Thibaut Labbé, Ernest Matagne and Bruno Dehez
The purpose of this paper is to propose a mechanism avoiding the topology optimization methods, and particularly those using gradient‐based algorithms, to be trapped in local…
Abstract
Purpose
The purpose of this paper is to propose a mechanism avoiding the topology optimization methods, and particularly those using gradient‐based algorithms, to be trapped in local minimizers when applied to the design of electromagnetic devices made of iron and permanent magnet.
Design/methodology/approach
Topology optimization methods aim at finding the optimal distribution of some materials in cells subdividing a design space, regarding a specific objective function. This paper suggests to consider that each cell contains an oriented microstructure of iron whose direction and shape are optimized by the method.
Findings
Coupled with convexity and sensitivity mappings quite common in the field of topology optimization, the use of the microstructure allows the optimization algorithm to converge systematically toward the same design. This achievement is illustrated on a practical case, i.e. the optimization of the rotor of a permanent magnet synchronous motor regarding its mean torque and under mass constraint. Also, this paper shows that intermediate iron materials can either be penalized or interpreted, thanks to the realistic physical relations derived from the iron microstructures.
Originality/value
This paper proposes a mechanism based on an iron microstructure for avoiding the topology optimization methods and the trap of local minimizers when applied to the design of electromagnetic devices made of iron and permanent magnet.
Details
Keywords
The paper aims at optimizing magnetic thrusts in the framework of the design of high‐dynamics linear actuators. The goal is to find the optimal topology of the permanent magnets…
Abstract
Purpose
The paper aims at optimizing magnetic thrusts in the framework of the design of high‐dynamics linear actuators. The goal is to find the optimal topology of the permanent magnets in order to maximize the velocity of the actuator.
Design/methodology/approach
The optimization is performed by a topology optimization method. The design space is divided in cells in which the method have to distribute permanent magnets and determine their magnetization directions.
Findings
Several aspects of the optimization are discussed in the paper, such as the effect of the introduction of a weight constraint on the thrust. Some issues are highlighted regarding the length of design space for the moving part and the presence of local minimizers in the optimization problem.
Research limitations/implications
Having different magnetization directions in each cell makes the manufacturing harder. The results could thus be completed either by the design of a system able to create such permanent magnets or by the introduction of a constraint limiting the number of magnetization directions.
Practical implications
Finding the optimal topology of magnetic thrusts is motivated by the interest in avoiding the shocks related to mechanical thrusts.
Originality/value
This paper applies the topology optimization approach for the design of magnetic thrusts in order to increase the performances of high‐dynamics linear actuators.
Details
Keywords
Grzegorz Galary, Bruno Dehez and Damien Grenier
Computational validation of the new concept of the rotor of the two‐degree of freedom spherical actuator is the aim of this paper.
Abstract
Purpose
Computational validation of the new concept of the rotor of the two‐degree of freedom spherical actuator is the aim of this paper.
Design/methodology/approach
The first approach study leading to optimize the rotor's structure and parameters, realized using finite element method‐based software is presented. Rotor with two layers and rotor with ferromagnetic so‐called “teeth” crossing external layer are discussed.
Findings
It is shown that the rotor with teeth ensures higher torque and efficiency, but a negative slot effect appears, which is, however, possible to reduce.
Research limitations/implications
Limitations in the 3D simulations, especially lack of the movement modeling possibility. For the future the study of some other parameters such as the influence of the magnetic material's saturation, the geometrical from of the tooth and the appearance of the higher harmonics in the signal connected to the non‐sinusodial coupling between the rotor and the stator is considered, as well as the experimental confirmation.
Originality/value
New structure of the spherical actuator's rotor and its advantages are presented.
Details
Keywords
Corentin Dumont de Chassart, Maxence Van Beneden, Virginie Kluyskens and Bruno Dehez
Optimizing an electromechanical device often requires a significant number of evaluations of the winding inductance. In order to reduce drastically the computing costs associated…
Abstract
Purpose
Optimizing an electromechanical device often requires a significant number of evaluations of the winding inductance. In order to reduce drastically the computing costs associated with the calculation of inductances, the purpose of this paper is to propose a semi-analytical toolbox to calculate inductances in any winding made of axial and azimuthal wires and lying in the air.
Design/methodology/approach
First, this paper presents a typical rectangular, spiral winding and the way its geometry is approximated for inductance calculations. Second, the basic formulas to calculate inductances of various windings arrangements are provided. The analytical model of the inductances is exposed, and the formulas for the inductances are derived. Finally, a validation is proposed by comparing analytical predictions to 3D FE simulations results and experimental measurements.
Findings
The semi-analytical predictions agree with the finite element methods (FEM) and experimental data. Furthermore, the calculation of the inductances was done using much fewer resources with the semi-analytical model than with FEM.
Research limitations/implications
The analytical formula for the mutual inductance between coaxial circular arcs is a series with an infinite number of terms which should be truncated appropriately. This is necessary because the term are found using a recurrence formula which may be unstable for a high number of terms.
Practical implications
The paper includes implications for the optimization of electromechanical devices comprising windings made of axial and azimuthal pieces of wires.
Originality/value
The main original result resides in the analytical expression of Neumann’s integral for the inductance between two coaxial circular arcs.