François Costa

Wide bandwidth, large AC current probe for power electronics and EMI measurements

Current measurements in power electronics or in EMI domains require high-performance probes. These probes must have a very wide bandwidth, be insensitive to electromagnetic interferences, and be able to measure large direct and alternating currents (AC-DC) without distortion. This paper is limited to AC current probes. Various principles are reviewed, in particular those based on the current transformer (CT); their limitations are analyzed, and a solution based on a two-stage transformer are proposed to extend low- and high-frequency performance. It is shown that the use of new magnetic materials, such as the amorphous or the nanocrystalline, can improve large-current low-frequency operations, while preserving the smallest possible probe size. Various solutions are provided to improve high-frequency operations. Different developments are depleted; frequency and time-domain results are presented.

Quantification and minimization of conducted interferences generated in hard switching and zero current switching cells

The purpose of this paper is to explain the mechanisms of generation of conducted interferences in static converters, to model and simulate them. A new quantification method based on energy measurement is discussed and its advantages compared to the spectral one. Finally an original active process to minimize the conducted common mode interferences is presented.<<ETX>>

EMI circuit modeling of a power train on composite ground plane

The aeronautics world is in continuous evolution. Actually, the tendency is to substitute the hydro mechanical actuators with electrical ones. However, this means introducing more power electronics and in doing so, the systems become more and more vulnerable to electromagnetic noise emitted. Moreover, the introduction of composite material based structures modifies ElectroMagnetic Interference (EMI) behavior in airplanes. The aim of this study is to be able to predict, via modeling, for frequencies ranging from 10 kHz to some MHz, the propagation pathways and the amount of common mode (CM) and differential mode (DM) current. Thus, the model developed as well as the optimization methods can benefit the aeronautical industry during preliminary phases of development of different equipments.

Single-switch inductorless power management circuit for electrostatic vibration energy harvesters

This paper presents a new power management circuit for electrostatic vibration energy harvesting devices. Compared to most of the existing electronic interfaces dedicated to electrostatic vibration energy harvesting, this circuit presents three main advantages. Firstly, it does not include any inductive element, enabling drastic miniaturization. Secondly, the switch control does not need to be synchronized with the mechanical motion of the electrostatic device and thirdly, the energy conversion cycle is self-maximized and does not require any optimization algorithm, enabling thus simple, ultra-low power implementation of the circuit.

Interface Circuit for Vibration Energy Harvesting with Adjustable Bias Voltage

This paper presents a new interface circuit for electrostatic vibration energy harvesting with adjustable bias voltage. An electronic switch is used to modify the circuit configuration so that the harvested energy increases the voltage across a biasing capacitor. Decrease of this biasing capacitor voltage occurs naturally due to the circuit imperfections. Such a control of the bias voltage enables to adjust the amount of energy converted by the variable capacitor on each cycle. This feature can be used to optimize the mechanical damping induced by the energy conversion process in order to maximize the harvested power. Another feature of this interface circuit is that it is capable to get high bias voltage whatever the battery voltage with low energy loss.

Using design by optimization for reducing the weight of a SiC switching cell

This paper uses the design by optimization method to determine the best combination of passives, EMC filter, heatsink, taking into account the components constraints, in order to reduce the weight of a SiC switching cell, implemented in a simple buck converter. All elements and associated restrictions are described using analytical expressions, and the optimizer performs the reduction of the objective function (weight) respecting all constraints. The models and the optimization strategy are described, and the optimization results are presented and discussed, in comparison with a conventional Si switching cell.

Interface circuit with adjustable bias voltage enabling maximum power point tracking of capacitive energy harvesting devices

The operation analysis of a new interface circuit for electrostatic vibration energy harvesting with adjustable bias voltage is carried out in this paper. Two configurations determined by the open or closed states of an electronic switch are examined. The increase of the voltage across a biasing capacitor, occurring when the switch is open, is proved theoretically and experimentally. With the decrease of this biasing voltage which occurs naturally when the switch is closed due to imperfections of the circuit, the bias voltage can be maintained close to a target value by appropriate ON and OFF control of the switch. As the energy converted by the variable capacitor on each cycle depends on the bias voltage, this energy can be therefore accurately controlled. This feature opens up promising perspectives for optimization the power harvested by electrostatic devices. Simulation results with and without electromechanical coupling effect are presented. In experimental tests, a simple switch control enabling to stabilize the bias voltage is described.

Modeling of a multi-electrodes traveling-wave piezoelectric transformer

This paper proposes a compact electromechanical modeling of multi-electrode piezoelectric transformer. This modeling can be applied to the study of standing or traveling flexural wave in piezoelectric systems and especially for ring type piezoelectric transformers. This modelling is based on the Euler-Bernoulli beam theory and from this theory and piezoelectric equations, transfer matrixes linking stresses, velocities and voltages for a beam are determined. In piezoelectric systems with no mechanical boundary in the propagation direction of the wave, for example a ring, an admittance matrix is obtained from the modeling linking all the currents and voltages. This modelling allows moreover the representation and electrical simulation of a piezoelectric element subjected to a traveling wave.

Autonomous DC-DC converter for RF energy harvesting

REE N°5/2016 119 URSI FRANCE 2016 DOSSIER 2 Autonomous DC-DC converter for RF energy harvesting Par Salah Adami1 , Christian Vollaire1 , Francois Costa2 , Bruno Allard3 1 Laboratoire Ampere, CNRS 5005, Ecole Centrale de Lyon, universite de Lyon 2 Laboratoire SATIE, CNRS 8029, ENS Cachan, universite Paris Est Creteil 3 Laboratoire Ampere, CNRS 5005, INSA de Lyon, universite de Lyon Figure 1: Topology of power management system for low power rectenna. Introduction Wireless sensors networks (WSNs) are nowadays ubi- quitous in various kinds of applications like monitoring and control, smart buildings, healthcare, etc. The expansion of WSNs is due, among other reasons, to the efforts made by designers in order to develop low-power circuits. Though those circuits are optimized for low-power and have excellent power budget, the problem of autonomy is still there. In fact, the performances required from an autonomous sensor are growing day by day and likewise for power consumption. In most applications, batteries are used alone in order to sup- ply WSN’s nodes. In this case, the sensor life-time is limited. So, designers begin to use energy harvesting as a support together with b

Electrostatic Energy Harvesting Circuit with DC-DC Convertor for Vibration Power Generation System

This paper presents an interface circuit with power control features for electrostatic vibration energy harvesting. A DC-DC convertor is used to control the output voltage of a diode-based charge pump circuit. Therefore, the maximum and minimum voltage across the variable capacitor of the energy harvester may be adjusted to track the maximum power point of the system. The power conversion function of the DC-DC convertor depends on the switches configuration. An example of Maximum Power Point Tracking (MPPT) for different conversion function is presented in this paper. Simulation results show that at least 10 μW is generated.