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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]

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]

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]

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]

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]

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]

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]