High frequency self-oscillating current switching for a fully integrated fail-safe stimulator output stage

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This paper presents a comprehensive analysis of the operational modes of the unidirectional DC/DC converter, featuring a medium frequency Y-Y transformer and output filter inductor (3-ph DC/DC). All modes of operation are presented for the first time for this converter and mechanisms and conditions governing the transitions between the modes are discussed. The converter steady-state model is given. Steady-state operation is studied in detail and trade-offs between operational modes are identified from the p

In converter-based grids (CBGs) without support from the main grid or synchronous generators, grid-forming converters (GFMs) are responsible for sustaining frequency and voltage stability. However, disturbances or load variations frequently lead to frequency and voltage deviations, and the operating point (OP) of GFM may not align with the desired stable state. Under severe faults, current-limiting actions may be triggered, potentially leading to instability. This paper proposes a Port-Hamiltonian (PH) fram

Transient Stability Assessment (TSA) is the process in which the stability of a system is characterized qualitatively or quantitatively. The TSA algorithm presented in this paper is derived from the well-established Single Machine Equivalent (SIME) method and can thus be categorized as a hybrid direct-temporal method. The novelty of the proposed algorithm is that it derives a Transient Stability Index (TSI) with a single TimeDomain (TD) simulation for both stable and unstable cases. The resulting TSI is uni

The development of front-end systems for the ATLAS tracker at the sLHC is now in progress and the availability of radiation tolerant buck converter ASICs enables the implementation of DC to DC converter based powering schemes. The front-end systems powered in this manner will be exposed to the radiated and conducted noise emitted by the converters. The electromagnetic compatibility between DC to DC converters and ATLAS short strip tracker hybrid prototypes has been studied with specific susceptibility tests

This article presents an inductive power link for a cortical implant. The link includes a Class-E power amplifier, an inductive link, a matching network, and a rectifier. The coils of the inductive link are designed and optimized for a distance of 10mm (scalp thickness). The power amplifier is designed in order to allow closed loop power control by controlling the supply voltage. A new packaging topology is proposed in order to position the implant in the skull, without occupying much area, but still obtain

The paper presents an influence of leakage effect observed in capacitive analog memories on learning process in hardware implemented Kohonen neural networks with MOS transistors used as switches connected with information holding capacitors. The learning results, i.e. variations (adaptations) of weight values, strongly depend on the transistor leakage currents. This is a cause for some quantization error associated with the weight adaptations during the network training. The unwanted leakage influence can b

We report on solar-blind metal-semiconductor-metal (MSM) detectors fabricated on stacks of (AI,Ga)N layers with different Al mole fraction. These structures were grown by molecular beam epitaxy on sapphire substrates to allow backside illumination and a low-temperature GaN buffer layer. They consist of a 0.3-0.4-mum active layer grown on a thick (AI,Ga)N window layer (approximate to 1 mum) that is transparent at the wavelength of interest. Different Al contents were used in the window layer. We observed tha

Conventional RF power amplifiers usually give their maximum efficiency near the maximum output power level. When the output power decreases, the efficiency drops sharply. Deep class AB or B PAs improve their efficiency by a self-adaptation of the current drawn from the power supply. However, in many cases, both deep class AB and B do not provide enough linearity like, for instance, in CDMA applications where spectral re-growth is of first concern. From class A to class B, RF PAs face the linearity-efficienc

Hybrid asymmetric multi-level inverters promise significant improvements for medium-voltage industrial drives. Floating sub inverters without feeding can only supply reactive power. An on-line non-linear model-predictive controller stabilizes their intermediate-circuit voltages in steady-state and during transients, as demonstrated by simulations and measurements. A pre-charge method assures converter start-up without additional equipment.

This paper presents a novel development method for interactive and distributed applications. The benefit that this method provides is that the design gives clear guidance towards the implementation. The method is based on three main elements: a concept of synchronous active objects that is closely related to that found in CSP; the Java environment; and a selection of the diagrams defined by UML. This approach alleviates many of the most serious problems that are encountered when using GUI builders, which hi

Nonlinear devices, such as power electronics converters, inject harmonic currents in the AC system and increase overall reactive power demanded by the equivalent load. Also, the number of sensitive loads that require ideal sinusoidal supply voltages for their proper operation has increased. In order to keep power quality under limits proposed by standards, it is necessary to include some sort of compensation. Different types of power quality compensators of higher or lower complexity have been reported. The

Flexible AC Transmission Systems (FACTS) are systems based on power electronics using GTO or IGCT semiconductors [1] that allow a better use of the transfer capacities of the transmission lines and permit to satisfy the requirements due to the liberalization of the electrical energy market. The Unified Power Flow Controller (UPFC) is one of the most versatile topologies of the FACTS family. The UPFC can be decomposed in two different power circuits: the parallel one maintaining the network bus voltage by co

This paper is focused on a general design principle of a uniform step multilevel converter, with K series-connected full bridges inverters per phase. A new design terminology is proposed and analytical relationships are established. The DC-voltage sources supplying partial inverters are supposed to be rationally unbalanced. The corresponding “Asymmetrical” topology provides more flexibility to the designer, and can generate a large number of levels (any odd number from 2K+1 to 3K) without increasing the num

Recent progress made in our lab. in the field of electrochem. promotion of heterogeneous catalytic gas reactions is reviewed. The phenomenon consists of electrochem. polarization of the catalyst/solid electrolyte interface resulting in a dramatic, non-Faradaic modification of the catalytic reaction rate. Two main aspects have been addressed, the mechanistic interpretation of the phenomenon and the development of bipolar cell configurations suitable for practical applications. Fundamental studies were made u

The non-linear dielectric properties of single crystals of PbMg1/3Nb2/3O3 relaxer ferroelectric were investigated experimentally by using measurements of the dielectric permittivity of this material as a function of the DC bias and the AC driving fields. The results were analyzed using four models of the dielectric response of relaxors currently discussed in the literature, It was shown that among them only one model was consistent with the experimental data. This provides strong evidence that the mechanism

The a.c. self-field loss in Bi-2223 Ag and Ag-alloy sheathed tapes with different number of filaments has been measured in the range 59-2500 Hz by means of a dual lock-in amplifier technique. We have been able to dissociate quantitatively the different self-field loss contributions: hysteretic, eddy current and flux-creep resistive loss (near Ic) due to their different frequency dependence and the wide frequency range of the measurements. The relative weight of eddy current losses is found to be inversely p

Multilevel inverters represent a high potential for realization of a high power controllable conversion system of different nature, rectifiers, inveters, high power amplifiers, etc. From the even more applied three-level inverter to the multiple AC stages VSI, different topologies are applied, withan increasing quanty of pssible levels. Usually, the theory of multilevel inverters is presented with different definition of the number o levels. The contrubution will give some logic definitions on basic schemes

This paper shows that the instabilities which are observed in cells cannot be explained by supposing that the mechanical and electromagnetic fields are independent of the space variable x3 corresponding to the length of the cell. For a model which is infinitely long in the x3-direction, we prove in particular that the kinetic energy due to the x1- and x2-components of the velocities tends to zero as the time tends to infinity.

The measurement of the transfer impedance of a screened coaxial cable using a low-power sinusoidal current has the disadvantage that the saturation effects which occur in the ferromagnetic screen are not reproduced. The authors describe a method for measuring the impedance using a source of current pulses with a magnitude of a few hundred amperes. The measurement results and a comparison between calculated and test values are given

High frequency self-oscillating current switching for a fully integrated fail-safe stimulator output stage

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Operational Mode Analysis of the Isolated Three-Phase DC/DC Converter

Transient Energy Shaping Strategy for Grid-Forming Converters Based on the Port-Hamiltonian Framework

A transient stability assessment method using post-fault trajectories

Low noise DC to DC converters for the sLHC experiments

Inductive Power Link for a Wireless Cortical Implant with Biocompatible Packaging

Influence of Information Leakage in Analog Memory on Learning Kohonen Network on Silicon

Multilayer (Al,Ga)N structures for solar-blind detection

Adaptation dynamique de la compression d'un amplificateur RF pour des signaux modulés en amplitude et en phase

Control of a Hybrid Asymmetric Multi-Level Inverter for Competitive Medium-Voltage Industrial Drives

A development method boosted by synchronous active objects

Unified power quality conditioner based on current source converter topology

Investigation of the 3-Level Unified Power Flow Controller (UPFC)

A Generalized Design Principle of a Uniform Step Asymmetrical Multilevel Converter For High Power Conversion

Electrochemical promotion of catalysts for gas phase reactions

Mechanism of polarization response and dielectric non-linearity of PbMg1/3Nb2/3O3 relaxor ferroelectric

Eddy current self-field loss in Bi-2223 tapes with ac transport current

An aid in the teaching of multilevel inverters for high power applications

A Bidimensional Stability Result for Aluminum Electrolytic Cells

Measurement of transfer impedance under impulse conditions