A switched Reluctance motor (SRM) has several desirable features, including simple construction, high reliability and low cost. However, it suffers from large torque ripple, highly non-uniform torque output and magnetization characteristics and large noise. Several studies have succeeded in torque ripple reduction for SRM using Direct Torque Control (DTC) technique. DTC method has many advantages over conventional voltage control and current chopping mode control such as simple algorithm, less torque ripple and instantaneous response to the torque command. In this paper, DTC method is proposed for a 5-phase 10/8 SRM. The performance of the motor is demonstrated through the computer simulation in Mtalab/Simulink. Then, the obtained results are verified by comparison with the corresponding results of a 3-phase 6/4 motor performance.

This paper presents a Direct Torque Control (DTC) strategy for the Permanent Magnets Synchronous Machine (PMSM). The principle relies on a Space Vector Modulation (SVM) technique that uses hysteresis comparators for the determination of the voltage module and angle, the proposed control method is simple to implement. It allows reducing the fluctuations level of the torque and the flux in low speed conditions. Contrary to the classical DTC technique, the proposed approach is able to handle and to control the switching frequency even for driving the motor with a low speed as a reference. Simulations results were obtained and allowed demonstrating better performance of this command especially in the behavior of the couple and the flux.

Background and Objectives: Due to the high torque ripple and stator current harmonics in direct torque control using a two-level inverter, the use of multi-level inverters has become common to reduce these two factors. Among the multilevel inverters, the Neutral-point-Clamped Inverter has been given more attention in the industry due to its advantages. This inverter has 27 voltage vectors by which torque and flux are controlled. In order to reduce torque ripple and current harmonic as much as possible, methods such as space vector modulation methods or the use of multi-level inverters with higher levels have been considered. But the main drawback of these methods is the increase of complexity and cost.Methods: In this article, virtual voltage vectors are used to increase the number of hysteresis controller levels. These vectors are obtained from the sum of two voltage vectors. In this way, we will have 12 voltage vectors in addition to the diode clamped inverter’s voltage vectors. Therefore, we can increase the number of torque hysteresis levels from 7 levels to 11 levels.Results: Considering that the proposed method uses virtual vectors and voltage vectors, it does not increase the cost and computational complexity. Also, one of the requirements of using this method is the use of fixed switching frequency, which solves the variable switching frequency problem of conventional methods. Therefore, the proposed control reaches an overall optimization.Conclusion: To verify the feasibility of the proposed method and compare it with the conventional method, both of these methods are simulated in the MATLAB /Simulink environment and the simulation results represent the efficiency of the proposed control method. This method achieves less torque ripple and harmonic current without increasing the cost and computational complexity.

Bearing-less induction motors (BLIMs) are suitable candidates for high-speed applications but suffer from low torque density and complex control issues due to the interaction of torque and levitation forces. To address these challenges, this paper presents a new control strategy that combines vector control and direct torque control (DTC) for torque management, alongside a novel force control method based on finite element analysis (FEA). The proposed approach minimizes interference between torque and force magnetic fields by employing a parallel winding structure and distinct control units for torque and force. Simulation results demonstrate that the proposed method significantly reduces torque ripple and improves steady-state performance compared to conventional vector control and DTC. Furthermore, the force control unit outperforms a dual field-oriented control (FOC) method in regulating rotor position, offering better suspension force control and faster stabilization. This work contributes to the development of more efficient control strategies for BLIMs, enhancing their performance in industrial applications.