Xavier Mininger

Thermal Model With Winding Homogenization and FIT Discretization for Stator Slot

The aim of the method detailed in this paper is to get an equivalent thermal model of a stator slot, in order to simplify the calculation of desired temperatures in an electrical machine winding. This study is divided in two steps: First, the equivalent thermal conductivity is deduced from a homogenization of the winding, and next, a discretization is achieved using the finite integration technique considering transient analysis. In order to evaluate the method, results from the equivalent model are compared with finite element simulations considering two slot geometries.

Finite Element Modeling of Magnetoelectric Sensors

The magnetoelectric effect, stemming from piezoelectric and magnetostrictive materials composite, is studied. A model based on the association of magnetoelastic and piezo-electric constitutive laws is presented. This model is implemented in a finite element formulation and a comparison with analytical solutions for piezoelectric/magnetostrictive composite is realized. A magnetoelectric displacement sensor is finally studied.

Finite element modeling of magnetic field sensors based on nonlinear magnetoelectric effect

Magnetoelectric effect in composite materials results from the combination of piezoelectric and magnetostrictive effects. This paper focuses on the development of a harmonic finite element formulation for such coupled problems, taking into account the nonlinearity of magnetostrictive behavior. An application to a magnetic sensor operating under dynamic excitation is presented in order to illustrate the formulation. The enhancement of the magnetoelectric coefficient when a low amplitude harmonic field is superimposed to the static field to be measured is shown to be related to the nonlinearity of magnetic and magnetostrictive behavior.

Effect of Stress on Switched Reluctance Motors: A Magneto-Elastic Finite-Element Approach Based on Multiscale Constitutive Laws

The design of electromagnetic devices submitted to high mechanical stress is a growing issue and requires consequently appropriate modeling tools. We propose in this paper to implement a multiscale model for magneto-elastic behavior into a finite-element code. The 2-D magneto-elastic constitutive law is derived from a multiscale model based on a local energetic approach. The method is applied to study the effect of stress on the magnetic behavior of a switched reluctance motor. This work provides a finite-element tool for the modeling of the effect of multiaxial stress on electrotechnical devices.

Piezoelectric Actuator Design and Placement for Switched Reluctance Motors Active Damping

This paper describes the design and the placement of piezoelectric actuators on switched reluctance motors by means of a genetic algorithm (nondominated sorting genetic algorithm II) for the purpose of reducing stator vibrations. Two distinct approaches are presented: one energy-related and the other based on a minimization of the resultant displacement. These methods lead to design and placement strategy for the piezoelectric actuators. A number of optimal actuators obtained using these kinds of approaches is also compared with mechanical finite-element simulations. At last, a solution is achieved in order to validate optimal placement using positive position feedback active filtering.

Sinusoidal feeding for Switched Reluctance Machine: Application to vibration damping

This paper examines a sinusoidal current shape applied to the switched reluctance machine (SRM) control issues. A comparison between rectangular and sinusoidal current shapes allows to determine the typical application targeted. The two current shapes are experimentally tested and compared for both electrical optimization and noise reduction.

Modeling of Magnetoelastic and Piezoelectric Coupling: Application to SRM Noise Damping

This paper examines a model of magnetomechanical and piezoelectric coupling. This model, based on the association of the magnetoelastic and piezoelectric constitutive laws, is implemented in a transient finite element formulation. The application is the reduction of the noise emitted by switched reluctance machines by means of an active damping. The active elements are piezoelectric actuators placed on the stator, for the purpose of reducing its vibrations. The control is based on a positive position feedback regulation. Thus, an infinite impulse response filter is added to the model in order to control the piezoelectric elements depending on information of the stator vibration.

Semiactive and Active Piezoelectric Vibration Controls for Switched Reluctance Machine

This paper presents two vibration control approaches using piezoelectric inserts applied to a switched reluctance machine (SRM) in order to reduce acoustic emission. The semiactive approach, called synchronized switch damping, consists of a particular voltage processing that increases the electromechanical energy conversion of the piezoelectric insert and leads to effective vibration energy dissipation. Piezoelectric inserts can also be considered as actuators: the active technique aims at imposing an adequate force in order to compensate the structure strain originated by the electromagnetic forces. These two techniques are compared on a single-phase structure mechanically similar to that of an SRM. Advantages and drawbacks depending on the chosen technique are then discussed.

Influence of Mechanical Boundary Conditions on Magnetoelectric Sensors

Magnetic field sensors are an important application for magnetoelectric composite materials. In these devices the external magnetic field is converted into an electric voltage. The sensitivity of the sensor is known to depend on different factors, including geometrical and material parameters. This work deals with the modeling of the influence of mechanical boundary conditions on the sensitivity of magnetoelectric sensors.

Finite Element Harmonic Modeling of Magnetoelectric Effect

The magnetoelectric (ME) effect in composite materials results from the combination of the magnetostrictive effect and the piezoelectric effect via elastic interaction. This work focuses on the modeling of multilayer structures under dynamic excitation. The calculated ME coefficient versus frequency shows the enhancement of the ME effect at mechanical resonance in accordance with experimental measurements. The impact of electric conductivity is investigated. Applications on the ME sensor and tunable inductor are proposed.