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Purpose – Static converters generate current harmonics in grids. Numerous studies on analytical frequency models of converters are often required to carry out their harmonic modeling in the context of sizing by optimization. Some formulations are proposed to solve such models. Each formulation has its own advantages and drawbacks. The paper mainly focusses on two formulations: the first to be solved by sequential quadratic programming (SQP) and the second to be solved by Newton-Raphson (NR). In this way, the purpose of this paper is to present the performances of each formulation and compare the results of both formulations for the modeling of a single-phase diode rectifier. Design/methodology/approach – The paper aims to compare SQP formulation and NR formulation, and to propose the ways to improve their convergence. In the modeling, by using an explicit formulation of the state variables combined to a numerical method, equations are defined to reduce, as far as possible, the number of unknowns. Findings – The difficulty is to find the good operating mode of the static converter. So, outside the equations and the constraints, the paper proposes to use the eigenvalues of the state-space matrixes to initialize the duration of every configuration and to consider the operating symmetries of the static converter that allow to reduce the research area and also the variables calculated. Research limitations/implications – The number of the conducting phase per half period is a priori, as the operating mode. Originality/value – The modeling is based on the use of linear components, ideal switches and the static converter operates in steady-state. The main difficulties are to formulate the equations representing the non-controlled switching of semiconductors, and to solve them. [ABSTRACT FROM AUTHOR]

Purpose – Multiphysical models are often useful for the design of electrical devices such as electrical machines. In this way, the modelling of thermal, magnetic and electrical phenomena by using an equivalent circuit approach is often used in sizing problems. The coupling of such models with other models is difficult to take into account, partly because it adds complexity to the process. The purpose of this paper is to propose an automatic modelling of thermal and magnetic aspects from an equivalent circuit approach, with its computation of gradients, using selectivity on the variables. Then, it discusses the coupling of various physical models, for the sizing by optimization algorithms. Sensibility analyses are discussed and the multiphysical approach is applied on a permanent magnet synchronous machine. Design/methodology/approach – The paper allows one to describe thermal and magnetic models by equivalent circuits. Magnetic aspects are represented by reluctance networks and thermal aspects by thermal equivalent circuits. From circuit modelling and analytical equations, models are generated, coupled and translated into computational codes (Java, C), including the computation of their Jacobians. To do so, model generators are used: CADES, Reluctool, Thermotool. The paper illustrates the modelling and automatic programming aspects with Thermotool. The generated codes are directly available for optimization algorithms. Then, the formulation of the coupling with other models is studied in the case of a multiphysical sizing by optimization of the Toyota PRIUS electrical motor. Findings – A main specificity of the approach is the ability to easily deal with the selectivity of the inputs and outputs of the generated model according to the problem specifications, thus reducing drastically the size of the Jacobian matrix and the computational complexity. Another specificity is the coupling of the models using analytical equations, possibly implicit equations. Research limitations/implications – At the present time, the multiphysical modelling is considered only for static phenomena. However, this limit is not important for numerous sizing applications. Originality/value – The analytical approach with the selectivity gives fast models, well adapted for optimization. The use of model generators allows robust programming of the models and their Jacobians. The automatic calculation of the gradients allows the use of determinist algorithms, such as sequential quadratic programming, well adapted to deal with numerous constraints. [ABSTRACT FROM AUTHOR]

Purpose – Due to the increase of the traffic, issues are appearing on DC-electrified railway feeding systems. One candidate solution to solve these issues and to improve their performances is to add storage systems in the railway DC electrical network. The purpose of this paper is to present a method based on an optimal power flow (OPF) for the analysis and design of DC railway feeding systems with storage. Design/methodology/approach – The paper describes a new methodology based on optimization to study DC-electrified railways, including storage systems. A load flow model of a DC 1,500 V railway electrification system is presented, including the mobility of the train sets. Then, an OPF model of the DC network, including energy storage systems and feeding substation rectifiers has been developed. Finally, the OPF model has been tested on a real application case showing its benefits while searching solutions in order to improve the network performances. Findings – An OPF model suitable for analysis of DC networks with storage is presented. It shows its ability to solve large scale problems. Research limitations/implications – The paper focusses on the physical model of the network. The optimization model will have to be extended with application constraints. Originality/value – The hypothesis presented in this paper allows to remove the discontinuities of the system in order to use a continuous optimization approach. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to deal with the design of passive filter for power electronics voltage inverters used in aircraft electrical drives (a permanent magnet synchronous machine fed by a six-phase voltage inverter with PMW control), using optimization for both sizing and sensibility analyses. Design/methodology/approach – The approach is generic. An aid allows to modify easily the frequency model and so to check various study cases, and to carry out the filter optimization for different topologies or control strategies. Findings – The approach is generic. An aid allows to modify easily the frequency model and so to check various study cases, and to carry out the filter optimization for different topologies or control strategies. Research limitations/implications – The power electronics load is supposed to be a set of predefined harmonic sources, obtained by experiment or time simulation plus fast fourier transformation before the optimization process. Practical implications – The problem has numerous constraints on the components, mainly technological constraints. The volume is minimized, respecting electromagnetic standards and an electro magnetic interference filter prototype has been made. Originality/value – The frequency model is automatically generated. A complex aircraft application has been studied thanks to the approach. Several sensibility analyses have been carried out. An EMC filter has been sized and an experimental prototype has been made, comforting the sizing by optimization. [ABSTRACT FROM AUTHOR]

Purpose |!|#8211; The frequency simulation and optimisation of electromagnetic compatibility (EMC) filter is often computation time consuming. The purpose of this paper is to propose an approach for easy and fast modelling and optimization of power electronics structures. Design/methodology/approach |!|#8211; The paper proposes an approach for easy and fast modelling and optimization of power electronics structures. It focuses on the EMC filter design. To achieve this task time simulation, FFT and automatic frequency modelling are combined. Findings |!|#8211; An automatic frequency modelling is proposed and also gives automatically the model gradients. Therefore, the model can be used to optimize the EMC filter, but also can help in choosing its topology. Several optimization algorithms are used and compared. Research limitations/implications |!|#8211; The power electronics load is supposed to be a set of predefined harmonic sources, obtained by time simulation + FFT before the optimisation process. Practical implications |!|#8211; The frequency model allows for the rapid designing and comparing of several structures or modelling hypothesis with regard to the parasitic elements and circuit imperfections. Originality/value |!|#8211; The frequency model is automatically generated, and sizing criteria on the component (e.g. inductors, capacitor) can be added in an analytical form, for example, to deal with volume or mass criteria. [ABSTRACT FROM AUTHOR]

Purpose |!|#8211; An analytical approach is preferred to carry out the harmonic modelling of power electronics converters because it is generally faster than time simulation chained with FFT. However, the difficulty of such an approach is to build the model and to manage the uncontrolled commutations that occur in the studied static converter, and also to deal with large equations. The purpose of this paper is to propose an aid in the frequency modelling of the drive elements, in the frequency domain, including all key parameters for sizing aim i.e. a way to optimize the EMC filter using different algorithms. Design/methodology/approach |!|#8211; The paper aims to propose an aid to create such models, and to assure its good solving, i.e. that the correct operating mode is represented. So, the solving problem is formulated as an optimization problem under constraints, to solve this difficulty. Findings |!|#8211; The difficulty is to be sure to deal with the good operating mode of the static converter when soft or uncontrolled commutations occur. So, the model is formulated as a constrained optimization problem. The paper proposes a symbolic approach, that allows to build automatically the frequency model. It is translated to be solved in Matlab. Research limitations/implications |!|#8211; The approach does not fit for static converters with a control implying numerous commutations per operating period. However, the approach deals with natural and soft commutations. Originality/value |!|#8211; The modelling is based on the use of linear components and ideal switches. [ABSTRACT FROM AUTHOR]

Purpose |!|#8211; The purpose of this paper is to present an effective optimization strategy applied in a physical structure optimization of a semiconductor power metal oxide semiconductor field-effect transistor (MOSFET), with an expensive integration constraint computation. Design/methodology/approach |!|#8211; In order to deal with inaccuracy due to inevitable numerical errors in the objective function calculation (the power losses of the power MOSFET) and in the constraint computation, the paper proposes to use the progressive quadratic response surface method (PQRSM). Findings |!|#8211; The paper focuses on four aspects: the inevitable numerical errors in the power loss and the integration constraint computation; the response surface approximation (RSA) method; the PQRSM principle; and finally the comparisons of several optimization methods applied on this application problem. Originality/value |!|#8211; An original optimization method, PQRSM, is proposed for reducing the oscillation problem of a semi-analytical model. The optimization results of PQRSM have been compared with the evolution strategy (ES) algorithm, with similar results but faster computation. [ABSTRACT FROM AUTHOR]