Analysis of Non-Minimum Phase System for AC/DC Battery Charger Power Factor Correction Converter

Electric mobility is nowadays one of the more important trends regarding pollution reduction and global warming due to fuel consumption. Big efforts are done in order to develop efficient and reliable power electronic systems for electric vehicles. In two stage on board-battery chargers, one way of improving efficiency is by means of ensuring the DC-DC isolated converter always operates in the nominal input/output voltage ratio, that could be achieved with a variable DC-link operation. In this paper, a four-switch buck-boost based AC/DC converter is deeply analyzed in order to improve its dynamic performance, the power factor and the total harmonic distortion. The converter suffers from a non-minimum phase characteristic in different input–output transfer functions, which reduces the closed-loop bandwidth of the system. Therefore, after a deep converter analysis has been done, different solutions have been evaluated and tested. Finally, a control to different output transfer functions of the converter become minimum phase, which allows us to increase the system bandwidth and, consequently, high power factor, low harmonics distortion, single control structure and fast dynamics for wide output voltage range are achieved.

Micro-recycling of spent Ni-Cd batteries for the obtention of electrocatalytic coatings

A micro-recycling approach was explored to produce catalytic metallic coatings for the hydrogen evolution reaction (HER). For this aim, discarded Ni-Cd batteries were employed as raw material. After dismantling the batteries, the active powder material, containing Cd and Ni compounds, was leached in a solution containing citric acid and hydrogen peroxide. The dissolved metals were electro-deposited on copper plates using a two electrodes cell at the following potentials (mV): -1900, -2000, and -2100 mV. The CdNi coating produced at -2000 mV, contained 92.6 % Cd and 7.4 % Ni. This coating was studied by cyclic voltammetry (CV) and potentiodynamic analysis in two different KOH solutions (0.1 M and 1.0 M). The CV analysis showed that the CdNi electrode was electrochemically stable in a wide operating voltage range (between oxygen evolution reaction and HER). Using an uncompensated resistance correction, the Tafel slopes for HER were obtained. The potentiodynamic analysis revealed that the synthesized CdNi electrode showed a catalytic activity for HER just 25.5 % smaller than the correspondent response of a standard pure Ni electrode. Our results serve as a proof of concept about the application of micro-recycling of spent batteries to produce sustainable electroactive catalytic materials for hydrogen production.

Low-Cost Clamp-On Photometers (ClampOD) and Tube Photometers (TubeOD) for Online Cell Density Determination

Optical density (OD) measurement is the gold standard to estimate microbial cell density in aqueous systems. Recording microbial growth curves is essential to assess substrate utilization, gauge sensitivity to inhibitors or toxins, or determine the perfect sampling point. Manual sampling for cuvette-photometer-based measurements can cause disturbances and impact growth, especially for strictly anaerobic or thermophilic microbes. For slow growing microbes, manual sampling can cause data gaps that complicate analysis. Online OD measurement systems provide a solution, but are often expensive and ill-suited for applications such as monitoring microbial growth in custom or larger anaerobic vessels. Furthermore, growth measurements of thermophilic cultures are limited by the heat sensitivity of complex electronics. Here, we present two simple, low-cost, self-assembled photometers—a “TubeOD” for online measurement of anaerobic and thermophilic cultures in Hungate tubes and a “ClampOD” that can be attached to virtually any transparent growth vessel. Both OD-meters can be calibrated in minutes. We detail the manufacturing and calibration procedure and demonstrate continuous acquisition of high quality cell density data of a variety of microbes, including strict anaerobes, a thermophile, and gas-utilizing strains in various glassware. When calibrated and operated within their detection limits (ca. 0.3–90% of the photosensor voltage range), these self-build OD-meters can be used for continuous measurement of microbial growth in a variety of applications, thereby, simplifying and enhancing everyday lab operations.

A Floating Differential DAC Expands the Output Voltage Range for Electrochemical Measurements

A floating differential DAC expands the output voltage range for electrochemical measurements

T/R RF Switch with 150 ns Switching Time and over 100 dBc IMD for Wideband Mobile Applications in Thick Oxide SOI Process

This paper presents a fast-switching Transmit/Receive (T/R) Single-Pole-Double-Throw (SPDT) Radio Frequency (RF) switch. Thorough analyses have been conducted to choose the optimum number of stacks, transistor sizes, gate and body voltages, to satisfy the required specifications. This switch applies six stacks of series and shunt transistors as big as 3.9 mm/160 nm and 0.75 mm/160 nm, respectively. A negative charge pump and a voltage booster generate the negative and boosted control voltages to improve the harmonics and to keep Inter-Modulation Distortion (IMD) performance of the switch over 100 dBc. A Low Drop-Out (LDO) regulator limits the boosted voltage in Absolute Maximum Rating (AMR) conditions and improves the switch performance for Process, Voltage and Temperature (PVT) variations. To reduce the size, a dense custom-made capacitor consisting of different types of capacitors has been presented where they have been placed over each other in layout considering the Design Rule Checks (DRC) and applied in negative charge pump, voltage booster and LDO. This switch has been fabricated and tested in a 90 nm Silicon-on-Insulator (SOI) process. The second and third IMD for all specified blockers remain over 100 dBc and the switching time as fast as 150 ns has been achieved. The Insertion Loss (IL) and isolation at 2.7 GHz are −0.17 dB and −33 dB, respectively. This design consumes 145 uA from supply voltage range of 1.65 V to 1.95 V and occupies 440 × 472 µm2 of die area.

Coupling aqueous zinc batteries and perovskite solar cells for simultaneous energy harvest, conversion and storage

Simultaneously harvesting, converting and storing solar energy in a single device represents an ideal technological approach for the next generation of power sources. Herein, we propose a device consisting of an integrated carbon-based perovskite solar cell module capable of harvesting solar energy (and converting it into electricity) and a rechargeable aqueous zinc metal cell. The electrochemical energy storage cell utilizes heterostructural Co2P-CoP-NiCoO2 nanometric arrays and zinc metal as the cathode and anode, respectively, and shows a capacity retention of approximately 78% after 25000 cycles at 32 A/g. In particular, the battery cathode and perovskite material of the solar cell are combined in a sandwich joint electrode unit. As a result, the device delivers a specific power of 54 kW/kg and specific energy of 366 Wh/kg at 32 A/g and 2 A/g, respectively. Moreover, benefiting from its narrow voltage range (1.40–1.90 V), the device demonstrates an efficiency of approximately 6%, which is stable for 200 photocharge and discharge cycles.

CMOS Low-Dropout Voltage Regulator Design Trends: An Overview

Systems-on-Chip’s (SoC) design complexity demands a high-performance linear regulator architecture to maintain a stable operation for the efficient power management of today’s devices. Over the decades, the low-dropout (LDO) voltage regulator design has gained attention due to its design scalability with better performance in various application domains. Industry professionals as well as academia have put forward their innovations such as event-driven explicit time-coding, exponential-ratio array, switched RC bandgap reference circuit, etc., to make a trade-off between several performance parameters such as die area, ripple rejection, supply voltage range, and current efficiency. However, current LDO architectures in micro and nanometer complementary metal–oxide–semiconductor (CMOS) technology face some challenges, such as short channel effects, gate leakage, fabrication difficulty, and sensitivity to process variations at nanoscale. This review presents the LDO architectures, optimization techniques, and performance comparisons in different LDO design domains such as digital, analog, and hybrid. In this review, various state-of-the-art circuit topologies, deployed for the betterment of LDO performance and focusing on the specific parameter up-gradation to the overall improvement of the functionality, are framed, which will serve as a comparative study and reference for researchers.

Magnetic capsulate triboelectric nanogenerators

Triboelectric nanogenerators have received significant research attention in recent years. Structural design plays a critical role in improving the energy harvesting performance of triboelectric nanogenerators. Here, we develop the magnetic capsulate triboelectric nanogenerators (MC-TENG) for energy harvesting under undesirable mechanical excitations. The capsulate TENG are designed to be driven by an oscillation-triggered magnetic force in a holding frame to generate electrical power due to the principle of the freestanding triboelectrification. Experimental and numerical studies are conducted to investigate the electrical performance of MC-TENG under cyclic loading in three energy harvesting modes. The results indicate that the energy harvesting performance of the MC-TENG is significantly affected by the structure of the capsulate TENG. The copper MC-TENG systems are found to be the most effective design that generates the maximum mode of the voltage range is 4 V in the closed-circuit with the resistance of 10 GΩ. The proposed MC-TENG concept provides an effective method to harvest electrical energy from low-frequency and low-amplitude oscillations such as ocean wave.

Solar Powered Resonant Inverter Fed a High Voltage DC Power Supply

This paper proposes a solar-powered resonant inverter fed a high-voltage DC power supply. In this converter, switching loss is controlled through zero-voltage switching and zero-current switching. This converter comprises a solar panel, boost converter, full-bridge LLC resonant tank, power transformer, and rectifier circuit. All power switches are operated with an interleaved switching cycle to ensure equal power flow from the tank. This proposed converter is designed to produce a regulated 19.5 KV at output, with an input voltage range of 300–350 V. The proposed converter was simulated in PSpice to verify the results.

Pragmatic method for fast programming of hybrid photon counting detectors

It is now been over 15 years since Hybrid Photon Counting Detectors (HPCD) became one of the standard position-sensitive detectors for synchrotron light sources and X-ray detection applications. This is mainly due to their single-photon sensitivity over a high dynamic energy range and electronic noise suppression thanks to energy thresholding. To reach those performances, all HPCD pixels must feature the same electrical response against photons of the same energy. From the analysis of a monochromatic beam, in case of an ideal HPCD detector, it would be sufficient to apply a fixed voltage threshold among all pixels, positioned at half of the mean pulse amplitude to count every photon above the threshold. However, in practical cases, it must be considered that noise baselines from all pixels are not always strictly located at the same voltage level but can be spread over some voltage ranges. To address this kind of issue, most of all HPCDs apply a conventional threshold equalization method, that mainly relies on three steps; the setting of a global threshold at an arbitrary value, the identification of pixels noise baseline around that global threshold through an in-pixel threshold trimmer, and the computation of the required threshold offsets for setting all pixels at their own noise baseline at the same time. However, in case of a first-time use of an HPCD prototype, the threshold equalization might be biased by parameters that are wrongly set. Those biases can sometimes be characterized by the inability to localize some pixel noise baselines, which could be outside the voltage range of the threshold trimmer. The recovery of those biased pixels could be performed by changing the position of the global threshold, or by increasing the voltage range of the threshold trimmer. Unfortunately, both solutions could be time consuming due to the lack of information on the required steps for recovering all noise baselines. In order to overcome this issue in a reasonable time, this work introduces a pragmatic method that can be applied to HPCDs for an early and effective identification of appropriate pixels’ parameters, avoiding the need to test a high number of pixels configurations. The application of this method, at the early stage of the HPCD calibration, may drastically reduce the investigation time for finding the optimal operating parameters of HPCD prototypes.