Patrick Poulichet

The Current Sensors in Power Electronics, a Review

Abstract Current sensors are widely used in all the fields of electrical engineering and power conversion. The applications are very diverse: current measurements in semiconductors, current sensing for variable speed drive, current measurement in high voltage networks. These examples show the great diversity of performances, electrical constraints and environmental constraints of these sensors. In this paper a state-of-the-art is presented about the main types of sensors, so that the user can optimise his choice with respect to the problem to solve.

High-frequency modeling of a current transformer by finite-element simulation

This paper depicts a method to elaborate a high-frequency (100 kHz to 50 MHz) model of a current transformer. The method uses finite-element analysis to determine the values of the parameters of the circuit model; all electrostatic and magnetic couplings are taken into account and calculated. The paper shows how parasitic capacitance and flux leakage alter the transformer frequency response. These effects are deeply modified by the primary conductor position, by an air gap in the core, and by the presence of a shielding case around the transformer. The paper compares simulation results with experimental ones to show the accuracy of the models.

Design and Fabrication Issues of a Silicon-Based Vibration Powered Electric Energy Generator Using Parallel Plate and In-Plane Mechanism

This paper focuses on the design and fabrication issues of a silicon-based, vibration powered, electric energy generator. Its architecture is based on the parallel plate configuration. It uses electrostatic damping of variable MEMS capacitor as the energy converting mechanism. Variable capacitance is achieved by in-plane movement of the top electrode. Hence capacitance variation is achieved by means of change in overlap area. The device is composed of a movable silicon proof mass with patterned electrodes on the underside, anodically bonded to a glass wafer with electrodes on top. High capacitance value can be achieved thanks to a low cost silicon-glass technology. FEM simulations along with the mechanical characterization have shown that 1.8 muW can be harvested for a 1 cm2 device at the mechanical resonance frequency of 300 Hz and starting voltage of 5 V

Continuous Intra Ocular Pressure Measurement Sensor for Glaucoma Diagnostic

Glaucoma is an ocular pathology usually associated with an increase in Intra Ocular Pressure (IOP). In this study, we are developing disposable eye lenses including a specific micro fabricated pressure sensor to measure IOP all day long. The information data will be wireless transferred via magnetic coupling to an external receiver. Our first work deals with the sensor design and fabrication. Simulation results based on classical electronic circuit tools will be presented and lead to several sensor solutions working at different RF frequencies. The fabrication process of the first sensors will also be described and an early IOP characterisation set-up will be presented to try to later quantify the sensor sensitivity, with IOP variations measured in the range 20 to 70mmHg.

A Thermally-Driven Micromixer Based on Fluid Volume Variation

In microfluidics, flows are laminar due to low Reynolds number (<1). Consequently, mixing between two liquids is mainly obtained by natural diffusion which may take a long time or equivalently requires centimetre length channels. However, it is possible to generate chaotic-like flows either by modifying the channel geometry or by creating an external perturbation of the flow. In this paper, an active micromixer is presented consisting on thermal actuation with heating resistors. In order to disturb the liquid flow, an oscillating transverse flow is generated by heating the liquid. Depending on the value of boiling point, either bubble expansion or volumetric dilatation controlled the transverse flow amplitude. The configuration is identical to the one of Dodge et al. [7], but the transversal oscillating flow is created by thermal actuation instead of pneumatic ones. A chaotic like mixing is then induced under particular conditions depending on volume expansion, liquid velocity, frequency of actuation[[ellipsis]] This solution presents the advantage to achieve mixing in a very short time (1 s) and along a short channel distance (channel width). It can also be integrated in a more complex device due to actuator integration with microfluidics.Copyright

Optical actuation and detection of MEMS resonators: Behavioral modeling and phase noise simulations

Optical actuation and detection of MEMS resonators can improve the resolution of their motion detection compared to standard detection techniques (capacitive, piezoelectric). In this paper, a behavioral model of MEMS resonator with optical actuation and detection and the associated oscillator circuit are presented and used to determine its performances.

Distributed Diameter sub-Coil Twisted Loop Antenna in non-radiative WPT

This letter focuses on the high-frequency wireless power transfer by electromagnetic induction and its dependence on the lateral misalignment and tilt of the small receiving coil relative to the transmitting coil. We combine two structures, the twisted loop antenna (TLA) and subcoils of a distributed diameter coil (DDC) for transmitting designs. Our system is then referred to as TLA-DDC. The radius of the subcoils is parametrically varied for different distances between the coils and performed in two positions for each distance (coaxial position when the receiving coil is parallel to the plane of the transmitting coil, and center position for the perpendicular orientation of both coils). Then, using different radii for the transmitting DDC TLA when the receiving coil is moved onto its surface allows us to obtain a greater value of efficiency at different positions: up to 2.4 times for the peak value and 1.5 for the average value for receiving coil in parallel plane. The efficiency of the magnetic coupling is determined by means of power efficiency with a comparison between the DDC TLA antennas and a standard coil antenna corresponding to the same inductance value.

MODELING OF SERIAL PARALLEL ASSEMBLY OF VALVELESS MICROPUMP USING BOND GRAPHS APPROACH

The bond graph methodology is used, in this work to model and study the working principle of valveless micropumps. Two kinds of architecture are considered. Their design is achieved by combining two single chamber valveless micropumps in serial and in parallel manner. Both architecture use a pair of pumping chambers provided with a pair of asymmetrical set of nozzle-diffuser. The working principle of the different parts used to create the liquid flow is analyzed. For each of these microfluidics systems, a global bond graph model is proposed to represent their dynamic behavior. From the analysis of the graphical representation, the corresponding mathematical models in state space representation are given in terms of dimensions. Considered as outputs of the two valveless micropumps models, the flow rate equations are proposed.