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Servo motor drive systems with ball-screw and timing-belt are widely used in a numerical control, robot, factory automation and industrial applications. Most of the servo motor and drive system transfer the motor torque to loads via mechanical connections. However, the nonlinear friction of coupled mechanical devices reduces the performance of a servo drive. Especially, in a low speed range, tracking errors are serious due to the break-away friction and Stribeck effects. In this paper, a new dual speed controller is proposed for the compensation of nonlinear friction torque. The proposed dual speed controller has an outer speed controller and an inner friction torque compensator. The friction torque compensator adds additional torque corresponding to a nonlinear friction of mechanical devices, so the actual speed quickly tracks the reference value. Since the proposed nonlinear friction torque compensator uses the actual speed information without any motor parameters and mathematical model, the proposed compensator has a very simple structure and high stability. The proposed control scheme is verified by computer simulation and experimental results. [ABSTRACT FROM AUTHOR]

Features a study which described and tested a novel excitation strategy for a switched reluctance motor (SRM) where the torque is produced by mutual-inductance as well as by self-inductance. SR drive with two-phase excitation; Advantages with the novel excitation scheme; Operational principle of the novel excitation scheme; Conclusion.

This study presents the design of a 2‐pole high‐speed BLDC motor for kitchen blenders and its control method with the aim to reduce the speed ripple that decreases the grinding performance in the high‐speed region. In blender machines, the high pulsating load caused by the blending materials such as ice cubes acting on the grinding blade, create significant speed ripple in the constant power region. Because current and torque are limited to protect the drive, the actual motor torque cannot overcome the pulsated load if the speed reference is maintained. Therefore, the speed fluctuates, and the grinding performance is lowered. In the proposed variable speed reference control scheme, the speed command is continuously modified to overcome the maximum pulsating torque requirement which results in lower speed ripple. To achieve this, if the load torque suddenly increases, the current value is then set based on the maximum load and speed reference value is temporarily lowered. If then the load torque becomes lower than the actual torque, the previously set speed reference value is reused. The design result and grinding performance of the proposed control method are verified by simulations and experiments. Hard white beans are used for actual performance testing. [ABSTRACT FROM AUTHOR]

Electric motors with a double air-gap structure offer increased power or torque density compared to their single air-gap counterparts, achievable through double-stator or double-rotor configurations. In a previous study, the authors proposed a double-stator permanent magnet synchronous motor (PMSM) with a magnetic screen placed in the middle of the rotor to isolate the outer and inner motors. However, the analysis of the magnetic screen was not provided in that study, as the design was arbitrarily chosen. This research focuses on the effects of the magnetic screen size and selects the appropriate dimensions for optimal motor performance. Finite element analysis (FEA) is employed to assess the electromagnetic characteristics of the screen. Subsequently, the motor is manufactured and tested. The results show that the chosen magnetic screen size contributes to significant efficiency improvements. In particular, the motor achieved an efficiency of 95.2% during the qualification test, surpassing the efficiency obtained in the previous study. [ABSTRACT FROM AUTHOR]

With the rapid development of power electronic techniques and the increasing cost of permanent magnets (PMs) materials, switched reluctance motors (SRMs) have recently gained more attention. However, traditional SRMs have a relatively low torque density. For the sake of increasing the motor torque density, this paper proposes a novel segmental rotor type SRM. The proposed motor adopts hybrid stator poles and concentrated windings in the stator side and a segmental rotor structure in the rotor side, which is completely different from the structures of the traditional SRM. The special structure of the motor shortens the magnetic flux paths of the motor, separates the parts of the magnetic flux paths from one another, and eradicates the magnetic flux reversal in the motor stator in order to improve the electric utilization and output torque density of the motor. Meanwhile, the requirement of the magneto-motive force and the core loss of the motor is also decreased, thereby improving the efficiency of the motor. For the purpose of proving the proposed structure, the characteristics of the motor are analyzed using the finite element method and are compared to those of the traditional 12/8 SRM, which is designed for the same application. Moreover, the prototypes of the traditional 12/8 and proposed SRMs are manufactured, and experiments based on the prototypes are performed. Finally, the effectiveness of the structure of the proposed motor is further proven by the experimental results. [ABSTRACT FROM AUTHOR]

In this paper, three types of bearingless switched reluctance motors (BLSRMs) which have decoupled flux characteristics between the torque and suspending current are presented in detail. The analyzed BLSRMs are an 8/10 hybrid BLSRM, a 12/14 hybrid BLSRM, and a double stator BLSRM. The 8/10 hybrid BLSRM has a low electrical frequency with decoupling characteristics. The 12/14 hybrid BLSRM has a short flux path to reduce core loss with higher decoupling characteristics. The double stator BLSRM has the best decoupling characteristics with a complex mechanical structure. All three structures have two types of stator poles: torque and suspending force poles. Due to the independent characteristics between the torque and suspending force poles, the torque control can be decoupled from the suspending force control. The characteristics of the three types, such as magnetic flux distribution, inductance, torque, suspending force, torque ripple, efficiency, and number of switches used in the drive systems, are analyzed and compared to induce the better magnetic structure and control scheme of the suspending force. To verify the validity of the three types, tests are executed and compared. [ABSTRACT FROM AUTHOR]

This paper presents the design and operation of a two-phase four-two pole switched reluctance motor (SRM) for a high-speed air blower. The air blower has unidirectional rotation and requires a wide positive torque region without torque dead zone. In order to achieve the requirements, a nonuniform air gap with asymmetric inductance profile is considered. For a flattop torque with a low torque ripple, the nonuniform air gap is also effective. Based on the output torque analysis at the rotor position for the given air gap, the air gap is modified to reduce the torque ripple. The optimized air gap at a given position cannot feel the effect of the air gap at a previous rotor position. Therefore, the output torque cannot fully satisfy the target torque in one optimization process. In order to satisfy the target torque and reduce the torque ripple, the second optimization process is implemented considering the output torque of the initial optimization process. The second target torque is determined by the torque error of the initial output torque and target torque of the first process. From this optimization sequence, the final air gap, as a function of the rotor position, can be determined to satisfy the torque ripple requirement. The proposed high-speed four-two pole SRM is tested to verify the high-efficiency and low-acoustic-noise characteristics. [ABSTRACT FROM PUBLISHER]

The shift-by-wire (SBW) system in vehicles aims to increase performance, safety, and comfort during driving. Switched reluctance motors (SRMs) are simple, resilient, and require only minimum maintenance; these factors make it a good option for use as an SBW actuator. Inherently, SRM generates a higher torque ripple than other AC machines, which can lead to a deterioration of its function. In this paper, a non-uniform air-gap rotor structure combined with the careful positioning of holes near the pole surface is proposed to reduce the torque ripple. The finite element method (FEM) is employed to analyze the electromagnetic characteristics of the design. The proposed motor is manufactured, and experiments are done to verify the performance. The design alone can reduce the torque ripple by 7% and flatten the torque waveform. The experimental result shows that the proposed motor can achieve the desired performance. The estimated torque ripple from the experiment is 26.65%. [ABSTRACT FROM AUTHOR]

This paper presents a sensorless-controlled, low-cost, low-power, and variable-speed drive system suitable for fan and pump applications. The main advantages of this drive system are the low system cost, simple converter structure, and simple but robust sensorless control technique. The drive motor is a special hybrid switched reluctance motor. The proposed sensorless control method beneficially utilizes the stator side PM field and its performance is motor parameter independent. The unique low-cost drive system solution, simple and robust sensorless control features of this drive system, is demonstrated in detail in this paper. Important design details for practical implementation of the sensorless control algorithm are included. The complete drive system performance is validated using a prototype drive system. [ABSTRACT FROM AUTHOR]

Abstract: A novel hybrid stator-pole switched reluctance motor (HSPSRM) to improve radial force for bearingless application is presented in this paper. The proposed motor can generate a constant suspending force independent of rotor position only using small current excitation. And torque control can be naturally decoupled form suspending force control. Measured data and the results of numerical analysis are given to evaluate the motor structure. In the numerical analysis, the finite element method (FEM) is employed due to the highly nonlinear nature of the motor. A prototype hybrid stator-pole SRM is manufactured and tested in the experimental studies. The obtained test and simulation results show that the hybrid stator-pole SRM structure has a constant suspending force, which can be controlled independent from torque control. [ABSTRACT FROM AUTHOR]

In this paper, the optimization and characteristics analysis of a three-phase 12/8 switched reluctance motor (SRM) based on a Grey Wolf Optimizer (GWO) for electric vehicles (EVs) application is presented. This research aims to enhance the output torque density of the proposed SRM. Finite element method (FEM) was used to analyze the characteristics and optimization process of the proposed motor. The proposed metaheuristic GWO combines numerous objective functions and design constraints with different weight factors. Maximum flux density, current density, and motor volume are selected as the optimization constraints, which play a significant role in the optimization process. GWO performs optimization for each iteration and sends it to FEM software to analyze the performance before starting another iteration until the optimized value is found. Simulations are employed to understand the characteristics of the proposed motor. Finally, the optimized prototype motor is manufactured and performance is verified by experiment. It is shown that the torque can be increased by 120% for the same outer volume, by using the proposed method. [ABSTRACT FROM AUTHOR]