Ahmed Chebak

Analytical Model for Design of High-Speed Slotless Brushless Machines with SMC Stators

This paper presents a general analytical model for the design of high-speed slotless permanent magnet brushless motors equipped with surface-mounted magnets and using soft magnetic composite material (SMC) in the stator. The electromagnetic model is formulated in polar coordinates and based on the prediction of the two-dimensional magnetic field distribution in the magnets/air-gap/windings/stator core regions, produced by the magnets and the stator currents windings. It takes into account the effects of the stator core eddy currents induced in the massive homogeneous SMC material. Different machine performances like the instantaneous torque under brushless operation and the total magnetic losses are evaluated. The analytical design model is validated by FE analysis in terms of magnetic field distribution and total stator core loss. The influence of the stator yoke thickness and the SMC material conductivity on the motor performances is investigated. Experimental results are given for the stator magnetic losses.

Development of a DC-link protection system for regenerative braking of Electric Vehicle using a pseudo-cascade controlled IGBT chopper

This paper presents a pseudo-cascade controlled IGBT chopper used for transient protection of the DC-link and battery of Electric Vehicles (EVs) with regenerative braking feature. During EVs traction and braking operation, the DC-link shows transient behavior that can seriously damage the main battery and the filtering capacitors. The proposed system is used to protect the battery against surge line charging current and the DC-Link against overvoltage while allowing maximum braking capacity and maximum battery charging efficiency. A theoretical model for controller parameter calculation is presented and implemented in Matlab-Simulink to validate the control scheme. Experimental results on a reduced power test bench are also presented.

Study of induction heating process applied to internal gear using 3D model

The current paper is principally dedicated to the study of geometry and frequency effects for internal spur gears heated by induction. The overall work is realized by the simulation efforts performed on Comsol multi-physics software. The 3D model used during this study is built basing on coupling between Maxwell’s and heat transfer equations. This model is used to calculate the temperature profile in the gear in function of machine parameters. The module and the frequency are varied to determinate their effects. In fact, two gears having the same external diameter but different modules are exploited during this study and the frequency is varied from low to high level. The obtained results allow understanding the effect of module and frequency on the final temperature distribution. Finally, the optimal frequency value permitting to have the best temperature profile is found.

Design and Optimization of a high torque in-wheel surface-mounted PM synchronous motor using concentrated winding

This paper presents a specific design process of a high-torque direct-drive in-wheel permanent magnet synchronous machine (PMSM) using concentrated winding and grain oriented (GO) silicon steel teeth for a hybrid All-Terrain Vehicle (ATV) application. Mechanical specifications and constraints of an off-road application are first demystified. An analytical design model, considering magnet flux and an induction reaction correction factors, is developed and used to determine geometric dimensions of a radial flux machine topology with surface-mounted permanent magnets (PM) and external rotor. The model also takes into account losses in winding, magnets, stator and rotor yokes and teeth. Electrical parameters of the equivalent machine circuit are determined to adapt the machine to the imposed converter voltage. All critical machine models parameters are validated with finite element (FE) simulations. The analytical design model is used to perform an iterative optimization procedure. This model is corrected during the optimization process by using correction factors derived from 2D FE analysis. The optimization process and some critical design validations are presented.

A New Approach in Optimizing the Induction Heating Process Using Flux Concentrators: Application to 4340 Steel Spur Gear

Abstract The beneficial effects of using flux concentrators during induction heat treatment process of spur gears made of 4340 high strength steel is demonstrated using 3D finite element model. The model is developed by coupling electromagnetic field and heat transfer equations and simulated by using Comsol software. Based on an adequate formulation and taking into account material properties and process parameters, the model allows calculating temperature distribution in the gear tooth. A new approach is proposed to reduce the electromagnetic edge effect in the gear teeth which allows achieving optimum hardness profile after induction heat treatment. In the proposed method, the principal gear is positioned in sandwich between two other gears having the same geometry that act as flux concentrators. The gap between the gear and the flux concentrators was optimized by studying temperature variation between the tip and root regions of gear teeth. Using the proposed model, it was possible identifying processing conditions that allow for quasi-uniform final temperature profile in the medium and high frequency conditions during induction hardening of spur gears.

Explorative Study and Prediction of Overtempering Region of Disc Heated by Induction Process Using 2D Axisymmetric Model and Experimental Tests

Thanks to many industrial benefits that it exhibits, induction heating process is very promising for its potential application in manufacturing production. To understand the industrial context, it is necessary to investigate the process by focusing on simulation and experimental aspects. In fact, this paper presents an original approach able to predict the overtempering zone with analyzing the temperature curves resulting from simulationand the hardness profile achieved by experimental validation. The proposed approach combines experimental validation and numerical simulation applied to 4340 steel disc in order to investigate the overtempering phenomenonand develop a very simplified and practical model able to predict the hardness curve with a fairly good accuracy. The developed model is validated by experimental tests and is used to evaluate the effect of machine parameters on the overtempering.

Sensitivity Study of Temperature Profile of 4340 Spur Gear Heated by Induction Process Using 3D Model

This paper presentsa sensitivity study using a Comsol3D model simulation for spur gear heated by induction process. Based on an adequate formulation and taking into account the material properties, a multi-physics 3D model is built to calculate the final temperature distribution determinate according the machine parameters and some geometrical factors (coil width and gap between coil and gear). Since the hardness profile is affected by thermal historic during heating, the surface temperatures are deeply analyzed versus the initial current density and the heating time using medium (MF) and high frequencies (HF). Finally, the sensitivity of hardness profile with the machine parameters variation isinvestigated using various statistical tools applied to the obtained results. The obtained results exhibits the main machine parameters and theirs effects on the hardness profile.

Development of renewable energy laboratory based on integration of wind, solar and biodiesel energies through a virtual and physical environment

This paper presents the concept of novel educational renewable energy laboratory. The proposed laboratory objective is to allow students to learn all aspects of renewable energies and take hands-on equipments for better understanding of clean energy technologies. This laboratory includes a hybrid power system (HPS) integrating wind energy conversion system (WECS), photovoltaic (PV) panel, biodiesel generator, maximum power point tracking (MPPT) controllers and storage battery. In this paper, the whole HPS dimensioning is performed and the three renewable energy source systems are simulated and analyzed separately. The PV panels are examined under solar radiation and cell temperature variation conditions. The solar power functioning are verified and studied through a direct connection to battery and resistive load. The WECS is also analyzed through the same connection under constant winds speed and variable winds speed. Furthermore, the biodiesel generator using permanent magnet synchronous machine was simulated and analyzed. The laboratory physical environment is described and the virtual platform is presented. The e-learning concept and the laboratory learning topics are also developed.

Voltage-source converter control under unbalanced grid conditions for a variable speed wind energy system

This paper presents a grid-side model and control for small wind turbines connected to the grid using a back-to-back converter. The control is developed to transmit all power generated by an induction machine to the grid and to match grid requirements. The grid synchronization is achieved by a Double Synchronous Reference Frame Phase Locked Loop (DSRF-PLL) even during grid faults or unbalanced conditions. The study of the DC-bus power leads to the compensator design which regulates the DC-bus voltage to a reference signal. Active and reactive power control is implemented so the system is able to act on each power independently. Thus, a vector oriented field control on currents is built to transfer all the power from the wind turbine to the grid and to keep the power factor to 1. Simulation results for the system performances under unbalanced conditions are presented.

Simulation of Helical Gear Heated by Induction Process Using 3D Model

This paper is devoted to develop a 3D model applied to helical gear heated by induction process. The global work is realised by multiphysicsimulation coupling electromagneticfields and heat transfer using Comsolsoftware. This model permits to establish the temperature distribution in function of simulation parameters. The results are very promising since they allow understanding the dissymmetry effect of heating that affect the real hardness profile. Finally, a global sensitivity study about nominal values of machine parameters is conducted to quantify the effect of power consumed by the part on the surface temperature.