Low Output Voltage Research Articles

Design of a bipolar Dickson voltage multiplier suitable for low output voltage conditions to provide efficient food processing

There has been a growing demand for soft and nutritious foods in recent years. However, general food processing applies heat to food, which destroys nutrients in it. For this reason, many researchers have devised several non-thermal food processing methods so far. However, these methods have potential for improvement in terms of manufacturing cost and processing time. Thereby, we proposed the Dickson voltage multiplier which has bipolar topology suitable for low output voltage conditions in order to provide efficient food processing with low cost. The system is equipped with a high-speed driver using IGBTs, which allows the high-voltage multiplier to operate at high speed. In addition, by using Dickson multiplier with a bipolar topology, the voltage stress on each circuit component is reduced. Furthermore, we performed theoretical analysis to calculate the internal resistance and voltage gain of proposed multiplier. Moreover, we confirmed experimentally the possibility of the proposed multiplier by using the prototype.

Electromagnetic vibration energy harvester using magnetic fluid as lubricant and liquid spring

Using vibration energy harvester (VEH) to achieve self-power supply is an effectively way to ensure long-term use of electronic devices. In this paper, an electromagnetic VEH using magnetic fluid (MF) as lubricant and liquid spring is proposed, the VEH uses a hollow shell with variable internal diameter together with MF to form a liquid spring with variable stiffness coefficient to replace the traditional mechanical or magnetic spring, and planar coils and helical coils are used together to harvest the vibration energy, thereby broadening response frequency, improving energy harvest efficiency, and reducing VEH volume and damping. The influence of MF on the lubrication, liquid spring, and vibration state is studied theoretically, and the induced voltage is simulated. A crank-slider linkage has been built to test the performance of VEH, and the influence of vibration frequency, mass of MF, and coil type on the output performance has been studied during a 7.5 mm reciprocating linear motion of VEH. Results show that an appropriate amount MF can improve the output voltage by 173 % at 3.25 Hz, but too much MF will cause a rapid drop in output voltage. Helical coils generate higher voltage than planar coils, and the output power density of the helical coil is 0.92 mW/cm3 at 8.5 Hz. The energy management module can manage electric energy well, and half wave rectifier with low forward voltage drop may be more suitable for VEH with low output voltage. Besides, the VEH delivers a 1.36 mW/cm3 power density with a 10 Ω load when it is swung by human at 6.4 Hz.

A High Conversion Ratio DC–DC Boost Converter with Continuous Output Current Using Dual-Current Flows

Recently, the demand for small, low-cost electronics has increased the use of cost-effective tiny inductors in power-management ICs (PMICs). However, the conduction loss caused by the parasitic DC resistance (RDCR) of a small inductor leads to low efficiency, which reduces the battery usage time and may also cause thermal problems in mobile devices. In particular, these issues become critical when a conventional boost converter (CBC) is used to achieve high-output voltage due to the large inductor current. In addition, as the output voltage increases, a number of issues become more serious, such as large output voltage ripple, conversion-ratio limit, and overlap loss. To solve these issues, this paper proposed a high-voltage boost converter with dual-current flows (HVDF). The proposed HVDF can achieve a higher efficiency than a CBC by reducing the total conduction loss in heavy load current conditions with a small inductor. Moreover, because in the HVDF, the current delivered to the output becomes continuous, unlike in the CBC with its discontinuous output delivery current, the output voltage ripple can be significantly reduced. Also, the conversion gain of the HVDF is less sensitive to RDCR than that of the CBC. To further increase the conversion gain, a time-interleaved charge pump can be connected in series with the HVDF (HVDFCP) to achieve higher output voltage beyond the limit of the conversion gain in the HVDF while maintaining the advantages of a low inductor current and small output voltage ripple. Simulations using PSIM were performed along with a detailed numerical analysis of the conduction losses in the proposed structures. The simulation results were discussed and compared with those of the conventional structures.

4 × 53 Gbit/s Electro-Optic Engine With a Surface-Normal Electroabsorption Modulator Array

Short-reach communication systems use electro-optic transmission engines based on low-voltage, wide bandwidth modulators to achieve high capacity and low power operation. Here, we demonstrate, for the first time, integration of a 4-channel array of surface-normal electroabsorption modulators (SNEAMs) with a 4-channel array of electronic drivers with low output voltage (~1.25-1.45 Vpp). We use this 4-channel SNEAM-driver array electro-optic engine to demonstrate <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4 \times 53$ </tex-math></inline-formula> Gbit/s non-return-to-zero on-off-keying transmission across up to 2 km of standard single mode fiber over a broad wavelength range (about 26 nm), the widest band of operation achieved with SNEAMs. Integration of a SNEAM array with a low output voltage driver array, a result that we achieved thanks to the use of SNEAMs that operate with low voltage swings, represents a fundamental milestone toward the realization of optical modules based on SNEAMs.

Multi-Objective Control Strategy for Switched Reluctance Generators in Small-Scale Wind Power Generations

Switched reluctance generators (SRGs) are widely used in wind power generation. However, due to the natural tendency of SRG, there are always nonnegligible conflicts to achieve high efficiency and low output voltage ripple at the same time. This creates difficulties for the high-performance of SRG. Thus, a multi-objective optimization control strategy is proposed in this paper to improve the static performance of SRG. The proposed control strategy contains following steps. First, in order to gain the maximum output power range at different rotor speeds, the turn-off angle is optimized off-line by simulated annealing algorithm (SAA). The optimized results are fitted as a function of rotor speed for on-line regulating; then, a closed-loop controller is built, and the reference current is regulated according to the difference between actual output power and required output power. Second, a multi-objective function is constructed as the evaluation result of SRG performance, which takes system efficiency, output voltage ripple and power converter loss into consideration. In the end, the turn-on angle is tuned by SAA according to the real-time multi-objective evaluation result. The proposed control strategy can be flexibly applied to SRGs with different structures and avoids the disadvantage of single-objective optimization. The simulation and experiments results show that the overall performance of SRG is improved.

Sensorless Model Predictive Control of Single-Phase Inverter for UPS Applications via Accurate Load Current Estimation.

Single-phase inverters with an output LC filter, can generate low distortion output voltages, which are suitable for uninterruptible power supply (UPS) systems. The UPS system provides emergency power in the case of utility power failure, requiring high reliability and clean power. The sensorless control method is actually a soft-sensing technique, that reduces system cost, measurement-related losses, and, especially important for UPS systems, enhances the system reliability. This paper proposes a load current sensorless finite control set model predictive control (FCS-MPC) scheme for a single-phase UPS inverter. A time varying observer is proposed, which offers the accurate estimation for individual components simultaneously in periodic load current signal, without subsequent complex calculations. Compared with another two typical sensorless methods (the low-pass filter and the Kalman filter), the proposed observer-based FCS-MPC strategy has smaller load current estimation error and lower output voltage distortion, under both linear and nonlinear loads. The theoretical analysis is verified through simulation and experiment. A single-phase inverter rapid control prototype (RCP) is set up with the Speedgoat real-time target machine, to confirm the effectiveness of the system.

PV-Fed Micro-Inverter with Battery Storage for Single Phase Grid Applications

Nowadays, micro-inverters are trending due to the latest features consisting in PV technology. However, integration of a high-gain boost converter is needed to improve the low rating output voltage of PV modules to meet the load demand. A high-gain converter with less component count is required for grid integration systems. This article proposes a new quasi z-source based high-gain DC–DC converter with reduced components, cost, and size. The proposed converter is integrated with the micro-inverter for single-phase grid applications along with battery storage. A radial basis function network algorithm is utilized for a PV system to track the maximum power point, an efficient hysteresis current controller is applied for the full-bridge inverter for the robust regulation of current and the energy can be stored through the bidirectional dc/dc converter to supply the power to grid when the sources are drained conditions. An efficient PV extraction, low total harmonic distortion and achieves unity power factor which is perfectly suitable for grid-connected PV systems. The operating modes in every aspect and analysis of the proposed configuration have been investigated in detail. The implementation of control strategies is discussed in detail. Simulation of the proposed micro-inverter is designed in MATLAB/SIMULINK tool to validate the efficiency under variable operating conditions. With the successful implementation of the proposed technique, total harmonic distortion is reduced to 2.05% and efficiency is enhance to the 98%.

Investigation of Energy Harvesting Capabilities of Metglas 2605SA1

In the framework of electromechanical energy conversion devices for vibrational energy harvesting, magnetostrictive materials are an attractive alternative solution to the brittleness of piezoelectric materials. Electromagnetic systems have low voltage output at a low frequency while magnetostrictive materials are suitable for a larger frequency bandwidth. In this work, a special experimental emphasis is placed on Fe80Si9B11 (also known as Metglas 2605SA1) alloy. The ultimate energy conversion abilities are investigated by performing experimental Ericsson cycles as well as through theoretical predictions using a dedicated model for the magnetic curves at the material scale. Typical output magnetic energy densities ranged between 0.1 and 1 mJ/cm3/cycle under moderate stress (&lt;100 MPa) and magnetic excitation (up to 4 kA/m). Apart from its energy conversion abilities, Metglas 2605SA1 also features attractive characteristics for realistic applications in microgenerators, such as a low price, which is an important advantage for the mass production and cost-effectiveness of the harvester. Furthermore, its soft magnetic property reduces the need for high magnetic fields and yields a well-adapted solution from a system point of view. It is therefore shown that this material is a suitable conversion material according to the available stress and magnetic excitation magnitudes, in addition to economic considerations.

Single-Inductor, Multiple-Input, Multiple-Output, DC-DC Converter Based on a New Software Zero-Current Switching (ZCS) Technique

A single-inductor multiple-input multiple-output converter is proposed in this paper that can be used in low-power systems due to low output current and voltage. This converter is implemented discretely, and only one microcontroller is employed to control the system. The unique zero-current switching (ZCS) technique considered in this paper is such that only by reading the inductor’s left-side voltage the optimal value of the inductor discharge duty cycle is determined. This method can be generalized to low-power and high-power converters, whether implemented and designed as discrete or integrated. This converter works in discontinuous conduction mode. It uses pulse width modulation control and the time-multiplexing control method, which makes the system have high efficiency and makes the cross-regulation problem between the converter’s outputs tiny. The control algorithm considered in this converter is digital, which determines the optimal charge and discharge duty cycles. Also, the switching frequency of this converter is constant, relatively low, and equal to 5[Formula: see text]kHz. The efficiency of this converter has reached 91.6% by using the ZCS technique and other mentioned control methods.

Development of Phase-Shift Full-Bridge Converter With Integrated Winding Planar Two-Transformer for LDC

This study proposes a new phase-shift full-bridge (PSFB) converter with an integrated winding planar two-transformer for a low-voltage dc–dc converter (LDC). An LDC is a dc–dc converter that supplies power to a 12-V auxiliary battery (A_BAT) and loads from the main battery (M_BAT) of electric vehicles (EVs), used in low-voltage and high-current output applications. PSFB converter is widely used as a suitable topology for such systems. In order to improve the power density, the integrated planar magnetics is designed in the proposed PSFB converter. Furthermore, the size of the transformer is optimized considering the footprint and core loss of components. To confirm the validity of the proposed converter, a 2.1-kW prototype LDC with an input voltage range of 400–800 V and an output voltage of 14 V is analyzed, and the operating characteristics are described. The proposed converter achieves a maximum efficiency of 95.4% and a power density of 5.2 kW/L.

Novel Modulation Scheme for Balancing Power Distribution Among Modules in Nine-Level Asymmetric Cascaded H-Bridge Inverter

When the conventional hybrid frequency (HF) modulation strategy applies to the asymmetric cascaded H-bridge (ACHB) inverter with dc voltage in a ratio of 1:1:2, there are uneven problems of switching loss in low-voltage cells and output power over all operating cells. Thus, a modified HF based on a dual-layer power balance (MHF-DPB) modulation strategy was presented. First, step modulation was still applied to a high-voltage cell on the basis of the conventional method, but improved level-shifted pulsewidth modulation (LS-PWM) was applied to two low-voltage cells. Subsequently, the power balance between high-voltage and low-voltage cells was controlled by adjusting the conduction angles of the power switch and then the carriers of the two low-voltage cells were rotated periodically in order to realize the two low-voltage cells’ power balance. The proposed method can not only realize the power balance of cascaded cells, but also distribute the switching loss of two low-voltage cells equally. In the meantime, it reduced the total switching loss of the inverter. Finally, it was validated by simulation and experimental results.

Boosting High‐Voltage Dynamics Towards High‐Energy‐Density Lithium‐Ion Capacitors

Lithium‐ion capacitors (LICs) are becoming important electrochemical energy storage systems due to their great potential to bridge the gap between supercapacitors and lithium‐ion batteries. However, capacity lopsidedness and low output voltage greatly hinder the realization of high‐energy‐density LICs. Herein, a strategy of balancing capacity towards fastest dynamics is proposed to enable high‐voltage LICs. Through electrochemical prelithiation of Nb2C to be 1.1 V with 165 mAh g−1, Nb2C // LiFePO4 LICs show a broadened potential window from 3.0 to 4.2 V and an according high energy density of 420 Wh kg−1. Moreover, the underlying mechanism between prelithiation and high voltage is disclosed by electrochemical dynamic analysis. Prelithiation declines the Nb2C anode potential that facilitates electron transmission in the interlayer of two‐dimensional Nb2C MXene. This effect induces small drive force for Li+ ions deposition and hence weakens the repulsive force from adsorbed ions on the electrode surface. Benefiting from even more Li+ ions deposition, a higher voltage is eventually delivered. In addition, prelithiation significantly increases Coulomb efficiency of the 1st cycle from 74% to 90%, which is crucial to commercial application of LICs.

Boost the voltage of a magnetoelastic generator via tuning the magnetic induction layer resistance

Using the giant magnetoelastic effect in the soft systems for ambient energy harvesting, namely, the magnetoelastic generator (MEG), is challenged by its relatively low voltage output. A conventional transformer could be employed to solve the problem by increasing the voltage at the expense of current; however, it holds a bulky and rigid configuration with considerable energy loss. Here, we developed the resistance-controllable magnetic induction (MI) layer with multi-walled carbon nanotubes (MWCNT) as an inner transformer to manipulate the electrical output of an MEG. With high electrical conductivity, flexibility, and mechanical strength, the resistance of the MWCNT-based MI layer can be designed by thickness, width, length, and turns of the coils, contributing to a power-transforming effect. As the resistances increased, the open-circuit voltage increased, while the short-circuit current showed a reversed trend. With a power density of 0.23 mV cm−2, the power-transforming MEG can charge a commercial capacitor at a rate of 0.63 mV s−1 with intrinsic waterproofness. This work introduces a compelling approach to boost the voltage output of the MEG via internally engineering the resistance of the MI layer.

Moist‐Electric Generator with Efficient Output and Scalable Integration Based on Carbonized Polymer Dot and Liquid Metal Active Electrode

AbstractMoisture‐enabled electricity generation (MEG) is highly promising in next‐generation energy conversion. However, the practical applications of existing MEG devices are limited due to their low current and voltage outputs, strong dependence on high moisture, and inflexible nature. Herein, an efficient MEG integrated with flexible, all‐weather, and scalable fabrication characteristics based on the rational combination of carbonized polymer dots (CPDs) and liquid metal (LM) active electrodes is developed for the first time. Remarkably, the fabricated MEG device can produce a stable voltage output of 800 mV and a record high current density of 1640 µA cm−2. Even at a low air humidity of 15%, the MEG device can provide a high voltage output of 0.65 V and a considerable current density of 12 µA cm−2. The prompted diffusion of hydrogen ions in CPDs and the additional metal ions ionized from the LM electrode contribute synergistically to the high electricity generation. Additionally, the device can be easily integrated on various flexible substrates and generate an ultrahigh voltage of 210 V to power commercial electronics, showing great potential in large‐scale fabrication and application.

A 53-µA-Quiescent 400-mA Load Demultiplexer Based CMOS Multi-Voltage Domain Low Dropout Regulator for RF Energy Harvester

A low-power capacitorless demultiplexer-based multi-voltage domain low-dropout regulator (MVD-LDO) with 180 nm CMOS technology is proposed in this work. The MVD-LDO has a 1.5 V supply voltage headroom and regulates an output from four voltage domains ranging from 0.8 V to 1.4 V, with a high current efficiency of 99.98% with quiescent current of 53 µA with the aid of an integrated low-power demultiplexer controller which consumes only 68.85 pW. The fabricated chip has an area of 0.149 mm2 and can deliver up to 400 mA of current. The MVD-LDO's line and load regulations are 1.85 mV/V and 0.0003 mV/mA for the low-output voltage domain and 3.53 mV/V and 0.079 mV/mA for the high-output voltage domain. The LDO consumes only 174.5 µW in standby mode, making it suitable for integrating with an RF energy harvester chip to power sensor nodes.

Non-local architecture for spin current manipulation in silicon platforms

We have developed a non-local architecture for spin current injection, manipulation, and detection in n-doped bulk Si at room temperature. Spins are locally generated at the indirect gap of bulk Si by means of circularly polarized light and then detected by exploiting the inverse spin-Hall effect (ISHE) occurring inside a thin Pt pad deposited at the top of the Si substrate. We demonstrate that it is possible to modulate the transport properties of the optically injected spin current by applying a bias voltage along the direction of motion of the particles. In this case, we are able to explore both the spin diffusion regime, characterized by a spin diffusion length Ls ≈ 12 μm, and the spin drift regime with applied electric fields up to E = 35 V/cm. We demonstrate that the spin transport length of the electrons can be increased (or decreased) by more than 100% for electric fields antiparallel (or parallel) to the diffusion direction. As a consequence, the ISHE signal can be electrically controlled to have high or low output voltages from the non-local device.

Binuclear Cu complex catalysis enabling Li–CO2 battery with a high discharge voltage above 3.0 V

Li–CO2 batteries possess exceptional advantages in using greenhouse gases to provide electrical energy. However, these batteries following Li2CO3-product route usually deliver low output voltage (<2.5 V) and energy efficiency. Besides, Li2CO3-related parasitic reactions can further degrade battery performance. Herein, we introduce a soluble binuclear copper(I) complex as the liquid catalyst to achieve Li2C2O4 products in Li–CO2 batteries. The Li–CO2 battery using the copper(I) complex exhibits a high electromotive voltage up to 3.38 V, an increased output voltage of 3.04 V, and an enlarged discharge capacity of 5846 mAh g−1. And it shows robust cyclability over 400 cycles with additional help of Ru catalyst. We reveal that the copper(I) complex can easily capture CO2 to form a bridged Cu(II)-oxalate adduct. Subsequently reduction of the adduct occurs during discharge. This work innovatively increases the output voltage of Li–CO2 batteries to higher than 3.0 V, paving a promising avenue for the design and regulation of CO2 conversion reactions.

Source-load-variable voltage regulated cascaded DC/DC converter for a DC microgrid system

&lt;span lang="EN-US"&gt;Solar energy is available abundantly, the utilization of solar energy is developing rapidly and the photovoltaic based direct current (&lt;/span&gt;&lt;span lang="EN-US"&gt;DC) microgrid system design is under demand but the stability of the DC voltage is of most important issue, as the variation of the output DC voltage is a common problem when the load or source voltage varies, hence a regulated DC output voltage converter is proposed. This paper presents source-load-variable (SLV) voltage regulated cascaded DC/DC converter which is used to obtain regulated output voltage of 203.1 V DC at 0.4 duty ratio with ±2% voltage fluctuations for the variation in the input source voltage and ±1.5% voltage fluctuations for the variation in load resistance of the nominal value with lower output voltage ripple and without use of sub circuits. A simulation model of SLV voltage regulated cascaded DC/DC converter in LTspice XVII software environment for the assessment of converter performance at different input source voltages and load resistances are verified.&lt;/span&gt;

Manufacturing thin ionic polymer metal composite for sensing at the microscale

Ionic polymer metal composites (IPMCs) are a class of materials with a rising appeal in biological micro-electromechanical systems (bio-MEMS) due to their unique properties (low voltage output, bio-compatibility, affinity with ionic medium). While tailoring and improving actuation capabilities of IPMCs is a key motivator in almost all IPMC manufacturing reports, very little efforts have been dedicated to sensing using IPMC thinner than 100 µm. Most reports on IPMC manufacturing and utilization rely on 180 µm-thick Nafion with platinum electrodes, too stiff for bio-MEMS applications. The same fabrication process on thinner membranes does yield in very poor electrodes and performance, and needs to be studied to increase flexibility and sensitivity in the microscale range. This study demonstrates an electroless Pt deposition method for fabricating bio-MEMS-suitable 50 µm-thick IPMC samples. First, we perform a comparative study on the platinum distribution within the Nafion backbone as well as on the surface for the standard electroless deposition recipe for thin (50 µm) and thick (180 µm) Nafion. We report strong differences in platinum distribution for thick and thin IPMC that experienced the same manufacturing process. By varying chemical concentrations from the standard recipe we obtain convenient platinum distribution on thin Nafion, with platinum mainly localized in proximity of surface, as well as electrodes with lower sheet resistance. We could measure the flexural rigidity as N·m2, 46 times lower than standard 180 µm-thick IPMC. The calculated sensitivity is 0.476 ± 0.02 mV mm−1 and the limit of detection for our sensor is 500 ± 20 µm. This procedure sets a milestone for manufacturing 50 µm-thick IPMC for transducers and sensors in bio-MEMS applications.

An integrated coupled inductor–capacitor DC–DC high step‐up converter

SummaryIn this paper, an integrated coupled inductor–capacitor DC–DC high step‐up converter is proposed for the renewable energy systems. A DC–DC high step‐up converter is mandatory owing to the comparative low output voltage of renewable energy systems. A new configuration has been proposed in this paper, in which capacitor and coupled inductor are integrated into a converter to achieve the required results. To charge the capacitor a coupled inductor is used, not only the voltage gain significantly boosted and the switch voltage clamped inherently but also the turns ratio and part count scale down. When proposed converter operates in ORF mode, this results in the decline of conduction losses and enhances its efficiency. The proposed converter has good efficiency and simplest structure as it has only six components. This paper illustrates the key state operation principles of the proposed converter and derivation of its steady‐state operations. A prototype is designed, and experiments are performed in the laboratory to verify the precision of the theoretical analysis. The highest efficiency of 97% has been achieved in the laboratory.