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Summary: The switched reluctance motor (SRM) is a prominent electrical machine drive with low cost and good performance in different drive applications. This machine's main drawbacks are torque ripple and flux ripple. However, the existing SRM‐operated direct torque control (DTC) Voltage vectors (VVs) give high torque ripples due to improper sector division and minimum selection of VVs switching states. On the other hand, a two‐level hysteresis torque band can result in torque ripples. Therefore, this paper proposed DTC using 16 partitions, active small and large VVs, and a multilevel hysteresis torque band (MHTB) strategy to mitigate the torque ripple further. More active VVs (i.e., 16) are employed in the modified sector‐based switching tables, suppressing the torque ripples. The proposed strategy is verified and validated using MATLAB/Simulink. The detailed result discusses the response of torque, flux, and speed of SRM. The DTC‐operated SRM drive experimental results prove the effective minimization of torque ripples in the proposed DTC compared to the existing DTC. [ABSTRACT FROM AUTHOR]

Due to the strong nonlinearity and large torque ripple of switched reluctance motor, a cascaded fractional order PID sliding mode control system is designed. Considering the difficulty of parameter adjustment caused by the complexity of the system, the optimization technology using dung beetle optimizer is introduced to optimize the designed cascaded controller and control the speed and torque ripple. To prove the effectiveness of the proposed cascaded controller, a control model is built in MATLAB/Simulink, and compared with whale optimization algorithm, particle swarm optimization, sparrow search algorithm to verify the response effect of the cascaded controller. A cascaded double PID controller is also built for comparison to verify the effectiveness of fractional order PID sliding mode controller. The results show that the cascaded fractional order PID sliding mode controller optimized by dung beetle optimizer is better than another cascaded double PID controller, produces the minimum torque ripple, and has better speed response and stability. The torque ripple of motor is suppressed. © 2024 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive analysis, electromagnetic evaluation, and prototyping of a novel motor structure called the sinusoidal rotor switched reluctance motor. In this innovative design, a significant departure from the conventional switched reluctance motor is observed, as modifications are made to the rotor with the goal of reduction torque ripple and radial force characteristics. Importantly, despite these advancements, the proposed motor retains the weight and volume characteristics of the traditional, type. The key attributes of these motors have been thoroughly assessed using the three‐dimensional finite element method, complemented by a sensitivity analysis aimed at identifying the most optimal configuration within the proposed design. The findings reveal that the suggested structure successfully achieves a notable reduction in torque ripple and radial force when compared to the traditional counterpart, albeit with an expected reduction in average torque. These features render the new topology particularly well‐suited for applications that prioritise noise and vibration reduction. Furthermore, the effectiveness of the proposed topology is corroborated through experimental tests, providing empirical evidence of its advantages and potential for practical applications. [ABSTRACT FROM AUTHOR]

Summary: Electric vehicles (EVs) have gained a forward approach for achieving the low carbon economy and green transportation. Switched reluctance (SR) motor‐based propulsion mechanisms have been popularly used for EVs due to the wide speed range capability. The conventional phase current regulation technique does not give the satisfactory reduction of torque ripple in SR motor drive, particularly for automotive applications. To overcome the issue, a frontend boost converter (FEBC) is proposed to realize the quick excitation and demagnetization. Initially, the problems associated with the conventional asymmetric half bridge converter are investigated at various levels of phase current. The various operating modes of proposed drive system with FEBC are explained in detail. The proposed FEBC has the significant benefit of being able to provide variable boosting voltages based on the dynamic behavior of the SR motor. The phase voltages are increased during the fast magnetization and demagnetization modes due to the inclusion of FEBC, and hence, quick magnetization and demagnetization have been achieved. The proposed FEBC drive system has been simulated through the Matlab Simulink toolbox. The experimental results are also carried out in order to validate the simulation results. [ABSTRACT FROM AUTHOR]

The structure of permanent magnet flux‐switching linear motor (PMFSLM) with permanent magnet and coil as short primary mover and slotted core as long secondary stator can solve the problem of high cost in the long‐stroke transportation field, but PMFSLM has the phenomenon of top magnetic flux leakage. The permanent magnet on the mover side of U‐shaped permanent magnet flux‐switching linear motor (UPM‐FSLM) is arranged in a U shape, which improves the utilization rate of the permanent magnet of the motor. In order to reduce the edge effect and suppress the thrust ripple, based on the size parameters of PMFSLM prototype, a UPM‐FSLM with arc‐shaped assistant permanent magnet teeth structure is proposed, its specific structure and operation mechanism are introduced; In order to obtain the optimal thrust characteristics, the Taguchi method is used to screen the arc‐shaped assistant permanent magnets teeth sensitive parameters, and then the NSGA II algorithm based on the response surface method is used for comprehensive multi‐objective optimization. The results show that compared with PMFSLM, the average thrust of the optimized motor is increased by 16.09%, and the thrust ripple is reduced by 91.78%. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

Parity‐time (PT) and anti‐parity‐time (anti‐PT) symmetries have provided important guiding principles in the research of non‐Hermitian physics. However, realizations of anti‐PT symmetry in photonic systems usually rely on optical nonlinearities and indirect‐coupling approaches. Here, they apply the channel interference principle mediated by synthetic gauge‐flux biasing in open‐cavity systems to construct anti‐PT symmetries. It is shown that a specific π‐flux biasing into a looped‐resonator array can force a frequency degeneracy between pairwise Bloch modes therein. By further coupling the array into two external waveguides with tailored positions of ports, the system near the degeneracy point can be described by an anti‐PT‐symmetric Hamiltonian. When a real gauge‐flux detuning is introduced, the system undergoes a spontaneous transition between anti‐PT and anti‐PT‐broken phases, through which the two extreme cases of complete channel‐drop tunneling and complete tunneling suppression can be switched. Finally, by superimposing a PT‐symmetric term onto the anti‐PT‐symmetric Hamiltonian via applying an imaginary gauge‐flux biasing, extreme channel‐drop amplifying effects can be further realized by exciting the "lasing" mode under the critical‐coupling condition. The work bridges the physical connection between synthetic gauge field and anti‐PT symmetry. This paradigm may also find many applications from optical routing, and switching to buffering and amplifying on a chip–scale platform. [ABSTRACT FROM AUTHOR]

Aiming at resolving the parameter uncertainty of the servo system under multi‐working conditions, a flatness‐based switched linear system model is proposed. Firstly, a fifth‐order linear switched discrete‐time system with uncertain parameters is established. The flatness properties of switched system is described and a de Bruijn's graph‐based framework is introduced for graphical description of the switched system. In addition, non‐linear bode diagrams are obtained via sweeping signals with multiple amplitudes. The discrete equations of the electromechanical servo system are established by the bode plots. The unknown parameters of the subsystems in switched model are identified by the simulated annealing algorithm, and compared with the least squares method to verify the accuracy of the identified parameters. Finally, the simulation model and experimental platform are constructed to verify the effectiveness of the proposed method. The switched model is compared with the classical transfer function model and single subsystems. The results indicate that the resolution of parameter uncertainty in servo systems is effective. The accuracy of the established switched model is about 99.5%. The accuracy of the switched linear system model of the electromechanical servo system is verified and the proposed modelling method is validated. [ABSTRACT FROM AUTHOR]

Summary: The energy coupling behavior is propagated through the magnetic field and would seriously affect the operation performance of two‐degree‐of‐freedom motion system based on linear‐rotary motor. This paper proposes a novel double‐stator linear‐rotary switched reluctance motor (DSLR‐SRM) to suppress the energy coupling behavior. First, the structure and operation principles of DSLR‐SRM are presented. The two stators of DSLR‐SRM are radially arranged to perform the independent magnetic circuit and suppress the energy coupling behavior through the magnetic field. Then, an equivalent circuit model is established to shorten the modeling and calculation time. It could be found that the energy coupling behavior directly affects the torque and force performance. Next, the sensitivity of the DSLR‐SRM dimensions is developed. Meanwhile, the dimensions of DSLR‐SRM are optimized to enhance the torque and force output via TOPSIS decision‐making. Finally, the validity of equivalent circuit modeling analysis and optimization results are verified through three‐dimensional finite element model. [ABSTRACT FROM AUTHOR]

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

Direct Instantaneous Torque Control (DITC) with an adaptive turn‐on angle technique is presented in this paper to improve the torque ripple of the Switched Reluctance Motor (SRM) for Electric Vehicle applications. Torque ripple suppression is achieved by employing two operating modes during the commutation interval. First, both the outgoing and incoming phase states are modified to track the required torque during the incoming phase's minimum inductance area. As soon as the incoming phase leaves its minimum inductance zone, the outgoing phase is demagnetised, and only the incoming phase state is modified for torque tracking. In addition, a closed‐loop regulator is used to dynamically control the turn‐on angle that drives the incoming current to reach its first peak at the instant of switching between the two operation modes when the rotor and stator poles initiate overlap, thus increasing the motor's efficiency. Simulation results showed that the proposed control method has superior advantages over the traditional DITC and Average Torque Controller. Furthermore, the simulation results were verified experimentally using a four‐phase 4kW, 8/6 SRM prototype. [ABSTRACT FROM AUTHOR]

Summary: This article addresses the problem of basis correction in the context of linear switched‐system (LSS) identification from input–output data. It is often the case that identification algorithms for the LSSs from input–output data operate locally. The local submodel estimates, identified individually by subspace algorithms from the input‐output data, reside in different‐state bases, which mandates performing a basis correction that facilitates their coherent patching for the ultimate goal of performing output predictions for arbitrary inputs and switching sequences. We formulate a persistence of excitation condition for the inputs and the switching sequences that guarantees the presented approach's success. These conditions are mild in nature, which proves the practicality of the devised algorithm. We supplement the theoretical findings with an elaborating numerical simulation example. [ABSTRACT FROM AUTHOR]

In this paper, an online compensation predictive control method based on hybrid torque sharing function (HTSF) is proposed to reduce current spikes in the torque sharing control of switched reluctance motor (SRM). First, predictive control is introduced to the torque sharing function (TSF) and a new cost function is designed with Laplace multiplier method by predicting the current and torque of the next cycle of SRM. Then the optimal current control amount is carried out. Second, the ratio of the torque error to the desired torque and its derivative are compensated online to the current phase at the beginning of the commutation overlap period to accurately track the torque, and the torque distribution is optimized by a HTSF at the end of the phase change to further reduce the current spikes and suppress the torque ripple. Finally, the experiment on 8/6 four‐phase SRM is achieved to verify the feasibility and effectiveness of the proposed control strategy, and the results show that the current spikes and the torque ripple are reduced by 25% and 14.5% respectively. Therefore, compared with traditional TSF control, this method can effectively reduce the SRM torque ripple and excessive current spikes. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The recent development of LA‐ICP‐MS/MS techniques enables in situ Rb‐Sr dating of micas, but there is not yet a matrix‐matched reference material (RM). In this contribution we optimised laser conditions and developed a new data reduction approach for Rb‐Sr dating of micas with non‐matrix‐matched RMs Mica‐Mg‐NP and NIST SRM 612. This was achieved by systematically investigating the effects of laser ablation settings, data reduction methods and the selection of the RMs on the Rb‐Sr dating quality of a 306 ± 1 Ma hydrothermal muscovite. We then tested this approach using twelve mica samples with known ages from 306 to 1.4 Ma. The results show that this technique can achieve accuracy of 2.5% or better, and precision of ~1–3% for micas > 15 Ma. The dating accuracy (> 9%) and precision (> 21%) decrease for micas younger than 5 Ma due to the short radiogenic accumulation time. This technique provides a way to date many types of mineral deposits and rocks, with a relatively high spatial resolution (down to 38 μm), a fast turnaround time and a higher closure temperature for muscovite than the Ar‐Ar system, which makes it a powerful tool in geochronological studies. [ABSTRACT FROM AUTHOR]

This study proposes a space vector pulse width modulation (SVPWM) driving method for the switched reluctance motor (SRM), which enables the use of a standard full‐bridge power converter to drive a three‐phase SRM with a ring structure, in place of the traditional asymmetric H‐bridge (AHB). Based on this driving topology, the SVPWM approach is employed to drive the SRM, and its performance is compared with that of the conventional SRM driving method utilising the AHB. The findings indicate that the SVPWM method can effectively reduce torque ripple in the SRM. Moreover, the experimental validation performed to verify the proposed driving topology and method yields results that closely align with the simulated outcomes. [ABSTRACT FROM AUTHOR]

Random jump of network communication topology challenges the tracking accuracy of linear switched reluctance motor (LSRM) system. This paper studies the pilot‐following consensus control of the multiple direct‐drive motion system (MDDMS) with semi‐Markov jump topology. The mathematical model of LSRM is constructed and the multi‐phase excitation strategy is studied. The directed graph is used to model the information transmission among the leaders and follower, and a new mechanism consensus based on previous states is provided. A consensus system based on semi‐Markov jump topology is constructed and the problem of consensus is shifted into a problem of stability analysis. A sufficient condition for consensus problem is obtained by using semi‐Markov switching system theory and graph theory. The MDDMS achieves consensus in the form of exponential convergence under the designed consensus controller. Several groups of simulation results verify the effectiveness of the proposed consensus control method. [ABSTRACT FROM AUTHOR]

A calculation model of radial electromagnetic force wave for permanent magnet assisted reluctance motor (PMaSynRM) with rotor slots is proposed in this paper. By introducing complex air gap relative permeance, the improved magnetic potential permeability method is applied to the calculation of electromagnetic force wave of the PMaSynRM. Considering the influence of both stator and rotor slots, the characteristics of electromagnetic force wave are analyzed theoretically. A multi‐physical coupling model of PMaSynRM is established. The natural frequency of the stator core is obtained by modal finite element analysis and modal hammer experiment. The harmonic response is analyzed by loading electromagnetic force wave into the structure field and the vibration on the housing surface is calculated. The results show that although the amplitude of electromagnetic force is small at zero‐order slot frequency, the vibration caused by electromagnetic force at frequency of stator slots and rotor slots, especially at the rotor slot frequency, is the biggest vibration source. The effectiveness and regularity of the calculation model are verified by the prototype vibration experiments. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The regulation and stabilization of a system's output to achieve desired performance and ensure system reliability require the use of different controllers, but selecting appropriate control parameters presents a challenge in ensuring robustness and stability. Proportional–integral–derivative (PID) controllers are popularly used due to their simplicity and effectiveness in addressing these challenges. In this paper, a simple, effective, and efficient, novel graphical technique is proposed to design PID and its variants (PI/PD) controllers, which addresses the challenges in selecting appropriate control parameters. The method involves creating three equispaced vectors for controller parameters (Kp,Ki,Kd)$(K_{\text{p}}, K_{\text{i}}, K_{\text{d}})$, and obtaining a 3D (2D in PI/PD) Cartesian grid of these vectors. All nodes in the grid provide several possible controllers, and integral time squared error (ITSE) is calculated for each controller from the closed‐loop step response of the system. The obtained ITSE is plotted in a 4D (PID) or 3D (PI/PD) graph, and controller parameters corresponding to the minimum value of ITSE are identified. Furthermore, the proposed graphical technique aids in choosing the lower and upper bounds (LB and UB) if the controller is designed using optimization techniques. The better selection of LB and UB reduces the search space resulting in lesser execution time and fewer iterations. To validate the proposed graphical technique, we designed various controllers for widely‐used brush‐less DC and switch reluctance motors in electric vehicles. Additionally, by choosing the LB and UB with the proposed technique, controllers are also designed using three optimization techniques: particle swarm optimization, black widow optimization algorithm, and honey badger algorithm. The obtained controllers using the graphical technique outperformed the optimization techniques in terms of time and frequency domain specifications, and the proposed selection of lower and upper bounds resulted in improved performance in terms of iterations and execution time. [ABSTRACT FROM AUTHOR]

Switched reluctance machines offer a robust structure, inexpensive maintenance, and a low‐cost drive. However, they can suffer from low mean torque, low torque density, and high noise. Techniques such as offering the stator poles at each phase in the shape of a C core, adding several teeth to the two poles of each C‐core, and embedding permanent magnets to overcome these deficiencies are presented. Permanent magnets are embedded into the structure to create a hybrid excitation that provides a higher torque density. The C‐core stator modules of the stator are toothed to improve the torque. The radial forces on the shaft are balanced. The design procedure, operating principles, and performance trade‐offs are explained. Also, a magnetic equivalent circuit model is introduced. The model provides continuous relationships over the operating regions and incorporates core saturation and accurate flux tubes to attain high precision. Finite element models are also employed in the analysis and design process. The motor is prototyped, and experimental results are extracted, closely matching those obtained with the model and finite‐element analysis. [ABSTRACT FROM AUTHOR]

This article describes the electromagnetic analysis of high efficient hybrid motor, which comprises the salient features of switched reluctance motor (SRM) and spoke‐type brushless DC motor. The main objective is to develop a motor with a high‐power density and winding faulty capability. Furthermore, this research article extends in the manner to increase the power density of the motor through the sensitivity analysis on rotor geometry by replacing the rotating part of SRM and adopting the rotor of spoke type brushless DC motor, originating the hybrid motor with the high‐power density and enhanced efficiency. To ensure the winding fault capability, a SRM‐based stator winding is adopted. Then, the modelling process for hybrid motor 48 V, 1500 RPM, 2 kW, and 12.7 Nm are detail in both analytical and finite element methods. The electromagnetic analysis is carried out to estimate the torque characteristics and flux pattern of the proposed motor. Furthermore, the proposed motor is analysed with the selection of laminating core material among M 27 24 Ga, 36F155, 46F165, 47F165, M 420 50D, and arnon 7. This infers 36F155 material assists proposed motor has high‐performance characteristics. The vibration frequencies are investigated in modal aspects to estimate the natural frequencies of vibrations. These analyses are validated among analytical and finite element results under no‐load conditions. [ABSTRACT FROM AUTHOR]

Here, the authors propose two new Permanent Magnet (PM) embedded linear switched reluctance motors; one is a modular linear hybrid reluctance motor (MLHRM), and the other one is a segmental linear hybrid reluctance motor (SLHRM). Both structures employ PMs between the side teeth of the modules/segments. The main contribution of the PMs is to increase the air‐gap flux density, which results in an enhanced thrust, and decrease the magnetic saturation in iron parts. The magnetic equivalent circuit model is used to demonstrate the positive effect of inserting PMs in the MLHRM and SLHRM compared to their PMless counterparts. The optimal pole number and design procedure are illustrated. The simulation results are obtained in terms of static thrust, flux linkage, flux density distributions, and steady‐state current and thrust. The results show that the proposed MLHRM and SLHRM offer a higher thrust and lower current compared to their PMless form. Also, the PMs decrease the root mean square (RMS) current under the steady‐state performance of the motors, in which a higher thrust is produced with a lower RMS current. Finally, the MLHRM and SLHRM are fabricated and the test results are obtained and compared with the simulations, which illustrate a satisfactory agreement. [ABSTRACT FROM AUTHOR]

The current‐limiting reactor is currently the most used fault current limiting technique to ensure the fault ride‐through of the multi‐terminal dc grid. However, its configuration will significantly prolong the fault current clearance time and increase the dissipated energy of dc circuit breakers. Therefore, this paper proposes a cost‐effective multiline fault current limiter for multiport application in multi‐terminal dc grids, which can effectively limit the rising speed of fault current through the integrated current‐limiting reactors without time delay and significantly reduce their negative impacts on the performance of dc circuit breakers by bypassing the current‐limiting reactors through the solid‐state switch units during the fault current interruption process. The topology and operation process of the multiline fault current limiter are introduced at first. Then, the economic comparison of the proposed device with the existing solutions is presented. Finally, the feasibility and superiorities of the proposed device are verified by extensive simulations and scaled‐down experiments. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

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

A supply and demand balance control method for an electrical submersible linear motor utilised in offshore oil exploitation is proposed in this study. The permanent magnet linear motor is replaced by an electrical submersible linear motor based on switched reluctance linear motor. The sensorless control method further enhances the stability of the oil exploitation system. Meanwhile, a supply and demand balance control method is proposed to maintain the fullness of the submersible plunger pump within an ideal range. An established speed function allows the speed of the electrical submersible linear motor to dynamically alter in response to the change in oil deliverability and increasing the system's production. Additionally, maintaining the fullness of the submersible plunger pump within the ideal range helps simplify the model and increase computation accuracy. Finally, the supply and demand balance control method is validated and compared with the intermittent oil exploitation control method by simulations and experiments. Results from the simulations and experiments indicate that the proposed method can increase the production of the offshore oil exploitation system in addition to causing the motor to follow changes in oil deliverability and adjust the speed. [ABSTRACT FROM AUTHOR]

Summary: To reduce the number of current sensors in the switched reluctance motor (SRM) system, a current estimation method of the SRM is proposed. There is only one current sensor needed to measure the sum of phase currents. Current estimation model consists of two equations, one is equation of the sum of phase currents and another is mechanical equation of the SRM. Torque, a variable in the mechanical equation, has complex nonlinear relation with phase currents. This makes it difficult to solve the current estimation model online. To deal with the problem, a piecewise modeling method is used to establish a simple analytical torque model. Accuracy of the established torque model is better than that of traditional torque models after comparisons. A parameter of speed and acceleration is defined to compensate errors of the torque model and avoid identifications of moment of inertia and friction coefficient. On the basis of features of the current estimation model and phase currents of the SRM, Newton's method is chosen to solve the current estimation model and a practical stop condition of iteration is given. Realization process of online computation is illustrated. Finally, the proposed current estimation method is validated by experiments. [ABSTRACT FROM AUTHOR]

In this study, to improve the speed tracking performance of the switched reluctance motor (SRM), a control scheme combining fast terminal sliding mode (FTSM) control and radial basis function (RBF) neural network is proposed. First, the convergence characteristic of the FTSM control is derived, and a basic control scheme is designed to ensure the fast convergence of SRM speed tracking errors. Second, the RBF neural network with adaptive parameters is introduced to replace the equivalent control law, which avoids the requirement for the precise mathematical model information of the system. At the same time, considering the network approximation error and unknown external disturbances, an adaptive control law with variables gain is designed. The chattering phenomenon is suppressed and the robustness of the system is enhanced. The updated law of the controller and the stability of the closed‐loop system are derived based on the Lyapunov stability theory. Finally, the simulation and experimental results of the SRM drive system show that the proposed control scheme has an excellent performance in terms of tracking accuracy, response speed, and robustness. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes a novel deadbeat predictive torque control (DPTC) scheme to minimize the torque ripple of switched reluctance motor (SRM) drives. The proposed DPTC consists of torque inverse model and flux‐linkage controller. The torque inverse model is used to realize the nonlinear mapping from the desired torque to the flux‐linkage. On this basis, the flux‐linkage controller predicts the required voltage for a given reference torque at each digital time step. Besides, an improved pulse width modulation (PWM) control is developed to offset the losses caused by power converter and winding resistance. And the digital delay in the actual implementation of the proposed DPTC algorithm is compensated through the estimation + prediction technology. Both simulation and experimental testing are carried out to verify the effectiveness of the proposed control scheme. The results show that the proposed DPTC method has better torque ripple suppression performance than the conventional direct torque control (DTC) scheme. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

The strong coupling effect between the torque system and the suspension system of the single‐winding bearingless switched reluctance motor (SWBSRM) would result in continuous interference to the system and bring difficulties to the design of the control system. Moreover, strong external disturbances will further reduce the stability of the control system. To improve the anti‐disturbance ability and enhance the robustness of the control system of SWBSRM, a design method of the entire control system based on the second‐order sliding mode (SOSM) controllers is proposed. The strongly coupled SWBSRM torque system and suspension system are linearised and decomposed through the feedback linearisation method to benefit the design of SOSM controllers. Then, combined with a super‐spiral algorithm, the super‐spiral sliding mode controllers in the outer loop for torque and suspension system are designed separately. The design of controllers considers the interference caused by the coupling effect and the influence of external disturbance. The range of gain, which can ensure the finite time convergence of the control system is determined through proof of stability. Simulation and experiment results show that the second‐order sliding mode controllers have faster response speed and control precision when suppressing coupled interference and strong external disturbance. [ABSTRACT FROM AUTHOR]

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

Due to the high back electromotive force and short commutation time at high speed, the phase current of switched reluctance motor (SRM) is difficult to reach a large value, which limits the output performance of the motor in high‐speed operation. This paper proposes a novel multilevel converter (MLC) with fast excitation and fast demagnetisation capability, which allows each phase to control independently even in overlapping conduction operation and is suitable for SRM with any number of phases. The excitation current in the rising inductance region is increased by high‐voltage fast excitation, thus increasing the phase current level of the motor at high speed; the current tailing in the falling inductance region is suppressed by high‐voltage fast demagnetisation, thereby reducing the generation of negative torque. Based on the novel MLC, a maximum torque per ampere (MTPA) control strategy is designed, and closed‐loop control of the boost capacitor voltage is developed. By optimising control, the output torque and efficiency of switched reluctance motor drive (SRD) are greatly improved, and the constant power operation range is extended. Simulation study and experimental results verify the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

A torque sharing function (TSF) with online compensation of excitation current control method is proposed for torque ripple reduction in electric excitation auxiliary switched reluctance motor (SRM) drives, which mitigates the problem of severe torque ripple inherent in traditional TSF control during the commutation of armature winding. The torque formula of the motor is derived and the finite element analysis of the static torque under different excitation currents is carried out, which proves that the output torque can be changed by adjusting the excitation current. Therefore, the proposed method is based on cosine TSF control, which uses a sliding mode control algorithm to adjust the amplitude of the excitation current to online compensate the torque fluctuations during commutation. Besides, Simulink, Simplorer and Maxwell co‐simulation and experiments are carried out on the traditional TSF control and the proposed method. The results demonstrate that the proposed method is superior to the traditional TSF control and the electric excitation auxiliary SRM has better torque performance and smaller torque ripple under the proposed method. [ABSTRACT FROM AUTHOR]

This paper reports on a novel unipolar current excited control scheme for the asymmetric bridge converter (ABC)‐based switched reluctance drive (SRD), where the 3D space vector modulation under three modes is developed to reduce the total harmonic distribution (THD) and torque ripple. Firstly, two different 3D vector distributions, namely, the small voltage amplitude mode and large mode are presented based on the asymmetric converter. For both distributions, the zero‐sequence voltages generated by the effective vectors are considered. Additionally, zero‐sequence vectors (1,1,1) and (−1,−1,−1) are no longer treated as null vectors and involved in the control of zero‐sequence current. Then, the duty cycles of both two modes are obtained by the combination of the zero‐sequence and two adjacent active vectors. Moreover, based on the large modulation mode, a novel method combined with the small mode is proposed to further optimise the switching costs and torque ripples. The effectiveness of the proposed modes is verified through the simulation in MATLAB and the experiment on a dSPACE‐1103‐based prototype. Compared with the conventional switched reluctance motor vector control, the proposed scheme delivers better performances of THD, efficiency and torque ripple reduction. [ABSTRACT FROM AUTHOR]

Whale optimization algorithm (WOA) imitates social conduct of humpback whales which is inspired by bubble net hunting strategy of humpback whales. In the present study, Cosine adapted modified whale optimization algorithm (CamWOA) which is a modified version of WOA, has been proposed where cosine function is incorporated for the selection of control parameter "d" which governs the position of whales during optimization process. Also, correction factors are employed to modify the movement of search agents during the search process. These changes provide a proper balance between exploration and exploitation phases in CamWOA technique. The performance of CamWOA is analyzed by testing on a set of benchmark functions and compared with other state‐of‐the‐art algorithms. It is observed that CamWOA outperforms other state‐of‐the‐art metaheuristic algorithms in majority of benchmark functions. The efficiency of CamWOA is also evaluated by solving a multiobjective engineering problem pertaining to control of switched reluctance motor. The simulation results confirm that CamWOA yields very promising and competitive results compared to that of WOA and other metaheuristic optimization algorithms. [ABSTRACT FROM AUTHOR]

This paper investigates the accuracy of rotor‐locked transient‐response (RLTR)‐based vibration model for switched reluctance machines (SRM). RLTR is stator vibration stimulated by abrupt change of radial force when turning off one phase of SRM with rotor being locked, the total vibration of SRM can be modelled as linear superposition of RLTR series. An electromechanical model is built to clarify the generation of SRM vibration, it is revealed that some velocity‐depend terms in electromechanical model would be neglected when rotor is locked, it leads to inevitable difference of RLRT between rotor‐locked condition and rotational condition, the difference is illustrated through multi‐physics simulation. A harmonic radial force model is proposed to quantitatively evaluate the accuracy of RLTR‐based vibration model, radial force spectrums with locked rotor and rotational rotor are compared to predict relative error between RLTR‐based vibration and actual vibration. The influence of turn‐off angle and velocity on accuracy of RLTR‐based vibration model is also analysed. The accuracy of RLTR‐based vibration model is evaluated through experiment on 3‐phase 12/8 SRM, the results showed that: (1) the accuracy of RLTR‐based vibration model is impacted by turn‐off angle and velocity; (2) relative error between RLTR‐based vibration and actual vibration can be predicted using harmonic radial force model. This paper illustrates the generation mechanism of modelling error for commonly used RLTR‐based vibration model of SRM, the proposed error prediction method could lead to improved accuracy on SRM vibration model through error compensation. [ABSTRACT FROM AUTHOR]

This paper introduces a variable magnet switched reluctance motor (VM‐SRM) drive that can be characterized with adjustable performance. It consists of a switched reluctance (SR) motor with low coercive force (LCF) magnets buried on stator yoke and a modified asymmetric half bridge (AHB) converter. Magnetization level of the LCF magnets is adjusted by injecting a current pulse to a phase winding of the VM‐SRM. The magnetization process does not need any extra coil and provides a simplicity owing to modified AHM converter. Possible magnetic saturation that limits the magnetization level is overcome by injecting current pulses to two phase windings at the same time. Thus, LCF magnets can be used with their full capacity. The presented analysis results demonstrate that proposed VM‐SRM drive provides a variable performance and might be a candidate for future variable speed applications. © 2022 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper proposes an automatic design method of typical parameters such as number of phases, number of poles, stack thickness, stator outer diameter, rotor outer diameter, and number of turns of a switched reluctance motor from the requirement of the N‐T characteristic. In particular, a specific parameter related to the magnetic saturation is defined in order to arbitrarily determine how much to use the magnetic properties of the iron core material. In the proposed method, the typical motor parameters in order to realize a miniaturized volume which satisfies an input N‐T characteristic are obtained by setting the parameter related to magnetic saturation, maximum electrical frequency, maximum current density, maximum copper loss, conductor slot fill factor, magnetic properties of material, and input voltage. The designed motor is analyzed using the Finite Element Method (FEM) in order to validate the proposed method. [ABSTRACT FROM AUTHOR]

In this paper, a novel control method based on model predictive control (MPC) and torque sharing function (TSF) is addressed to minimize the torque ripple of switched reluctance motor (SRM). Firstly, an accurate SRM model is established based on flux‐linkage characteristic curves obtained from the locked rotor test, which can predict the future operation state of the SRM drive system. Secondly, an improved TSF curve is proposed, and genetic algorithm is used to optimize TSF parameters to reduce torque ripple in commutation region. Besides, the MPC is integrated into the TSF control framework to replace the traditional hysteresis controller, and establishes a new TSF‐based model predicted torque control (MPTC) method, which avoids the frequency conversion problem caused by torque or current hysteresis controller. Further, a sector division scheme is addressed to decrease the number of candidate voltage states, whereby the computation of the controller in each sampling period is effectively reduced. Finally, in order to verify the correctness of the MPTC method, it is compared with the traditional direct instantaneous torque control (DITC). Both simulations and experiments on a three‐phase 12/8 pole SRM have confirmed that MPTC scheme can not only decreases torque ripple and stator copper losses, but also has higher efficiency than DITC. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

To obtain a short flux path and improve the torque performance, a double‐phase excitation (DE) was generally used for switched reluctance motor (SRM). But the torque ripple of the SRM working under DE with traditional winding distribution increases because of the inconsistent electromagnetic field. To deal with this problem, an 8/6 SRM working under DE with novel winding distribution (DESRM) is proposed here. In order to comprehensively analyse the electromagnetic performance of DESRM, it is compared with a traditional single‐excitation SRM and double‐excitation SRM with traditional winding, in terms of air flux density, radial and tangential force components, inductance, torque, and losses. The theoretical and finite element analysis results reveal the cause of differences on torque and vibration of the motor as well as the mechanism of generating different motor performance. In addition, the analysis shows that the proposed DESRM generates a higher torque with a reduced torque ripple. Finally, a pair of prototypes with different winding configurations is designed and used to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

Summary: In this article, the equivalent control strategy based on Laplace transform is proposed for the problem of stochastic delay in networked control systems. The original system is transformed into an equivalent control system without random delay block by Laplace transform. Then, a new augmented variable and equivalent control system is introduced to construct an augmented system. An adaptive fault diagnosis observer is designed based on the augmented system. The adaptive turning rate of the observer is obtained by solving the corresponding linear matrix inequality. Based on the information of online fault diagnosis and state estimation, a fault‐tolerant controller based on PI control strategy is designed to compensate the fault. Finally, a model of the switched reluctance motor system is considered to show the effectiveness of this method. [ABSTRACT FROM AUTHOR]

This article investigates the effect of utilising rotor conducting screens within a switched reluctance machine (SRM). Conducting, non‐magnetic materials such as aluminium or copper are inserted into the interpole regions of the rotor. The effective unaligned inductance decreases, which increases the conversion area allowing the machine to develop more power. Predicting machine performance implies knowing the value of the unaligned inductance. A procedure for calculating the effective unaligned inductance for screened motors using the flux tube method is presented. Finite element analysis results establish the validity of the proposed calculation method. A detailed design procedure for screened SRM is presented. [ABSTRACT FROM AUTHOR]

A novel dual 6/3 Transverse Flux Bearingless Switched Reluctance Motor is proposed to solve the coupling problem between torque and suspension of conventional Switched Reluctance Motor. The working principle is introduced in detail, the motor is modelled by ANSYS, and the accurate mathematical model of the suspension force is deduced and verified. The electromagnetic characteristics of the motor are simulated, and the torque characteristics, suspension characteristics and the coupling characteristics between them are verified. The simulation results show that the torque and suspension force can be stabilised by using the zoning control of torque and suspension force, and the decoupling between torque and suspension force is excellent. [ABSTRACT FROM AUTHOR]

Switched reluctance motors (SRMs) are considered as a potential candidate in many high‐reliability demanding applications, including electrical vehicles (EVs), hybrid EVs and more electric aircrafts. For precise and stable control performance, normally an SRM drive requires one current sensor for each phase winding. Failure of any of these sensors will inevitably degrade the system's performance. The behaviour of an SRM drive under current sensor failure is investigated and a fault‐tolerant control technique is proposed by changing the current sensor installation scheme without adding extra current sensors. Moreover, through the analysis of the detected currents by the phase current sensors and the dc‐link sensor, a diagnostic scheme for current sensors failure is presented. The excitation current in the faulty phase under postfault conditions is reconstructed through a simple calculation without injecting a high‐frequency signal or modifying the switching signals, thereby reducing the current distortion and avoiding voltage penalty issues. Motor drive can operate with satisfactory control performance even when all the phase current sensors are in fault conditions. Detailed analysis under both steady state and dynamic conditions through thorough simulations and experiments has been carried out on a three‐phase 12/8 SRM. The extensive results validate the effectiveness of the proposed technique. [ABSTRACT FROM AUTHOR]