Output Space Mapping Technique Research Articles

Optimal sizing design of a 1.5 MW permanent magnets synchronous generator for an onshore wind conversion system

This paper proposes a fast and accurate optimal sizing design of 1.5 MW Permanent Magnets Synchronous Generator (PMSG) for a grid-connected wind application. A design strategy inspired from the output space mapping technique is adopted. A fast analytical model is used and detailed to determine the parameters and the performances of the PMSG. Then, the results are validated by a precise finite element model and adjusted iteratively until coherence between the two models is obtained. A multi-objective particle swarm optimization algorithm is deployed with aim of reducing the total losses and weight of the generator. The algorithm's parameters and results are given and analyzed. Three optimal machines are chosen and tested using a 2D-finite element model. The main design parameters of the optimal generators are given and discussed. Good efficiency and optimal designs are obtained for the sized machines thanks to the adopted design strategy.

Proposal of a Bi-Objective Kriging Adapted Output Space Mapping Technique for Electromagnetic Design Optimization

Multi-objective optimization with finite-element model (FEM) for the optimal design of electromagnetic devices is a complex task and also time costly. Output space mapping (OSM) techniques allow having an affordable computation cost with a minimum number of computationally expensive FEM evaluations. In this paper, a bi-objective Kriging adapted OSM, an original space-mapping technique based on adaptive nonlinear corrective projection, is proposed. First, the proposed technique is validated using a mathematical test function; Second, it is applied on a three-phase brushless dc motor, which is represented through two modeling levels: 1) coarse (analytical model) and 2) fine (2-D FEM). An advantage of this new technique is its ability to make the coarse model converge effectively toward the fine model.

Comparison of three space mapping techniques on electromagnetic design optimization

PurposeThis paper aims to investigate three low-evaluation-budget optimization techniques: output space mapping (OSM), manifold mapping (MM) and Kriging-OSM. Kriging-OSM is an original approach having high-order mapping.Design/methodology/approachThe electromagnetic device to be optimally sized is a five-phase linear induction motor, represented through two levels of modeling: coarse (Kriging model) and fine.The optimization comparison of the three techniques on the five-phase linear induction motor is discussed.FindingsThe optimization results show that the OSM takes more time and iteration to converge the optimal solution compared to MM and Kriging-OSM. This is mainly because of the poor quality of the initial Kriging model. In the case of a high-quality coarse model, the OSM technique would show its domination over the other two techniques. In the case of poor quality of coarse model, MM and Kriging-OSM techniques are more efficient to converge to the accurate optimum.Originality/valueKriging-OSM is an original approach having high-order mapping. An advantage of this new technique consists in its capability of providing a sufficiently accurate model for each objective and constraint function and makes the coarse model converge toward the fine model more effectively.

Infinitesimal Dipole Model Using Space Mapping Optimization for Antenna Placement

The infinitesimal dipole model (IDM) is very appealing for antenna placement problems, especially since antenna design details need not be available. The method has been mainly used to model antennas radiating in free space or above an infinite perfectly conducting ground plane, with synthetic data. The direct application of the method considering finite ground planes is impracticable because of the complexity of the associated Green's functions. In this letter, we propose a methodology to devise the equivalent model, taking into account edge diffraction effects due to the finite ground plane, but still maintaining a relatively low computational cost. We combine the classical IDM with the output space mapping technique so that the burden of model optimization is placed on the analytical model, and the more accurate but computationally intensive model is evaluated only a few times. To demonstrate the applicability of the method, we model a radar altimeter antenna operating at 4.3 GHz in a typical case of antenna integration: Only the measured far-field data are available. The equivalent model obtained is then incorporated into a commercial electromagnetic simulation package to compare its installed radiation pattern with the actual antenna measured pattern. An excellent agreement is verified.

Proposal of a Kriging Output Space Mapping Technique for Electromagnetic Design Optimization

Using the finite-element model (FEM) to achieve the optimal design of electromagnetic devices is a complex and time-consuming process. Space-mapping techniques reduce computation cost by aligning two models with different granularities, namely, a coarse model and a fine model. In this paper, Kriging output space mapping (OSM), an original space-mapping technique based on adaptive nonlinear corrective projection, is proposed and compared with a conventional OSM technique. The device for optimal sizing is a five-phase linear induction motor, which is represented through two modeling levels: 1) coarse (Kriging model) and 2) fine (2-D FEM). An advantage of this new technique is its ability to provide a sufficiently accurate model for each objective and constraint function and make the coarse model converge effectively toward the fine model.

Electromagnetic Actuator Design Analysis Using a Two-Stage Optimization Method With Coarse–Fine Model Output Space Mapping

Electromagnetic actuators are energy conversion devices that suffer from inefficiencies. The conversion losses generate internal heat, which is undesirable, as it leads to thermal loading on the device. Temperature rise should be limited to enhance the reliability, minimize thermal disturbance, and improve the output performance of the device. This paper presents the application of an optimization method to determine the geometric configuration of a flexure-based linear electromagnetic actuator that maximizes output force per unit of heat generated. A two-stage optimization method is used to search for a global solution, followed by a feasible solution locally using a branch and bound method. The finite element magnetic (fine) model is replaced by an analytical (coarse) model during optimization using an output space mapping technique. An 80% reduction in computation time is achieved by the application of such an approximation technique. The measured output from the new prototype based on the optimal design shows a 45% increase in air gap magnetic flux density, a 40% increase in output force, and a 26% reduction in heat generation when compared with the initial design before application of the optimization method.

N-level output space mapping for electromagnetic design optimization

Purpose – The aim of this paper is to reduce the evaluations number of the fine model within the output space mapping (OSM) technique in order to reduce their computing time. Design/methodology/approach – In this paper, n-level OSM is proposed and expected to be even faster than the conventional OSM. The proposed algorithm takes advantages of the availability of n models of the device to optimize, each of them representing an optimal trade-off between the model error and its computation time. Models with intermediate characteristics between the coarse and fine models are inserted within the proposed algorithm to reduce the number of evaluations of the consuming time model and then the computing time. The advantages of the algorithm are highlighted on the optimization problem of superconducting magnetic energy storage (SMES). Findings – A major computing time gain equals to three is achieved using the n-level OSM algorithm instead of the conventional OSM technique on the optimization problem of SMES. Originality/value – The originality of this paper is to investigate several models with different granularities within OSM algorithm in order to reduce its computing time without decreasing the performance of the conventional strategy.

Fast Optimization of a Linear Induction Motor by 3-Level Space Mapping Technique

For the design and analysis of a linear electrical motor, an analytical solution of electric and magnetic fields is barely achieved with the required accuracy, due to the end and edge effects, and the nonlinear characteristic of the materials. Optimal design with the finite element models (FEM) is often expensive, in terms of the computation time. The space-mapping techniques allow having an affordable computation cost with a minimum number of computationally expensive FEM evaluations. In this paper, based on a kriging model, a 2D FEM and a 3D FEM, a 3-level adapted output space-mapping technique is employed. The results show that the proposed algorithm allows saving a substantial amount of computation time compared to conventional 2-level output space-mapping technique.

Improvements for multi‐objective optimizations using output space mapping technique

PurposeThe purpose of this paper is to focus on the implementation and management of multi‐objective optimizations, with the help of heuristic algorithms such as space mapping methods.Design/methodology/approachThe authors consider the design of electromechanical actuators by the use of mathematical and computer means. Experiments are then virtual, because they correspond to numerical simulations. Dimensioning is then ensured by an optimization procedure of the space mapping type, whose main characteristic consists in using two models of the same size actuator (instead of a single one for classical optimization methods). Moreover, one considers here that multiple outputs are defined: this defines a multi‐objective optimization. This paper proposes several techniques making it possible to include the definition of multiple objectives to be fulfilled as part of an output space mapping optimization process.FindingsThe proposed approaches make it possible to stabilize and accelerate the convergence of multi‐objective optimizations performed by space mapping. This is illustrated by the example of the dimensioning of a resonant linear electromagnetic actuator.Originality/valueThe approach presented in the paper is original because it allows finding of a solution to the multi‐objective problem, without building any Pareto front, and most effectively by improving the convergent behavior of the optimization algorithm.

Three-Level Output Space Mapping Strategy for Electromagnetic Design Optimization

Optimal design with finite element model is often expensive in terms of computation time. The output space mapping technique allows benefiting both the rapidity of the analytical model and the accuracy of the finite element model. In this paper, a three-level output space-mapping technique is proposed to reduce the computation time. Three models having a different granularity and describing the same device are used jointly within the optimization process. Proposed strategy is applied for solving the optimal design problems of two electromagnetic devices. Results show that three-level output space mapping strategy allows saving a substantial computation time compared to the classical two-level output space-mapping.

Comparison between efficient global optimization and output space mapping technique

The optimization of electromagnetic devices by direct use of finite element models is computationally expensive. This paper presents two effective surrogate-assisted optimization algorithms: Output Space Mapping and Efficient Global Optimization which are employed with regard to a minimum number of finite element model evaluations. A parallel between the two algorithms is made through a single phase safety isolating transformer optimization problem using 3D finite element models.

Adapted Output Space-Mapping Technique for a Bi-Objective Optimization

Multi-objective optimizations by means of 3-D finite element models result in very high computation burden. To have an affordable computation cost, the output space-mapping technique is applied with a new method where the scalar correction of the model outputs is replaced by a set of corrective functions. This method is used for the bi-objective optimization of a transformer and allows finding the complete Pareto optimal set in less than two days on a laptop.