Competitive Torque Research Articles

Attitude control of combined spacecraft with fuzzy neural network disturbance observer

A finite-time control strategy based on a fuzzy neural network disturbance observer (FNNDO) and nonsingular terminal sliding mode (NTSM) is proposed for the attitude control system of a combined spacecraft in the presence of non-cooperative targets with competitive torque output. First, a mathematical model of the combined spacecraft attitude is established with the service spacecraft as the reference. Then, the external disturbances and competitive torque output from non-cooperative targets are treated as generalized disturbances, and FNNDO is employed for tracking and compensation. Subsequently, a NTSM controller is designed to achieve finite-time attitude takeover control of non-cooperative targets. The stability of the disturbance observer and controller is proven using Lyapunov stability theory. Simulation results demonstrate that this control strategy effectively handles the competitive actions of non-cooperative targets while rapidly stabilizing the combined spacecraft’s attitude at the desired values.

Acoustic Noise Reduction of a High-Efficiency Switched Reluctance Motor for Hybrid Electric Vehicles With Novel Current Waveform

One of the major topics of switched reluctance machines (SRMs) is how to reduce the acoustic noise and vibration without decreasing the efficiency. In this paper, a few novel current profiling methods are proposed to reduce the acoustic noise by flatting the radial force sum and to reduce optimal torque ripple with best efforts to enhance the efficiency. The proposed method is adopted to the 18/12 pole SRM, which has identical outer dimensions and competitive torque, output power, efficiency, and operating region of the permanent-magnet motor used in the hybrid vehicles. It is found that the proposed method can improve not only the radial force ripple characteristic but also the iron loss minimization. The efficiency enhancement is also found to be possible in a few cases depending on the demanding criteria; thanks to the phase shift of the fundamental component of the current waveform. The proposed method is verified in the experiments.

High Torque Density Macro-scale Electrostatic Rotating Machines: Electrical Design, Generalized <inline-formula> <tex-math notation="LaTeX">$d-q$</tex-math> </inline-formula> Framework, and Demonstration

The use of advanced dielectric liquids and manufacturing techniques for enhanced surface area per unit volume, along with other multiplicative gains, is enabling macro-scale electrostatic machines with competitive torque densities. This emergence prompts the need for circuit modeling—that guides machine design and drive controls—rooted in the canon of well-established electromagnetic machinery practices. In this study, prior dielectric and manufacturing innovations are combined with a newly developed unified electrostatic machine $d-q$ -axis framework to form a machine that demonstrates industrial utility. Design, equivalent circuits, and performance are validated by an experimental prototype intended for low-speed direct-drive servo actuators. A prototype electrostatic machine was constructed entirely of aluminum and printed circuit boards, and possesses active material torque densities ≥1.4 N⋅m/kg and ≥2.65 N⋅m/L without the need for forced air or liquid cooling. Additional features include near zero loss at stall and low torque ripple.

Optimization design and analysis of a hybrid permanent magnet flux-switching motor with compound rotor configuration

This paper proposes a type of flux-switching permanent magnet (FSPM) motor, where the design concept of the hybrid permanent magnets (HPM) and the compound rotor are incorporated into the motor design. In such design, the proposed motor can not only realize the significant reduction of NdFeB volume, but also artfully convert external magnetic flux leakage into the air-gap field to achieve competitive torque density and desirable PM usage efficiency. For extensive investigation, two topologies of the HPM are designed and analyzed for the proposed motor, which consist of the parallel-magnetic-hybrid (PMH) mode and serial-magnetic-hybrid (SMH) mode. To fully exploit the potential advantages of the proposed motor, a multi-objective optimization design is conducted, where the response surface method (RSM) and sequential non-linear programming (SNP) method are purposely utilized. After optimization, the electromagnetic performances of the motor with PMH mode and SMH mode are evaluated and compared by using finite element method (FEM), which include the back-EMF, cogging torque, output torque, and so on. Furthermore, the partial demagnetization of the ferrite PM is also investigated in the paper. Finally, the theoretical analysis and simulation study verify the effectiveness of the proposed motor and corresponding optimization design.

Analysis of Fractional-Slot Concentrated Winding PM Vernier Machines With Regular Open-Slot Stators

Permanent magnet (PM) vernier (PMV) machines have been extensively researched for direct-drive applications due to their inherently high torque density. This paper presents a quantitative investigation on fractional-slot concentrated winding PMV (FSCW-PMV) machines with regular open-slot stator topology. Based on winding theory, the configuration of two winding types, i.e., nonoverlapping winding and FSCW with two-slot coil pitch are analytically derived for PMV machines, respectively. Through finite element analysis, comparative study of FSCW-PMV machines, regular integral slot winding PMV machines, and regular PM machines are performed. It is found that the flux modulation effect also exists in regular nonoverlapping winding PM machines. In other words, the regular nonoverlapping winding PM machine also belongs to the PMV machine family. The PMV machine with two-slot coil pitch is newly proposed, and turns out to be a promising PMV machine topology with competitive torque capability and power factor. Finally, a prototype of 18-slot, 14-rotor pole pair, and 4-stator pole pair PMV machine with two-slot coil pitch is built. Experimental results show that the torque density of the prototype can reach 20.0 kNm/m3 and the power factor is 0.91.

Viable Arcuate Double-sided Magnetic Gear for Competitive Torque Density Transmission Capability

Magnetic gears (MGs) offer significant potential advantages relative to conventional mechanical gears, such as: no contact, no friction, no lubrication, inherent overload protection and free from noise and vibration. Despite of these superior features they have received little attention due to complexity of operation and relatively low torque density transmission. This paper introduces a new magnetic gear topology with a highly competitive torque density transmission capability. This configuration is inspired of combination of the traditional radial and axial flux MGs. The assurance of accuracy based on a basic design of axial flux magnetic gear dimensions leading to Proof-of-Concept “Arcuate Double-Sided MG”. The Proof-of-Concept seeks to provide a better solution to the problems of flux maldistribution and concentration compared to what has been proposed previously. Thus, torque density performance of this MG is intensively augmented. The cogging torque is also computed in further simulations. However, the above requires advanced numerical techniques and hence 3-Dimensional simulations for calculating localized flux density and the corresponding torque density. Completion of this development will mark an important milestone in magnetic gear technology, and significant performance improvement will be realized.

Weighted Factor Multiobjective Design Optimization of a Reluctance Synchronous Machine

The relationship between the well-known competitive torque density and less-competitive power factor of reluctance synchronous machines (RSMs) is investigated in this study. The investigation was carried out by implementing a complete machine model in the optimization, with varying machine-pole number and flux-barrier number combinations. Furthermore, the study consists of a multiobjective design optimization implementing a weighted-factor optimization technique. Determination of the weighting of this specific parameter relationship enables the designer to select an optimum multiobjective relationship during optimization. A specific machine was selected for analysis, then analyzed and manufactured for validation of simulation results.

Optimization of an 80-kW Segmental Rotor Switched Reluctance Machine for Automotive Traction

There is significant interest in the development of switched reluctance machines (SRMs) for use in automotive traction applications. This has been driven by their low cost compared with rare earth permanent-magnet-based motors, driven by the high cost of rare earth permanent magnets, coupled with their potential for competitive torque densities. This paper describes the development of a variant of the SRM, utilizing a segmental rotor construction, which has previously been demonstrated to provide the potential for significant improvement in torque densities compared with SRMs with a conventional toothed rotor construction. This paper describes a strategy that has been developed to optimize the Segmental Rotor SRM to maximize efficiency with the aim of achieving performance equivalent to that of the 80-kW interior permanent-magnet machine utilized in Nissan's LEAF electric vehicle. Optimization applies a combination of static and dynamic analyses in order to achieve a full and computationally efficient assessment of motor performance across different regions of the torque speed envelope. Test results from a prototype motor are also presented.

Comparative Study on Novel Dual Stator Radial Flux and Axial Flux Permanent Magnet Motors With Ferrite Magnets for Traction Application

This paper proposes two novel traction motors with ferrite magnets for hybrid electric vehicles (HEVs), which have competitive torque density and efficiency as well as operating range with respect to a referenced rare earth magnet motor employed in the third-generation Toyota Prius, a commercialized HEV. The two proposed traction motors, named as dual stator radial flux permanent magnet motor (DSRFPMM) and dual stator axial flux permanent magnet motor (DSAFPMM), adopt the same design concept, which incorporates the unaligned arrangement of two stators together with the use of spoke-type magnet array and phase-group concentrated-coil windings for the purpose of increasing torque density and reducing torque ripple. A finite element method is utilized for predicting the main characteristics, such as back electromotive force, cogging torque, electromagnetic torque, iron loss, and efficiency in both of the proposed motors. Moreover, a comparative study between the proposed DSRFPMM and DSAFPMM is performed under the same operating condition. As a result, it is demonstrated that both of the proposed ferrite permanent magnet motors could be good alternatives for traction application, replacing the rare earth magnet motors.

Comparison of the Test Result and 3D-FEM Analysis at the Knee Point of a 60 kW SRM for a HEV

The maximum torque values in computer analysis and experiment in the switched reluctance motor (SRM), having competitive torque density and efficiency with respect to the rare-earth permanent magnet motor employed in the 2009 Toyota Prius, have been compared. The SRM is highly saturated to provide the maximum torque for a short time; thus, the torque value tends to have considerable error of 15% even in the 3D FEM analysis with respect to experimental result because of the incomplete material setting. A comparison of the flux-linkage and current is also provided for consideration. The results of the 2D-FEM and 3D-FEM analysis as well as a test machine are presented. The maximum torque in the 3D-FEM analysis is shown to be within errors of 5.0% with respect to that in the test machine.

Torque Density and Efficiency Improvements of a Switched Reluctance Motor Without Rare-Earth Material for Hybrid Vehicles

A machine design of a switched reluctance motor having competitive torque and efficiency as well as compactness with respect to an interior permanent-magnet (IPM) synchronous motor (IPMSM) in a hybrid electric vehicle (Toyota Prius 2003) has been investigated. A torque of 400 N·m is set as a target with an outer diameter of 269 mm with an axial length of 156 mm, including coil end lengths. In addition, a 50-kW field weakening capability must be competitive to the IPMSM. The highest efficiency of 95% is also aimed. Stator and rotor structures and iron material are investigated. Test machines are built. Static and light load tests are carried out.

Design, analysis and realisation of a high-performance magnetic gear

Magnetic gears offer significant potential advantages compared with mechanical gears, such as reduced maintenance and improved reliability, inherent overload protection, and physical isolation between the input and output shafts. However, to date they have received relatively little attention, probably due to the relatively poor torque transmission capability of the magnetic circuit topologies which have been proposed. A new magnetic gear topology which combines a highly competitive torque transmission capability and a very high efficiency is described.