Multi Voltage Research Articles

High voltage generation from wastewater by microbial fuel cells equipped with a newly designed low voltage booster multiplier (LVBM)

Although microbial fuel cells (MFCs) can produce renewable energy from wastewater, the generated power is practically unusable. To extract usable power from an MFC fed with wastewater, we newly developed a low voltage booster multiplier (LVBM), which is composed of a self-oscillating LVB and multistage voltage multiplier circuits (VMCs). The low output MFC voltage (ca. 0.4 V) was successfully boosted up to 99 ± 2 V, which was the highest voltage that has been ever reported, without voltage reversal by connecting an LVB with 20-stage VMCs. Moreover, the boosted voltage (81 ± 1 V) was stably maintained for > 40 h even after disconnecting the LVBM from the MFC. The energy harvesting efficiency of LVBM was > 80% when an LVB with 4-stage VMCs was charged to 9.3 V. These results clearly suggest that the proposed LVBM system is an efficient and self-starting energy harvester and storage for low-power generating MFCs.

Recent advances in digital Positron Emission Tomography

Positron Emission Tomography (PET) is a non-disruptive functional imaging technique, which provides a high resolution and high-sensitivity measurement of the functional processes in biological systems. The recent developments in biology and radio-chemistry enabled PET to study an increasing number of functional processes, but became highly demanding in terms of sensitivity, spatial resolution, and adaptability to the variable size of the biological systems ranging from few millimeters up to several centimeters. In this paper we show how digital signal processing in PET plays an important role in the technological advancement. We report the recent results of digital signal processing methods based on the Multi Voltage Threshold technology, exploring the performances of a series of digital PET systems built upon this principle. We further describe developments of the MVT theory including space-pattern digital signal analysis and the related idea of the integration of the MVT technology within intelligent CMOS SiPM sensors for PET.

High‐voltage pulse transformer for IOT modulators

Neutron sources like European Spallation Source consist of linear proton accelerator and beam target. The linear accelerator is supplied by inductive output tubes (IOTs) or klystrons that require high-voltage DC supply (40 kV). This study describes the design and experimental evaluation of high-voltage dry-isolation pulse transformer design evaluation prototype for interleaved IOT supply modules. In order to withstand high-voltage stress, a modular secondary winding module with multistage voltage field equalisation are designed. Inter-winding connections are realised in the air as the separate winding outputs are routed together through common high-voltage isolators. The novelties of the current manuscript are new pulse transformer design and the experimental work. Experiments with full-scale prototype verified the advantages and revealed, also, some drawbacks of this construction. Proposed transformer design could be used not only in IOT or klystron power supplies but also in high-voltage DC/DC or AC/AC converters and power electronic transformers, used in the medium-voltage distribution grids.

Energy transmission control for a Gridconnected modern power system Non-Linear loads with a Series Multi-Stage Transformer Voltage Reinjection with controlled converters

The effective way of energy transmission plays a key factor in improving the overall transmission systems efficiency. Many methods are proposed to control the reactive power flow, voltage fluctuations and power factor improvement, The proposed converter topology gives a much significant improvement in transmission systems performance which includes multistage transformers control with the controlled converters along with the series active filters. The overall control strategy which involves the Multistage Voltage Re-Injection Transformer Controlled Converters (MSVRITCC) to reinject the voltages into the grid to compensate the voltages and remaining parameters and power flow control. The proposed topology improves the grid security, flexibility in reaching the desired load requirements with grid adaptability and reduces THD values into a significant values and made the control of power conditioning circuit flexible and easy to perform the voltage compensations in grid to load connected applications. The binary control is used to trigger the power converter circuits which made the controlling much simpler.

Multi-Stage Voltage Support Optimization for Microgrids With Multiple Distributed Generation Units

With the proliferation of microgrids (MGs) into the utility grid (UG), MGs with multiple distributed generations (DGs) face challenge to flexibly support voltage during UG faults. In this paper, a multi-stage voltage support optimization method is proposed to stabilize voltage, current and power, for safeguarding the MG operation and providing flexible power delivery capacity. The proposed method consists of three stages: 1) voltage stage in which the phase voltage instead of the sequence voltage regulation is considered to support voltage more precise; 2) current stage in which a novel current generation strategy with maximum current limiting (MCL) is formulated by directly embedding network impedance features; 3) power stage in which multiple matching scenarios for max/min active/reactive powers are developed to improve the flexibility of power delivery capacity. Several test cases are presented and pertinent results are discussed to validate the effectiveness of the proposed method for voltage support of MG with multiple DGs.

The JOINBON SiPM for the readout of LySO crystals: a Multi Voltage Threshold approach

The JOINBON Silicon Photomultiplier is a novel commercial silicon sensor for weak photon flux. In this paper we report a characterization of the sensor for the readout of LySO crystals with potential application to Positron Emission Tomography. We measured a energy resolution of approximately (13.50±0.03)% (FWHM) and a coincidence time resolution ranging between (215±3) ps for a 5 mm long crystal up to (290±2) ps for a 20 mm long crystal. Finally we tested the feasibility of the JOINBON SiPM to a Multi Voltage Threshold readout and we obtained a energy resolution compatible with the intrinsic system performance.

Low Power Checks in Multi Voltage Designs

Leakage power consumption has been almost a serious problem these days in semiconductor industry. Many low power techniques like multi-voltage, power gating etc. are deployed to improve power saving. Power aware verification hence has become a critical issue now. Static low power verification has been developed to verify that low power architectures are designed in correct approach meeting all electrical rules in SoC. The UPF(Unified Power Format) is the standardized format that has all power intent information and can be used throughout the design flow to ensure that the power specification is intact. Firstly, this paper describes the special cells and its operation used in low power techniques. Secondly it describes the major checks examined at each stage using Synopsys VCLP tool and finally debugging with the tool and conclusion.

Improvements of on-demand electrohydrodynamic injection of droplet and droplet pair in a dielectric liquid

This paper deals with the extraction from a meniscus of water droplets of small size into an immiscible insulating liquid by the use of a multistage voltage pulse. A previous study on a particular oil established that this EHD Drop-on-demand technique allows producing droplets of size smaller or much smaller than the needle diameter. The case of a dielectric liquid characterized by a rather high value of the water/oil interfacial tension is considered here. It is shown that by adequately modifying the shape and level of the multistage voltage pulse, droplets are produced with a diameter ranging over a large interval. It was expected that the short enough pulse duration would give electrically neutral droplets; in practice it is found that the droplets carry minute but nonzero charges. An explanation is given for the charging mechanism and other changes of the pulse shape allow to further minimize the droplets charge. Finally having in mind the possibility to investigate experimentally the electrocoalescence of two close drops, results are presented concerning the injection of two successive droplets.

Exploiting uncertain timing information in time‐based SAR ADCs

Time-based successive approximation register (SAR) analogue-to-digital converters (ADCs) are gaining attraction in ultra-low voltage circuit design. Such ADCs typically use multi-stage voltage controlled delay lines (VCDLs) to perform voltage to time conversion in order to mitigate limited headroom of voltage signals. Although multi-stage VCDLs are used, only the outputs of the final VCDL stages are compared during bit trials. This work demonstrates that additional bit information can be extracted by scavenging timing information revealed at VCDL intermediate stages. The additional bit information can be used to accelerate the ADC conversion process or improve signal-to-noise distortion ratio (SNDR). To cope with uncertainties associated with signals from VCDL intermediate stages, an uncertainty-tolerant SAR procedure is developed. Also, this work presents techniques for adaptively selecting which intermediate stage signals to be tapped along the conversion process. The proposed techniques are applied in the design of a 0.4 V 9-bit SAR ADC in a 130 nm CMOS technology. Silicon measurement results show that with the additional information extracted from VCDL intermediate stages the conversion for the vast majority of ADC inputs can be completed in 7 or 8 clock cycles. Measurement results also demonstrate the potentials of using the intermediate stage signals to improve ADC SNDR.

Thermodynamic/Electrochemical Description of High-Voltage Spinels for Lithium-Ion Batteries

High-voltage (HV) spinels obtained by partially substituting Mn with other elements in are promising cathode materials for lithium-ion batteries (LIBs) due to their superior energy capacities and recyclability. The improved performance of HV spinels comes from the appearance of multi voltage plateaus without phase transformation during lithiation/delithiation process. To optimize the doping elements is one significant routine to develop new cathode materials. However, it is difficult to investigate HV spinels with multi doping elements due to increased variables. For the first time, we investigate the typical HV spinel, using one single thermodynamic model with Compound Energy Formalism (CEF), i.e., and described Ni substitution of Mn as well as lithiation/delithiation behaviours. Both the high voltage (around 4.7 V) and low voltage (around 4.1 V) plateaus of the Li-Ni-Mn-O spinel cathodes are predicted by correctly describing competition between and redox pairs. Meanwhile, we have successfully modelled the key property parameters including the voltage profile, energy density, stability, and cyclability. The presented design scheme is based on the superior cell performance compared to the widely studied which results in the slightly Li-rich HV spinel because of higher energy density and improved cyclability. The here adopted research strategy enables efficient design of the new-generation multi-doped HV spinel (M = Li, Al, Co, Cr, Cu, Mg, Fe, Ni, Zn, etc.).

Multi objective reactive power and voltage optimization of distribution network based on adaptive genetic annealing algorithm

In this paper, a multi-objective reactive power optimization model of distribution network is established, which takes the minimum of line loss, reactive compensation capacitor switching loss and node voltage deviation as objective, considering the constraints of node voltage, reactive power of wind turbine, capacitor switching times. The improved adaptive genetic annealing algorithm is used to solve the model. IEEE33 system is taken as an example to verify the effectiveness of the reactive power optimization model. When the shunt capacitor and wind turbine are in the optimal reactive power compensation, the line loss of the distribution network can be minimized.

Diode Reverse Recovery Process and Reduction of a Half-Wave Series Cockcroft–Walton Voltage Multiplier for High-Frequency High-Voltage Generator Applications

This paper investigates the diode reverse recovery process and reduction of a half-wave (HW) series Cockcroft–Walton (CW) voltage multiplier based on the steady-state analysis for high-frequency high-voltage (HV) generator applications. The diode reverse recovery process for a multistage voltage multiplier is analyzed after the introduction of steady-state operation. The diode reverse recovery problem is the bottleneck to further increase the circuit operation switching frequency for achieving high power density and short HV pulse rise and decay times. The diode reverse recovery problem is mainly caused by the diodes in the first-stage voltage multiplier. It is suggested that the most effective and economic way to alleviate the diode reverse recovery problem is by employing diodes without reverse recovery such as silicon carbide Schottky diodes in the first stage only. The silicon carbide Schottky diode without reverse recovery needs to be used only in the first stage of the voltage multiplier to effectively mitigate the reverse recovery problems at high frequency. The 300 kHz switching frequency three-stage voltage multiplier circuit hardware prototype experimental results finally validate the analysis. A technology demonstrator of a 300 kHz 8 kW 160 kV HV generator based on the proposed hybrid silicon carbide and silicon diode solution for the HW series CW voltage multiplier is provided finally.

New Digital Plug and Imaging Sensor for a Proton Therapy Monitoring System Based on Positron Emission Tomography.

One of the most challenging areas of sensor development for nuclear medicine is the design of proton therapy monitoring systems. Sensors are operated in a high detection rate regime in beam-on conditions. We realized a prototype of a monitoring system for proton therapy based on the technique of positron emission tomography. We used the Plug and Imaging (P&I) technology in this application. This sensing system includes LYSO/silicon photomultiplier (SiPM) detection elements, fast digital multi voltage threshold (MVT) readout electronics and dedicated image reconstruction algorithms. In this paper, we show that the P&I sensor system has a uniform response and is controllable in the experimental conditions of the proton therapy room. The prototype of PET monitoring device based on the P&I sensor system has an intrinsic experimental spatial resolution of approximately 3 mm (FWHM), obtained operating the prototype both during the beam irradiation and right after it. The count-rate performance of the P&I sensor approaches 5 Mcps and allows the collection of relevant statistics for the nuclide analysis. The measurement of both the half life and the relative abundance of the positron emitters generated in the target volume through irradiation of protons in approximately 15 s is performed with 0.5% and accuracy, respectively.

Lower-Order Compensation Chain Threshold-Reduction Technique for Multi-Stage Voltage Multipliers

This paper presents a novel threshold-compensation technique for multi-stage voltage multipliers employed in low power applications such as passive and autonomous wireless sensing nodes (WSNs) powered by energy harvesters. The proposed threshold-reduction technique enables a topological design methodology which, through an optimum control of the trade-off among transistor conductivity and leakage losses, is aimed at maximizing the voltage conversion efficiency (VCE) for a given ac input signal and physical chip area occupation. The conducted simulations positively assert the validity of the proposed design methodology, emphasizing the exploitable design space yielded by the transistor connection scheme in the voltage multiplier chain. An experimental validation and comparison of threshold-compensation techniques was performed, adopting 2N5247 N-channel junction field effect transistors (JFETs) for the realization of the voltage multiplier prototypes. The attained measurements clearly support the effectiveness of the proposed threshold-reduction approach, which can significantly reduce the chip area occupation for a given target output performance and ac input signal.

A New Data Fusion Method for Multi Terminal Fault Location Based on Sensor Networks

Data fusion with different types of data that used for grid fault location can bring more accurate and clear results. Therefore, a new method for fault location which contains multi grid current and voltage, time and coordinate data information is proposed. Transient traveling wave is analyzed for determine the required data information in the first place, and then affirm the positioning principle and the selection rules of positioning network according to characteristics of multi fault traveling wave. Finally, Grid fault location will be precisely positioned by applying multiple data grid fault location algorithm. Simulation results shows that the proposed method is feasible, and the new algorithm has higher positioning accuracy.

Research on classification of voltage sag sources based on recorded events

In recent years, with the wide application of power electronic devices and stringent requirement of industrial process, voltage sag has caused much attention in many countries. To design effective and efficient mitigation and management strategies, it is essential to have accurate classification of voltage sag sources. In this study, based on the analysis of massive voltage sag events in the grid recorded by online power quality monitoring systems in several different regions in China, a more extensive and practical classification of voltage sag sources is given. The voltage sags are divided into eight categories due to short-circuit faults with symmetric and asymmetric faults included, transformer energising, induction motor starting, lightning faults, self-extinguishing faults, the combined action of short-circuit faults and heavy load starting, upgrade faults and multi-stage voltage sags. For each category of the voltage sag sources, both the instantaneous value and the root mean square value of the waveform of the typical recorded events are given. In addition, the reasons are analysed and the waveform characteristics are summarised for each category of the voltage sag sources. Finally, the frequencies of eight categories under different voltage levels and the statistical result analysis are given.

Improved characterization of multi-stage voltage dips based on the space phasor model

This paper proposes a method for characterizing voltage dips based on the space phasor model of the three phase-to-neutral voltages, instead of the individual voltages. This has several advantages. Using a K-means clustering algorithm, a multi-stage dip is separated into its individual event segments directly instead of first detecting the transition segments. The logistic regression algorithm fits the best single-segment characteristics to every individual segment, instead of extreme values being used for this, as in earlier methods. The method is validated by applying it to synthetic and measured dips. It can be generalized for application to both single- and multi-stage dips.

A High Voltage Low Ripple Voltage Multiplier Circuit and Its Characteristics Analyses

The ripple voltage and voltage drop of Cockcroft-Walton voltage multiplying rectifiers are affected by the square or cube of stage number respectively. When increasing the number of the stage, the ripple voltage and voltage drop would significantly increase. For overcoming this problem, the proposed circuit adopts phase shift superposition to realize 2N time voltage multiplier circuit. By using three-phase transformer composed by three independently single phase transformer, output winding is connected to DC double voltage circuit. 12 times voltage circuit is built by parallel input, serial output to realize 6 pulses periodic superposition. Through the overlay, the ripple is greatly weakened. The theoretical analysis is made for ripple and voltage drop, and comparisons to the typical and symmetrical Cockcroft-Walton multistage voltage multiplier circuit are carried out. Results show that the circuit can significantly reduce the voltage ripple and voltage drop, and significantly shorten the output voltage steady set up time.

Enhanced Passive RF-DC Converter Circuit Efficiency for Low RF Energy Harvesting.

For radio frequency energy transmission, the conversion efficiency of the receiver is decisive not only for reducing sending power, but also for enabling energy transmission over long and variable distances. In this contribution, we present a passive RF-DC converter for energy harvesting at ultra-low input power at 868 MHz. The novel converter consists of a reactive matching circuit and a combined voltage multiplier and rectifier. The stored energy in the input inductor and capacitance, during the negative wave, is conveyed to the output capacitance during the positive one. Although Dickson and Villard topologies have principally comparable efficiency for multi-stage voltage multipliers, the Dickson topology reaches a better efficiency within the novel ultra-low input power converter concept. At the output stage, a low-pass filter is introduced to reduce ripple at high frequencies in order to realize a stable DC signal. The proposed rectifier enables harvesting energy at even a low input power from −40 dBm for a resistive load of 50 kΩ. It realizes a significant improvement in comparison with state of the art solutions.

Technique to characterise transient behavioural of multistage RF power amplifier for two‐way radio applications

A new technique to characterise the behavioral response of multistage RF power amplifier (PA) is presented. A simplified design methodology of closed loop PA with DC current sensing of multistage PA (cascaded) and voltage shaping algorithm is introduced in this study. An accurate characterisation of transient behavioral which includes ramping of RF energy from noise level to steady state level and adjacent channel transient power (ACTP), shows a high degree of correlation with measurement level for wideband RF PA operation (400-520 MHz). A prototype board is fabricated and measurement results demonstrated good correlation with transient behavioral model simulation. On board measurements demonstrated transient timing response of 1 ms while maintaining good ACTP of less than -60 dB over the wide frequency range of 400-520 MHz.