Pascal Bevilacqua

A predictive control for a matrix converter-fed permanent magnet synchronous machine

Many research efforts have been dedicated to matrix converters for several years. As major technological issues are now solved, this structure will widespread in industrial applications, in particular with AC motors. Current control is a key issue for AC motor drives, so many control schemes have been proposed. Some of them proposed at first for inverters, were applied to matrix converters. Among algorithms used with inverters, predictive control shows very good performances. In this paper a new control scheme is proposed for a matrix converter- fed permanent magnet synchronous machine. Literature about matrix converter technology and control and about predictive control for inverter-fed AC machines is reviewed. The proposed predictive control principle, the model of the whole machine - converter and the cost-function are detailed. The method offers a trade-off between the quality of motor currents and input power factor. Finally experimental results are reported. The feasibility and the effectiveness of the proposed method is assessed.

Hybrid control of a three-cell converter associated to an inductive load

This paper presents a control scheme for a multilevel multi-cell converter. For this type of converters, load current and capacitor voltages must be jointly controlled. Moreover the real-time constraint is important. This constraint leads us to propose a control based on a simplified state-space model. The model allows predicting the state vector evolution for every converter configuration. The control algorithm directly determines the converter switching state which minimizes a simple cost function. A normalization of the state variables is proposed for the cost function calculation in order to ensure a trade-off between the tracking of the load current and the tracking of the capacitor voltages. The proposed control scheme is detailed and compared with a classical control scheme with simulations. Finally, experimental results are presented to show the effectiveness of the proposed method.

Optical beam induced current measurements based on two-photon absorption process in 4H-SiC bipolar diodes

Using a pulsed green laser with a wavelength of 532 nm, a duration pulse of ∼1 ns, and a mean power varying between 1 and 100 mW, induced photocurrents have been measured in 4H-SiC bipolar diodes. Considering the photon energy (2.33 eV) and the bandgap of 4H-SiC (3.2 eV), the generation of electron-hole pair by the conventional single photon absorption process should be negligible. The intensity of the measured photocurrents depends quadratically on the power beam intensity. This clearly shows that they are generated using two-photon absorption process. As in conventional OBIC (Optical Beam Induced Current), the measurements give an image of the electric field distribution in the structure under test, and the minority carrier lifetime can be extracted from the decrease of the photocurrent at the edge of the structure. The extracted minority carrier lifetime of 210 ns is consistent with results obtained in case of single photon absorption.

SiC power semiconductor devices for new applications in power electronics

This paper addresses the benefits of SiC semiconductor, owning excellent physical properties able to fulfill new scope of applications in terms of high temperature, high voltage and for more specific applications. Devices and applications developed at Ampere laboratory are detailed.

A 100 MHz 91.5% Peak Efficiency Integrated Buck Converter With a Three-MOSFET Cascode Bridge

High-switching frequency dc-dc converters are present in many applications, where wide regulation bandwidth and high efficiency are needed. A three-MOSFET cascode bridge is presented to get full benefit from digital CMOS technology advancements. Three-dimensional assembly with a capacitive interposer is proposed for high-frequency efficient decoupling. A test-chip is designed in 40-nm CMOS technology, validating the operation and the efficiency performance of the converter using the proposed cascode bridge. A conversion peak efficiency of 91.5% is demonstrated when converting 3.3 to 2.4 V with a 150-mA load current, while switching at 100 MHz.

High Temperature Ageing of Fe-based Nanocrystalline Ribbons

The impact of long-term high-temperature stress on nanocrystalline Finemet materials is measured by keeping samples at 200 °C for 1300 hours. The standard industrialized, high permeability Finemet materials as well as the recently available low permeability Finemet materials are investigated. Characterizations are performed at different frequencies, temperatures and magnetic field excitations on both aged and non-aged samples. Their complex permeability is also measured during the ageing test. Irreversible changes are pointed out on permeability, coercive field and magnetic flux density at saturation. Regarding the design considerations for high temperature power electronics, the suitability of these materials is demonstrated but an ageing effect has to be considered nonetheless. The presented data can be extrapolated to several thousand hours at 200 °C using the presented empiric ageing law.

Application of averaged models to real-time monitoring of power converters

The reliability of a power converter may be controlled by monitoring the converter state during operation. This paper describes an experimental real-time monitoring application using an extended nonideal averaged model of the power converter. The advantage of this approach is discussed along with experimental results, particularly the estimation of silicon temperature.

An energy saver for tramway networks using double active bridge and supercapacitors

An industrial energy saver system for transportation networks is designed using analytical models and simulation. This off-board energy saver uses the high power capabilities of supercapacitors and an innovative soft switching topology with a nanocrystalline insulation transformer. A laboratory demonstrator is presented, life expectancy of the storage unit is estimated. Field measurements on the industrial product demonstrates the concept.

Measurement of Carrier Lifetime Temperature Dependence in 3.3kV 4H-SiC PiN Diodes Using OCVD Technique

This paper reports on the influence of temperature on the electrical carrier lifetime of a 3.3 kV 4H-SiC PiN diode processed with a new generation of SiC material. The Open Circuit Voltage Decay (OCVD) is used to evaluate ambipolar lifetime evolution versus temperature. The paper presents a description of the setup, electrical measurements and extraction fittings. The ambipolar lifetime is found to rise from 600 ns at 30 °C to 3.5 μs at 150 °C.

300/spl deg/C operating junction temperature inverter leg investigations

A silicon carbide JFET cascade sample is characterized at temperatures up to 300degC with the design of a diode-less inverter in mind. The JFET is considered as a power switch, on-off gate voltages are applied during testing, conduction capability and blocking are measured, reverse conduction is investigated experimentally. Switching losses are considered and total losses of the inverter leg are estimated