Search

Background and Objectives: Due to exclusive advantages of the permanent magnet synchronous motors (PMSMs) such as large torque/power density, high efficiency and wide speed range in constant power region, special attention has been paid to these motors especially for electric vehicle (EV) application. A conventional type of PMSMs which is more suitable for EV application is the interior permanent magnet synchronous motors (IPMSM). The main objective of the present paper is design optimization of this type of PMSM to increase efficiency and reduce torque ripple which are important for EV application. Methods: Using different shape design optimization methods including rotor notch, flux barrier and skewed rotor, design optimization of the delta-shape IPMSM is done and an optimized design is suggested first. One of the most important factors affecting the performance of the IPMSM is the magnet arrangement in the rotor structure. Based on the design of experiments (DOE) algorithm, optimal values of some design parameters related to magnet are then determined to improve more the motor performance of the suggested structure. Results: The simulation results based on finite element method (FEM) are provided for a typical high-power IPMSM to evaluate the effectiveness of the proposed technique. In comparison to the initial design, 7% increase of average torque, 50% reduction of torque ripple and 1.4% increase of efficiency are resulted for the optimized motor. Conclusion: Using the proposed hybrid design optimization procedure (shape design optimization with optimum design parameters), significant improvement of some characteristics related to the delta-shape IPMSM including efficiency, average torque and torque ripple is resulted and this conclusion is desirable for EV application. [ABSTRACT FROM AUTHOR]

This paper presents a wave-based modeling and control approach for suppressing torsional vibrations of an elastic shaft driven by a motor at one end and an inertial load at the other end. A two-port network model representing the dynamics of torsional displacements is obtained starting from the partial differential equations governing a shaft in torsion. By incorporating appropriate boundary conditions, the infinite dimensional transfer function of the system is obtained. Furthermore, the system is represented by delay elements that can be used for simulation purposes. An inversion-based controller that can be used to suppress vibrations while rotating the shaft according to a specific trajectory is then developed. The performance of the controller is further studied using numerical simulations. [DOI: 10.1115/1.2776338] Keywords: torsional vibrations, infinite dimensional systems, vibration control two-port networks, time-delay systems

In this paper, modular design of embedded feedback controllers using field-programmable gate array (FPGA) technology is studied. To this end, a novel distributed-arithmetic (DA)-based proportional-integral-derivative (PID) controller algorithm is proposed and integrated into a digital feedback control system. The DA-based PID controller demonstrates 80% savings in hardware utilization and 40% savings in power consumption compared to the multiplier-based scheme. It also offers good closed-loop performance while using less resources, resulting in cost reduction, high speed, and low power consumption, which is desirable in embedded control applications. The complete digital control system is built using commercial FPGAs to demonstrate the efficiency. The design uses a modular approach, so that some modules can be reused in other applications. These reusable modules can be ported into Matlab/Simulink as Simulink blocks for hardware/software cosimulation or integrated into a larger design in the Matlab/Simulink environment to allow for rapid prototyping applications. Index Terms--Distributed arithmetic (DA), embedded controllers, field-programmable gate array (FPGA) design, power and speed optimization, proportional-integral-derivative (PID) controller.

Optimal shape design of an interior permanent-magnet (IPM) synchronous motor can substantially reduce its torque pulsation. However, the shape design variations should be feasible and practical. We report on an optimal shape design obtained by drilling small circular holes in the rotor. We found that an optimal location and radius of the holes effectively suppresses the torque pulsation of the IPM drive for various loads under steady-state conditions. The optimal design at rated load is considered as the final design. We use a transient finite-element analysis that is coupled with motion and adequate electric excitation for optimization purposes. An evaluation of the optimal design at various operating conditions showed torque ripple reduction and average torque improvement under all load conditions. The optimal design also shows improvement in the field-weakening region for high-speed operation. Index Terms--IPM synchronous motor-drive, shape design optimization, time-stepped finite-element method.

Internet-based telerobotic systems have been evolving rapidly in recent years. Using Web-based technology, telerobotic systems have been shown to have an increasing potential for a variety of applications including remote control, manufacturing, surgery, training, and education. In this paper, we present an Internet-based distributed, multiple-telerobot system that enables operators to use remote robots in order to perform cooperative tasks. Several multiple-telerobot demonstration programs have been designed, including it single telerobot training program, a multiple-telerobot "group object-handling" program, and pairs of telerobots serving Internet participants playing with a Rubik's Cube to illustrate Internet-based interaction and collaboration. Experimental tests have been performed on three demonstration programs that are presented in this paper. Index Terms--Graphical simulation and visualization, Internet-based teleoperation, multiple-telerobots, telerobotics, web-based robotic system.

In this paper, a novel multiobjective optimization method based on a genetic-fuzzy algorithm (GFA) is proposed. The new GFA method is used for optimal design of a switched reluctance motor (SRM) with two objective functions: high efficiency and low torque ripple. The results of the optimal design for an 8/6, four-phase, 4 kW, 250 V, 1500 rpm SRM show improvement in both efficiency and torque ripple of the motor. Index Terms--Multiobjective optimization, SRM design.

This paper addresses data acquisition and feedback control of electron-beam positions in the Duke University Free-Electron Laser Facility. The control system consists of a distributed system of VME-based hardware and processors connected through a network to host workstations. The host workstations provide graphical data presentation to the user and are also used for high-level supervisory control. The electron-beam profile is controlled by electromagnetic forces generated by passing currents through the coils of correction magnets distributed around the ring. A desired control objective is to move the stored electron beam to specific locations in the vacuum chamber and to stabilize the orbit in the presence of disturbances. The technical details of implementing the data acquisition and control scheme and their integration with the existing control system modules are presented along with experimental results. Index Terms--Attenuation, data acquisition, distributed computing, feedback systems, free-electron lasers, stability.

A transformation technique in conjunction with coupled magneto-thermal FE field analysis is used to obtain temperature distribution profile of underground power cables. The transformation technique is used to limit the open region of the solution space, resulting in more accurate solutions with fewer mesh elements and less computing time than that required by open boundary FE solution. Two test problems have been solved and the results are compared with the results obtained from lumped resistive and open boundary FE methods. Index terms - Coupled field analysis, Finite element method

The Magnetic Equivalent Circuit (MEC) method has been used to model the nonlinear magnetic field in electromagnetic devices for steady-state and dynamic conditions. However for highly saturated electromagnetic device, the conventional MEC method is inaccurate in predicting device characteristics. With experience gained from the Finite Element (FE) method, the MEC method can be modified to provide significant accuracy improvement in the field solution results. The main modification is done in the modeling of the highly saturated regions. The Improved Magnetic Equivalent Circuit (IMEC) is used to predict the characteristics of a Switched Reluctance Motor (SRM). The results from IMEC are compared with those obtained by conventional MEC, FE methods, and measurement. Index terms - Magnetic circuits, electromagnetic devices, nonlinear analysis.

Recently, bonded composite patch repair, because of its significant advantages over traditional methods, has been highly accepted in several industries, particularly in aerospace applications. In this paper, a multi-scale finite element algorithm is proposed to simulate crack growth of repaired plates under fatigue load by considering the effects of composite micro-scale properties. The algorithm is verified through conducting an experimental set up and the proposed model is in reasonable agreement with experiments. The influences of different fiber volume fractions (VF), number of layers and fiber orientation of composite patch on the fatigue responses of adhesively bonded patch are investigated. For this purpose, Python scripts are written to automatically increase the size of the crack in ABAQUS. In this study, glass–epoxy and boron–epoxy patches are selected with volume fraction 0.1 to 0.7, the numbers of layers of 4, 8 and 16 as well as 5 different fiber orientation lay-ups. The maximum enhancement of fatigue life experimented by the variation of volume fraction is 133% in the mentioned range. Also, increment in the number of cycles by about 287% and 172% were seen per different number of layers and fiber orientation, respectively. [ABSTRACT FROM AUTHOR]

Copyright of West Indian Medical Journal is the property of West Indian Medical Journal (WIMJ) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)