the optimization algorithms increase computational complexity, which limits the applicability of such TRM techniques under transient state of the IPMSM drives. Unlike with existing methods, the proposed TRM technique designs reference d-axis current using a computationally efficient algorithm and remarkably minimizes the torque ripples. Moreover, the reference d-axis current is designed online based on an FS to keep the stator current of the IPMSM inside the rated value, especially at the transient state. The proposed TRM strategy is validated through simulation and experimental investigations by using a MATLAB/Simulink software and a prototype IPMSM drive with TI TMS320F28335 digital signal processor. Comparative theoretical and experimental investigations prove that the proposed TRM technique is computationally efficient and ensures more reduced ripples in the electromagnetic torque and dq-axis currents with d-axis current significantly close to zero than conventional maximum torque per ampere based technique without TRM and conventional current control-based TRM technique under critical load conditions. [ABSTRACT FROM AUTHOR]

In this article, a new torque sharing function (TSF) method is proposed for torque ripple reduction in switched reluctance machines (SRMs). The proposed TSF achieves lower current tracking error by establishing a new current reference generation strategy. The phase current reference is first derived from the torque command using offline calculations and also from the phase current response that is obtained from the dynamic model of the SRM. Then, an optimization problem is formulated to shape the current reference for the objective of minimizing the torque ripple and copper losses, while maintaining the required average output torque at the given operating speed. The dynamic simulation of the SRM model is also utilized in the optimization problem. Compared to the existing conventional and optimization-based TSFs, the proposed TSF exhibits lower current tracking error due to the consideration of the current dynamics. Better torque–speed performance with improved average torque and reduced torque ripple is also obtained, especially during commutation. Simulations and experiments under different operating conditions are carried out to verify the proposed TSF method. [ABSTRACT FROM AUTHOR]

In this article, an improved direct instantaneous torque control (DITC) based on adaptive terminal sliding mode control (ATSMC) is proposed to suppress torque ripple and enhance the anti-interference ability for switched reluctance motors (SRMs). The proposed speed controller used in the outer loop of DITC is based on the rate of change in load torque. The state of the system converges quickly to the equilibrium point and realizes fast output of the given torque without known disturbance upper bound. Moreover, a novel reaching law is proposed to reduce torque ripple and startup time. The stability of the adaptive terminal sliding mode motion is verified by using the Lyapunov function. The improved DITC system is implemented on a 16/10 segmented-rotor SRM. Compared with sliding mode control and terminal sliding mode control, the proposed ATSMC in the DITC system behave with better performances in aspects of the speed and torque response, antiinterference ability, robustness, and torque ripple suppression. Simulation and experimental results are given to verify the effectiveness of the improved DITC. [ABSTRACT FROM AUTHOR]

In order to combine the advantages of modularity and hybrid-excitation for motor torque and power density enhancement, this article proposes a 12/4 modular-topology, permanent magnet (PM) assist, hybrid-excitation switched reluctance machine (HESRM) with both segmented-stator and -rotor. The machine topology and basic operating principle are presented. Three key parameters of the machine are optimized for assessment on the torque production. The three-dimensional finite-element analysis is employed to consider the effects of end winding and core saturation. The static magnetic characteristics and dynamic performances are simulated and compared with a 12/4 segmented SRM (SSRM) without PM and a 12/10 segmented-stator HESRM. Two prototypes of the proposed 12/4 HESRM and a 12/10 segmented-stator HESRM with the same size are manufactured and developed for experimental verification. Both results show that the proposed motor can achieve higher dynamic average torque and higher power/torque density at high-speed operation. It also has a stronger starting capability, more rapid response for command changes, as well as better stability and tracking features. [ABSTRACT FROM AUTHOR]

The industrial application of the switched reluctance motor (SRM) is limited by its high torque ripples caused by the doubly salient structure. In this article, an improved direct torque control (DTC) with sliding mode controller and observer is developed to reduce the torque ripples of a four-phase SRM. First, a sliding mode controller based on a new reaching law is developed for designing a sliding mode speed controller (SMSC) for the DTC system. An antidisturbance sliding mode observer (ADSMO) is then proposed and combined with the SMSC to build a composite antidisturbance speed control strategy. Moreover, detailed simulation validations are carried out to reveal the effectiveness of the new reaching law, SMSC and ADSMO. Finally, experiments are conducted to verify the performance of the proposed SMSC–ADSMO in a DTC system with a four-phase SRM prototype. [ABSTRACT FROM AUTHOR]

This article proposes an optimized direct instantaneous torque control (DITC) scheme for switched reluctance motor (SRM) drives with a novel adaptive dynamic commutation strategy, which can effectively reduce torque ripple and improve system efficiency. To minimize torque ripple, two operational modes are developed for torque tracking during commutation regions. In Mode I, the torque error is compensated by the outgoing phase during the current buildup region of the incoming phase; in Mode II, the torque error is compensated by the incoming phase during the demagnetization region of the outgoing phase. To implement the proposed DITC scheme in a more effective conduction range, the commutation instants are dynamically adjusted according to the varied operation conditions. For each phase, the turn-on and turn-off angles are modified in each electrical cycle by a torque error regulator and a phase current endpoint detector, respectively. By employing the proposed strategy, the torque generation capability is fully utilized for minimized torque ripple, and the phase currents work within a more effective conduction range for improved system efficiency. The simulation and experiments on a three-phase 12/8 SRM are carried out to verify the feasibility and effectiveness. [ABSTRACT FROM AUTHOR]

Permanent magnets (PMs) have been widely used in different types of electrical machines to improve their performance. This article introduces a novel multi-tooth hybrid-excited switched reluctance motor (MT-HESRM) with PMs placed between the end teeth of the adjacent modules. Thanks to the innovative method of embedding PMs, a unique design is developed. First, the operating principle of the motor is explained, and the magnetic circuit model of the motor is analyzed. The magnetic characteristics in terms of flux density, flux linkage, inductance, and torque are obtained and compared with those of its PM-less counterpart. The mathematical model of the reluctance and PM torques is presented. The reluctance and PM torques are decoupled using the finite-element analysis, and the torque contribution of the PMs is discussed. The steady-state operations of both motors with both current chopping and single-pulse controls are analyzed and compared under different speeds. Finally, both motors are manufactured, the laboratory tests are done, and the experimental results are extracted. Both the simulation and test results elucidate that the MT-HESRM, which has only three small PMs as auxiliary flux sources, has unique features in terms of high output power and torque with a negligible cogging torque. [ABSTRACT FROM AUTHOR]

In order to increase structure compactness, critical rotor speed, and output torque of existing 12/12 bearingless switched reluctance motor (BSRM) with axial-biased permanent magnet, an improved modular permanent magnet BSRM is comprehensively investigated. First, basic structure and operation principle for torque and suspending force are briefly introduced. Second, magnetic design, including torque and suspending force, is taken into account. In addition, basic size estimation, self-starting capability, maximum suspending force, and selection of secondary air-gap are comprehensively considered in design. Third, several characteristics, such as torque, suspending force, etc., are deeply analyzed. Finally, a prototype motor is manufactured based on the above-mentioned analysis and design method. And the implemented experiment results show that the improved structure has good performance. [ABSTRACT FROM AUTHOR]

To effectively find an optimal solution in the development process of electrical machines, it is essential to predict machine iron loss and thermal behavior in the predesign stage. Most existing publications only consider thermal behavior by roughly limiting the maximum current density. However, especially for high-speed application, iron loss can also be an essential part in thermal-behavior estimation. This paper proposes a simplified model to efficiently calculate iron loss and thermal behavior in the design procedure of switched reluctance machines. For this purpose, a maximum coenergy 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. Besides, a simplified lumped parameter thermal network is applied for machine sizing. Furthermore, the impact of number of turns and peak magnetomotive force on the losses and machine sizing is discussed. The efficiency and power density of various machine geometries are comparatively analyzed. Finally, the accuracy of the simplified model is verified by comparison with finite element simulations and experiment results. [ABSTRACT FROM AUTHOR]

This paper proposes a promising cost-effective phase current detection scheme for different multiphase switched reluctance motors (SRMs) by employing the multiplexed current sensors. According to the phase current characteristics for the odd-numbered multiphase SRM with m phases and even-numbered multiphase SRM with n phases, the phase windings are specially divided into (m + 1)/2 and n/2 groups, respectively, and each group shares one Hall-effect current sensor. By building the matrix functions to express the relationship between phase currents and sensor currents, the phase currents can be calculated in real time with a simple algorithm and fewer current sensors. Compared to existing phase current detection schemes, the developed method has high universality and can achieve the intact phase current detection without losing any excitation, freewheeling, and demagnetization currents. Moreover, the presented method is easy to implement without any converter change and pulse injection, which shows great potential for massive industrial application to avoid the voltage penalty, current distortion, higher switching loss, and further electromagnetic interference issues. The simulation and experiments are carried out to validate the feasibility and effectiveness of the developed phase current detection scheme. [ABSTRACT FROM AUTHOR]

The direct torque control (DTC) method was introduced into the switched reluctance motor to reduce its inherent output torque ripple. However, the conventional DTC method produces negative torque more or less, which reduces the torque–ampere ratio of motors. This paper proposes a new DTC method by three improvements. First, the hysteresis-loop control of flux is removed. New selection rule of voltage vectors is established to reduce the torque ripple. Second, the sectors divided in electrical space are reorganized by their actual positions according to the inductance profile. The boundaries between certain sectors are calculated and updated according to real-time working conditions. Finally, the alternative voltage vectors for increasing or decreasing torque are distinguished by whether any phase is excited. Therefore, the output torque tracks the reference accurately, which reduces the torque ripple. Moreover, the negative torque is avoided by the real-time regulation of the turn-off angle, and the torque–ampere ratio is increased accordingly. Simulation and experimental results verify the demonstrated performance of the proposed DTC method. [ABSTRACT FROM AUTHOR]

In this paper, a unified controller for switched reluctance motors is proposed for wide speed operations. The proposed controller achieves minimum output torque ripple at low and medium speeds and operates in a single-pulse mode at high speeds. Overlapping regions between the phases are controlled such that direct instantaneous torque control (DITC) and current control (CC) can be implemented simultaneously on different phases. This simplifies the torque sharing during commutation and minimizes torque ripple due to imperfect current tracking and mutual torque. A demagnetization curve concept to demagnetize the phase currents at an optimum angle is introduced to ensure high torque per ampere and single-pulse mode operation. This results in extending low ripple operation to medium speed ranges. The seamless combination of DITC, CC, and the demagnetization curves leads to torque ripple minimization, automatic excitation angle control, and smooth operation over a wide speed range. The effectiveness of the proposed unified controller is verified through simulation and experimental studies. [ABSTRACT FROM AUTHOR]

This paper proposes a new position sensorless method for a direct torque control system using the inductance inflection point of a switched reluctance motor (SRM). The SRM essentially requires knowledge of the rotor position in the torque control system; this is because it generates torque by exciting the stator windings according to the rotor position. This rotor position information is an important factor used to obtain phase commutation point and to calculate instantaneous torque. Various rotor position detection methods have been used, but most of the methods increase the construction cost by requiring additional hardware and use many parameters for high-order analysis modeling, causing problems such as increasing the number of calculations. Therefore, in this paper, we propose a method using the inductance inflection point to solve these problems. It is possible to estimate the position of the rotor by detecting where the inductance inflection point occurs due to the rotor and stator overlapping with each other, and the phase commutation point and instantaneous torque can be calculated. The calculated instantaneous torque is used for direct torque control and torque ripple reduction through the torque-sharing function. The proposed method is verified through simulation and experiments. [ABSTRACT FROM AUTHOR]

In order to improve the performances of switched reluctance machines (SRMs), such as torque production and power density, combining segmented structure and hybrid-excitation is a proper and useful method. This paper develops a kind of segmented-stator hybrid-excitation SRMs (SS-HESRMs) assisted with permanent magnets (PMs) and investigates on them with different rotor pole numbers. To evaluate the effects of different rotor topologies, the static magnetic characteristics and dynamic performances of two SS-HESRMs with 12/10 and 12/8 poles are briefly presented. Moreover, both SS-HESRMs are compared with two segmented-stator SRMs (SS-SRMs) which have the same basic structure and stator/rotor pole combinations but without PMs. The results reveal that SS-HESRMs produce higher electromagnetic torque than SS-SRMs with the same stator/rotor pole configuration. The 12/10 SS-HESRM exhibits better characteristics, such as higher dynamic average torque, lower torque ripple, and higher power/torque density, than the 12/8 SS-HESRM at low-speed operation. While at high speed, the 12/8 SS-HESRM exhibits better characteristics than 12/10 SS-HESRM. The 12/10 SS-HESRM has stronger starting capability but lower steady-state speed under the same starting condition. Finally, a 12/10 SS-HESRM and a 12/8 SS-HESRM with the same structure and size are prototyped and tested to confirm the predictions. [ABSTRACT FROM PUBLISHER]

In this paper, an improved winding current control scheme for switched-reluctance motor drive is developed and evaluated. The current feedback controller (CFBC) is augmented with an observed back electromotive force (EMF) current feedforward controller (CFFC) and a current tracking error adapted dynamic commutation shift controller (DCSC). In the proposed DCSC, the rising winding current tracking errors of all phases are extracted, synthesized, and processed to generate the suitable advanced commutation shift angle. The effects of motor back EMF and nonlinear winding inductance can be reduced to yield improved winding current tracking waveforms under a wide operation range. The gradual improvements in current responses and efficiencies by augmenting the CFBC with the CFFC and then the DCSC are verified experimentally. Then, the robust speed control scheme is properly designed to achieve good acceleration/deceleration, reversible running, and dynamic characteristics. [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]

Recently, bearingless switched reluctance motor (BLSRM) has been received more and more attention. To realize the stable levitation and rotation, the corresponding suspending force and torque should be controlled. In this paper, different from the conventional bearingless SRM control, one independent control scheme for levitation force and torque is presented. In the control, a complex control algorithm based on a lookup table is not needed. Torque control is separated from radial force control, and each channel of radial force is independently controlled. Therefore, the control is very simple to be implemented. First, based on the brief introduction of the BLSRM structure and operating principle, the mathematical relationship of levitation force with respect to current and displacement is derived. Furthermore, the rotor dynamics model, in which levitation force in four degrees of freedom is considered, is established. Based on the given analysis, the digital control system, which includes torque and suspending force, is designed by means of TMS320F28335, and an experimental platform is established. According to the experimental results, the proposed BLSRM can be steadily levitated in the static and rotating conditions. [ABSTRACT FROM PUBLISHER]

A switched reluctance motor has been designed with identical outer dimensions, maximum torque, operating area, and maximum efficiency as rare-earth permanent-magnet motors used in the Toyota Prius. In this paper, a test machine has been constructed, and test results are presented over the entire speed range. The targets are torque of 207 \N\cdot\m, a shaft output of 60 kW, and the maximum efficiency of 96%, as well as a speed range of 2768–13 900 r/min with an output of 60 kW and an outer diameter and an axial length of 264 and 112 mm, respectively. It is found that a shaft output of 100 kW is possible at high rotational speed under the voltage and current ratings. The possible operation area in a torque–speed plane is found to be enhanced. It is also found that the design stage prediction is close to the test results, except in two operation regions. [ABSTRACT FROM PUBLISHER]

This paper presents the numerical modeling of a classical switched reluctance motor (SRM) and a mutually coupled SRM (MCSRM); both have three phases with 12 slots and 8 poles. The multiphysics models have been developed, which can take into account the electromagnetic characteristics, mechanical vibration, and acoustic noise of the foregoing machines. A 2-D electromagnetic model has been used to calculate the magnetic force which is the main source of vibration of the entire motor system. The vibration of the motor is calculated by a mode superposition method, while the acoustic noise is predicted by a 3-D finite-element acoustic model. In order to validate the numerical models, experiments have been carried out. A good agreement between measured and numerical results has been observed, and it is found that the vibration and the noise levels of MCSRM are considerably lower than those of classical SRM. [ABSTRACT FROM PUBLISHER]

In this paper, a novel type of hybrid reluctance motor (HRM) drive is presented. This new motor is characterized by a stator formed by a combination of independent magnetic structures, each one composed of an electromagnet, the magnetic core with one or several coils wound on it, associated with a permanent magnet disposed between their poles. The rotor has the same configuration of a switched reluctance motor (SRM) without any coil, magnets, or squirrel cage. A particular case of this HRM, with three electromagnets with permanent magnets in the stator and five salient poles in the rotor, is studied. The motor is then analyzed and simulated. Finally, experimental results are given, and this type of motor drive is compared with the SRM drives of the same size. This new type of HRM does not present cogging torque and has higher power and efficiency than an SRM of the same size. [ABSTRACT FROM PUBLISHER]

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]

Switched reluctance motors (SRMs) have ease of manufacturing, low cost, and robustness in withstanding centrifugal force advantages. Therefore, they are very suitable for high-speed applications. However, when running at high speeds, rapid braking becomes difficult because the regeneration energy may increase the dc-link voltage to a critical level if a diode rectifier bridge is used for ac–dc conversion. This paper investigates the relationship between the regeneration energy and the dc-link voltage and proposes an electric braking scheme employing two-phase excitations. During braking, instead of regenerating the excessive rotor kinetic energy back to the dc link, the energy is dissipated in the stator winding resistance. Therefore, the rotor can stop safely within a short time. The proposed control scheme is verified experimentally using a four-phase SRM. [ABSTRACT FROM PUBLISHER]

Switched reluctance machine (SRM) has been viewed as a low-cost machine with concentrated windings on the stator and no magnetic source on the rotor. Owing to the higher torque-production capability with lower ripple, an SRM with a higher number of rotor poles is a potential candidate for traction applications in hybrid and plug-in hybrid electric vehicles. However, since external phase commutation and rotor-position detection are necessary to run the SRM, its control can be challenging. In case of an SRM with a higher number of rotor poles, each phase is energized more frequently in one revolution, and the current conduction time is shorter due to the smaller interpolar gap between rotor poles. This paper investigates potential control complexity owing to the higher number of rotor poles, self-starting, and fault tolerance of the machine. A 5-hp drivetrain with a three-phase 6/10 SRM has been developed for traction application. Conventional current and speed controls have been implemented to experimentally evaluate the dynamic performance of the new family of SRMs. It has been shown that the 6/10 SRM is capable of operating even if two of its phases develop a fault. Moreover, the 6/10 SRM is capable of starting by itself with an initial hard alignment when only two phases are operating. [ABSTRACT FROM PUBLISHER]

Some types of bearingless switched reluctance motors (BSRMs) have been developed up to now. Their differences mainly focus on different stator-rotor tooth number and winding structures: two layers of windings and single layer of windings for 12/8 or 8/6 BSRM. Their driving principles are just the same: driving current and radial force current are regulated to generate torque and radial force separately. The main difference is the loading of two currents on one single layer of windings or on two separate layers of windings. Further analysis proves that single layer winding structure has more advantages, for example simpler motor and winding structure. Based on the above researches, one 8/6 BSRM with simpler single layer of winding structure has been developed furthermore. Its main characteristic is that the total winding number of motor is decreased from eight to six, which is only two more than four windings of a normal 8/6 SRM. Only six converters are demanded to achieve levitation operation. Its special driving theory and speed regulation technique of the motor by applying three phase windings have been introduced. To testify the new idea, theoretical analysis and practical test have been finished for one test motor. One initial speed of 5000 r/min of levitation operation has been achieved. [ABSTRACT FROM PUBLISHER]