Terms Of Output Torque Research Articles

Design and Optimization of a Dual-Permanent-Magnet Vernier Machine With a Novel Optimization Model

In this article, the optimal configuration of the stator for the dual-permanent-magnet vernier machine (DPMVM) is investigated. A novel numerical model used to perform the optimization and compare the performances between different permanent magnet (PM) arrangements on the stator part is first presented in this article. According to the proposed numerical model, the effects of the location of PMs at different positions of the stator are studied in terms of output torque, torque ripple, efficiency, and power factor (PF). It is found that the PMs at stator slots contribute more to the output torque than PMs on stator teeth. Moreover, it is found that the stator PMs will add extra cogging torque to the machine compared with the rotor-PM machine. The PF of the dual-PM machine with the combination of the selected stator slots and rotor poles can be higher than 0.9, which is relatively higher compared with both the rotor-PM machine and stator-PM machine.

Performance Analysis of a New Switched Reluctance Motor With Two Sets of Embedded Permanent Magnets

This article proposes an enhanced-torque switched reluctance motor with two sets of permanent magnets (PM-SRM) embedded inside the stator yoke and the end teeth of the neighboring modules. The PMs contribute to intensify the air-gap flux density and reduce the magnetic saturation in the stator poles. As a result, the output torque can be enhanced to a significant extent. The working principle of the proposed PM-SRM is clarified using its magnetic circuit model (MCM). The characteristics of the PM-SRM are obtained and compared with classical 12/8 and 6/5 SRMs and hybrid reluctance motors (HRMs) in terms of static and average torque and average torque per PMs volume. The steady-state performance of the PM-SRM in terms of current and torque waveforms is carried out, and the PM-SRM is compared with considered SRMs and HRMs in terms of output torque, power, and efficiency. All the comparisons demonstrate the out-performance of the proposed PM-SRM over other SRMs and HRMs. To validate the simulation results, a prototype of the PM-SRM is manufactured and the experimental results are obtained. Both the simulation and experimental results are indicative of the fact that the proposed PM-SRM can gain high torque and high PM utilization factor, simultaneously.

Optimisation‐based procedure for characterising switched reluctance motors

This study introduces an optimisation-based procedure for characterising switched reluctance machine (SRM) performance and studies the optimisation to determine the conduction angles in SRM drives. The objectives employed in the optimisation cases are maximising average output torque, maximising the ratio of average torque over root mean square (RMS) value of phase current, and minimising RMS value of net torque ripple. Combinations of these objectives are used in four different cases, which are formulated either as single- or multi-objective problems. These cases are then compared in terms of output torque, torque ripple, and efficiency. One method of the four is selected and the performance of the motor over the entire operating range is characterised based on optimised turn-on and turn-off angles. Experimental results are used to verify the motor performance obtained from the optimisations for selected operating points.

Three-Phase 24/16 Switched Reluctance Machine for a Hybrid Electric Powertrain

This paper presents the design process of a 60-kW switched reluctance motor for traction application in a hybrid electric vehicle. The motor has 24 stator poles and 16 rotor poles. A multiobjective optimization method has been employed in the optimization of conduction angles for priority operating points and over the entire operating range. Two objectives, maximizing output torque and minimizing torque ripple, are used in the optimization problem. A comprehensive comparative performance analysis with varying stator pole height, stator taper angle, rotor pole arc angle, and pole shoe shape is also presented. The performance of the proposed motor over the entire operating range has been characterized based on the optimized conduction angles. The finite element analysis results of the machine demonstrate the potential of the proposed motor in hybrid powertrains in terms of output torque, torque quality, and efficiency.

Three dimensional simulation of J-shaped Darrieus vertical axis wind turbine

The present research aims to investigate the concept of J-shaped blade in a straight–bladed Darrieus type VAWT in terms of output torque and power by employing high-fidelity 3D numerical simulations. Theoretically, since the J-shaped blades can benefit from the lift and drag forces simultaneously, this combined forces help the turbine possess faster operation at low wind speeds, thereby resulting in the termination of self-starting problem and improving power coefficients, especially at low and moderate tip speed ratios. In this study, NACA0015 is served as the base airfoil and has been modified to generate the desired J-shape profile. The attained results indicate improvements on torque and power coefficients, more specifically in the first half of revolution namely 0° < θ < 180°. Additionally, the amplitude of power and torque oscillation in each revolution has been curtailed and shifted up. A chunk of these improvements can be attributed to the inherent geometry of J-shaped profile through which the generated vorticities are trapped inside the blade and released behind the rotor. Not only that, the volumetric representation of turbulent kinetic energy discloses that the wake region behind the J-shaped rotor is free from slow dissipation of vorticities and possesses much less turbulency.

Cogging Torque Reduction of a Hybrid Axial Field Flux-Switching Permanent-Magnet Machine With Three Methods

The hybrid axial field flux-switching permanent-magnet machine (HAFFSPMM) is a novel hybrid excited machine with short axial length and high torque density, which is suitable for electrical vehicle drive. However, the HAFFSPMM exhibits a higher cogging torque than traditional permanent-magnet machines due to the doubly salient structure and the high flux density. To reduce the cogging torque, three cogging torque reduction methods by tangential displacement of stators, asymmetric rotor pole shape, and segment-twisted rotor are investigated in this paper. The influences of the asymmetric angle of the three methods on the cogging torque and the output torque are analytically investigated and numerically verified by a three-dimensional finite-element method. The results show that the cogging torque can be greatly reduced, whereas the output torque decreases slightly even increases. In no terms of output torque, the cogging torque with segment-twisted rotor is less than the other two methods; in terms of output torque, the cogging torque reduction with an asymmetric rotor pole shape is better than the others.

Performance analyses of a spark-ignition engine firing with gasoline–butanol blends at partial load operation

Biofuels seem to represent one of the most promising means for the limitation of the greenhouse gas emissions coming from traditional energy systems.In this paper, the performance of a “downsized” spark-ignition engine, fueled by gasoline and bio-butanol blends (20% and 40% butanol mass percentage), has been analyzed.In the first phase of this activity, the experimental tests have been carried out at operating points ranging from low to medium engine speed and load.The first investigations were aimed to assess the main differences among the different fuels in terms of output torque, thermal efficiency, combustion duration and optimal spark timing. In order to study the engine behavior in a wide range of fuel mixtures, these parameters have been evaluated for equivalence ratio values ranging from 1.25 to 0.83.The results obtained in this step show that both the engine torque and thermal efficiency slightly decrease (meanly about 4%) when the blend alcohol content increases. However, butanol increases the burning rate of lean mixtures and an interesting result is that the spark advance does not require adjustments when fueling changes from neat gasoline to bio-butanol/gasoline blends.Later, the pollutant emissions and the CO2 emissions, for both rich and lean mixtures of pure gasoline and gasoline bio-butanol blends, have been measured. In general, firing with alcohol blends, NOx and CO emissions remain quite the same, HC emissions slightly decrease while the CO2 emissions slightly increase.At the end, in order to reproduce the real world urban driving cycle, stoichiometric mixtures have been analyzed. In these conditions, the engine thermal efficiency, at given speed and torque, has been evaluated for each kind of fueling. The results obtained in these operating points have shown that the alcohol blend fueling performs an efficiency penalty less than 2 percent.

A travelling wave rotary motor driven by three pairs of langevin transducers

In this work, numerical simulations and experimental measurements carried out on a high-power ultrasonic motor are presented. The proposed motor is composed of an annular shaped stator and two cone-shaped rotors. The rotors are pressed into contact with the edges of the inner surface of the stator by means of a pre-stress system. A traveling rotating wave is generated in the stator by three pairs of Langevin transducers suitably shifted both in space and time. Each transducer is designed to excite radial nonaxisymmetric modes in the ring. The motor has been effectively clamped to the housing by using two flanges passing through the middle plane of 2 transducers. Finite element analysis was employed to evaluate two different configurations of the motor, both using 6 driving transducers, and to analyze the effect of the flange on the design and on the performance of the transducer. Experimental measurements carried out on a manufactured prototype show that the proposed motor exhibits greatly improved performance in terms of output torque and mechanical power compared with similar previous prototypes which use fewer driving transducers and a different clamping system. The motor weighed 0.67 kg, and had a working frequency of 23.6 kHz, maximum rotational speed of 116 rpm, and static torque of 0.94 Nm.

Alternate Poles Wound Flux-Switching Permanent-Magnet Brushless AC Machines

Flux-switching permanent-magnet (FSPM) brushless machines have emerged as an attractive machine type by virtue of their high torque densities, simple and robust rotor structure, and the fact that permanent magnets and coils are both located on the stator. Both 2-D and 3-D finite element analyses are employed to compare the performance of a conventional all poles wound (double-layer winding) topology with that of three modular alternate poles wound (single-layer winding) topologies, in terms of output torque, flux-linkage, back EMF, and inductances. It is shown that the FSPM machine can be designed in this way without incurring a significant performance penalty, but that some degree of rotor skewing or a variation in stator and rotor pole combination may be required in order to maintain a sinusoidal back-EMF waveform and reduce the torque ripple. Experimental validation is reported for both conventional all poles wound and alternate poles wound FSPM machine topologies.