Moez Ghariani

Experimental Investigations for Thermal Mutual Evaluation in Multi-Chip Modules

The thermal behavior of power modules is an important criterion for the design of cooling systems and optimum thermal structure of these modules. An important consideration for high power and high frequency design is the spacing between semiconductor devices, substrate structure and influence of the boundary condition in the case. This study focuses on the thermal behavior of hybrid power modules to establish a simplified method that allows temperature estimation in different module components without decapsulation. This study resulted in a correction of the junction temperature values estimated from the transient thermal impedance of each component operating alone. The corrections depend on mutual thermal coupling between different chips of the hybrid structure. A new experimental technique for thermal mutual evaluation is presented. Notably, the classic analysis of thermal phenomena in these structures, which was independent of dissipated power magnitude and boundary conditions in the case, is incorrect.

Sliding mode control and neuro-fuzzy network observer for induction motor in EVs applications

In order to deal with the major problems of electric vehicle (EV) propelled by an induction motor (IM), a neuro-fuzzy sliding mode control was designed. The proposed scheme uses an adaptive observer that is based on a full order model of the IM in indirect vector-controlled drive. Moreover, it is evaluated on an EV global model taking into account the vehicle dynamics, the thermal effect and the parameters variations. The neuro-fuzzy network is used to adaptively adjust the parameters prediction. However, the sliding mode control can offer many good properties such as good performance against unmodelled dynamics, insensitivity to external disturbance rejection and fast dynamic. Simulations results carried out on a test vehicle, show that the proposed controller is superior to PID one at response speed, steady-state tracking error and resisting perturbation whenever driving or braking. This shows that the proposed scheme is good candidate for EVs propulsion.

Induction machine DTC optimization using artificial intelligence for EV's applications

A three-phase squirrel-cage induction motor is used as a propulsion system of an electric vehicle (EV). The motor is controlled at different operating conditions using a direct torque control (DTC) technique known to have simple control structure with comparable performance. Whereas in a conventional DTC drive, the weakest points is the optimal voltage space vector choice. In this paper Artificial Intelligence is used to achieve an optimal selection of voltage space vectors. The European drive cycle ECE-15 is used for validation. The simulation results show that the proposed DTC optimization using artificial intelligence scheme for induction motors is a good candidate for EVs propulsion.

Power Factor Correction Rectifier with a Variable Frequency Voltage Source in Vehicular Application

This paper presents a PFCVF (Power Factor Correction) rectifier that uses a variable frequency source for alternators for electric and hybrid vehicles application. In such application, the frequency of the signal in the alternator changes according to the vehicle speed, more over the loading effect on the alternator introduces harmonic currents and increases the alternator apparent power requirements. To overcome these problems and aiming more stability and better design of the alternator, a new third harmonic injection technique is proposed. This technique allows to preserve a good THD (Total Harmonic Distortion) of the input source at any frequency and to decrease losses in semiconductors switches, thereby allowing more stability and reducing the apparent power requirements. A comparative study between the standard and the new technique is made and highlights the effectiveness of the new design. A detailed analysis of the proposed topology is presented and simulations as well as experimental results are shown.

Performance comparison on three parameter determination method of fractional PID controllers

The objective of this work is to define the fractional order PID and the approximation of the integral and derivation of fractional order to render the system from irrational to rational. The parameters of PID are determined by three methods. These fractional controllers have two parameters more than the conventional PID controller, two more specifications can be met, improving the performance of the system, the fractional orders, α and β are determined by minimized the ISE. For the tuning of the controller an iterative optimization method has been used, based on a nonlinear function minimization. Illustrative example is presented and simulation results show the effectiveness of this kind of controllers.

Developing a Simplified Analytical Thermal Model of Multi-chip Power Module

Abstract The study of the thermal behavior of power modules has become a necessity regarding the known rapid development in modern power electronics, and the prediction of temperature variation has generally been performed using transient thermal equivalent circuits. In this paper we have developed a simplified analytical thermal model of a power hybrid module. This analytical method is used to evaluate the thermal parameters of a device. The model takes into account the thermal mutual influence between the different module chips based on the analytical method. The thermal interaction between components is dependent on the boundary condition, the dissipated power value in the different components and the number of operating chips constituting the module. This effect is modelled as a source energy and a thermal resistance simply computed tanks to reasonably low measurement applied on the module. The derived thermal models offer an excellent trade-off between accuracy, efficiency and CPU-cost.

Grid stability study after the integration of a wind farm

Although the integration of wind farms into power grids is beneficial, it generally disturbs the quality and stability of power supply. In order to overcome the problems caused by electromechanical oscillation, additional stabilizing signals are used. Automatic voltage regulators act on the exciters to reach the desired voltage, and turbine governors act on the admission servo-motor to rectify the speed of the generator. Nonetheless, the interaction between the power system components and these devices requires optimization. The various results of simulations realized in the PSAT environment show the performance of the regulators integrated into the synchronous generators.

Electrothermal modeling of hybrid power modules

Purpose – Power modules including the insulated gate bipolar transistor (IGBT) are widely used in the applications of motor drivers. The thermal behavior of these modules makes it important to choose the optimum design of cooling system. The purpose of this paper is to propose an RC thermal model of the dynamic electro‐thermal behavior of IGBT pulse width modulation inverter modules.Design/methodology/approach – The electrothermal model has been implemented and simulated with a MATLAB simulator and takes into account the thermal influence between the different module chips based on the technique of superposition.Findings – This study has led to a correction of the junction temperature values estimated from the transient thermal impedance of each component operating alone.Originality/value – In this paper, an experimental technique of a thermal influence evaluation is presented.

Performance comparison of PI, SMC and PI-Sliding Mode Controller for EV

This paper presents three different control strategies for controlling an induction motor “IM” in an electric vehicle (EV) application. The control techniques analyzed and compared are: the proportion-integral regulator (PI), the sliding mode control (SMC) and the PI-Sliding Mode Control (PI-SMC). Simulation results show the comparison performance in term of robustness.

Thermal model for induction machine

This paper presents a thermal circuit model to simulate the behaviour of an electric motor during the transient duty leading to steady-state operation under rated load. The proposed model allows the calculation of the temperature distribution in the radial direction of the electric motor, from the shaft inside to the motor frame surface. Several heat sources inside the motor as well as the heat conduction and the thermal contact resistances have been considered. The surface convection heat transfer inside the motor and at its external surfaces is modelled by using heat transfer coefficients. Due to its flexibility and ease of implementation, the software MATLAB SIMULINK was used as the platform for modelling and simulation. The simulation points out the importance for a correct modelling of internal heat generation and contact resistances in order to predict the transient behaviour.