Accurate Measurement of Dynamic on-State Resistances of GaN Devices under Reverse and Forward Conduction in High Frequency Power Converter

Because of trapped charges in GaN transistor structure, device dynamic ON-state resistance RDSon is increased when it is operated in high frequency switched power converters, in which device is possibly operated by zero voltage switching (ZVS) to reduce its turn-ON switching losses. When GaN transistor finishes ZVS during one switching period, device has been operated under both reverse and forward conduction. Therefore its dynamic RDSon under both conduction modes needs to be carefully measured to understand device power losses. For this reason, a measurement circuit with simple structure and fast dynamic response is proposed to characterise device reverse and forward RDSon. In order to improve measurement sensitivity when device switches at high frequency, a trapezoidal current mode is proposed to measure device RDSon under almost constant current, which resolves measurement sensitivity issues caused by unavoidable measurement circuit parasitic inductance and measurement probes deskew in conventional device characterisation method by triangle current mode. Proposed measurement circuit and measurement method is then validated by first characterising a SiC-MOSFET with constant RDSon. Then, the comparison on GaN-HEMT dynamic RDSon measurement results demonstrates the improved accuracy of proposed trapezoidal current mode over conventional triangle current mode when device switches at 1MHz

Modeling and Design of Passive Planar Components for EMI Filters

Les composants magnétiques en technologie planar répondent aux exigences actuelles de l Electronique de Puissance (EP), à savoir la montée en fréquence de commutation des structures d EP et la réduction du volume des convertisseurs. La première tendance impose des contraintes fortes en termes de compatibilité électromagnétique (CEM) des équipements. Ces dernières doivent être prises en compte par les ingénieurs dès la phase conception des convertisseurs en se basant sur des modèles fiables, peu développés pour les composants planar dans la littérature scientifique. Ce travail de thèse porte ainsi sur la modélisation des composants planar pour applications aux filtres CEM. Différentes méthodes sont développées au cours de cette thèse pour arriver à évaluer de manière fine les éléments parasites des inductances planar de mode commun : capacités parasites et inductances de fuite. Une partie du travail a porté sur la modélisation par circuits équivalents du comportement fréquentiel des inductances de MC. Une approche automatisée, basée sur un algorithme de fitting a ainsi été développée pour élaborer des circuits équivalents fiables et robustes. Des approches analytiques (Décomposition du Champ Electrique) et semi-analytiques (Fonctions de Green) ont aussi été proposées pour évaluer les valeurs des éléments parasites. La dernière partie de la thèse est plus orientée conception, avec la réalisation de deux structures de composants innovantes, la première se basant sur une technique de compensation des capacités parasites à l aide d éléments parasites structuraux et la seconde sur l association de deux noyaux magnétiques, possédant matériaux et géométries différentesThe magnetic components with planar technology join in the current trends in Power Electronics (PE), namely increasing the switching frequency of PE structures and reducing the size of the power converters. The first tendency imposes strong constraints in terms of electromagnetic compatibility of equipments. The latter has to be considered by engineers at the beginning of the design of Power converters on the basis of reliable models, which are not sufficiently developed for planar components in scientific literature. This PhD work thereby focuses on the modeling of planar components for the applications of EMI filters. Different methods are developed during this study in order to accurately evaluate the parasitic elements of planar common-mode chokes: parasitic capacitances and leakage inductances. A part of this dissertation concerns the equivalent circuit modeling of the frequency behavior of CM chokes. An automated approach, based on a fitting algorithm developed for elaborating reliable and robust equivalent circuits. Analytical approaches (Electric Field Decomposition) and semi-analytical (Green s Function) are proposed as well for calculating the values of these parasitic elements. The last part of this dissertation is oriented to conception, with the realization of two structures of innovative components, the first one based on a parasitic capacitance cancellation technique using structural parasitic elements and the second one on the association of two magnetic cores with different materials and geometriesVILLENEUVE D'ASCQ-ECLI (590092307) / SudocSudocFranceF

Investigation on Single and Split Output Gate Configurations Influence on the GaN-HEMTs Switching Behaviours

This work investigates the power GaN-HEMTs switching behaviour differences resulted from usage of two gate driving configurations: single and split outputs. The analysis based on simulation and experimental results show that GaN-HEMTs could switch slower and cause higher switching losses when the split output configuration is used. This is because the output capacitance (Coss) of MOSFETs inside gate driver will be charged during the turn-on process of GaN-HEMTs, and this charging process can reduce the charging speed of input capacitance (Ciss) of GaN-HEMTs. Moreover, the gate resistance and parasitic inductance are the main parameters selected for analysis, and their distribution can amplify this effect by increasing the impedance ratio of turn-on and turn-off loop. This research provides guiding suggestions for gate driver and high-efficiency GaN-HEMTs power module design.</p

A GaN-HEMT compact model including dynamic r_DSon effect for power electronics converters

In order to model GaN-HEMT switching transients and determine power losses, a compact model including dynamic RDSon effect is proposed herein. The model includes mathematical equations to represent device static and capacitance-voltage characteristics, and a behavioural voltage source, which includes multiple RC units to represent different time constants for trapping and detrapping effect from 100 ns to 100 s range. All the required parameters in the model can be obtained by fitting method using a datasheet or experimental characterisation results. The model is then implemented into our developed virtual prototyping software, where the device compact model is co-simulated with a parasitic inductance physical model to obtain the switching waveform. As model order reduction is applied in our software to resolve physical model, the device switching current and voltage waveform can be obtained in the range of minutes. By comparison with experimental measurements, the model is validated to accurately represent device switching transients as well as their spectrum in frequency domain until 100 MHz. In terms of dynamic RDSon value, the mismatch between the model and experimental results is within 10% under different power converter operation conditions in terms of switching frequencies and duty cycles, so designers can use this model to accurately obtain GaN-HEMT power losses due to trapping and detrapping effects for power electronics converters

Automated tool for 3D planar magnetic temperature modelling: application to EE and E/PLT core-based components

International audienceThermal performance of power converters is a key issue for the power integration. Temperatures inside active and passive devices can be determined using thermal models. Modelling the temperature distribution of high frequency magnetic components is quite complex due to diversity of their geometries and used materials. This paper presents a thermal modelling method based on lumped elements thermal network model, applied to planar magnetic components made of EE and E/PLT cores. The 3D model is automatically generated from the component's geometry. The computation enables to obtain 3D temperature distribution inside windings and core of planar transformers or inductors, in steady state or in transient case. The paper details the proposed modelling method as well as the automated tool including the problem definition and the solving process. The obtained temperature distributions are compared with Finite Element simulation results and measurements on different planar transformers

Integrated drive and reliabilities: fault tolerant architectures and supply

One major challenge of e-aerospace motor is high densities (kW/kg, Nm/kg) keeping a high functional reliability. With high switching frequency Voltage Source Inverter (VSI) using Wide-Band Gap (WBG) components, the DC-bus capacitor mass can be reduced. On contrary, because of very short commutation time (<50ns), the requirements for the connexion between VSI and machine terminals are higher. For a better proficiency, the integration of VSI inside the machine is then desirable. Besides, with WBG components, the temperature limit of the VSI is becoming higher than 150°C and consequently close to those of machines, favouring a common cooling and so, mass reduction. Finally, in integrated drive, the major drawback of fault-tolerant multiphase machines due to numerous external cables is alleviated. In order to benefit of this evolution, new topologies of integrated drive can be imagined. The paper examines different candidates of multiphase machines for integration and proposes an original topology taking into account simultaneously different constraints and opportunities

Estimation des permittivités relatives des noyaux magnétiques pour la détermination des capacités parasites des bobines des filtres CEM

International audienc

Étude de la commande autour de la tension de seuil (CATS) des transistors de puissance à grille isolée et de ses applications

La Commande Autour de la Tension de Seuil (CATS) permet de contrôler de façon simple les gradients de courant et de tension lors des commutations des transistors de puissance à grille isolée (MOSFET ou IGBT). Au lieu de commander les transistors à partir de créneaux de tension évoluant entre 0 et 15V, un palier intermédiaire, de durée et d'amplitude réglables, est introduit à la fermeture et à l'ouverture de l'interrupteur. L'introduction de ce palier permet d'intervenir directement sur les commutations pour que celles-ci se déroulent dans de bonnes conditions, comme peuvent le faire les circuits d'aide à la commutation classiques, mais avec une souplesse de réglage beaucoup plus grande, et sans la nécessité de stocker de l'énergie dans des éléments passifs. Ce circuit de commande permet de réduire les perturbations conduites et rayonnées générées par les convertisseurs de puissance. En effet, lors des commutations des transistors à grille isolée, les gradients de courant et de tension excitent les éléments parasites des circuits de puissance, ce qui provoque des perturbations en diminuant les gradients de tension et de courant. La commande CATS permet également de faire fonctionner en toute sécurité un hacheur alternatif avec une maîtrise complète des contraintes en tension et en courant subies par les différents interrupteurs. Par rapport aux dispositifs existants, celui-ci a pour avantages un circuit de commande trés simple, un fonctionnement indépendant des formes d'ondes commutées et la possibilité de démarrer sous pleine tension.LILLE1-BU (590092102) / SudocSudocFranceF

High frequency modelling of power transformer application to railway substation in scale model

The paper presents the first step uf an EMC (Electromagnetic Cumpatlblllty) analysis uf a railway puwer substatlun in high frequency with reduced scale mudel. The muck-up uf the substation is puwered by a 220 V three-phase vultage supplied by a 15 kVA puwer transfurmer, a rectifier and loads. The study consists in designing an equivalent electrical circuit of puwer transfurmer in high frequency, available uver a large panel of loads. The mudel of puwer transfurmer was deduced frum measurements in frequency domain within the range 40 Hz tu 30 MHz

Méthode de détermination des capacités parasites des bobines toriques nanocristallins

International audienceLes capacités parasites des bobines impactent leur impédance à haute fréquence. Un modèle semianalytique de la capacité parasite équivalente pour des bobines à noyau conducteur (nanocristallin) est proposé pour expliquer son origine et la réduire, notamment pour des applications de filtrage pour la compatibilité électromagnétique (CEM) à haute fréquence. Une approche énergétique est utilisée pour calculer la capacité parasite équivalente à partir du nombre de tours et de la valeur des capacités parasites élémentaires issues de simulation éléments finis. Les erreurs relatives par rapport aux mesures montrent que le modèle proposé améliore la précision de la prédiction par rapport aux modèles classiquement utilisés dans la littérature et prend en compte correctement l’évolution avec le nombre de tours et les espacements inter-spires, et spire-noyau