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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]

In this article, a general-purpose low-speed position estimation scheme using pulse injection is proposed for sensorless switched reluctance motor (SRM) drives. For the conventional low-speed sensorless control methods, magnetic characteristics are often used for position estimation, but it requires offline measurement and reduces the generality of sensorless control algorithms. To solve the issue, a new position estimator based on a regional phase-locked loop (RPLL) is designed. The approach utilizes a self-commissioning process to capture the unsaturated inductance adaptively at the initial stage. The RPLL is then adopted to estimate the full-cycle rotor position from the idle-phase inductance during sensorless operation. The speed-reversible sensorless control capability is also realized by a simple heterodyne design. Furthermore, stability analyses and parameter design are given to prove the robust local stability and convergence. Finally, comparative experimental validation is conducted on a 5.5-kW 12/8 SRM setup to verify the proposed method's effectiveness under both no-load and load conditions. [ABSTRACT FROM AUTHOR]

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

This article from a discrete-time model and stability analysis is developed using a Lyapunov approach, taking into account the one sample implementation delay present in digital control applications. Experimental results are provided to demonstrate the effectiveness of the proposed approach, where a conventional hysteresis controller is used as a benchmark. Results show that the proposal is able to deliver adequate reference tracking while using significantly lower sampling frequencies. Moreover, when compared to the hysteresis controller, superior tracking is observed at low speeds, while maintaining a similar level of computational complexity. [ABSTRACT FROM AUTHOR]

In order to maximize the reluctance torque component, multiple-layer flux barriers are usually employed in permanent magnet-assisted synchronous reluctance (PMAREL) motors. However, the permanent magnet (PM) dimension of each layer should be carefully designed to achieve the best performance with the minimum PM material. This article investigates this issue and proposes a method to define the PM width according to the sinusoidal no-load airgap flux density distribution. First, the accuracy of the no-load magnetic circuit for airgap flux density calculation is verified with finite element analysis (FEA), considering single or multiple flux-barriers per pole. The effects of the location, width, and thickness of the PM are investigated separately. Then the PM width is derived by the equations developed from the no-load magnetic circuit. The proposed method reduces both the PM mass and the torque ripple. This approach provides a fast and efficient way to determine the width of the magnets in different layers of flux barriers. [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, a time-efficient torque shaping technique for the switched reluctance machines is proposed to reduce the torque ripples while optimizing the copper loss. To reduce the computational time for solving the time-consuming bi-objective optimization problem, an efficient and desirable linear space for the SRM is utilized through the torque mapping between the linear space and nonlinear space. The feasible regions and properties of this torque mapping for SRM are studied in detail first. Then, based on this torque mapping, the current reference is generated by solving a convex optimization problem in the linear space and later converted to the current reference in nonlinear space. Compared to the traditional method that only adopts nonlinear space, the proposed current reference generation method requires less than 10% of the time. Furthermore, the proposed method saves more than 70% time consumed by the traditional method for the bi-objective optimization problem but possesses the similar torque ripple reduction performance. The effectiveness of the proposed method has been verified by extensive simulation and experimental tests on a four-phase 5.1 kW 8/6 SRM setup. [ABSTRACT FROM AUTHOR]

The article proposes a nonlinear state observer (NSO) for robust position-sensorless control of switched reluctance motor (SRM) drives over medium- and high-speed range. A classical reference flux-linkage method is adopted to capture a feature position of the SRM, which avoids the use of 3-D magnetic characteristics and has better universality. However, the estimation accuracy of this method would be deteriorated due to flux-linkage errors. To ease the problem, the NSO is developed to enhance the robustness against flux-linkage distortions for more accurate position and speed estimation. This observer can first reconstruct complete position information from a low-resolution feature position. The adverse impact of flux-linkage errors on position estimation is then investigated through a novel small-signal approximation and suppressed by an augmented state estimator. Afterward, a parameter design scheme is given to ensure the observer's stability and improve the capability in distortion suppression. To baseline the performance, comparative experimental validation between the proposed NSO and a widely used linear prediction method is conducted on a 12/8 SRM setup. The results show that the proposed strategy can improve the overall position-sensorless control performance in both the steady and transient states. [ABSTRACT FROM AUTHOR]

This paper makes the case that Switched Reluctance Motor (SRM) is an exceptionally attractive technology to respond to the increasing demand in propulsion applications for high-efficiency, high-performance, and low-cost motors with a more secure supply chain. The paper also presents methods to effectively reduce torque ripple and acoustic noise, which have been the major issues impeding the widespread use of SRMs. Finally, SRM designs for two propulsion motors, one for an e-bike and the other for a hybrid electric vehicle application, are presented which have been proposed to replace permanent magnet machines. [ABSTRACT FROM AUTHOR]

In this paper, a concentrated‐wound exterior‐rotor direct‐drive electric bicycle (e‐bike) mutually coupled switched reluctance motor (MCSRM) has been designed to match the performance parameters and dimensional constraints of a commercially available permanent magnet e‐bike motor. Different stator and rotor pole configurations are compared for a 3‐phase MCSRM. During the design process, many parameters have been evaluated and analysed. The finalised performance capabilities of all pole configurations are summarised, and the choice of pole configuration for the final design is justified. The full dynamic torque‐speed performance of the finalised 15/10 MCSRM is presented, along with a detailed thermal analysis. Finally, the MCSRM performance is compared to a 12/16 non‐coupled SRM and a commercially available permanent magnet motor. [ABSTRACT FROM AUTHOR]

In this paper, an exterior-rotor direct-drive electric bicycle (E-Bike) switched reluctance motor has been designed, based on the performance parameters and dimensional constraints of a commercially available permanent magnet e-bike motor. Motor dimensions have been adjusted to find the best balance between power factor and motor efficiency. The efficiency maps for different rotor pole configurations are compared for 3-phase SRMs with 12 stator poles. The firing angles for each efficiency map operating point are optimized using multi-objective Genetic Algorithm optimization. During the design process, several design parameters have been evaluated and their effects have been investigated. The final design characteristics of the 12/16 SRM e-bike motor are validated experimentally. [ABSTRACT FROM AUTHOR]

This work investigates the application of the adjoint variable method (AVM) to switched reluctance motors (SRMs). A MATLAB toolbox developed by the authors estimates the sensitivities of the required objective function with respect to different geometric design parameters using at most one adjoint simulation. In this work, the AVM evaluates the sensitivities of the x and y components of the magnetic flux density, the phase flux linkage, and the electromagnetic torque of switched reluctance motors with respect to teeth height, yoke thickness, teeth pole arc angle, and teeth taper angle of both stator and rotor. The nonlinearity of the motor magnetic material is taken into consideration. The estimated sensitivities using AVM are compared with those obtained using the more accurate but time intensive central finite differences (CFD). An interior-point optimization algorithm utilizes the sensitivities of the electromagnetic torque of an SRM to maximize the motor static torque profile. Structural mapping technique is used to control the geometric design parameters through the optimization process. [ABSTRACT FROM AUTHOR]

Robustness, simple construction, and low cost are some of the advantages of switched reluctance machines (SRMs). These are all desirable characteristics of an electric motor, especially in the automotive sector, where high-temperature and high-speed operation, and low cost are always in demand. However, the acoustic noise generation by conventionally controlled SRMs can prevent its use in applications where acoustic comfort is required. Acoustic noise is radiated by the stator frame when a vibration mode is excited by the respective spatial order at a forcing frequency that is close to the stator's modal natural frequency. The excitation surface wave is the radial force density waveform, which is a function of time and spatial position. In this paper, a phase radial force shaping method is proposed by using harmonic content analysis. A generic function for the radial force shape is identified, whose parameters are calculated by an optimization algorithm to minimize the torque ripple for a given average torque. From the phase radial force profile, a current reference is obtained. The proposed methodology is experimentally validated with a four-phase 8/6 SRM through acoustic noise measurements at different speed and load conditions. [ABSTRACT FROM AUTHOR]

An offline torque sharing function (TSF) is introduced in this paper for torque ripple reduction in switched reluctance machines (SRM). This TSF uses static flux linkage characteristics of the machine obtained from finite element analysis or experiments that describe the machine dynamics to determine optimal current profiles such that the torque ripple reduction is achieved with minimal copper losses. Due to this feature, the proposed TSF performs well across a wide speed range. Additionally, the objective function of the proposed TSF uses only one weight parameter, which facilitates the use of this TSF. In this paper, an intuitive justification for the selection of this weight parameter is given, and the performance of this TSF is validated in simulation and experimentally on a 5.2 kW, four phase SRM. To baseline its performance, the proposed TSF has been compared to the offline TSF in the literature, which shows that it has better current tracking performance at higher speeds due to the inclusion of flux linkage characteristics. Finally, it has been compared to conduction angle control at speeds above the base speed to show that it can be a viable alternative for the control of SRM even in an operation region normally not considered for TSF. [ABSTRACT FROM AUTHOR]

This paper proposes the design and development of an external rotor permanent magnet in-wheel motor for an electric bicycle application. The proposed machine utilizes V-shape magnets embedded in the external rotor to achieve enhanced magnetic flux concentration and, hence, high torque and power output. Detailed design principles and performance characteristics of the proposed machine are comprehensively evaluated with finite element analysis. Various design concerns are further investigated to ensure machine rigidity and operational safety. Finally, this paper validates the design concept with a prototype machine. High torque and high power output are achieved and the experimental results confirm the design simulations with good agreement. [ABSTRACT FROM AUTHOR]

In this work, we report on the application of the adjoint variable method (AVM) to sensitivity analysis of switched reluctance motors (SRMs). Using at most one adjoint simulation, the sensitivities of the desired response with respect to all geometrical and material parameters are estimated. In this work, the AVM evaluates the sensitivities of the air region magnetic energy and the electromagnetic torque of a SRM with respect to all parameters. Good match is achieved between the AVM sensitivities and those estimated using the more accurate but computationally expensive central finite differences (CFD). [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]

An asymmetric three-level neutral point diode clamped converter for switched reluctance motor drives is proposed in this paper. The modulation method, the dc-link voltage balancing algorithm, and the current control scheme of this converter are presented. The proposed three-level converter is compared with the conventional two-level asymmetric half-bridge converter in terms of cost, current ripple, noise, and power losses. Compared to the conventional two-level converter, the proposed three-level converter has much lower current ripple, lower noise, and higher efficiency. The effectiveness of the proposed converter is verified by both simulation and experimental results. [ABSTRACT FROM AUTHOR]

This study introduces an optimisation-based procedure for characterising switched reluctance machine (SRM) performance and studies the optimisation to determine the conduction angles in SRM drives. The objectives employed in the optimisation cases are maximising average output torque, maximising the ratio of average torque over root mean square (RMS) value of phase current, and minimising RMS value of net torque ripple. Combinations of these objectives are used in four different cases, which are formulated either as single- or multi-objective problems. These cases are then compared in terms of output torque, torque ripple, and efficiency. One method of the four is selected and the performance of the motor over the entire operating range is characterised based on optimised turn-on and turn-off angles. Experimental results are used to verify the motor performance obtained from the optimisations for selected operating points. [ABSTRACT FROM AUTHOR]

This paper presents a method to calculate the acoustic noise of conventional switched reluctance motor (CSRM) and mutually coupled switched reluctance motor (MCSRM). This method is based on dynamic electromagnetic models, combined with analytical estimation of the stator eigenmodes and radiation efficiency, considering the switching effects and frame effects. The proposed method is applied to predict and compare the acoustic noise performances of a CSRM and an MCSRM in a wide speed range. The results are validated using commercial finite element analysis software, JMAG for electromagnetics and ACTRAN for acoustics. An acceleration test based on a setup with a 12/8 CSRM is used for experimental validation. Results show that the proposed method can provide reliable prediction of main acoustic noises during acceleration. [ABSTRACT FROM PUBLISHER]

In this paper, a new position sensorless control method for switched reluctance motor drives is proposed. Rotor position is initially calculated based on the flux linkage-position–phase current characteristics by numerical method. Then, a third-order-phase-locked loop considering the acceleration variation is designed to undermine the impact of current sampling noise and numerical residual error on the estimated rotor position. A new start-up sequence is proposed. Simulation and experimental results show that the proposed position sensorless control method has achieved sufficient accuracy in terms of position and speed estimation. [ABSTRACT FROM PUBLISHER]

In external‐rotor electric machine configurations, the rotor can be the major source of noise. This study analyses the distribution and the effects of radial forces and vibration in a 6/10 external‐rotor switched reluctance motor designed for an E‐bike application. The distribution of the electromagnetic force vector depends on the switching sequence, the geometry of the motor and the direction of rotation. Therefore, the effect of the switching strategy on the rotor radial force waveform has been analysed. It is shown that adjusting the turn‐on angle can reduce the high rate of change of radial force waveform at the pole corners. The effect of switching angles on the reduction of rotor vibration has also been examined. [ABSTRACT FROM AUTHOR]

In this paper, a PWM current controller for the switched reluctance motor drives is proposed and digitally implemented. Parameter adaption is employed to guarantee both fast dynamics and robustness of the proposed current controller. The relationship between the proposed controller and the conventional controllers including PI and dead-beat controller is also presented. An improved sampling method is designed to avoid PWM delay in the control loop. Simulation and experimental results show that the proposed controller keeps similar dynamic response and accuracy as hysteresis controller under various testing conditions. However, compared with the hysteresis controller, the proposed current controller needs much lower sampling rate and has a constant switching frequency. [ABSTRACT FROM AUTHOR]

This paper examines the effect of frame on the acoustic noise and vibration of a high-speed and high-power switched reluctance machine (SRM). Five types of frame/ribs are investigated, where different frame thicknesses, types of cooling ribs, and frame shapes have been analyzed. For this purpose, a 12/8 SRM has been designed at 22 000 r/min and 150 kW and two stages have been applied. In the first stage, a new equivalent stiffness of the frame is utilized in order to estimate the resonant frequencies for different frame shapes. The paper provides a mathematical calculation method and evaluates its effectiveness with finite-element simulations. The results indicate an improvement between 4% and 25% in the estimation natural frequencies. The second stage includes the vibration and acoustic noise analysis using 3-D finite-element method. Considerations for acoustic noise reduction in high-speed SRM using different frame types and cooling ribs are discussed. Particularly, radial and screw-type configurations represent a better solution to decrease the sound pressure level up to 12 dB. [ABSTRACT FROM PUBLISHER]

A new toroidally wound switched reluctance machine (TSRM) with a single continuous multitapped winding is presented. This machine may be driven by a 6-switch asymmetric converter that supplies unipolar coil currents or by a 12-switch voltage source converter that supplies bipolar coil currents. The TSRM magnetic design and power electronic control is described, and its performance is compared with a conventional switched reluctance motor (CSRM) and with a previously reported toroidal format switched reluctance machine that utilizes six discrete winding coils in a three-phase wye connection (WSRM) driven by a voltage source inverter. A fixed 6–4 CSRM magnetic circuit design is selected for the comparative analysis of the three machine topologies by static and dynamic finite-element simulations. [ABSTRACT FROM AUTHOR]

With the era of modern vehicle electrification, electric machines with high traction torque–speed output and compact volume are highly desired. This paper presents a family of switched reluctance machine configurations that are composed of double rotors and one stator integrated in one machine housing. The machines are potentially more compact and lower cost, while providing two independent mechanical outputs suitable for hybrid electric vehicle transmissions. The detailed design process of a double-rotor switched reluctance machine (DRSRM) is presented, comprising of analytical calculations, finite-element field analysis, and full-drive system simulation. Additionally, some optimizations are applied to maximize the machine performance and minimize the machine weight and volume. A scaled prototype machine is designed and built according to chosen vehicle drive cycles to evaluate and validate the DRSRM prototype. [ABSTRACT FROM AUTHOR]

In this paper, an offline torque sharing function (TSF) for torque ripple reduction in switched reluctance motor (SRM) drives over a wide speed range is proposed. The objective function of an offline TSF is composed of two secondary objectives with a Tikhonov factor to minimize the square of the phase current (copper loss) and derivatives of current references (rate of change of flux linkage). The proposed TSFs with different Tikhonov factors are compared with the conventional TSFs including linear, cubic, and exponential TSFs in terms of efficiency and torque–speed performance while operating in both magnetic linear and saturation regions. Then, the Tikhonov factor is selected based on a tradeoff between the copper loss and torque–speed performance. The maximum torque-ripple-free speed of the selected offline TSF is validated to be seven times as high as the best case in these conventional TSFs. The performance of the offline TSF is verified by simulations and experiments with a 2.3-kW, three-phase 12/8 SRM. Results show that the proposed offline TSF can significantly reduce the torque ripple of SRM without increasing copper loss over a wide speed range. [ABSTRACT FROM AUTHOR]

In this paper, a fast and accurate analytical method is proposed to analyze the loss and efficiency of switched reluctance machines (SRMs) under various operating conditions. The analyses are applied on a four-phase 16/12 SRM with high power density and wide speed range, which was designed for traction application. A direct method is proposed to calculate hysteresis and eddy current loss without empirical equations. The machine is discretized into a limited number of elements according to the magnetic flux density distribution using an analytical magnetic circuit method. Variable loss coefficients are used for each element to improve the accuracy. The developed method has been validated with simulation and experimental results. [ABSTRACT FROM PUBLISHER]

An approach to eliminate mutual flux effect on rotor position estimation of switched reluctance motor drives at rotating shaft conditions without a prior knowledge of mutual flux is proposed in this paper. Neglecting the magnetic saturation, the operation of conventional self-inductance estimation using phase current slope difference method can be classified into three modes: Mode I, II, and III. At positive-current-slope and negative-current-slope sampling point of one phase, the sign of current slope of the other phase changes in Mode I and II, but does not change in Mode III. Theoretically, based on characteristics of a 2.3 kW, 6000 rpm, three-phase 12/8 SRM, mutual flux introduces a maximum ±7% self-inductance estimation error in Mode I and II, while, in Mode III, mutual flux effect does not exist. Therefore, in order to ensure that self-inductance estimation is working in Mode III exclusively, two methods are proposed: variable-hysteresis-band current control for the incoming phase and variable-sampling self-inductance estimation for the outgoing phase. Compared with the conventional method which neglects mutual flux effect, the proposed position estimation method demonstrates an improvement in position estimation accuracy by 2°. The simulations and experiments with the studied motor validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, an extended-speed low-ripple torque control of switched reluctance motor (SRM) drives using torque sharing function (TSF) is proposed. Two operational modes are defined for the online TSF during commutation: In Mode I, absolute value of rate of change of flux linkage (ARCFL) of incoming phase is higher than outgoing phase; in Mode II, ARCFL of outgoing phase is higher than incoming phase. In order to compensate the torque error produced by imperfect tracking of phase current, a proportional and integral compensator with torque error is added to the torque reference of outgoing phase in Mode I and incoming phase in Mode II. Therefore, the total torque is determined by the phase with lower ARCFL rather than the phase with higher ARCFL as in conventional TSFs. The maximum torque-ripple-free speed of the proposed TSF is increased to more than ten times as the best case in conventional TSFs. Finally, the proposed TSF is verified by both simulations and experiments with a 2.3 kW, 6000 rpm, three-phase 12/8 SRM operating in both linear magnetic and saturated magnetic regions. Results show that the proposed TSF has higher average torque, and much lower torque ripples compared to conventional TSFs. [ABSTRACT FROM AUTHOR]

Switched reluctance machines (SRMs) are of great interest because of their simplicity, low-cost, reliability, robustness, fault-tolerance and extended-speed constant-power operation. However, conventional SRMs suffer from high torque ripples. There exist several methods, which have been proposed to reduce torque ripples. One of the proposed methods is to change the geometric structure of the machine. However, analysis of the state-of-the-art designs show that, despite achieving favourable results in applications, the moulding pins of the machines are normally neglected. A motor that gives positive results may get affected negatively by its random moulding during its manufacturing. In this paper, mitigation of torque ripples in short-pitched SRMs (SPSRMs) and fully-pitched SRMs (FPSRMs) are investigated. Three-phase SPSRM and FPSRM are chosen for this study and the effects of the geometric points of moulding pins in the machines are studied comparatively. Maxwell 2D program is used for the analysis and two different models are compared for both SPSRM and FPSRM. The obtained results show that the torque ripples of the two machines are lower when moulding pins are closer to the rotor position. It is reduced by 2.56% at 10 Amps in the proposed SPSRM and 12% at 6 Amps in the proposed FPSRM. It is also observed that the applied method is more effective in reducing torque ripples of FPSRMs than SPSRMs. [ABSTRACT FROM AUTHOR]

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]

Switched reluctance motors (SRMs) exhibit advantageous features such as low inertia, fault tolerance, high efficiency, and simple design. However, its control is fairly complex due to nonlinear characteristics of the magnetic flux linkage seen on the stator windings. Several memory and/or processor intensive solutions have been proposed to deal with the control problem, constraining the use of the motor to high-cost and high-performance applications. The focus of this paper is to develop a simple controller for the SRM based on state-switching digital control. The concept of state-switching digital control is to control the motor state (speed) by applying a high or a low energy pulse—above and below the desired steady state of the motor. Such a controller can be implemented in low-complexity analog circuitry. This paper presents two methods of motor control: one for single-speed applications and another for variable speed applications. In addition, this paper derives the control equations and disturbance rejection response. Simulation and experimental results for various operating modes are presented. [ABSTRACT FROM PUBLISHER]

Proper synchronization of the excitation with respect to the rotor position is essential in optimal control of switched reluctance motor (SRM) drives. To avoid additional cost, size, and unreliability caused by the external position sensors, magnetic status of the SRM can be directly monitored to detect commutation instants. A one-to-one correspondence between magnetic status of the SRM and rotor position removes the need for an explicit access to the rotor position. In order to obtain a good precision over the entire speed range, educated modifications on the structure of the sensorless strategy is necessary. This is due to the impact of the operational regions on dynamic behavior of the SRM. In addition, introduction of SRM technology to industrial and domestic applications has raised the need for four-quadrant operation of the SRM drives. The present paper introduces a range of strategies that are necessary to accommodate this requirement in a sensorless format. Our experimental findings indicate that high-grade sensorless operation in a four-quadrant SRM drive is possible and can be integrated in a variety of applications. [ABSTRACT FROM AUTHOR]