Frederic Dubas

Design of axial flux PM motor for electric vehicle via a magnetic equivalent circuit

The TRAX project aims at developing a generation of electric motors (7.5 to 15 kW) for the automotive power trains. The vehicles covered are “all electric” without gearbox in the range of heavy quadricycle. The two objectives of this project are to: i) design an innovative axial flux PM motor (AFPMM) and industrially feasible in series, ii) use an analytical model (AM) based on reluctances networks (i.e., the magnetic equivalent circuit) in order to design an optimal electric motor. The electromagnetic design by AM has enabled us to achieve a first prototype of AFPMM. The analytical results are compared to those experimentally obtained.

High frequency PMSM and inverter losses analysis-application to flywheel system on real cycle operation

In this paper the authors present an overview of losses in inverter and electrical machine of flywheel system under real cycle stress. Depending on the adopted control strategy, the aim is to study the evolution of Permanent-Magnet (PM) Synchronous Machine (PMSM) and various voltage source inverter (VSI) losses. A thermal study to analyse the temperature effect (sensitivity) on various losses generated during a real cycle operation is also discussed. For this study, a high frequency analytical model was developed enabling prediction of system behaviour on real cycle operation.

Analytical model of PMSM designed for high-frequency operation machine and inverter sizing compromise

In this paper the authors present an analytical model of Surface-Mounted Permanent-Magnet (PM) Synchronous Machine (SMPMSM), in order to predict the evolution of the motor behavior with frequency in the range of 0–80kHz, what we called here ‘high frequency’. We assume that the copper proximity effects can be neglected by using Litz winding, so that we only consider the evolution with frequency of the stator winding inductance and of the equivalent resistance modeling the two-dimensional (2-D) PM eddy-current losses. By using a harmonic single-phase equivalent circuit, the interest of the proposed model is to calculate with a good accuracy the PM and inverter losses for various voltage source inverter (VSI) structures (two levels or three levels) and control laws (full wave, synchronous PWM…) In industrial and transportation applications, where high speed and high frequency machines are more and more used, this approach enables to achieve the good compromise between the designs of the machine and the inverter, considering the global losses.

Analytical modeling of 2-D permanent-magnet losses harmonic equivalent resistance of PM

In this paper, we investigate losses in multipole surface-mounted permanent-magnet (PM) motors (SMPMM) driven by pulse-width-modulation (PWM) inverter. The purpose of this work is to provide a two-dimensional (2-D) analytical solution of PM eddy-current losses represented by a harmonic equivalent resistance. These losses, neglecting the slotting effect, are calculated with assuming to be resistance-limited. The circumferential segmentation effect of PMs is taken into account in the 2-D analytical solution. The calculated losses are compared to a 2-D finite-element method (FEM) to verify the validity of analytical model in our operating frequency range.

Nonlinear Analytical Prediction of Magnetic Field and Electromagnetic Performances in Switched Reluctance Machines

This paper deals with the nonlinear analytical harmonic modeling (HM) of three phases, and 6/4 conventional switched reluctance machine (SRM). The proposed model consists in computing magnetic field distribution and electromagnetic performances of an SRM with conventional winding. Because an SRM has inherently nonlinear characteristics, the analytical subdomain model that does not take into account the saturation has a limited accuracy. This is due to the assumption of infinite tooth permeability. The new analytical model (AM) based on the HM technique, which overcomes this limitation, is presented with the consideration of the local magnetic saturation on the stator and rotor teeth. The results obtained with the nonlinear AM have been compared with the linear AM based on the subdomain method (i.e., without the saturation effect) and nonlinear finite-element method solutions.

Original design of axial flux PM motor and modeling of the magnetic leakage using a magnetic equivalent circuit

This paper deals with a part of the French project TRAX, whose aim is to develop a generation of direct drive electric motorization for “all electric” vehicles. The two objectives of this project are: to design an innovative axial flux permanent magnet motor (AFPMM) and industrially feasible in series, to use an analytical model (AM) based on reluctances networks (i.e., a Magnetic Equivalent Circuit M.E.C.) in order to design an optimal electric motor. The magnetic leakage between the magnets is modelized and the analytical results are compared to those of 2D and 3D FEM models.

Design of a high-speed permanent-magnet machine for electrically-assisted turbocharger applications with reduced noise emissions

This paper addresses the issue of mitigating the noise emission of high-speed permanent-magnet (HSPM) machines. HSPM machines are increasingly used in a large field of applications for their power density and compactness. However, increasing the speed tends to intensify the noise emissions where more and more applications require a quiet operation. The focus of this paper is to propose a HSPM structure to cope with this problem that is also well-suited to competitive markets where cost is an important factor. First, high-speed machine topologies are briefly presented in the general case and a comparison between a reference PM slotted structure with tooth-coil windings and a slotless structure toroidally wound is made. Then, general considerations are given regarding the design parameters that impact the vibrational behavior with an analytical description and a three-dimensional (3-D) mechanical finite element analysis (FEA). Finally, the noise emission and losses for both machines are compared showing that the slotless toroidal machine can be a good candidate in this field of applications.

Three-dimensional automatic generation magnetic equivalent circuit using mesh-based formulation

In this paper, a three-dimensional (3-D) generic magnetic equivalent circuit (MEC) using mesh-based formulation was developed for the electrical engineering applications. The particularity of this model consists in a discretization with hexahedral mesh elements, which can be chosen by the designer. For example, the 3-D generic MEC has been applied to a U-cored static electromagnetic device. In order to confirm the effectiveness of the proposed technique, the semi-analytic results have been compared with those obtained using 3-D finite-element analysis (FEA). The computation time is divided by 3 with an error less than 1 %.

NonLinear analytical calculation of magnetic field and torque of switched reluctance machines

The paper deals with the nonlinear analytical harmonic modeling (HM) of 3-phases, and 6-slots/4-poles switched reluctance machine (SRM). The proposed model consists in computing magnetic field distribution and static torque of a conventional winding distribution SRM. Because a SRM has inherently nonlinear characteristics, the analytical subdomain model which does not take into account the saturation has a limited accuracy; this is due to the assumption of infinite tooth permeability. The new analytical subdomain model based on the HM technique, favorable to beyond this limitation, is presented with the consideration of the local magnetic saturation on the teeth. The results obtained with the nonlinear analytical model (NAM) are compared with the analytical subdomain model (without the saturation effect) and nonlinear finite elements method solutions.