International Journal of Applied Electromagnetics and Mechanics

The bending strain in the Nb _3 Sn composite superconductors can cause degradation of the critical current in a significant portion of superconducting filaments. For a correct estimate of the bending strain in the "react and wind" coil conductors it is necessary to take into account that they can be deformed plastically during insulation and winding processes. Cases of plastic deformation due to the tensile stress in a macroscopically homogeneous multifilamentary composite superconductor the prestress of which is smaller than the yield stress in tension are considered in the paper.

The aim of this investigation was to develop a specific modelling approach capable of reducing the size of the fuel injector solenoid device while improving its response time and attraction force. Several developed modelling and simulation procedures have focused on various aspects of solenoid component modifications in order to develop an evolution process of miniaturising a fuel injector solenoid, using the latest finite element method(FEM) tool software. The specific factors that influenced the optimum operation of the fuel injector solenoid were the geometrical shape of individual solenoid components, material properties, air-gap constraints, boundary conditions, current source conditions, mass constants, and damping coefficients of the plunger. The attraction force distribution in the main air-gap was directly influenced by the taper angle of the 2D and 3D plunger pole faces, plunger length and the permanent magnetism. The precise definition of the electro-mechanical motion of plunger was of enormous importance in reducing the fuel injector solenoid response time, closely related to stroke and mass of the plunger, spring characteristics, motion and rebound of the plunger. Using the developed approach, the initial size of the fuel injector has been reduced by 35%, the attraction force increased by 26% and the response time reduced by 76%. However, by frequently repeating the design trials and conducting a thorough experimental investigation, the final minimum response time was achieved by the virtual rebound delay model. The reduction in response time from the 'optimal' experimental to virtual model was by 35%. The simplicity and effectiveness of the developed methods, allowed for quick and accurate evaluation.

Classical microeconomics and game theory offer a conceptual frame to solve a design problem, characterized by multiple objective functions in mutual conflict. This viewpoint is largely accepted for the design of high-tech products as seen in aerospace engineering. However, for long-established products – like electromechanical and electromagnetic devices – the ongoing evolution in design strategies is not fully influenced by the impact of new design methodologies and software facilities. With this rationale, the shape design of a permanent-magnet three-phase motor is considered as an example of small actuator for house appliances; the analysis of the magnetic field is based on a finite-element model of the device. The design goal is to identify the magnet shape, such that the cogging torque of the motor is minimum for a given value of radial induction at the air-gap. More generally, the problem is cast in terms of multiobjective design: find the set of magnet shapes such that the torque is minimum and the induction is maximum, subject to the given constraints. Solutions in terms of Pareto front and Nash equilibrium are obtained by means of an evolutionary algorithm; during the automated search, discrete-valued design variables were considered, for the sake of a realistic design. The paper shows that the application of multi-objective optimisation in electromechanics gives a powerful design tool. Requirements in terms of timing and facilities are compatible with the resources of a research-and-development(R&D) centre of an industrial company in the area of electrical engineering.

The interaction between a harvesting structure and a storage circuit is modeled using a full-bridge rectifier. In order to focus on the challenges associated with modeling the intrinsic nonlinearity of the rectifier, the authors have considered a piezoelectric plate in the thickness-stretch mode of oscillation and have represented the storage circuit by a simple LRC circuit in this first attempt. It is found that the primary performance of such a model energy harvester can be characterized by two non-dimensional parameters, i.e., the non-dimensional aspect ratio of the piezoelectric plate and the non-dimensional inductance of the LRC circuit, and that the power density of this model harvester can be optimized by adjusting these two parameters properly. Specifically, for each fixed non-dimensional aspect ratio there exists an optimal non-dimensional inductance, at which the power density is maximized, and conversely, for each fixed non-dimensional inductance there is an optimal non-dimensional aspect ratio, leading to a maximum of the power density when the volume of the plate is kept constant. The analysis for this simplified model piezoelectric harvester, though not realistic, provides a framework for further development on design guidelines for piezoelectric energy harvesters of optimal performance.

This paper addresses the anti-vibration control produced by manipulator movements of contactless planar actuator with manipulator (CPAM). The manipulator on top of the planar actuator has 2-DOF which provides precise linear and rotary movement of the end tip of the manipulator. The successful suppression of the vibration will improve the position accuracy of the CPAM. For the purpose of the anti-vibration control design, a platform of 3-DOF contactless planar actuator with 2-DOF manipulator has been designed and manufactured. The platform, that mimics the magnetic array of the planar actuator, is suspended by 9 voice coils which are distributed into regular array to simulate the topology of the planar actuator and will be used for gravity compensation and for manipulator platform control in 3-DOF: vertically and two tilting angles. The other 3-DOF is fixed by the suspension system consisting of 3 stiff rods. Nine inductive sensors are mounted on the base plate to measure the posture of the platform when the manipulator is working. The CPAM model is based on rigid body dynamics and movement of the manipulator is taken as a disturbance in the platform control. According to the concept of loop shaping, robust H∞ controllers for each of the DOF of the platform are then designed depending on the estimated disturbance force and torque from the manipulator. Control responses in 3-DOF are then presented. The results illustrate high positioning stability.