Predetermination of Currents and Field in Short-Circuit Voltage Operation for an Axial-Flux Permanent Magnet Machine

Risk of irreversible magnet demagnetization during short-circuit fault is analyzed in case of an axial-flux dual-rotor machine, using a three-dimensional finite-element method (3D-FEM). In order to validate the numerical model, calculated waveforms of the currents are compared with experimental results for short-circuit at low speeds. Then currents and magnetic flux density inside the magnets are computed for short-circuit at higher speeds in order to predetermine the maximum admissible speed for the machine

Identification of sensitive R-L parameters of a Multi-phase drive by a vector control

This paper focuses on an experimental method to determine the electric parameters of a seven-phase low-voltage multiphase drive. The drive is a belt driven starter-alternator for powerful cars with Hybrid Electrical Vehicles (HEV) functions. The resistive and inductive parameters are necessary to obtain the six characteristic time constants of the control modeling. Classical direct measurements lead to imprecise results because of very low values for the windings electric resistance (a few mΩ) and inductance (a few μH). Effects of the imprecision on the measurements are all the more important that time constants are obtained by a ratio of cyclic inductances by resistance, with cyclic inductances being a linear combination of seven measured inductances. The methodology for identification detailed in this paper is based on a stator current vector control, in a multi-reference frame. This methodology allows us to get directly these time constants. Numerous measurements allow the robustness of the method to be evaluatedThis work was supported by the French car supplier Valeoand the regional council of France Region-Nord-Pas-De-Calais

Identification of a 7-phase claw-pole starter-alternator for a micro-hybrid automotive application

This paper deals with the identification of a new high power starter-alternator system, using both: a Finite Element Method (FEM) modeling and an experimental vector control. The drive is composed of a synchronous 7-phase claw-pole machine supplied with a low voltage / high current Voltage Source Inverter (VSI). This structure needs specific approaches to plan its electrical and mechanical behaviors and to identify the parameters needed for control purpose. At first, a Finite Element Method (FEM) modeling of the machine is presented. It is used for the predetermination of the electromotive forces and of the torque. Experimental results are in good accordance with numerical results. In a second part, resistive and inductive parameters of the drive are determined by an original experimental approach that takes into account each component of the drive: the battery, the VSI and the machine.Futurelec IV (Region Nord Pas de Calais

Modeling and Control of a 7-phase Claw-pole Starter-alternator for a Micro-hybrid Automotive Application

This paper deals with the modeling and the control of a new high power 12V Integrated Starter Alternator (ISA). This system is used to bring micro-hybrid functions to standard Internal Combustion Engine (ICE) vehicles. The drive is composed of a seven-phase synchronous claw-pole machine with separate excitation, supplied with a seven-leg Voltage Source Inverter (VSI) designed for low voltage and high current. The system is modeled in a generalized Concordia frame and a graphical description is used to highlight energetic properties of such a complex system. A control scheme is then deduced from this graphical description. Two controls are achieved in generator mode and compared: one is using the VSI in a square-wave mode, the other in a Pulse Width Modulation (PWM) mode. Experimental results are provided.This work was supported by the French car supplier Valeoand the regional council of France Region-Nord-Pas-De-Calais

Vectorial Approach Based Control of a Seven-Phase Axial Flux Machine Designed for Fault Operation

Version éditeur disponible à l'adresse suivante : http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=4519973&isnumber=4636792This paper deals with easy-to-implement control strategies when a seven-phase axial flux permanent magnet machine supplied by a seven-leg voltage source inverter is in fault operation mode. Using a vectorial multimachine description, a seven-phase machine presenting a heightened ability to be controlled with one or two open-circuited phases has been designed. The machine is first presented, and experimental results are provided when one or two phases are open circuited. Based on a vectorial approach, new current references are calculated to avoid high-torque ripples

Conception et modélisation d'une machine synchrone à 7 phases à aimants permanents et flux axial : commande vectorielle en modes normal et dégradé

For the variable speed drives, the electric machine being no more directly coupled to the three-phase network, the choice of phase number can be reconsidered. We are interested in this thesis in the design of variable speed drives comprising unsaturated permanent magnet synchronous machines with smooth poles but with more than three phases. The aim is to simultaneously examine the constraints related to the machine and to the voltage/control inverter, with the aim of making a high performance multiphase drive. The work developed in this study examines the specific possibility of multiphase machines to have magnetomotive and electromotive forces with space harmonics while presenting a very low magnitude of the torque ripples in normal operation or in fault mode operation with one or two phases not supplied. In the chapter II, for a fixed distribution of windings, we examine the effect of electromotive force modulations while modifying the kind and the space repartition of the permanent magnets on the rotors for the design of a 7 phase axial flux machine with double rotors. In the chapter III, a comparison between experimental results and results obtained by analytical and numerical (3D calculation) approaches is carried out. It makes possible to validate the analytical multi-harmonics approach and puts forward the contribution of numerical calculation. In the chapter IV, a control structure is built by causal inversion and a vector control is described and put into experimental set-up for normal and fault mode operationsPour les entraînements à vitesse variable, la machine électrique n'étant plus directement couplée au réseau triphasé, le choix du nombre de phases peut être reconsidéré. On s'intéresse dans la thèse à la conception d'entraînements comportant des machines synchrones à aimants permanents à pôles lisses et non saturées mais à plus de trois phases. L'objectif est d'examiner simultanément les contraintes liées à la machine et à l'ensemble onduleur de tension/commande dans le but de réaliser un ensemble polyphasé performant. Les travaux développés dans cette étude explorent la possibilité spécifique des machines polyphasées de posséder des harmoniques spatiaux de force magnétomotrice et de force électromotrice tout en présentant des couples pulsatoires de très faible amplitude tant en mode normal que dégradé avec une ou deux phases non alimentées. Dans le chapitre II, pour une structure de bobinage imposée, nous examinons lors de la conception d'une machine à 7 phases à flux axial à double rotor l'effet d'une modulation des forces électromotrices en jouant sur la nature et la distribution des aimants permanents sur les rotors. Dans le chapitre III, une comparaison entre résultats expérimentaux et résultats obtenus par approches analytique et numérique (calcul 3D) est effectuée. Elle permet de valider l'approche analytique multi-harmoniques et met en exergue l'apport du calcul numérique. Dans le chapitre IV, une structure de commande est élaborée par inversion causale et une commande vectorielle est décrite et implantée expérimentalement pour un fonctionnement en mode normal ou dégradé

Design and Study of a Multi-phase Axial-flux machine

Adresse URL de l'éditeur http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1608484&isnumber=33780 Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, a 7-phase Axial-flux Double-rotor Permanent Magnet Synchronous Machine is studied using analytical and Finite Element methods. This type of machine shows a higher sensitivity to the inductance harmonics and electromotive force (emf) compared with the 3-phase machines. So, the conventional analytical modeling method, in which only the first harmonic is taken into account, leads to significant errors in the determination of the control parameters, e.g. the frequency of Pulse Width Modulation Voltage Source Inverter. A multi-machine model explains the reasons for this sensitivity and a more sophisticated analytical method is used. Results are compared with those obtained by the 3-D FEMCNRT Genie Electrique/ Region Nord Pas de Calais/FEDER/FUTURELEC

Design and Study of a Multi-phase Axial-flux machine

Adresse URL de l'éditeur http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=1608484&isnumber=33780 Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this paper, a 7-phase Axial-flux Double-rotor Permanent Magnet Synchronous Machine is studied using analytical and Finite Element methods. This type of machine shows a higher sensitivity to the inductance harmonics and electromotive force (emf) compared with the 3-phase machines. So, the conventional analytical modeling method, in which only the first harmonic is taken into account, leads to significant errors in the determination of the control parameters, e.g. the frequency of Pulse Width Modulation Voltage Source Inverter. A multi-machine model explains the reasons for this sensitivity and a more sophisticated analytical method is used. Results are compared with those obtained by the 3-D FEMCNRT Genie Electrique/ Region Nord Pas de Calais/FEDER/FUTURELEC

Limited Power Point Tracking for a Small-Scale Wind Turbine Intended to Be Integrated in a DC Microgrid

Limited power point tracking (LPPT) is emerging as a new technology for power management controllers for small-scale wind turbines (SSWTs) thanks to its advantages in terms of operation flexibility, economy and system security. LPPT operates in such a way that power requested by the user can be extracted from the wind turbine while respecting constraints. However, operating in LPPT mode still requires a deep understanding to obtain a compromise between minimizing power oscillations and transient response. For that, three LPPT power control strategies for an SSWT intended to be integrated in a direct current (DC) urban microgrid are investigated. These methods concern perturb and observe (P&O) with fixed step size, P&O based on Newton’s method and P&O based on the fuzzy logic (FL) technique. The experimental results highlight that all methods function correctly and reach the limited power point (LPP). The FL method improves dynamic performances with more steady oscillations around LPP compared to fixed step size and Newton’s methods. The sudden variation of wind velocity and power lead us to conclude that the FL method ensures a good balance between reducing oscillation of wind turbine (WT) output power around the operating point and convergence of rising time toward LPP