Khalil El Khamlichi Drissi

High-Input-Voltage High-Frequency Class E Rectifiers for Resonant Inductive Links

The operation of traditional rectifiers such as half-wave and bridge rectifiers in wireless power transfer applications may be inefficient and can reduce the amount of power that is delivered to a load. An alternative is to use Class E resonant rectifiers that are known to operate efficiently at high resonant frequencies and at large input voltages. Class E rectifiers have a near sinusoidal input current which leads to an improved overall system performance and increased efficiency, especially that of the transmitting coil driver. This paper is the first to investigate the use of Class E resonant rectifiers in wireless power transfer systems based on resonant inductive coupling. A piecewise linear state-space representation is used to model the Class E rectifier including the rectifying diodes forward voltage drop, its ON resistance, and the equivalent series resistance of the resonant inductor. Power quality parameters, such as power factor and total harmonic distortion, are calculated for different loading conditions. Extensive experimental results based on a 10-W prototype are presented to confirm the performed analysis and the efficient operation of the rectifier. An impressive operating efficiency of 94.43% has been achieved at a resonant frequency of 800 kHz.

Generalized Form of Telegrapher's Equations for the Electromagnetic Field Coupling to Buried Wires of Finite Length

In this paper, a generalized form of telegraphers equations for electromagnetic field coupling to buried wires is derived. The presented approach is based on thin-wire antenna theory. The effect of a dissipative half-space is taken into account via the reflection/transmission coefficient approximation. The conductor losses can be taken into account via the surface impedance per unit length. The derived equations are treated numerically via the Galerkin-Bubnov indirect boundary element method. Numerical results are presented for induced current along the wire, and compared with transmission-line (TL) and modified TL (MTL) approximations, respectively, for the case of perfectly conducting electrode buried in a lossy medium. It is shown that the TL and MTL approximations can result in an inaccurate induced current distribution along the conductor at HFs and for shorter electrode lengths, respectively.

Discontinuous Random Space Vector Modulation for Electric Drives: A Digital Approach

Space vector modulation (SVM), with its many advantages over classical pulsewidth modulation technique (PWM), is gaining in popularity. However, only deterministic SVM exists. Randomized PWM (RPWM) with its cleaner harmonic spectrum is gaining interest for industrial applications required to meet electromagnetic compatibility standards. Inverter switching losses are optimized and life expectancy can be increased using a suitable discontinuous modulation technique. Here, we present, a discontinuous and randomized-modulation technique based on space vector calculation, intended for electric-drive oriented hybrid electric vehicle, which has the advantages of SVM and clean harmonic-spectrum and the efficiency of RPWM and DPWM, respectively.

Effects of symmetric distribution laws on spectral power density in randomized PWM

The effects on the spectral power density (SPD) of randomized pulse width modulation (RPWM) waveforms by the choice of different probability distribution laws are investigated. The distribution laws under studied are symmetric uniform, normal, laplace, and parabolic. A comparison method, based on a normalized deviation with respect to the uniform distribution law, is devised. It is shown, by way of analytical derivation and simulations, that uniform distribution produces power spectrum comparable to those generated by other relatively more complex distributions under studied. Significantly, it means that uniform distribution, which is the simplest to implement, is the preferred probability law for randomization in a RPWM scheme.

Angular Modulation of Dual-Inverter Fed Open-End Motor for Electrical Vehicle Applications

In this paper, angular modulation index (AMI) implemented through a modified space vector modulation for the dual voltage source inverters (VSI) is proposed with the primarily aiming to reduce switching losses. The desired voltage across the load is synthesized by applying appropriate phase-angle displacement between space vector references. The proposed approach avoids the use of a dc/dc boost converter (which imposes loss and weight/price penalty to duplicate the dc-link voltage) and results to be particularly suitable for electrical/hybrid vehicle applications. Namely, the application of saving energy to keep driving has been identified as major concern. Hence, this work focuses on the strategy to enhance efficiency. The principles of the proposed controlling method and switching loss, which is reduced at least by 50%, are theoretically evaluated. This paper proposes a pioneering mathematical approach to correctly determine total harmonic distortion (THD) value of the voltage/current for the dual-VSI structure. Furthermore, simulation and experimental results prove that the proposed method insures benefits in terms of common-mode voltage, THD of the voltage, and switching loss reduction. The dual-VSI prototype supplying 1.5-kW induction motor is assembled in the laboratory to experimentally evaluate performance of the proposed method. Also, the simulation results carried out through MATLAB/Simulink environment are given to confirm performance of this easy-to-implement and high-efficient method.

Random space vector modulation for electric drives: A digital approach

SVM, with its many advantages over PWM, is gaining popularity. However, only Deterministic-SVM exist. Whereas Randomised-PWM with their cleaner harmonic-spectrum, are gaining interest for industrial applications required to meet EMC-Standards. Here we present, Randomised-SVM intended for Electric-Drive oriented HEV, which has the advantages of SVM & clean harmonic-spectrum of Randomised-PWM.

Transient Response of Straight Thin Wires Located at Different Heights Above a Ground Plane Using Antenna Theory and Transmission Line Approach

Transient electromagnetic field coupling to straight thin wires parallel to each other and located at different heights above a perfectly conducting or dielectric ground plane is analyzed using wire antenna theory and a transmission line method. The time-domain antenna theory formulation is based on a set of the space-time Hallen integral equations. The transmission line approximation is based on the corresponding time-domain Telegraphers equations. The space-time integral equations arising from the wire antenna theory are handled by the time-domain Galerkin-Bubnov scheme of the indirect boundary element method. The time-domain Telegraphers equations are solved using the finite-difference time-domain method. Time-domain numerical results obtained with both approaches are compared to the results computed via NEC 2 code combined with an inverse Fourier transform procedure. Some illustrative comparisons of results obtained by means of antenna theory and transmission line approach are presented throughout the paper.

Comparison of Matrix Pencil Extracted Features in Time Domain and in Frequency Domain for Radar Target Classification

Feature extraction is a challenging problem in radar target identification. In this paper, we propose a new approach of feature extraction by using Matrix Pencil Method in Frequency Domain (MPMFD). The proposed method takes into account not only the magnitude of the signal, but also its phase, so that all the physical characteristics of the target will be considered. With this method, the separation between the early time and the late time is not necessary. The proposed method is compared to Matrix Pencil Method in Time Domain (MPMTD). The methods are applied on UWB backscattered signal from three canonical targets (thin wire, sphere, and cylinder). MPMFD is applied on a complex field (real and imaginary parts of the signal). To the best of our knowledge, this comparison and the reconstruction of the complex electromagnetic field by MPMFD have not been done before. We show the effect of the two extraction methods on the accuracy of three different classifiers: Naive bayes (NB), K-Nearest Neighbor (K-NN), and Support Vector Machine (SVM). The results show that the accuracy of classification is better when using extracted features by MPMFD with SVM.

Novel technique to reduce leakage current and commutation losses in electric drives

The continuous advancements in solid state device engineering have considerably minimized the switching transients for power switches. These fast switches are gaining popularity because of lower switching losses for hard switched systems. However this introduces high leakage current in electric drives. A technique to simultaneously reduce the leakage current and the switching losses is presented in this paper.

Random discontinuous space vector modulation for variable speed drives

The recent advances in Digital Signal Processor technology has made cheap implementation of SVM possible. SVM has gained wide acceptance due to the many advantages it off ers compared to conventional PWM methods. In this paper Random PWM (RPWM) and Discontinuous PWM (DPWM) techniques would be extended to SVM to increase the inverter efficiency while reducing Electromagnetic Interference caused by the switching harmonics. A discontinuous SVM scheme with the capacity to auto-adjust to the load characteristics to optimize the inverter performance, decrease the thermal stress on the power switches, regulate the temperature imbalance amongst the inverter legs hence increase the lif e expectancy of the system.