Power Pulsation Research Articles

Cardiovascular and vasomotor pulsations in the brain and periphery during awake and NREM sleep in a multimodal fMRI study.

The cerebrospinal fluid dynamics in the human brain are driven by physiological pulsations, including cardiovascular pulses and very low-frequency (< 0.1 Hz) vasomotor waves. Ultrafast functional magnetic resonance imaging (fMRI) facilitates the simultaneous measurement of these signals from venous and arterial compartments independently with both classical venous blood oxygenation level dependent (BOLD) and faster arterial spin-phase contrast. In this study, we compared the interaction of these two pulsations in awake and sleep using fMRI and peripheral fingertip photoplethysmography in both arterial and venous signals in 10 healthy subjects (5 female). Sleep increased the power of brain cardiovascular pulsations, decreased peripheral pulsation, and desynchronized them. However, vasomotor waves increase power and synchronicity in both brain and peripheral signals during sleep. Peculiarly, lag between brain and peripheral vasomotor signals reversed in sleep within the default mode network. Finally, sleep synchronized cerebral arterial vasomotor waves with venous BOLD waves within distinct parasagittal brain tissue. These changes in power and pulsation synchrony may reflect systemic sleep-related changes in vascular control between the periphery and brain vasculature, while the increased synchrony of arterial and venous compartments may reflect increased convection of regional neurofluids in parasagittal areas in sleep.

A Reinforced Model Predictive Control to Eliminate Power Pulsation Residual Components and Achieve High-Purity Grid Currents Under Unbalanced Grids

A Reinforced Model Predictive Control to Eliminate Power Pulsation Residual Components and Achieve High-Purity Grid Currents Under Unbalanced Grids

Solar Wireless Electrical Vehicle Charging System

Abstract: Electric vehicles are becoming more popular as an alternative to conventional gasoline- powered vehicles. In order to strengthen charging infrastructure, dynamic wireless charging (DWC) is apromising technology through which the vehicle battery can be continuously charged while the vehicle is in motion. The main challenge of the DWC system is to investigate the capability for power transfer with the variation in operating parameters in consideration of enhanced efficiency. This project proposes an innovative approach to improve the performance of dynamic wireless charging systems by investigating the magnetic coupler via finite element analysis, exploring power pulsation and mutual inductances with variations in longitudinal, lateral, and air gap distances as variable factors. In addition to this, efficiency analysis is also explored with respect to the mutual inductance and various compensation schemes. The simulation studies are carried out using computer-assisted software, i.e., MATLAB version2022b. Finally, a comparative analysis of power transferred, mutual inductance, and efficiency is presented by the compensation schemes

A Proportional-Integral-Resonant Current Control Strategy for a Wind-Driven Brushless Doubly Fed Generator during Network Unbalance

This article proposes a proportional-integral-resonant (PIR) current control strategy for a wind-driven brushless doubly fed generator (WDBDFG) during network unbalance. Firstly, four control objectives of WDBDFG, including eliminating unbalanced currents of power winding (PW), pulsations of control winding (CW) currents, torque, and PW power, are discussed and different from current controls in which the references to PW currents were computed; the CW current references are derived here. Then, an improved CW current controller using a PIR controller is proposed to achieve different control objectives. In contrast with current controls, CW currents are not involved with sequence extraction in the proposed control and can be totally regulated only in a positive synchronous reference frame. Hence, the system control structure is greatly simplified, and dynamic characteristics are improved. Furthermore, in order to obtain completely decoupled control of current and average power, feedforward control, considering all the couplings and perturbances, is also applied in CW current loops. Simulation results for a 2 MW grid-connected WDBDFG show that the proposed control is capable of achieving four control objectives, including canceling CW current distortion, PW current unbalance, pulsations of PW active power or pulsations of reactive power, and machine torque. Its dynamic process is much more smoothly and quickly than that of current controls, and therefore the proposed control has better dynamic control characteristics during network unbalance.

Comprehensive Review on Power Pulsation in Dynamic Wireless Charging of Electric Vehicles

Comprehensive Review on Power Pulsation in Dynamic Wireless Charging of Electric Vehicles

Influence of liquid layer height on pressure pulsations during evaporation/boiling under reduced pressure conditions

The paper presents experimental data on the influence of the height of the horizontal liquid layer on the amplitude of pressure pulsations obtained during evaporation/boiling under reduced pressure conditions. Also presented are the spectra of pressure pulsation power versus frequency obtained using fast Fourier transform for different heights of the horizontal liquid layer under reduced pressure conditions. It is obtained that the use of a thin film of working fluid during evaporation/boiling under reduced pressure conditions reduces the amplitude of pressure pulsations compared to thicker fluid layers. Analysis of the pressure pulsation spectra for explosive boiling regimes allows us to determine the characteristic frequency corresponding to the periodicity of explosive boiling. Also, this approach allows a quantitative comparison of the power of pressure pulsations obtained in different heat exchange systems and apparatuses.

Composite Second-Order Sliding Mode and Backstepping Control for Power Pulsation Suppression in Dynamic Wireless Charging

Composite Second-Order Sliding Mode and Backstepping Control for Power Pulsation Suppression in Dynamic Wireless Charging

Power Dissipation Measurements at Power Pulsation Compensators for Single-Phase Grid-Connected Converters

Power Dissipation Measurements at Power Pulsation Compensators for Single-Phase Grid-Connected Converters

Effect of sleep deprivation and NREM sleep stage on physiological brain pulsations.

Sleep increases brain fluid transport and the power of pulsations driving the fluids. We investigated how sleep deprivation or electrophysiologically different stages of non-rapid-eye-movement (NREM) sleep affect the human brain pulsations. Fast functional magnetic resonance imaging (fMRI) was performed in healthy subjects (n = 23) with synchronous electroencephalography (EEG), that was used to verify arousal states (awake, N1 and N2 sleep). Cardiorespiratory rates were verified with physiological monitoring. Spectral power analysis assessed the strength, and spectral entropy assessed the stability of the pulsations. In N1 sleep, the power of vasomotor (VLF < 0.1 Hz), but not cardiorespiratory pulsations, intensified after sleep deprived vs. non-sleep deprived subjects. The power of all three pulsations increased as a function of arousal state (N2 > N1 > awake) encompassing brain tissue in both sleep stages, but extra-axial CSF spaces only in N2 sleep. Spectral entropy of full band and respiratory pulsations decreased most in N2 sleep stage, while cardiac spectral entropy increased in ventricles. In summary, the sleep deprivation and sleep depth, both increase the power and harmonize the spectral content of human brain pulsations.

New design of high-power in-motion inductive charger for low power pulsation

The magnetic coupler is the most vital component for charging EV wirelessly. Through it, the output power can be transported from the transmitter to the receiver by means of electromagnetic fields. Therefore, this manuscript presents a proposed design of a magnetic coupler in the form of Double-D (DD) on both sides, which is suitable for in-motion inductive charging. This charger is capable of transferring power of 200-kW through an airgap of 250 mm with an efficiency of 91.88% and an operating frequency of 85 kHz. Computational modeling is conducted to obtain the magnetic coupler and the compensation parameters of the proposed system. The appropriate dimensions of the coils, magnetic and metallic shielding are obtained by using the finite element model (FEM). The effect of misalignments on the self and mutual inductances of the two coils (Lp, Ls, M), the output power (Po), and the transmission efficiency (η) is studied in case of one and two coils at transmitter side. The output power in the distance between the two transmitter coils (d) is improved by controlling the operating frequency, adding magnetizable concrete (MC), or both together. These techniques have proven effectiveness in improving the output power by 45.15% for small d and 72.51% for large d. In addition, the efficiency improved by 15.95% for small d and 60.76% for large d. Moreover, these improvement cases were compared in terms of size, weight and cost for a 100-m driving track.

Global ULF Waves Excited by Solar Wind Dynamic Pressure Impulses: 2. The Spatial Distribution Asymmetry

AbstractAsymmetry is a prevalent characteristic in numerous space physics phenomena. In this study, we investigate the statistical properties and spatial variations of ultra‐low frequency power globally after positive dynamic pressure pulses, utilizing high‐resolution magnetic field data from SuperMAG between 2012 and 2019. Specifically, we focus on the dawn‐dusk and north‐south asymmetries of Pc2‐5 fluctuations. Our analysis reveals that the power enhancement in the Pc2 band at approximately 30° magnetic latitude (MLAT) in the southern hemisphere is attributable to the South Atlantic Anomaly region. At MLAT ≈ 15°, the power of Pc3‐5 waves in both hemispheres exhibits a local minimum, which is associated with the strong coupling of compressional and Alfvén waves. Moreover, around MLAT = 60°, the dawnside Pc5 wave power exceeds that on the duskside when the interplanetary magnetic field (IMF) is westward, and the result is reversed when the IMF is eastward. Notably, Pc3‐5 wave power from MLAT = 30° to MLAT = 75° in the northern hemisphere is generally higher than that in the southern hemisphere. In regions with MLAT &gt; 75°, which corresponds to the polar cap between 0 and 15 magnetic local time, the power of Pc3 pulsations is higher during summer in the northern hemisphere and higher during winter in the southern hemisphere. These findings underscore the significant role of the solar wind and the IMF in controlling geomagnetic pulsations and further deepen our understanding of the coupling between fluctuations in the ionosphere and the magnetosphere.

Power Decoupling Control of Electrolytic Capacitor-Less Dual-Inverter to Reduce Interharmonic Currents Under Periodic Load Fluctuation

This study proposes a control method for an electrolytic capacitor-less dual-inverter with an aim to reduce the interharmonic currents. Owing to the low-energy buffer of the electrolytic capacitor-less inverter, load fluctuations superimpose harmonic currents on the input current. The proposed control method facilitates output power pulsation control of main inverter, which is a constant frequency regardless of load fluctuations. The experimental results exhibit a reduction in the interharmonic currents at 20 and 80 Hz by 68 and 72 %, respectively. Moreover, the power factor is improved by 11 pt., and total harmonic distortion (THD) of the input current is reduced by 26 pt. under rated load conditions. Therefore, the proposed control method can effectively reduce the interharmonic currents and improve the power factor and THD of the input current.

A 3D numerical model of controlled drug delivery to solid tumor by means of mild microwave hyperthermia-activated thermo-sensitive liposomes

A computational 3D analysis of liposomal drug delivery to investigate the effectiveness of this innovative therapy as an alternative to conventional chemotherapy is shown in this study. The temperature field evolution is obtained via the Local Thermal Non-Equilibrium (LTNE) bioheat model by including both variable porosity and blood vessels sizes to describe the local structure of the investigated tissue. Heating is induced by means of a microwave antenna directly inserted in tumor tissue, supplying a pulsating power to avoid tissue necrosis. Interstitial flow and drug diffusion are modeled by means of Darcy's law and convection-diffusion equations, respectively; Starling's law is included to simulate transcapillary exchange. After validating the model with available literature data, the results show that liposomal drug delivery leads to a 10% improvement in therapeutic outcomes (i.e., Fraction of Killed Cells, FKC). It is also proved that considering blood flow in the LTNE porous media model yields a more realistic evolution of drug diffusion and subsequent FKC, while severe tissue damage is avoided because of the pulsating power supply. This study highlights the potential benefits of using liposomal drug delivery in cancer chemotherapy via microwave-induced heating.

Midlatitude bursts of PiB geomagnetic pulsations and night airglow during stormtime sawtooth events

We explore bursts of broadband pulsations (PiBs) and airglow using the ISTP midlatitude observatories during substorm activations in the course of severe magnetospheric storms. We detected bursty pulsations in the Pi1B short-period range not only when the boundary of the auroral and field-aligned currents (FACs) region was near Irkutsk, but also when the boundary was up to 10° northward. Earlier, we associated such events with sharp pulses of the solar wind (SW) ram pressure, Pd, and/or to fast substorm-related variations in FACs during superstorms. In this paper, we show observations of such bursty phenomena during substorm sawtooth events (STEs) in the course of two storms both with and without strong Pd pulses or their moderate variations. The possibility of periodic substorm activations during STEs by a global magnetotail instability and excitation of the nighttime Alfvén resonator is discussed. We suppose and test a technique for timing the substorm explosive phase onset by the start of the surge in the spectral power of Pi1B pulsations.

A Single-Phase Transformerless Common-Ground Type PV Inverter With Active Power Decoupling

To solve the problems of existing non-isolated PV grid-connected inverters such as leakage current, power pulsation and harmonic current, a single-phase common-ground-type non-isolated grid-connected inverter with power decoupling capability is proposed in this paper. The integration of the traditional boost converter and the switched capacitor technology obtains the structure that the neutral point of the grid is directly connected with the negative terminal of PV array, and the leakage current is eliminated. Due to the time-sharing multiplexing of circuit components, which can achieve power decoupling and high step-up, fewer semiconductor devices are required in proposed inverter. At the same time, the improved control strategy ensures that the inverter can adapt to the voltage ripple of large decoupling capacitor. This paper introduces the working principle, mode, performance and control strategy of the novel topology in detail. Finally, the experimental prototype with rated output power of 320W verifies the superior performance of the inverter.

Power Decoupling Rectifier With Common-Ground Concept for Lighting Applications

The lightweight and the electrolytic capacitor-less are the development trends of microconverters for transportation lighting applications. Some solutions available to address the power fluctuations are caused by electrolytic capacitor-less. However, the leakage currents caused by nonisolated converters have been little studied. Given this, an improved transformerless single-phase rectifier based on the virtual dc-bus concept is proposed in this letter. This solution connects the negative of the LED array directly to the grid neutral, thus shorting the stray capacitance to the ground, suppressing leakage currents, and improving system reliability. In addition, the active pulsating power buffering solution is introduced with only one additional power switch due to the sharing of cells. Finally, the experimental results verify the correctness and superior performance of the proposed solution.

Data-Driven Prediction of Unsteady Vortex Phenomena in a Conical Diffuser

The application of machine learning to solve engineering problems is in extremely high demand. This article proposes a tool that employs machine learning algorithms for predicting the frequency response of an unsteady vortex phenomenon, the precessing vortex core (PVC), occurring in a conical diffuser behind a radial swirler. The model input parameters are the two components of the time-averaged velocity profile at the cone diffuser inlet. An empirical database was obtained using a fully automated experiment. The database associates multiple inlet velocity profiles with pressure pulsations measured in the cone diffuser, which are caused by the PVC in the swirling flow. In total, over 103 different flow regimes were measured by varying the swirl number and the cone angle of the diffuser. Pressure pulsations induced by the PVC were detected using two pressure fluctuations sensors residing on opposite sides of the conical diffuser. A classifier was constructed using the Linear Support Vector Classification (Linear SVC) model and the experimental data. The classifier based on the average velocity profiles at the cone diffuser inlet allows one to predict the emergence of the PVC with high accuracy (99%). By training a regression artificial neural network, the frequency response of the flow was predicted with an error of no more than 1.01 and 5.4% for the frequency and power of pressure pulsations, respectively.

Operation Characteristics of Discontinuous Current Mode for a Dual-Active-Bridge AC-DC Converter with an Active Energy Buffer

This paper discusses operation characteristics of discontinuous current mode (DCM) for an ac-dc isolated converter for on-board battery chargers of electric vehicles. The converter discussed in this paper consists of a front-end diode-bridge rectifier, an active energy buffer, and a dual-active-bridge dc-dc converter. The energy buffer circuit absorbs the power pulsation form the single-phase ac line into a small-rated capacitor, and thus, makes it possible to reduce a required capacitance of the dc-link capacitor. This paper explains details of the DCM control method including a technique of the ripple cancel of the inductor current, to realize the power factor correction of the line current and the voltage control of the buffer capacitor at the same time without complex calculations. Then, a reference value of the inductor current and an operation range of the dc-output voltage are discussed. Experimental results obtained by a 220-V, 6.6-kW experimental setup demonstrate a sinusoidal-line current and a controlled buffer capacitor voltage as well as a smoothed dc-output current.

Topological Overview of Auxiliary Source Circuits for Grid-Tied Converters

This paper reviews different types of capacitors and auxiliary source circuit topologies and presents an introduction to control strategies used for circuit applications reducing DC-BUS capacitance. The paper argues in favor of replacing bulky electrolytic capacitors in capacitor-supported power electronic systems with auxiliary source circuits. DC-BUS capacitors are widely used in grid-tied power converters (rectifiers) and utilized for power balance, voltage ripple limitation, and short-term energy storage. The electrolyte capacitor is the Achilles heel of any rectifier and power converter due to its higher rate of failure than other circuitry components. Auxiliary source circuits are key components to qualitatively improve the reliability of the DC links, where they divert the instantaneous pulsating power into extra reliable storage components. Unlike previous work, this review serves to provide a clear picture of an auxiliary source circuit design, in favor of optimal solution selection according to the specific application. Therefore, energy storage components (capacitors), topologies, and control strategies of auxiliary source circuits are comprehensively reviewed in this paper. Additionally, detailed explanations, comparisons, and discussions of auxiliary source circuits are offered.

Bridgeless PFC Converter without Electrolytic Capacitor Based on Power Decoupling

Due to fewer conduction devices in operating condition, the bridgeless power factor correction (PFC) converter is more efficient than the traditional PFC circuit. However, to achieve a low output voltage ripple on the DC side, a large electrolytic capacitor must be connected in parallel to the output end. To reduce the value of capacitance, this paper proposes a dual-boost bridgeless PFC converter with a bidirectional buck/boost power decoupling converter in the latter stage. The bidirectional converter absorbs double-line-frequency ripple, lowering the power pulsation at the output end while realizing power decoupling. The one-cycle control is adopted in bridgeless PFC converter, so that the input current can follow the input voltage to achieve power factor correction and decrease harmonic pollution. The power decoupling circuit is designed with a voltage outer loop using PI control and a current inner loop using model predictive current control, which alleviates the output voltage fluctuation caused by the reduction of the capacitance value of the filter capacitor, for the purpose of realizing non-electrolytic capacitor. Finally, the topology and control strategy involved in this paper are simulated and experimented to verify the validity and superiority of the theory.