In this article, a new analytical method is proposed to estimate eddy currents inside linear conductive materials. The novel closed-form formulation takes into account the effects of both conductor reaction field that dominates at high frequencies as well as the spatially non-homogeneous nature of the magnetic field penetrating the material. Although the model is suitable for most kinds of permanent magnet machines, it is particularly useful for Surface-mounted Permanent Magnet (SPM) machines where both of these phenomena are prominent. The numerical implementation of the proposed model, which consists of a combination of the method of images and 4-D Fourier transform, is presented. The model is then validated against 2-D and 3-D finite element models (FEMs) for a simple magnetic circuit, showing good agreement. Finally, the eddy current magnet loss in an SPM synchronous machine is evaluated and results are discussed.

This article presents the optimal design and experimental prototype testing of a low-cost motor applied for a city battery electric vehicle, zero emission A-segment. Respecting the car performance specifications, the aluminum cage rotor induction machine is designed to reduce motor cost using totally enclosed fan-cooled technology and a commercial speed encoder of internal combustion engine. An optimization approach and finite elements analysis validation are coupled with thermal calculations and used to size the thermo-electromagnetic parts of the machine. The prototype is manufactured with full instrumentation. During the experiments, an indirect flux-oriented control model is built based on simulations in MATLAB/Simulink environment. Using this real time control platform, the motor control is calibrated on the prototype in test-bench, to ensure the optimum energy consumption and the current and speed regulations in the entire large operating range. Finally, the experimental prototype testing results are shared to show the ideal design solution in term of peak performances, efficiency, thermal and noise, vibration, and harshness behaviors.

This paper presents the optimal design and experimental prototype testing of a low-cost motor applied for a city battery electric vehicle (BEV), zero emission A-segment. Respecting the car specification performances, the aluminum cage rotor induction machine (IM) is designed to reduce motor cost using totally enclosed fan-cooled (TEFC) technology and commercial speed encoders of internal combustion engine (ICE) car. Optimization approach and finite elements analysis (FEA) modeling validation, coupling with thermal calculations are used to size the thermo-electromagnetic parts. After selecting suppliers for motor components, prototypes are manufactured. For the experimentation, first, the indirected flux oriented flux control model is built based on simulation in Matlab/Simulink environment. Then the motor control calibration is tuned on the prototype in test-bench in order to ensure the optimum energy consumption, the current and speed regulations in the entire large operating area. We finally show the experimental prototype testing results to validate the obtained design solution in terms of peak performances, efficiency, thermal and NVH behaviors.

Audible noise of electric machines has become an important criterion in their design. In this paper we used a multi-physics numerical model (electromagnetic-dynamic) in order to predict mechanical vibration caused by magnetic pressure in a wound rotor synchronous machine. The final objective is to reduce this mechanical vibration. The novelty of this paper is to use an optimization method with this multi-physics numerical model in order to reduce important vibration peaks thanks to magnetic pressure harmonics.

Cet article porte sur les vibrations et le bruit acoustique d'origine magnetique, du aux forces de Maxwell, dans les machines electriques tournantes synchrones (aimants permanents ou rotor bobine - machines a reluctance variable exclues). Le phenomene de bruit magnetique y est analyse, et les differentes sources harmoniques d'efforts magnetiques sont caracterisees analytiquement en termes d'ordre spatial et de frequence. Des outils analytiques et numeriques de prediction du niveau de bruit rayonne sont presentes, ainsi que differentes regles de conception silencieuse. Enfin, des donnees d'essais vibro-acoustiques sont interpretees.

A previous study has shown that the current low frequency harmonics, even with low amplitudes, have a strong influence on the global vibrations of a wound rotor synchronous machine. Therefore an harmonic dedicated regulation of the machine currents, allowing to manage in a low cost way their harmonic content, can drastically improve the acoustic noise of this machine. The main goal of this paper is to experimentally demonstrate the acoustic gain that could be attempted while decreasing the harmonic content of the currents using a harmonic dedicated regulation. A particular attention is given to the regulation of the 5th and 7th currents harmonics. The strong link between current harmonics and magnetic forces is theoretically introduced in the first part of this study, harmonic regulation principle is then detailed and finally experimental results present the important gains allowed by this technique.

An automatic and fast numerical coupling method between 2-D electromagnetic and 3-D structural FEM software is presented. The described coupling method permits to compute the electromagnetic noise in electric machines for different realistic alimentation currents. Thanks to this tool, the strong influence of the supply harmonics on the acoustic level of a synchronous machine is clearly shown. This method has been developed for a wound rotor synchronous machine (WRSM) but can be applied for any non-skewed machines. First of all, the global principle of the study and the magnetic noise theory is briefly introduced. Then, computation algorithms coupling magnetic forces to structural mesh are developed and finally simulation results show the influence of supply harmonics on global vibration levels.

In electric vehicles, a major emphasis is placed on iron loss reduction to maximize machine efficiency and its vibratory and acoustic behavior to meet users' expectations of a silent drive. This paper describes a method to simultaneously reduce iron losses and magnetic noise of a wound-field synchronous machine considering various stator tooth lengths and rotor pole airgap surface radii. The impact of design parameters on acoustic noise and iron losses is analyzed to provide the possibility to make adequate choices during the design. A novel approach is presented to compute iron losses as well as details of the weak coupling between the magnetic and structural finite element models used to compute the magnetic noise. Simulations results suggest simple rules to improve the machine's global performance.

Eccentricity is considered as a major problem for every people dealing with the realization of an electrical machine. Generally linked to manufacturing tolerances and rotor balance quality, rotor dynamic eccentricities contribution to vibro acoustic behaviour of the machine is here investigated for a synchronous machine during a full run up. We will establish, thanks to finite element models coupling, that additional harmonics linked to eccentricities lead to new acoustic noise components. Finally a direct link between eccentricity and vibratory level will be achieved.

RENAULT aims to become the first full-line manufacturer putting to market zero-emission affordable electrical vehicles and is therefore developing 100 % electric powertrains. NVH problems related to electric machine design have nothing in common with those of gasoline or diesel engines: electric whistling is a high frequency harmonic phenomenon, easily detectable due to the low background noise of a non-thermal vehicle and mainly perceived as very unpleasant by the customer.Therefore we have developed a coupled numerical simulation between electromagnetic and structural models, making it possible to understand the influence of magnetic parts design on noise and vibration level. Impact of the spatial and time coherence between magnetic pressures and vibration modes of the motor will be explained. The novelty of our approach is to already take into account the whole powertrain structure radiation, including reducer and power supply boxes. Moreover we investigate the influence of the harmonic content of the supply current due to the regulation system, as well as the tangential forces effect on stator teeth.

For the comfort and security of users, noise of electric motors is a critical issue. The harmonic content of the magnetic pressure inside the air gap being the source of the sound radiated by the stator, it suits to know the impact of field weakening. We will show that for some load angles the pressure harmonics change so that the field weakening could be heard.

This paper describes an automatic and fa st numerical coupling method between 2D electromagneti c and 3D structural FEM programs software. This approach has been developed for a WRSM but can be applied for an y nonskewed machines. The presented coupling method perm its to predict the electromagnetic noise in electric machi nes for different realistic current alimentation. First, an analytical model will be briefly introduced to present the magnetic noise theory, computation algorithms coupling magnetic forces to structural mesh are then developed and finally simu lation results will show the influence of supply harmonics on the global vibration level.