Daniel Matt

Design of a Mean Power Wind Conversion Chain with a Magnetic Speed Multiplier

The first, the most common, links the turbine to the generator via a mechanical speed multi‐ plier. In this configuration, the mechanical power is transmitted at high speed to the electri‐ cal machine. The size of the latter may then be easily reduced. This method has the major advantage of allowing the use of simply designed synchronous or asynchronous generators, which are readily available and inexpensive. This first method is mainly used for high power wind turbines (above a few tens of kilo‐ watts, to establish an order of magnitude) because at this power level, the large size of the generator becomes a problem, it becomes difficult to do without the speed multiplier.

Design of a High-Performance Multi-Air Gap Linear Actuator for Aeronautical Applications

The aim of this paper is to present an original architecture for a linear electric actuator; a multi-air gap actuator for aeronautical applications. This linear actuator is designed to replace pneumatic or hydraulic devices functioning as a cylinder. One particularity of this actuator is the friction of movable parts on fixed parts, allowing the use of active parts with very small dimensions, thereby increasing performance. We present the definition of this concept, its operating principle, the study performed, and experimental results from a prototype. Experimental results confirm the high performance of this structure (1000 N/kg and 5000 N/dm3).

Estimation of rotor eddy-current losses for high speed SPMSM

Surface-mounted permanent magnet synchronous machine (SPMSM) is widely used in various fields due to its high power density and reliability (compressors, turbine generators...) [1], in our case it is used in aeronautics. However, in high-speed operations eddy-current losses can be important and lead to a damage because of an overheating (PM detachment, demagnetization...). Therefore, it is important to estimate these losses during the design phase. This paper describes a technique to estimate rotor eddy-current losses (magnets and sleeve) for the design of 25 kW, 10.5 krpm 3-phase motor by means of both analytical and finite-element approach. Firstly, we study the spatial variation of the magnetic flux density in the magnets and the sleeve. Consequently, it results a segmentation of magnet and sleeve according to the half of slot pitch. Secondly, we estimate the maximum variation of magnetic flux density (36 mT in the summit of magnets, 125 mT in the sleeve) by finite-element analysis (COMSOL Multiphysics). Finally, this paper presents the result of computation of rotor eddy-current losses (97 Watt).

A design approach for an axial-flux permanent magnet motor

Research on the electric motors with high level of performance led the Energy and Materials Group of the Institute of Electronics of the South to design a disc-type machine. This motor was created from permanent magnet and multi-air gap structure. This paper presents an axial-flux motor used in an application requiring several constraints: a high torque, a low speed, a low volume, without any reduction gear. The originality of the structure consists in its modular concept and in the specific organization of single-phase elements. So as to limit the axial encumbrance, this special architecture allows the reduction of the magnetic circuits, in combination with the optimization of the specific torque. The design method, starting from elementary cells, is described here after. An optimization approach of the performance by analyzing the characteristics sensitivity to the principal functional parameters is proposed.

Multiairgap friction direct drive linear actuator with permanent magnets

These article deals with a special high performances, large extension, direct drive linear actuator for an aeronautical application. The purpose of this actuator is to remove the mechanical transmission, classically used, in order to increase the reliability. This actuator can reach very high performances in terms of mass and volume because of the multiplication of the number of airgaps. A particularity of this actuator is also the friction of the movable parts on the fixed parts. It allows to use very small dimensions on the active parts and so to increase the performances. The experimental results confirm the high performances of this structure (~ 1000 N/kg and ~ 5000 N/dm3).

Optimisation of the Association of Electric Generator and Static Converter for a Medium Power Wind Turbine

This chapter shows the ways of optimising a medium power wind power electromechanical system, generating anything up to several tens of kilowatt electric power. The optimisation criteria are based on the cost of the electromechanical generator associated with a power electronic converter; on the power efficiency; and also on a fundamental parameter, often neglected in smaller installations, which is torque ripple. This can cause severe noise pollution. For a wind turbine generating several kW of electric power, the best solution, without a shadow of a doubt, is to use a permanent magnet electromagnetic generator. This type of generator has obvious advantages in terms of reliability, ease of operation and above all, efficiency. Despite problems concerning the cost of magnets, almost all manufacturers of small or medium power wind turbines use permanent magnet generators (Gergaud et al. 2001). This chapter deals with this type of system. The objective is to demonstrate that only a judicious choice of the configuration of the permanent magnet synchronous generator, amongst the different options, will allow us to satisfy the criteria required for optimal performance. We will study examples of a conventional permanent magnet generator with distributed windings, a permanent magnet generator with concentrated windings (Magnusson & Sandrangani, 2003) and a non-conventional Vernier machine (Matt & Enrici, 2005). How these different machines work will be detailed in the following paragraphs.

Formalism and finite element study of actuator with toothed coupling

Toothed coupling machines and multi-air gap machines are interesting solutions for direct drive because of the high specific performances they can achieve.

Impact of mechanical stresses on flat double sided linear electric motor multi-air gap structure guided or friction plates

The design of a linear electric machine with high-frequency alternative motion intended for the creation of the acoustic wave of a system of thermo-acoustic conversion.

Simulation and testing of a low power wind system

This paper describes the implementation of a test bench intended to study low power wind systems. It is used with an energy conversion chain including a variable reluctance magnet machine (VRMM), used as a direct-driven generator. We first present the principle and working equations of the VRMM, and the converters associated with it. Equations used to model VRMM and PWM rectifier in a d, q rotating frame are then detailed and so are different control methods used to drive the VRMM. A Simulink model of the system including the wind turbine is proposed. We show simulation results computed with a short wind profile, which enable to estimate the efficiency of a control method of the VRMM. These models are used to implement the test bench. In this one, the wind turbine is emulated by a DC machine. The drive of the DC machine and of the VRMM is realized with the help of a real-time board. We use the bench to compare the association of VRMM with different AC/DC converters. We finally foresee the later developments of the system.