Stephane Vivier

Combination of Finite-Element and Analytical Models in the Optimal Multidomain Design of Machines: Application to an Interior Permanent-Magnet Starter Generator

This paper proposes to apply optimal multiphysic models to the design of highly constrained electrical machines, such as interior permanent-magnet (IPM) machine intended for an automotive integrated starter generators. One of the main problems in the use of such optimal approaches remains the accuracy of the models used by the optimizer. In a recent study, we proposed a design model linked to three strong hypotheses: 1) Iron losses are calculated according to the flux density fundamental (sinusoidal approach); 2) flux densities are estimated with a saturated but decoupled d,q reluctant circuit model neglecting the cross saturation effect; and 3) thermal states are indirectly treated with a current density limit. This paper improves these models by using first the finite element method for the determination of flux and iron losses in the machine and then an equivalent thermal steady-state lumped-parameter network. These models are included in the optimization loop and so are evaluated at each iteration. The optimization method uses standard sequential quadratic programming algorithm and Sequential Simplex algorithm. A comparison between the design of an IPM machine with the previous model and the new one will be performed.

Design of a Brushless Rotor Supply for a Wound Rotor Synchronous Machine for Integrated Starter Generator

Wound rotor synchronous machines present interesting performances for integrated starter generator. Nevertheless, the lack of reliability of their gliding contacts remains their main drawback. The following paper proposes to replace the gliding contacts of such a wound rotor synchronous machine by an iron silicon axial rotary transformer operating as a contactless transmission power system. The design process is based on an accurate non-linear multidisciplinary analysis model divided into a magnetic, thermal and electrical part, optimized thanks to a sequential quadratic programming algorithm. The method is applied to a particular wound rotor synchronous machine and the electromagnetic and thermal performances are subsequently confirmed using the finite element method (FEM). The optimal result indicates that the rotary transformer is a good challenger to gliding contacts in term of compactness. Other advantages and limitations of the optimal rotary transformer are discussed.

Combination of Finite Element and Analytical Models in the Optimal Multi-Domain Design of Machines : Application to an Interior Permanent Magnet Starter Generator

This paper proposes to apply optimal multiphysics models to the design of highly constrained electrical machines, such as interior permanent magnet machine (IPM) intended for an automotive integrated starter generators (ISG). One of the main problems in the use of such optimal approaches remains the accuracy of the models used by the optimizer. In a previous paper, we proposed a design model linked to three strong hypotheses : (1) Iron losses are calculated according to the flux density fundamental (sinusoidal approach); (2) Flux densities are estimated with a saturated but decoupled d,q reluctant circuit model neglecting the cross saturation effect; (3) Thermal states are indirectly treated with a current density limit. The present paper improves theses models by using first the finite element method (FEM) for the determination of flux and iron losses in the machine and then an equivalent thermal steady state lumped parameter network. These models are included in the optimization loop and so are evaluated at each iteration. The optimization method uses standard sequential quadratic programming algorithm (SQP) and sequential simplex algorithm. A comparison between the design of an IPM machine with the previous model and the new one will be performed.

Comparison of Two Optimal Rotary Transformer Designs for Highly Constrained Applications

The lack of reliability of gliding contacts in highly constrained environments induces manufacturers to develop contactless transmission power systems such as rotary transformers. The following paper proposes an optimal design methodology for rotary transformers supplied from a low-voltage source at high temperatures. The method is based on an accurate multidisciplinary analysis model divided into magnetic, thermal and electrical parts, optimized thanks to a sequential quadratic programming method. The technique is used to discuss the design particularities of rotary transformers. Two optimally designed structures of rotary transformers : an iron silicon coaxial one and a ferrite pot core one, are compared.

Application of output Space Mapping method for fast optimization using multi-physical modeling

This paper focuses on the use of a technique of Space Mapping (SM) for the optimization of a Permanent Magnet Machine (PMM) used as an Integrated Starter Generator (ISG). To demonstrate the benefits of such a design approach, it has been applied in the context of a realistic and very constrained application, particularly from the thermal point of view. Thus, this actuator is considered to function in start mode during which the rotation speed is low and thermal sources (mainly copper losses) are very high for a short time. Indeed, it is necessary to consider temperature increases versus time, as if several consecutive starts were imposed to the machine (car). To realistically simulate the operation of the motor, significant efforts were made to improve the quality of multi-physical modelings, especially regarding thermal aspects. Finite Element Analyses (FEA) are used for the evaluation of the electromagnetic behavior. Temperature distributions are computed by the use of equivalent lumped parameter networks, while mechanical considerations are taken, through analytical relations, to ensure the mechanical holding of rotating parts. Finally, physical couplings (between models) constitute important considerations. They are essentially related to mechanical, copper and iron losses. SM techniques operate on two (multi-physical) modelings of the same machine. Hence, using this optimization approach requires the definition of two sets of magnetic-electric-mechanical-thermal descriptions of the PMM to be dimensioned. This paper presents the choices made for their building, and the results obtained.

A new modelling of DC machines taking into account commutation effects

In some specific manufactured electromechanical applications, power electronic converters must be avoided due to hostile environment. In such a context, stand-alone DC machines are good candidates because of their high reliability and low cost. However, the mechanical commutation is a big problem in this kind of machine especially in high current and low voltage applications. Losses due to arching contacts can be significant. The authors present an original technique to take into account every electrical aspect of brushes contacts (mechanical sliding contact and arching contact). The aim of this study is to determine currents and voltages of conductors during commutation in order to reduce significantly losses due to sliding contact. These evolutions are very important data for finite element analysis too.

Fast optimization of an IPMSM with Space Mapping technique

The work presented in this article relates to the design procedure of a permanent magnet synchronous machine, by the use of Output Space Mapping type methods. This type of optimization technique reduces significantly the time necessary to the search for optimal configurations, by the use of a fast modeling of the device to be optimized. At the same time, a second model, slower but more accurate, ensures the validity of the optimal configurations obtained. Two techniques belonging to this family of methods are applied in this study. Their results and performances are compared.

Improvements for multi‐objective optimizations using output space mapping technique

Purpose – The 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/approach – The 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.Findings – The proposed approaches make it possible to stabilize and accelerate the convergence o...

Fast Optimization of a Linear Actuator by Space Mapping Using Unique Finite-Element Model

This paper focuses on the optimization of a linear actuator by the “output space mapping (OSM)” method. The underlying objective of this work lies in the minimization of the time required for the achievement of this optimal design. Indeed, in addition to the sole costs of optimization processes strictly speaking, the time needed for the developpement of the models is taken into account. In the context of OSM, two different finite-element models of the same actuator are used. This paper presents these modeling solutions and considers their corresponding accuracy. Results of this multi-objective optimization method are presented and compared with those obtained by the sequential simplex (SS) method based solely on the fine model. Both approaches give similar results. However, the comparison of their performances clearly shows that the OSM algorithm is an effective technique for reducing the computation time of optimization studies, even in the case of relatively simple electromagnetic structures. Hence, this approach leads to an original and effective optimization methodology.

Fast optimization of a linear actuator by space mapping using unique finite element model

This paper focuses on the optimization technique of a linear actuator by computer means. The authors sought to minimize the time required for this optimal design. In addition to the sole efficiency of optimization methods, strictly speaking, the time development of the models was taken into account. This approach leads to an original and effective methodology.