Static Torque Characteristics Research Articles

Static Torque Analysis of Micro Claw-Pole Stepper Motor Based on Field-Circuit Combination.

Because of the complexity of the structure and magnetic circuit of the micro claw-pole stepper motor, it is difficult to analyze this kind of motor quickly and accurately. Therefore, it takes a lot of time to accurately model and use the three-dimensional finite element analysis method to accurately analyze the motor. Regarding the three-dimensional finite element method, the equivalent magnetic circuit method analysis is fast, but the accuracy is not high. In order to better study the performance of this kind of micro claw-pole motor and reduce the cost of optimization time, this paper adopts the method of combining the equivalent magnetic circuit method and three-dimensional finite element analysis to analyze the static torque characteristics of the micro permanent magnet claw-pole stepper motor. Firstly, the equivalent magnetic circuit method is used for theoretical analysis, the air-gap flux equation is deduced, and the relationship between the electromagnetic torque and the geometric parameters of the motor is deduced. Then, the three-dimensional finite element simulation results are substituted into the relevant formulas defined by the equivalent magnetic circuit method to obtain a more accurate electromagnetic torque. Finally, through the comparison and analysis of the experimental data, simulation data, and theoretical calculation values, the error rate of the derived motor torque is within 8.5%. The micromotor studied in this paper is optimized, and the holding torque is increased by 12.5% under the premise that the braking torque does not change much. The simulation calculation time is effectively shortened, the analysis difficulty is reduced, and the calculation accuracy is high. It is shown that the method combining the equivalent magnetic circuit method and the three-dimensional finite element analysis method is suitable for preliminary design research and optimization calculation of the micro claw-pole stepper motor.

AN EFFICIENT NUMERICAL SCHEME FOR STATIC TORQUE PROFILING OF SWITCHED RELUCTANCE MACHINE WITH EXPERIMENTAL VALIDATIO

In AC and DC drives, the use of switched reluctance machine (SRM) is becoming popular as it has a few preferences over AC and DC drives in a simple and robust construction without brushes, low inertia, and high torque to weight ratio, without rotor windings, simple circuit power converter, etc. SRM is widely used in variable speed and servo drives. Because of the double saliency structure and the high nonlinearity of magnetic material, it is difficult to represent the flux-linkage and static torque characteristic of the SRM. This work promotes the use of an improved numerical integration scheme for the static characteristics of SRM. The static torque function that depends on the rotor position and the phase current of the flux linkage features family (for different rotor positions) is improved in the proposed work. Firstly, we use an experimental setup for the electromagnetic characteristic of SRM. Then, we use the improved scheme to develop an efficient mathematical model for static characteristics and finally simulate the static characteristic of SRM through MATLAB code. In the last step, we compare the performance of the proposed integrator model with an existing approach for better efficiency of the static characteristic of SRM with experimental validation.

Comprehensive study on divided‐teeth and permanent magnet assisted outer‐rotor switched reluctance motors

A comprehensive study on divided-teeth permanent-magnet assisted outer-rotor switched reluctance motors (SRMs) is carried out. Foremost, it looks into the impact of the number of teeth per stator pole. The average and maximum torque profiles of the compared structures are obtained using finite-element simulations. It is shown that as the number of teeth increases, higher torque is obtained. Then, six small PMs are inserted inside the teeth of neighbouring modules to form new hybrid reluctance motors (HRMs). The four permanent-magnet assisted SRMs are compared in terms of the average and maximum torques using finite-element simulations. Based on the comparison results, the 48/50 HRM is selected as the best candidate among all compared SRMs and HRMs. The magnetic flux density distributions, static torque, and flux linkage characteristics of the proposed HRM are obtained. Moreover, the cogging torque profile of the motor is obtained, which approximates to zero. Next, the steady-state performances of the proposed HRM are obtained under low- and high-operating speeds. Finally, a prototype of the machine is constructed and the test results are obtained and compared with those of the simulations, which show that there is a good agreement between these results.

Torque Enhancement of Switched Reluctance Motor with Teethed Stator Pole

Switched Reluctance motors are very demanding among all type of motor due to its simple construction. Feedback circuit (control circuit) and design of Switched Reluctance Motor (SRM) require information of its parameters, like inductance, flux linkage and torque. High torque, high reliability and cheap manufacturing cost are the attractive features of the SR motors. In this paper we have simulated SR motor with initial design, teethed stator pole and multi-teethed stator pole using COMSOL multi-physics CAD software. We have plotted inductance profile and static torque characteristics which shows that the static torque characteristics has peak value with sharp reduction in torque in intermediate position with teethed stator pole, that can be overcome by using multi-teeth stator pole with compromising in maximum torque.

Comparative Analysis of Fault-Tolerant Dual-Channel BLDC and SR Motors

This article presents the results of a comparative analysis of two electronically commutated brushless direct current machines intended for fault-tolerant drives. Two machines designed by the authors were compared: a 12/14 dual-channel brushless direct current motor (DCBLDCM) with permanent magnets and a 12/8 dual-channel switched reluctance motor (DCSRM). Information is provided here on the winding configuration, the parameters, and the power converters of both machines. We developed mathematical models of the DCBLDCM and DCSRM which accounted for the nonlinearity of their magnetization characteristics in dual-channel operation (DCO) and single-channel operation (SCO) modes. The static torque characteristics and flux characteristics of both machines were compared for operation in DCO and SCO modes. The waveforms of the current and the electromagnetic torque are presented for DCO and SCO operating conditions. For DCO mode, an analysis of the behavior of both machines under fault conditions (i.e., asymmetrical control, shorted coil, and open phase) was performed. The two designs were compared, and their strengths and weaknesses were indicated.

The Computational fluid dynamics Performance Analysis of Horizontal Axis Wind Turbine

<span lang="EN-US">Computational fluid dynamics (CFD) simulations were performed in the present study using ANSYS Fluent 18.0, a commercially available CFD package, to characterize the behaviour of the new HAWT. Static three-dimensional CFD simulations were conducted. The static torque characteristics of the turbine and the simplicity of design highlight its suitability for the GE 1.5xle turbine. The major factor for generating the power through the HAWT is the velocity of air and the position of the blade angle in the HAWT blade assembly. The study presents the effect of The blade is 43.2 meters long and starts with a cylindrical shape at the root and then transitions to the airfoils S818, S825 and S826 for the root, body and tip, respectively. This blade also has pitch to vary as a function of radius, giving it a twist and the pitch angle at the blade tip is 4 degrees. This blade was created to be similar in size to a GE 1.5xle turbine by Cornell University [1]. In addition, note that to represent the blade being connected to a hub, the blade root is offset from the axis of rotation by 1 meter. The hub is not included in our model. The experimental analysis of GE 1.5xle turbine, so that possible the result of CFD analysis can be compared with theoretical calculations. CFD workbench of ANSYS is used to carry out the virtue simulation and testing. The software generated test results are validated through the experimental readings. Through this obtainable result will be in the means of maximum constant power generation from HAWT.</span>

Effect of Auxiliary Blade on Aerodynamic Characteristics of Vertical Axis Wind Turbine by Numerical Simulation

In order to improve the aerodynamic characteristics of the Straight-bladed Vertical Axis Wind Turbine (SB-VAWT), a rotor structure with auxiliary blade installed behind the main blade was proposed in this study. To investigate the effects of relative thickness and the fixing angle of the auxiliary blade on aerodynamic characteristics of SB-VAWT, numerical simulations were carried out. Two shapes of NACA 4-digital series blade-section, NACA0018 and NACA0024, were selected as the main blades in this work. Effects of relative thickness and fixing angles of auxiliary blade on the aerodynamic performance of SB-VAWT had been analyzed in detail, which had 5 kinds of relative thickness and 3 kinds of fixing angles combined into 13 working conditions. And the main blades and the auxiliary blades were also decided as the NACA series airfoil with five kinds of relative thickness. Three kinds of fixing angle of auxiliary blade installed behind main blade were used including 0°, 5°, and 10°. The simulations included the output power coefficients, the static torque coefficients, and the flow fields around the main blade and auxiliary blade for both the dynamic and static conditions at some typical azimuth angles. The results show that the auxiliary blade with certain relative thickness and fixing angle can improve the output power characteristics and static torque characteristics of SB-VAWT, which can also provide research reference for improving the performance of VAWT.

Performance Improvement for Segmented-Stator Hybrid-Excitation SRM Drives Using an Improved Asymmetric Half-Bridge Converter

This paper presents an improved asymmetric half-bridge converter (AHBC) to enhance the output performance of a segmented-stator hybrid-excitation switched reluctance motor (SSHE-SRM) drive. Differences from conventional AHBC include an additional boost capacitor, a power switch, and two diodes added between the dc-bus and the AHBC. The static torque characteristic of a 12/8 SSHE-SRM is briefly analyzed and compared with a conventional SRM (CSRM). Based on the magnetic characteristic, the SSHE-SRM appears to have higher torque production capability. The improved AHBC is employed in order to increase the dc-bus voltage under dynamic operation. Higher voltage can be applied to phase windings and faster excitation and demagnetization currents can be obtained owing to the addition of capacitor voltage. Detailed simulations of the SSHE-SRM drive with the improved AHBC are carried out as well as compared with conventional AHBC. Finally, a 12/8 SSHE-SRM is prototyped. The SSHE-SRM drive based on the improved AHBC and conventional AHBC are experimentally tested. The measured results of static magnetic characteristic and dynamic performances are presented to validate the analysis and effectiveness of the novel converter.

Investigation of Static Characteristics in Six-Phase Switched Reluctance Motors under Different Winding Connections

The effect of the winding connections on the static torque in six-phase switched reluctance motors (SRMs) is investigated in this paper. Different winding connections for the six-phase SRMs are shown and compared. Under the conditions of different winding connections, the self-inductance and mutual inductance of a six-phase SRM are compared and analyzed. Six-phase SRMs can be running in two-phase excitation mode and three-phase excitation mode, and in these two modes, the static torque characteristics with different poles polarities arrangements are compared and analyzed. The comparison of the static torque in a six-phase SRM with different winding connections is obtained by the Maxwell 2D and experiments. Based on the results, an optimal winding connection mode for starting stage of the six-phase SRMs is proposed.

Starting performance effect of a truncated-cone-shaped wind gathering device on small-scale straight-bladed vertical axis wind turbine

In order to improve the starting performance of straight-bladed vertical axis wind turbine (SB-VAWT), an innovative truncated-cone-shaped wind gathering device (WGD) which could be installed up and down of the rotor was proposed to collect more incoming flow and increase wind speed. The main object of this study is to research the starting performance effects of the main structural parameters of the WGD on small-scale SB-VAWT. The studied parameters of the WGD included the cone angle, height and the distance to rotor. Based on the method of quadratic rotary orthogonal combination design, starting torque performance effects of the three parameters of WGD on SB-VAWT were researched by numerical simulation firstly. Two better structural parameter combinations of WGD were obtained. The static flow fields around the rotor with WGD were calculated. Furthermore, the model of the two kinds of WGD were designed and made. Wind tunnel tests were carried out on the static torque characteristics, rotational speed performance from static condition to stable rotational condition and the power characteristics at different tip speed ratios. According to the results, the new WGD proposed in this study was proved to be effective for both the static and dynamic performance improvement of SB-VAWT. This research can provide a reference for the study of optimum WGD for improving the performance of SB-VAWT.

Smoothing the static torque characteristic of synchronous reluctance motor by Taguchi optimization method

Smoothing the static torque characteristic of synchronous reluctance motor by Taguchi optimization method

Torque Characteristics Estimation Method of Multi-Degree-of-Freedom Spherical Actuators Using Flux linkages Variations

Multi-degree-of-freedom (multi-DOF) spherical actuators have been developed for the fields of robotics and industrial machinery. In general, an actuating system with several-DOF is composed of single-DOF motors, which results in large, heavy and complicated structures. Therefore, multi-DOF spherical actuators are expected to solve these problems, and various actuators have been studied. Unlike single-DOF motors, the multi-DOF spherical actuators can generate torques in various directions at various positions. Due to this, it is difficult to measure the static torque characteristics. In this paper, in order to evaluate the static torque characteristics experimentally, a measuring torque constant method is proposed. This method can evaluate the static torque characteristics over the entire movable range by measuring several point. Finally, the effectiveness of this method is discussed.

Centrifugal pediatric ventricular assist device with 5-DOF controlled self-bearing motor

Mechanical circulatory support is one of the strongest candidate for heart disiese treatment. Research interest in pediatric circulatory support using ventricular assist devices (VADs) increases due to the succsessful use of VADs in adult heart failure therapy. In this study, a next generation continuous flow maglev VAD with a 5-degrees of freedom (5-DOF) controlled axial gap type self-bearing motor has been developed for pediatric circulatory support. The developed pediatric VAD prototype, which consists of a top stator, a bottom stator, a centrifugal blood pump and a levitated rotor impeller, has 31 mm in external diameter and 36 mm in hight. This paper investigated the disturbance force acting on the levitated impeller and the magnetic levitation stability in several driving condition of the centrifugal pump. The distrurbance force was estimated by using static suspension force and torque characteristics of the 5-DOF controlled self-bearing motor. The developed pediatric VAD suppressed the disturbance force and indicated non-contact levitation up to a rotating speed of 5000 rpm.

Torque characteristics of double-stator permanent magnet synchronous machines

Abstract The torque profile of a double-stator permanent magnet (PM) synchronous machine of 90 mm stator diameter having different rotor pole numbers as well as dual excitation is investigated in this paper. The analysis includes a comparative study of the machine’s torque and power-speed curves, static torque and inductance characteristics, losses and unbalanced magnetic force. The most promising flux-weakening potential is revealed in 13- and 7-rotor pole machines. Moreover, the machines having different rotor/stator (Nr/Ns) pole combinations of the form Nr = Ns ± 1 have balanced and symmetric static torque waveforms variation with the rotor position in contrast to the machines having Nr = Ns ± 2. Further, the inductance results of the analyzed machines reveal that the machines with odd rotor pole numbers have better fault-tolerant capability than their even rotor pole equivalents. A prototype of the developed double-stator machine having a 13-pole rotor is manufactured and tested for verification.

Evaluation Method for Multidegree-of-Freedom Spherical Actuators Under Power Control

Multidegree-of-freedom (multi-DOF) actuators have been developed for the fields of robotics and industrial machinery. In general, an actuating system with multi-DOF is composed of single-DOF actuators, which results in large, heavy, and complicated structures. Therefore, multi-DOF actuators are expected to become a key technology to solve these problems, and various actuators have been proposed and evaluated using their own methods. However, evaluation methods for absolute comparisons of the actuators have not been proposed. In order to evaluate the characteristics of the spherical synchronous actuators under the same condition, an evaluation method based on a torque equation and singular value decomposition is proposed. The proposed method can evaluate the static torque characteristics using a torque area that is composed of torques around arbitrary axes. The effectiveness of the proposed method is verified by comparing the static torque characteristics of several spherical actuators.

Experimental Evaluation of the Static Characteristics of Multi-Degree-of-Freedom Spherical Actuators

Multi-degree-of-freedom (multi-DOF) actuators have been developed to be applied in the fields of robotics and industrial machinery. In general, an actuating system with several-DOF is composed of single-DOF motors, which results in large, heavy, and complicated structures. Therefore, multi-DOF actuators are expected to solve these problems, and various actuators have been studied. Unlike single-DOF motors, the multi-DOF actuators can generate torque in various directions at different positions. Due to this, it is difficult to measure the static torque characteristics. In this paper, a measuring method of the torque constant is proposed in order to measure the static torque characteristics. This method can be used to evaluate the static torque characteristics over an entire movable range by measuring only a limited number of points. Finally, the effectiveness of this method is discussed.

Fabrication and test of an axial-field HTS rotating machine with integrated magnetic coupling

High temperature superconducting (HTS) electrical machines have high torque density with a very high efficiency. Torque tubes are usually used to transmit the torque from the cold to the warm environment which results in thermal losses and mechanical problems. To overcome these difficulties, we propose to transmit the torque of the HTS machine through an integrated HTS magnetic coupling. A prototype has been constructed and tested showing the effectiveness of the proposed solution. The machine and the coupling share the same HTS rotor while the torque produced by the machine is transmitted to the load via a permanent magnets rotor. This solution allows the reduction of the thermal losses and a natural protection against overload during fault. The electromagnetic design is carried out using 3D finite elements (FE). The HTS material electrical behavior is described using a power law so it was possible to determine the operating current of the HTS coils of the device. Many test results such as curves of the HTS coils, static torque, back-EMF and on-load characteristics are presented and checked by the FE computations.

ナノMR流体を用いた触覚提示用MRデバイスの開発と特性試験

In this study, we developed a torque controllable device using a magnetorheological fluid with several ten nanometer sized Fe particles (Nano-MRF). We described the structure of the device and measured the static and dynamic torque characteristics with a rotational testing machine. The results shows the Nano-MRF showed better stability and response times than those of a commercial MRF.

Data-Reconstruction-Based Modeling of SRM With Few Flux-Linkage Samples From Torque-Balanced Measurement

This paper proposes a combined modeling method for switched reluctance machine (SRM) with few samples of flux linkage characteristics measured without rotor clamping devices and position sensors. The proposed method mainly consists of two steps, namely data reconstruction and characteristic description. In data reconstruction, the entire flux linkage characteristics are obtained by training support vector machine (SVM) with the measured few samples. The characteristics from the trained SVM are consistent well with those from the rotor-clamping measurement. In characteristic description, back-propagation neural network (BPNN) is adopted to describe the reconstructed flux linkage characteristics and calculated static torque characteristics. On this basis, the simulation model of the SRM prototype is built in MATLAB. The results from simulation under both motoring and generating mode are compared with those from experiments, and good agreements can be found, which prove the effectiveness of the proposed modeling method. To further demonstrate the accuracy and application of the entire flux linkage characteristics obtained from data reconstruction, BPNN is used again to build the mapping from flux linkage and phase current to rotor position for rotor position estimation, and some results are presented. The applicability of the proposed method to different SRM topologies is discussed as well.

多自由度球面同期アクチュエータの定電力下における静特性評価手法の提案

Multi-degree-of-freedom (multi-DOF) actuators have been developed for the fields of robotics and industrial machinery. However, evaluation methods for the multi-DOF actuators have not been proposed. In order to evaluate the characteristics of the actuators, an evaluation method based on a torque equation and singular value decomposition is proposed. The evaluation method can be used to evaluate the torque characteristics using a torque area that is composed of an absolute torque and its direction. Finally, the static torque characteristics of some previously developed multi-DOF actuators are evaluated using the proposed evaluation method.