Voltage Suppression Research Articles

Electroencephalographic (EEG) Stages in Patients With Cerebral Edema Following Cardiac Arrest.

To describe electroencephalographic (EEG) changes in pediatric patients with cerebral edema after cardiac arrest. A retrospective study of patients admitted to the pediatric intensive care unit from July 2021 to January 2023. We included patients with cardiac arrest and changes in EEG background with clinical changes and/or neuroimaging consistent with cerebral edema. We excluded patients with electrographic seizures. We applied American Clinical Neurophysiology Society standardized critical care EEG terminology to classify EEG background, noting timing of the change in background classification. Clinical variables included age, sex, and neuroimaging findings and were described with descriptive statistics. Nine patients met inclusion criteria, with median age 24 months (interquartile range 21-49), and 89% were male. There were 5 common EEG stages: stage 1, burst suppression/burst attenuation; stage 2, continuous/discontinuous ± multifocal sporadic epileptiform discharges ± rhythmic or periodic patterns; stage 3, discontinuous/burst suppression/burst attenuation ± rhythmic or periodic patterns; stage 4, gradual voltage suppression; and stage 5, diffuse suppression. The ranges for each stage were as follows: stage 1, 2-10 hours; stage 2, 2.5-15.5 hours; stage 3, 0.5-6.24 hours; and stage 4, 0.5-11 hours. We could not calculate the duration of stage 5 given no uniform time to EEG discontinuation. One patient had a clinical change in stage 3. Remaining patients presented with fixed and dilated pupils with global anoxic injury. EEG stages of cerebral edema have not been described after pediatric cardiac arrest. These stages may be relevant to other patient populations. Early stages may be a therapeutic target for intracranial pressure-lowering medications and/or neuroprotective strategies to minimize sequalae of cerebral edema.

Electrochemical production of HO2- and O2 for sulfide removal from sewage

In this study, a comparative analysis of two electrochemical methods for sulfide control in sewer networks was performed for the first time. In addition, the mechanism of sulfide control by HO2- was elucidated, and an analysis of the device operation and electrolyte selection was performed. The two-electron oxygen reduction reaction (2e--ORR) using untreated gas diffusion electrode (GDE) was superior to the hydrogen evolution reaction (HER) using stainless-steel mesh in terms of cell voltage, product formation, and sulfide suppression. The GDE maintained a stable HO₂⁻ production capacity, achieving a concentration of 4566.6 ± 173.3 mg L⁻¹ with a current efficiency (CE) of 84.13 ± 3.5 %. During the electrolysis period, a stable dissolved oxygen (DO) level in sewage was consistently observed due to continuous in-situ oxygen production in anode. HO2- exhibited a notable increase in sewage pH (10.20 ± 0.01), effectively inhibiting the release of 99.93 % of sulfides. Moreover, the combined treatment of HO2- and DO significantly surpassed that of individual treatments. Seawater treated with cation exchange resin (CER) emerged as the most promising alternative to freshwater as the electrolyte. Overall, this study demonstrates that in-situ generation of HO₂⁻ and oxygen is a more effective strategy for sulfide control in sewer systems.

Finite control set model predictive current control for three phase grid connected inverter with common mode voltage suppression

This research introduces an advanced finite control set model predictive current control (FCS-MPCC) specifically tailored for three-phase grid-connected inverters, with a primary focus on the suppression of common mode voltage (CMV). CMV is known for causing a range of issues, including leakage currents, electromagnetic interference (EMI), and accelerated system degradation. The proposed control strategy employs a system model that predicts the inverter’s future states, enabling the selection of optimal switching states from a finite set to achieve dual objectives: precise current control and effective CMV reduction, a meticulously designed cost function evaluates the potential switching states, balancing the accuracy of current tracking against the necessity to minimize CMV. The approach is grounded in a comprehensive mathematical model that captures the dynamics of CMV within the system, and it utilizes an optimization process that functions in real-time to determine the most suitable control action at each interval, Experimental validations of the proposed FCS-MPCC scheme have demonstrated its effectiveness in significantly improving the performance and durability of three-phase grid-connected inverters, Experimental validations of the proposed (MPC with CMV) scheme have demonstrated its effectiveness in significantly improving the performance and durability of three-phase grid-connected inverters. The proposed method achieved substantial reductions in CMV, notable improvements in current tracking accuracy, and extended system lifespan compared to conventional control methods.

Discontinuous PWM-based common-mode voltage suppression method for three-phase inverter

Discontinuous PWM-based common-mode voltage suppression method for three-phase inverter

Model predictive control for single-phase cascaded H-bridge photovoltaic inverter system considering common-mode voltage suppression

In this article, a model predictive control (MPC) with common-mode voltage (CMV) suppression is proposed for single-phase cascaded H-bridge (CHB) inverters, which can also simultaneously achieve control objectives of grid-connected current tracking, voltages balancing of different H-bridge submodules on the DC-side and switching frequency reduction. To suppress high-frequency components of the common-mode voltage without additional switching devices, the algorithm proposed designs the predicted and reference values of the CMV and incorporates them in the cost function. At the same time, the capacitor voltages balancing control is integrated in the calculation of the optimal modulation function of the H-bridge, which reduces the complexity of control effectively. Besides, switching times of the MOSFETs are compared in two cycles. The cost function is constructed to represent comprehensive effect of the control. Finally, an experiment is performed on the hardware-in-the-loop experimental platform. The experimental results show that the proposed algorithm can offer a better voltage THD and reduce the times of switch action by nearly half while maintaining high-precision current tracking and maximum power point of photovoltaic modules, which alleviate the potential electromagnetic interference and cabling problem.

Novel common-mode voltage suppression method for indirect matrix converters based on open-active vectors

Novel common-mode voltage suppression method for indirect matrix converters based on open-active vectors

A reduced vector model predictive controller for a three-level neutral point clamped inverter with common-mode voltage suppression

This paper presents a novel, state-of-the-art predictive control architecture that addresses the computational complexity and limitations of conventional predictive control methodologies while enhancing the performance efficacy of predictive control techniques applied to three-level voltage source converters (NPC inverters). This framework's main goal is to decrease the number of filtered voltage lifespan vectors in each sector, which will increase the overall efficiency of the control system and allow for common mode voltage reduction in three-level voltage source converters. Two particular tactics are described in order to accomplish this. First, a statistical approach is presented for the proactive detection of potential voltage vectors, with an emphasis on selecting and including the vectors that are most frequently used. This method lowers the computational load by limiting the search space needed to find the best voltage vectors. Then, using statistical analysis, a plan is presented to split the sectors into two separate parts, so greatly limiting the number of voltage vectors. The goal of this improved predictive control methodology is to reduce computing demands and mitigate common mode voltage. The suggested strategy's resilience is confirmed in a range of operational scenarios using simulations and empirical evaluation. The findings indicate a pronounced enhancement in computational efficiency and a notable diminution in common mode voltage, thereby underscoring the efficacy of the proposed methodology. This increases their ability to incorporate renewable energy sources into the electrical grid.

Cascade model predictive control strategy for medium voltage flexible interconnected systems with arc suppression capability under single phase grounding fault

The distribution network faces problems such as diversified electricity demand and difficulty in ensuring power quality. At the same time, complex working environments often lead to brief single-phase ground faults, resulting in zero sequence currents in the distribution network. The flexible interconnection system of medium voltage distribution network plays an important role in balancing loads and providing electrical reliability. This article uses a three-phase four-wire converter as a flexible interconnection device, injecting zero sequence current into the neutral point through the fourth bridge arm. Simultaneously, a novel control strategy for medium voltage flexible interconnected systems based on cascaded model predictive control is proposed. The simulation and experimental results demonstrate the effectiveness of the proposed control strategy, which comprehensively achieves power mutual benefit, neutral point displacement voltage suppression, and active arc suppression during single-phase grounding faults in flexible interconnected systems.

Simplified Reactive Torque Model Predictive Control of Induction Motor with Common Mode Voltage Suppression

Simplified Reactive Torque Model Predictive Control of Induction Motor with Common Mode Voltage Suppression

A boost converter-based CSI-fed PMSM drives with common-mode voltage suppression for low-input voltage application

A boost converter-based CSI-fed PMSM drives with common-mode voltage suppression for low-input voltage application

Voltage suppression strategy for multi-stage frequency regulation of DC-side energy storage batteries in doubly-fed induction generator

When DC-side energy storage batteries participate in frequency regulation, inconsistent inertia requirements exist for frequency deterioration and recovery stages. In addition, the frequency regulation power can lead to the DC overvoltage of the DFIG. To address these issues, this paper proposes a voltage suppression strategy (VSS) during multi-stage frequency regulation with the DC-side energy storage batteries. In the frequency deterioration stage, a SOC segmented feedback inertia control (SSFIC) is developed to reduce the frequency change rate. In the frequency recovery stage, to mitigate transient maximum frequency deviation, a maximum frequency differential inertia control (MFDIC) is constructed by incorporating the transient maximum frequency deviation into inertia control coefficient. In the frequency regulation stage, to decrease the steady state frequency deviation and avoid the secondary frequency drop, an exponential inertia droop control (EIDC) is created by considering the droop coefficient as an exponential function of the frequency change rate. To suppress the DC voltage fluctuation, a DC voltage compensation control (DVCC) is presented to transform the active power of SSFIC, MFDIC and EIDC to the d-axis current compensation increment of GSC. Extensive simulation results have proved that the proposed strategy can successfully enhance the frequency regulation and voltage suppression ability.

Suppression of High Threshold Voltage for Boron-Doped Diamond MOSFETs

Suppression of High Threshold Voltage for Boron-Doped Diamond MOSFETs

The Value of Electroencephalogram (EEG) Findings in the Evaluation and Treatment Management of Pediatric Acute Liver Failure.

Background Pediatric acute liver failure (PALF) is still life-threatening and requires urgent care. The presence of encephalopathy is a clinical diagnosis, but it is more difficult to diagnose in children than in adults, and an electroencephalogram (EEG) can be invaluable. The role of EEG in managing the treatment of patients with PALF, other than the identification of encephalopathy, is unknown. This study aimed to investigate patients' EEGs, which may guide in choosing the most appropriate treatment in encephalopathy children. A further aim was to investigate a new score method, based on the laboratory results, which might indicate the presence of encephalopathy in cases with PALF. Methods Medical data of 33 PALF patients followed in our clinic were reviewed retrospectively. This study included 33 patients, whose EEG recording was taken on the first day of supportive treatment due to liver failure in the pediatric intensive care unit (PICU). The EEG findings were categorized into three classes: normal, epileptic and non-epileptic paroxysmal, and background encephalopathic patterns including widespread slowing and voltage suppression. Result This retrospective study included 13 male and 20 female patients with a mean age at presentation of 4.82±4.81 months whose EEG was performed on the first day of supportive therapy for liver failure in the PICU.The EEG findings were categorized into three groups: normal, epileptic and non-epileptic paroxysms, and encephalopathic patterns including diffuse background slowing and voltage suppression. Comparing EEG findings and treatments, we found that the normal EEG group responded well to liver-supporting therapy and the rate of plasmapheresis treatment was significantly higher in the diffuse slowing group. Patients with diffuse slowing of the EEG were 9.6 times more likely to receive plasmapheresis. We found that above a cut-off of ≥7.5 for the TAI (total bilirubin, albumin, and international normalized ratio (INR)) score used in our study, the risk of developing encephalopathy increased 14.4-fold. Conclusions In PALF, EEG findings can provide findings that will help clinicians in determining treatment selection and prognosis, as well as detecting epileptic focus and encephalopathy. The TAI score can be used to assess the risk of encephalopathy in cases of PALF, when it is challenging to identify encephalopathy or when an EEG is not possible.

Applications of safety transient voltage suppressors in the track circuits of railway signaling systems

This research presented the utilization of Safety Transient Voltage Suppressors (STVS) in the track circuits of railway signaling systems, occurring during circuit switching due to changes in track occupancy conditions, resulting in damage and malfunction of the BR966F2 relay. The study employed Failure Modes and Effect Analysis (FMEA) combined with 1kV actual transient overvoltage testing featuring a waveform slope of 184/380 μs. Results revealed two transient voltage suppression levels encompassing Set A_(a,b), Set B_(a) and Set C_(a,b) as well as Set A//Set B//Set C and All Mode. These configurations achieved a clamping voltage of 41.6 V, categorized as Stage 1. Configurations like Set A_(c), Set B_(b,c) and Set C_(c) displayed increased series circuit behavior leading to a clamping voltage of 48.6 V, categorized as Stage 2. The application of STVS device in the track circuit of the signaling system reduced the transient voltage by diversion of the Transient Current or ISTVS through the STVS device into the ground system or the clamping voltage at the STVS device. This prevented the transient power from flowing into and damaging the relays of the track circuit, leaving only the clamping voltage with a missing peak wave. This contributed to the stability of the track circuit within the railway signaling system while also raising the Safety Integrity Level (SIL) to a higher standard, in accordance with the specifications of IEC 16508-4 and the unique requirements of the State Railway of Thailand. These enhancements increased the advanced safety system within the track circuit, particularly for train control and train operation functions of the State Railway of Thailand

Hydrogen gas can ameliorate seizure burden during therapeutic hypothermia in asphyxiated newborn piglets.

We previously reported that hydrogen (H2) gas combined with therapeutic hypothermia (TH) improved short-term neurological outcomes in asphyxiated piglets. However, the effect on seizure burden was unclear. Using amplitude-integrated electroencephalography (aEEG), we compared TH + H2 with TH alone in piglets 24 h after hypoxic-ischemic (HI) insult. After a 40-min insult and resuscitation, 36 piglets ≤24 h old were divided into three groups: normothermia (NT, n = 14), TH alone (33.5 ± 0.5 °C, 24 h, n = 13), and TH + H2 (2.1-2.7% H2 gas, 24 h, n = 9). aEEG was recorded for 24 h post-insult and its background pattern, status epilepticus (SE; recurrent seizures lasting >5 min), and seizure occurrence (Sz; occurring at least once but not fitting the definition of SE) were evaluated. Background findings with a continuous low voltage and burst suppression were considered abnormal. The percentage of piglets with an abnormal aEEG background (aEEG-BG), abnormal aEEG-BG+Sz and SE was lower with TH + H2 than with TH at 24 h after HI insult. The duration of SE was shorter with TH + H2 and significantly shorter than with NT. H2 gas combined with TH ameliorated seizure burden 24 h after HI insult. In this asphyxiated piglet model, there was a high percentage of animals with an abnormal amplitude-integrated electroencephalography background (aEEG-BG) after hypoxic-ischemic (HI) insult, which may correspond to moderateand severe hypoxic-ischemic encephalopathy (HIE). Therapeutic hypothermia (TH) was associated with a low percentage of piglets with EEG abnormalities up to 6 h after HI insult but this percentage increased greatly after 12 h, and TH was not effective in attenuating seizure development. H2 gas combined with TH was associated with a low percentage of piglets with an abnormal aEEG-BG and with a shorter duration of status epilepticus at 24 h after HI insult.

Predictive load‐feedforward control for DC‐link voltage suppression and dynamic improvement of battery charging and discharging converter

AbstractWith the continuous progress of new energy technology, new energy vehicles have ushered in a stage of rapid development. As the central core of new energy vehicle, the power accumulator batteries have been attracting increasing attention. To obtain the exact electrical characteristics of the power battery, battery charging and discharging are integral component. A bidirectional grid‐connected AC/DC converter with predictive load‐feedforward compensation is presented in this article. Derive a predictive load‐feedforward model from the state space model of the rear DC/DC converter to reduce the bus voltage fluctuations caused by load variations. Firstly, the system structure for battery charging and discharging system is presented, and then the underlying principle of predictive load‐feedforward control is analyzed. Secondly, the predictive load‐feedforward model is built and discussed. Finally, build a system simulation model in MATLAB/Simulink and set up an experimental platform in the lab. Simulation results show that the predictive load‐feedforward control can reduce the bus voltage fluctuation and regulation time by about 84% and 50%, respectively, when the load power varies substantially. The findings of experimental studies also indicate that with predictive load‐feedforward control can significantly suppress bus voltage fluctuations and improve the dynamic response of the converter.

Coordination of Varistors With Transient Voltage Suppression Diodes in Automotive DC Systems

Coordination of Varistors With Transient Voltage Suppression Diodes in Automotive DC Systems

A Universal Common Mode Voltage Suppression Algorithm for AC Motors with Odd Phase Number

A Universal Common Mode Voltage Suppression Algorithm for AC Motors with Odd Phase Number

Improved Transient Performance of a DFIG-Based Wind-Power System Using the Combined Control of Active Crowbars

A significant electromotive force is induced in the rotor circuit of a doubly fed induction generator (DFIG) due to its high vulnerability to grid faults. Therefore, the system performance must be increased with appropriate control actions that can successfully offset such abnormalities in order to provide consistent and stable operations during grid disturbances. In this regard, this paper presents a solution based on a combination of an energy storage-based crowbar and a rotor-side crowbar that makes the effective transient current and voltage suppression for wind-driven DFIG possible. The core of the solution is its ability to restrict the transient rotor and stator overcurrents and DC-link overvoltages within their prescribed limits, thereby protecting the DFIG and power converters and improving the system’s ability to ride through faults. Further, the capacity of an energy storage device for transient suppression is estimated. The results confirmed that the proposed approach not only kept the transient rotor and stator currents within ±50% of their respective rated values in severe system faults but also limited the DC-link voltage variations under ±15% of its rated value, achieving transient control objectives precisely and maintaining a stable grid connection during the faults.

Distinctive Amplitude-Integrated EEG Ictal Pattern and Targeted Therapy with Carbamazepine in KCNQ2 and KCNQ3 Neonatal Epilepsy: A Case Series.

Carbamazepine (CBZ) is effective in treating KCNQ2/3-related seizures, which may present with a distinctive amplitude-integrated electroencephalography (aEEG) pattern. To assess how improved recognition of the distinctive aEEG ictal pattern associated with KCNQ2/3 variants has enabled early and effective targeted therapy with CBZ. Retrospective descriptive study of five neonates with KCNQ2/3 pathogenic gene variants admitted at a level 3 neonatal intensive care unit (NICU) over an 8-year period. The distinctive ictal aEEG pattern was recognized in four neonates after an average of 61.5 hours (minimum 12 hours, maximum 120 hours) from the first electroclinical seizure and prompted the use of CBZ that was effective in all. The two most recently diagnosed patients could avoid polytherapy as they received CBZ as the first and second antiseizure medication, respectively. Three out of five patients with continuous normal voltage (CNV), sleep-wake cycling (SWC), and shorter postictal suppression had normal neurodevelopmental outcome. Regarding the remaining two infants, one was not trialed with CBZ and had a high seizure burden, both presented with a prolonged postictal suppression, no SWC, and had moderate-to-severe developmental delay. Genetic results became available after the neonatal period in all but one of the infants, who had a prenatal diagnosis. Recognition of the distinctive ictal aEEG pattern in the NICU allowed early and effective targeted therapy with CBZ in four neonates, well before genetic results became available. Furthermore, a CNV background pattern with SWC and short postictal suppression were associated with normal developmental outcomes.