David Malec - Academia.edu (original) (raw)

Papers by David Malec

Smart Grid and Renewable Energy

IEEE Transactions on Industry Applications

Engineering

A new structure of integrated low-pass LC filter of DC-DC power converter is proposed in this pap... more A new structure of integrated low-pass LC filter of DC-DC power converter is proposed in this paper. This filter consists in a circular planar coil enclosed between two ferrites substrates. Mn-Zn ferrite has been chosen because of its high permeability and permittivity. In this filter Mn-Zn substrates act not only as a magnetic core but also as a capacitor. In order to reduce the conduction losses in the part of the ferrite used as a capacitor, a particular topology using a blocking layer is proposed. A modelling of the dielectric behaviour of the materials has been performed and injected in a simulation in order to find the resulting LC filter performances and its power range of use. In order to increase the filter efficiency, different solutions have been explored. In particular the inter-turn gap evolution has been optimized to reduce the inter-turn losses. Regarding the bulk losses, BaTiO 3 blocking layers have been added, either upon the ground or the conductor. In this last case a co-firing ferrite tape has been inserted between turns to increase the LC product. Finally the use of low losses Mn-Zn and BaTiO 3 has been proposed and the final characteristics (both electrical and dimensional) of our filter have been compared to conventional ones.

Mathematics and Computers in Simulation

Key points in the development of More Electrical Aircraft (MEA) are currently DC power distributi... more Key points in the development of More Electrical Aircraft (MEA) are currently DC power distribution in higher voltage levels (540 V) and the use of disruptive technology such as Wide BandGap (WBG) semiconductors in power inverters. Using WBG components (SiC and GaN) increases the power converter mass density. However, fast switching of WBG components (tens of kV/µs) induces voltage transient overshoots due to parasitic elements within the inverter. In addition, propagation and reflection phenomena along the harness connected to this inverter, even for small lengths, cause a significant voltage overshoot across the loads. Such overvoltage in Adjustable Speed Drives (ASD: association of inverter, harness and motor) supplied by the new HVDC 540 V aeronautical network could be fatal for the Electrical Insulation System (EIS). This paper proposes a fast and accurate modeling methodology to predict transient overvoltage; it allows us to analyze the impact of SiC inverter technology on overvoltage at motor terminals.

The Fifth International Conference on Power Electronics and Drive Systems, 2003. PEDS 2003., 2000

In railways applications high voltage IGBT power modules are used to build power converters. Such... more In railways applications high voltage IGBT power modules are used to build power converters. Such an approach allows increasing at the same time the reliability, the thermal and electrical performances, to decrease the cost and to achieve an improved design. From a material point of view, such modules have to be considered as a stack of different types of materials.

IEEE Transactions on Dielectrics and Electrical Insulation, 2016

2016 IEEE International Conference on Dielectrics (ICD), 2016

Engineering, 2016

High voltage power modules are used in numerous applications to build high power converters. Tech... more High voltage power modules are used in numerous applications to build high power converters. Technically, these modules are made of different materials and among them, dielectric materials are organic and inorganic. Organic insulators (gels) are used to avoid corona discharges in the vicinity of connecting wires and high voltage dies (diodes and transistors) and to protect them from moisture and contaminants. Inorganic insulators (ceramic substrates) are used to insulate the high voltage which dies from the grounded elements and to transfer heat to the heat sink. Despite being used since the late 90s, there is a lack of fundamental knowledge about the electrical properties of these substrates. Consequently, manufacturers tend to assure the reliability by over sizing them. As there are no clear rules for how to do that, failures occur, leading to the converter shutdown. The aim of this study is to bring new information about the understanding of the dielectric strength of ceramic materials used in these modules. We have focused our work on the correlation between the mechanical and the dielectric properties of ceramics by using relevant experiments. We provide new information about the impact of existing cracks on the ceramic dielectric failure, according to the electromechanical breakdown model. Our conclusions bring crucial information about the precautions to be taken during manufacturing and implementation of these substrates in power modules to reduce the likelihood of the particular causes of failure.

European Journal of Electrical Engineering, 2014

Proceedings of the Ieee 1995 National Aerospace and Electronics Conference Naecon 1995, May 22, 1995

IEEE Transactions on Dielectrics and Electrical Insulation, 2015

OATAO is an open access repository that collects the work of Toulouse researchers and makes it fr... more OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible.

2000 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.00CH37132), 2000

1999 Annual Report Conference on Electrical Insulation and Dielectric Phenomena (Cat. No.99CH36319), 1999

Measurement Science & Technology, 2000

The laser induced pressure wave propagation method is often used to measure the space charge dist... more The laser induced pressure wave propagation method is often used to measure the space charge distribution in solid insulators. This method gives rise to many advantages, so it is widely used both in industrial and in research laboratories. However, it is necessary to take some precautions before treating induced signals in order to minimize calculation errors. Here, some quantitative information

8th IEEE Symposium on Diagnostics for Electrical Machines, Power Electronics & Drives, 2011

In the context of more electric aircrafts, the reliability of the low voltage insulation systems ... more In the context of more electric aircrafts, the reliability of the low voltage insulation systems in rotating machines is an important issue. But, modeling and understanding their electrical ageing is a complex phenomenon especially when they are fed by PWM inverter. They involve a large amount of parameters related to both operating conditions and material design, which act together. Accelerated ageing tests are usually run in order to describe the electrical ageing process and to determine the lifetime of these materials. Nevertheless, full ageing tests with all the various parameters for different samples become rapidly time consuming. Moreover, there is not any complete model for insulation lifetime prediction under accelerated ageing tests. In this paper work, we propose a method based on the design of experiments (DoE) method, which is a useful statistical approach that would lead to a reliable and significant interpretation of the different ordering parameters of the insulation ageing process. Moreover, this method will help to reduce the number of required experimental or numerical trials and will, take into account the possible failure mechanisms and the various synergetic effects between them. Using the (DoE) method, a preliminary model of the insulation "lifetime" is presented with respect to the most important parameters at play and interactions between them.

Revue internationale de génie électrique, 2003