Cyril Buttay

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.

High temperature, Smart Power Module for aircraft actuators

More electric aircraft require converters that can operate over a wide temperature range (−55 to more than 200°C). Silicon carbide JFETs can satisfy these requirements, but there is a need for suitable peripheral components (gate drivers, passives. . . ). In this paper, we present a “smart power module” based on SiC JFETs and dedicated integrated gate driver circuits. The design is detailed, and some electrical results are given, showing proper operation of the module up to 200°C.

Design and Manufacturing of a Double-Side Cooled, SiC based, High Temperature Inverter Leg

In this paper, we present a small (25x25x3 mm 3 ) power module that integrates two silicon-carbide (SiC) JFETs to form an inverter leg. This module has a sandwich structure, i.e. the power devices are placed between two ceramic substrates, allowing for heat extraction from both sides of the dies. All interconnects are made by silver sintering, which offers a very high temperature capability (the melting point of pure silver being 961 °C). The risk of silver migration is assessed, and we show that Parylene-HT, a dielectric material that can sustain more than 300 °C, can completely coat the module, providing adequate protection.

An Airborne High Temperature SiC Power Converter for Medium Power Smart Electro Mechanical Actuators

Normally-On Silicon Carbide (SiC) JFETs are good candidates for power switches in high temperature applications, in Three-Phase Voltage-Fed Inverters used to drive Electro-Mechanical Actuators (EMA) for the more electrical aircraft where the ambient varies from -55 °C to 200 °C. The power of the EMA is in the 1 to 5 kW range, the DC bus voltage is 540 V. It is also necessary to implement passive subsystems such as Electro-Magnetic-Interference (EMI) flters, power inductors, transformers, packaging and interconnection solution that withstand the wide temperature range. The gate driver for normally-On devices must include a safe solution against short-circuit in the event of a power supply failure. The experimental converter is built using engineering samples such as SiC JFETs, SOI drivers and laboratory made components such as inductive wire wound, nano-crystalline core components, SOI integrated driver, assembled with a high temperature package and technology. Finally, the Smart EMA test bench is presented.