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The transient and static behavior of an insulated gate bipolar transistor (IGBT) are analyzed through finite elements simulations and physically based equations. The standard model using a bipolar transistor driven by a MOSFET is abandoned for three partial voltage drops in series, each with its specific static and dynamic behavior. One voltage drop on the internal MOSFET, one on the base and one on the collector-base junction. It is found that the dynamic model can be drastically simplified by focusing on the equivalent electron density. This takes into account the most important phenomena related to the carrier mobilities, necessary for an accurate transient modeling. The specific behavior of the gate-collector capacitance in soft switching conditions is discussed. An equation set based on semiconductor physics is developed to determine the static operating points for each contribution. The importance of the minority carriers transit time in soft switching conditions is then shown. The similarity observed between the waveforms obtained through a finite element simulation and the waveforms obtained using the developed IGBT model within various external structures validates the proposed approach. Index Terms--Insulated gate bipolar transistor (IGBT).

This paper proposes two frequency based methods for parallel active filtering of current harmonics in utility grids. Active filter (AF) reference prediction and AF current control are the two key-points to obtain high performances. This paper deals with the AF reference prediction. The two proposed methods are based on the Fourier Series and its implementation on Dsp. They. belong to two prediction structures: 1) the open-loop structure which predicts the reference currents from the load currents; 2) the closed-loop structure which predicts the reference currents from the grid currents. Fourier Series based methods are very flexible and have several interesting properties. These two methods have been successfully implemented and tested. The latter method cancels permanent errors and results in better performances. Both methods are very flexible. Index Terms--Active power filtering, closed loop, FFT.

A new converter topology for drives is presented in this paper: a three-phase multilevel converter with separately regulated dc power supplies. The dc voltages are provided by medium-frequency dc-dc converters. The applications for the converter are especially high-power traction systems, where the voltage applied to the induction motor is bigger than 1 kV. The motor current is of a very high quality, compared to a classical three-phase converter. This allows keeping the switching frequency low by using phase-shifted pulsewidth modulation (PWM) carriers. Different modulation methods have been developed and simulated. Experimental tests have been made on a 12-kW prototype. Index Terms - DC-DC converter, high-speed motor drives, multilevel converter, PWM modulation, three-phase converter.

A new feed-forward control technique for a dc–dc step-up converter based on the asymmetric multistage stacked boost architecture (MSBA) is proposed. The developed feed-forward controller directly handles the load current and the perturbations that may be caused by the dynamic operation of the converter. Thus, there is no time delay for estimating the error in a control process, and therefore, both robust steady-state operation and high dynamic performance can be achieved. The asymmetric MSBA dc–dc converter is a single-output high-voltage topology that embodies several in-series active voltage-balancing circuits. Thus, there is a need for an improved balancing control method. This can be accomplished by replacing the conventional proportional-integral controllers with feed-forward type and therefore improved balancing between the stages can be attained, because the steady-state errors are suppressed and the dynamic response can be enhanced. A thorough theoretical analysis is conducted for verifying the stability of the suggested feed-forward control technique in an asymmetric MSBA converter, and selective simulation and experimental results are demonstrated in order to validate the effectiveness and feasibility of the proposed control scheme. [ABSTRACT FROM PUBLISHER]

Focuses on a study that presented a configurable topology as front-end converter for a locomotive that can be operated as well on a high voltage alternating current (ac)-system as on a medium voltage direct current (dc) system. Multilevel chain with energy-exchange with a common dc-link via medium-frequency dc-dc converters; Configurable converter topology for multiple current systems; Experimental verification of the double-stage converter module.