AC Voltage Source Research Articles

Solving dynamic electric circuit with nonlinear hysteretic inductor using harmonics interpolation method

SummaryThe aim of this paper is to present a methodology for solving а dynamic electric circuit with nonlinear hysteretic inductor without the use of hysteresis model or equivalent circuits. A consideration of nonlinear and hysteretic behaviour of the magnetic core under quasistatic conditions is based on applying harmonics interpolation method (HIM) to the measured magnetising field strength waveforms. A dynamic behaviour of the magnetic core is considered through the application of the statistical theory of losses (STL). A considered electric circuit consists of AC voltage source connected in series with shunt resistor, additional linear resistor and inductor, as well as a nonlinear hysteretic inductor. The solution for electric current of the circuit is obtained by solving equation derived from Kirchhoff's laws through a series of successive iterations. Coupling of electric and magnetic part of the circuit is obtained from fundamental laws of electromagnetism. Methodology is validated for four cases of the considered electric circuit — without additional elements, with one additional or both additional elements, for sinusoidal voltage source amplitudes of 2, 4, 6, 8 and 9 V and frequency of 50 Hz. Validation is repeated for frequencies of 100, 200 and 300 Hz while keeping the ratio of the amplitude to frequency constant. Detailed theoretical approach and methodology, comparisons between measured and calculated results, as well as adequate discussion are presented.

Explicit-time Floquet topological superconductivity in a microwave/infrared frequency AC voltage-driven Josephson junction

Anomalous Floquet topological superconductivity with chirality can be achieved by applying a dc-bias voltage across the Josephson junction with a sandwiched magnetic topological insulator (TI), in which the intrinsic Josephson phase provides a time-dependent periodic driving [R.-X. Zhang and S. Das Sarma, ]. In this work, we remove the bias voltage and connect the magnetic TI to an external AC voltage source to modulate the chemical potential, thus bringing about an explicit-time Floquet periodic driving. In the context of the driving, the system is similarly found to convert into a two-dimensional anomalous Floquet topological superconductor with chirality. By tuning the AC voltage source's frequency, we obtain a rich variety of novel Floquet topological superconducting phases with chirality. Particularly, by manipulating such static parameters as Zeeman field and superconducting pairing potential, a series of topological superconducting phase transitions are also exhibited, accompanied by exotic Floquet topological superconducting phases with chirality. Published by the American Physical Society 2024

High current density DC-DC converter with Modified PI controller for fast charging applications in EVs

As electric vehicles (EVs) become increasingly prevalent, the demand for efficient and high-performance DC–DC converters in the charging infrastructure is paramount. Electric vehicles, powered by rechargeable batteries or fuel cells, hence is necessary to have a cost-effective and efficient battery charger to deliver the consistent output current needed for the designated EV's battery. This paper adds a new and more effective approach of design and control of a DC–DC converter with bidirectional capability appropriate for incorporation in EV charging systems aimed at enhancing the current density and control issues inherent in the charging /discharging process. It appears to provide the necessary high current density besides battery out as soon as possible and also to impose an unimportant overshooting of the charging time for demanded lithium-ion battery system while charging it. The converter circuit contains the following equipment in its construction include single phase AC voltage source, linear transformer, passive component that includes the inductor and capacitor and bridge rectifier. Usually, Simulink/MATLAB is used for the purpose of various simulations. Using the MATLAB simulation the design of the concept system offered in this proposal has been proved. Monitored the current in amperes that the battery charger is supplying to the battery, closely observed the condition and voltage of the battery.

An integrated charging equalizing converter based on Cuk converter for solar home system

AbstractA solar home system (SHS), containing three independent parts, namely a load voltage dc–dc converter, an energy storage device (ESD) charger, and an ESD equalizer, will become bulky and costly. Thus, based on Cuk converter, an integrated charging equalizing converter (ICEC) is proposed. The ICEC can achieve load voltage converting, battery/supercapacitor (SC) charging, and equalizing simultaneously. The idea of the ICEC is using a voltage multiplier (VM) to replace the capacitor in Cuk convertor, and then reusing the VM as a charging equalizer. When the Cuk converter is operating, the voltage ripple generated on the VM, which can be regarded as an ac voltage source, is utilized to drive the VM. Therefore, compared with the traditional methods, the charging and equalizing can be achieved without extra switches and magnetic elements. A prototype for four SCs is built to verify the feasibility of the proposed method. And the system efficiency is 87%, corresponding to the input power 5.6 W, the load output power 3.54 W, and the charging balance power 1.33 W. Moreover, a quantitative comparison shows the proposed method can reduce the system size and cost effectively.

MOSFET-based HTS flux pump

We have developed a high-temperature superconducting (HTS) flux pump using high-power metal-oxide-semiconductor field-effect transistors (MOSFETs) for switching. For its primary coil, two commercial transformers are utilized, each consisting of two copper coils wound on a single iron core, which enables changing the load current over primary current ratio (101 or 194) between the primary and secondary coils. Full-wave rectification is achieved with two half-wave secondary circuits, each of them having six HTS one-turn coils to lower the resistance. Each secondary coil is composed out of nickel-reinforced BSCCO tapes, where 12 MOSFETs have been soldered in parallel straight to the tapes and controlled with analog electronics. Secondary coils are clamped to custom-made copper-stabilized HTS current leads. A support structure for keeping the HTS coils in place was 3D-printed using cryogenic-compatible composite material PETG-CF20. Resistances of the two secondary circuits were measured to be 4 and 7 at 77 K with a total critical current of 980 A. We successfully ramped up a 50 µH Conductor on Round Core solenoid at 77 K using our HTS flux pump with 50 Hz AC voltage source. We achieved a maximal load current of 900 A and exceeded the 715 A critical current of the solenoid. During the thermal runaway of the magnet, the increased load voltage limits the maximum load current supplied by the flux pump.

The Influence of Cavity Size and Location Within Insulation Paper on the Partial Discharge Activities

This paper examines the influence of cavity size and location in the insulation paper on the Partial Discharge (PD) activities through Finite Element Method (FEM). The model consisted of a conductor wrapped with insulation paper. Two different locations of the spherical cavities were introduced in this study, namely Location 1 (L1) and Location 2 (L2), located at the center and left corner of the insulation paper. The model introduced two different sizes of cavities with diameters of 0.5 mm and 0.8 mm. An AC voltage source of 17 kV, 50 Hz, was applied at the conductor while the bottom of the insulation paper was grounded. The real and apparent PDs were obtained by integrating the current flowing through the cavity and ground electrode with the respective surface area. The simulation was carried out for 100 cycles. The resultant model was used to study the PD occurrence, magnitude, and Phase Resolved Partial Discharge (PRPD) within the insulation paper. It is found that the large cavity size produces a lower number of PD occurrences per cycle than the small cavity size. The large cavity size produces a higher charge magnitude as compared with the small cavity size. The PD occurrence per cycle and charge magnitude are higher for the cavity location at L1 compared to L2. The PRPD yields the same pattern for cavity location at L1 and L2, whereby the differences are only on the charge magnitude and PD occurrence per cycle.

Development of Rechargeable Lawn Mower

Lawn mower is device to mow grass. The lawn mower will be having a problem such as the lawn mower widely used around by handle manually with hand. Next, the power source for lawn mowers is from petrol energy. That energy is nonrenewable energy and has bad impacts on the environment and people. In this paper, a prototype of lawn mower is designed and fabricated with its operation movement system through the Smartphone via Wi-Fi connection. The lawn mower is powered using the sealed acid battery that it can charging by using the photovoltaic cell or AC voltage source. The development of rechargeable lawn mower using ESP32 to keep and process data before sending to the webpage IP Address 192.168.4.1 to show the control movement of lawn mower via Smartphone. Based on experimental test results, the lawn mower was able to control its movement via a smartphone through a Wi-Fi connection. Next, the results were revealing the ability of solar panels for 2 hours and AC voltage for 1 hour to fully charged the sealed lead-acid batteries. Finally, a grass trim performance test was carried out on a lawn mower in the yard of the house and the result was that the grass could be cut. After that, the battery consumption of lawn mower operation for 1 hour was obtained the result around 50% of the capacity which is fully discharge because occurs the maximum depth of discharge of sealed lead acid batteries.

Adaptive model predictive control for grid‐forming converters to achieve smooth transition from islanded to grid‐connected mode

AbstractOne of the main capabilities of grid‐forming converters is the ability to operate in both islanded and grid‐connected modes. The grid‐forming converters work autonomously and behave as an AC voltage source when they are isolated from the bulk power system. In a grid‐connected mode, it is necessary for them to offer a set of grid‐forming capabilities for enhancing system inertia and strength. A grid‐forming converter may experience significant fluctuations in voltage, current, and frequency when the transition occurs. This paper investigates an improved adaptive model predictive control (AMPC) method for grid‐forming converters to achieve a smooth transition from islanded to grid‐connected mode and balance the contradiction between frequency stability and response speed. The AMPC method uses the angular frequency and phase angle as the performance indicators and introduces the angular frequency variations to adaptively adjust its weight coefficient in the objective function. The implementations and effects of the proposed AMPC method on the grid‐forming converter are theoretically evaluated. Compared to the conventional control, the proposed control scheme can not only suppress voltage, current, and frequency fluctuations, but also achieve a smooth transition. Additionally, the frequency control strategy in the islanded mode is improved for better independent operation. Finally, experiment tests on a controller‐level hardware‐in‐the‐loop simulation platform are carried out to validate the proposed control strategy for achieving a smooth transition.

Dynamics of the Rotating Arm of an Electromechanical System Subjected to the Action of Circularly Placed Magnets: Numerical Study and Experiment

This paper considers the experimental and numerical study of an electromechanical arm powered by a DC motor and subjected to the action of permanent magnets. The magnetic torques arise from permanent magnets mounted at the free end of the arm and along a circle. The electrical subsystem is powered by two forms of input signal (DC and AC voltage sources). For each case, we determine the condition for complete rotation of the mechanical arm versus the parameters of the system such as the arm length, the number of magnets, and the frequency of the external signal. The nonlinear dynamics of the system is examined by means of time-histories, bifurcation diagrams, Lyapunov exponents and phase portraits. Chaotic and periodic dynamics are detected numerically and confirmed experimentally.

그리드포밍 인버터 자원 기반 전력계통의 블랙스타트 및 계통 동기화 영향 연구

The increasing use of inverter-based resources, while reducing synchronous generators, decreases the system"s inertia, leading to an increased risk of power outages. The shift from a centralized power generation structure to a decentralized structure can be effective for stable operation of inverter-based power generation sources and to mitigate the risks of power outages. The grid forming inverter can perform the same role as a synchronous generator and can contribute to energizing primary restorative transmission systems. Grid-forming inverters must meet several requirements to replace synchronous generators in power systems. One of the most important requirements is the ability to operate as AC voltage sources. This means that the grid-forming inverter must be able to provide a stable AC voltage to the grid, just like a synchronous generator. To address this, a black start study using inverter resources was conducted, and a pumping generator-IBR cooperative black start was simulated through cooperation with an existing black start resource. The paper proposed the grid-synchronization method of grid-forming inverter and emphasizes the need for independent and quick recovery of inverter resources, which must operate as AC voltage sources to replace synchronous generators and contribute the primary power system restoration. The effectiveness of the proposed method to increase the input capacity and speed by stably inputting through synchronization has been studied and were verified through PSCAD/EMTDC simulation.

A novel approach to design of a power factor correction and total harmonic distortion reduction-based BLDC motor drive

This study describes a novel approach to design of a power factor correction (PFC) and total harmonic distortion (THD) reduction-based brushless DC (BLDC) motor drive. The drive was designed to obtain a reduced THD for PFC. The basic design of the BLDC motor drive contains an AC voltage source as input for a diode bridge rectifier. The output DC voltage is filtered out to reduce ripples. The smooth DC output voltage is supplied to the modified Zeta converter. The output voltage of the modified Zeta converter is controlled by using pulse width modulation (PWM). The modified Zeta converter is utilized in discontinuous inductor current mode (DICM) for better power factor. This controlled DC voltage is supplied to the voltage source inverter (VSI) as input. The VSI is designed to convert input DC into a suitable AC voltage source. The output voltage of the VSI depends upon switching patterns applied to power transistors generated by space vector PWM. Additionally, the output of the VSI is supplied to the BLDC motor for speed control. The main purpose of this paper is to simulate and assess BLDC motor function via the MATLAB/Simulink environment, using SimPowerSystems and the Simscape toolbox, with the goals of improved power factor, lower THD, and better speed control. The PFC modified Zeta converter topology produced the best power factor, currently 0.981, which is better than other topologies, with a THD of only 9.81%, the lowest of all three topologies, which demonstrates the significance of the proposed model.

Revelation and experimental verification of quasi-periodic bursting, periodic bursting, periodic oscillation in third-order non-autonomous memristive FitzHugh-Nagumo neuron circuit

It has been declared that constructing physical hardware circuits with the reproduction of abundant electrical activities of neurons is significant in neuron-based engineering applications. To this end, a novel third-order non-autonomous memristive FitzHugh-Nagumo (FHN) neuron circuit is designed by employing a first-order generalized memristive-diode-bridge (MDB) emulator and an AC voltage source. The memristive FHN neuron circuit can generate abundant electrical activities since the involvement of the MDB emulator. In theoretical analysis and numerical simulation, the corresponding circuit state equations and normalized system are formulated to analyze the characteristics of the equilibrium point and investigate the dynamical behaviors related to the internal resistor of the MDB emulator. Then phase portrait, time-domain waveform, bifurcation diagram, and Lyapunov exponent spectra are numerically simulated, from which abundant non-chaotic firing activities of quasi-periodic bursting, periodic bursting, and periodic oscillation are revealed. Additionally, the 0–1 test is utilized to further distinguish the above three non-chaotic behaviors. In hardware experiment, a breadboard hardware circuit is constructed and experimental measurements are executed. It is demonstrated that the experimental results well support the numerical simulations. Studying these non-chaotic behaviors is very important to understand the intrinsic nature of neuronal firing activities. Most notably, the numerical revelation and experimental verification of quasi-periodic bursting behavior have been rarely reported in the previously published literature.

Interaction Mechanism Analysis and Additional Damping Control for Hybrid Multi-Infeed HVDC System

With the emergence of the hybrid multi-infeed high voltage direct current (HMIDC) system, there is complex dynamic interaction between the AC/DC system and converter stations, while the interaction mechanism of the HMIDC system is unclear. For this purpose, this paper establishes the HMIDC linearized model based on the motion equation concept. Then, after decoupling and reconstructing the interaction path of the HMIDC system, the damping coefficients are derived. The AC system strength and voltage source converter (VSC) terminal voltage controller parameters are selected to analyze the impacts on damping coefficients, and the interaction mechanism of the HMIDC system is analyzed. In order to solve the potential instability issue, an additional damping controller in the VSC terminal voltage loop is proposed to enhance the voltage stability of HMIDC system, which is realized by adjusting the reactive power/amplitude coupling damping coefficient. Finally, the RT-LAB-based hardware-in-the-loop experiments verify the accuracy of the interaction mechanism analysis of the HMIDC system and the effectiveness of the proposed controller.

A single‐phase p‐type ac–ac converter with reduced components count and high boost factor

AbstractThis paper proposes a new single‐phase direct step‐up ac–ac converter by modifying the p‐type impedance source. It provides a high boost factor as well as high efficiency, while only six parts are required to design it, involving just two bidirectional power switches. A safe commutation method has been applied to power switches to make the converter snubber‐free and high efficient. Input and output harmonic filters are no longer required since input and output currents variate continuously with small ripple and low total harmonic distortion (THD). The proposed topology only modulates the output voltage amplitude, not the phase and frequency, so the output frequency is identical to the input frequency and constant. Thus, it can be utilized in step‐up conversion applications, like inductive power transmission from low ac voltage sources. Input and output have the same ground, which is a good protective feature. In this paper, the operating principle of the converter is demonstrated. Experimental results have been represented to evaluate the performance of the converter. For this purpose, an experimental prototype has been fabricated. Results are investigated and compared with other previous step‐up ac–ac converters. Results confirm the theory, operating principle, and performance of the converter.

Modeling a Simple Single-phase Grid-connected Photovoltaic System Using Negative Conductance of Solar Cells

This paper presents the simulation of a simple single-phase grid-connected photovoltaic (PV) system using the PSPICE model. The modeling system consists of a PV string, a single-phase current source inverter (CSI), load, and a grid voltage source. The system uses the PV string as the current source. The single-phase CSI was controlled by the grid AC voltage. The operation of the system employs the negative conductance characteristics of the PV string. We studied the voltage and current waveform at the inverter output terminal, the current waveform at the load, the AC power with various open-circuit voltages and temperatures of the PV string. The result showed the current waveform at the inverter output terminal follows the I-V characteristics of the PV string. The current waveform at the load depends on its impedance characteristics. The AC power increased with the open circuit voltage. We found that the maximum efficiency of the AC power conversion system was 63.3% at the peak of the AC voltage source, which was equal to the maximum power voltage of the PV string. In addition, the prototype was built for testing and testing verified the simulation results. The experimental results showed the current waveform at the inverter terminal and load were similar to the simulation results.

Study on Energy Efficiency and Harmonic Emission of Photovoltaic Inverters

The paper presents the results of an experimental study of 26 brand new photovoltaic (PV) inverters widely available for sale on the EU market; the study was conducted in 2021 by researchers at the AGH University of Science and Technology and Tauron Dystrybucja (Polish DSO). The purpose of the study was to compare and assess PV inverter performances in terms of their DC/AC conversion efficiencies, MPPT efficiencies, and harmonic current emissions. To examine the PV inverters, a laboratory test stand was prepared according to the standard EN 50530 and the technical report IEC/TR 61000-3-15. It was composed of a photovoltaic array simulator, a programmable regenerative AC voltage source, and a power analyzer. Each PV inverter was tested in various operating states determined by the DC voltage levels and the volume of active power generation. The results allowed for a benchmark assessment of PV inverters available on the market. The results showed how various energy efficiency indicators of individual PV inverters changed depending on their operating points. The results also revealed that, based on the performed harmonic emission tests, individual harmonics were within the normative requirements; however, in the case of several PV inverters, attention was drawn to the presence of relatively high switching frequency-related components exceeding permissible levels.

Research on Input-Parallel Single-Switch Wireless Power Transfer System With Constant-Current and Constant-Voltage Output

The full-bridge can further improve the output power through parallel inverters. The inverter output voltage of single-switch <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -resonant circuit is a combination of trapezoidal wave and half-sine wave; there is no relevant research on parallel connection of single-switch <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -resonant circuit. Therefore, this article presents a novel input-parallel single-switch <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> -resonant circuit; this topology adopts switchable secondary networks for constant-current (CC) and constant-voltage (CV) output, and prevents shoot-through of power switches. The decoupling between transmitters simplifies the analysis and calculation. The input-parallel structure avoids the unbalanced input voltage of each inverter and improves the stability of the wireless power transfer system. CC and CV output modes can be achieved by controlling one relay without adding dc–dc converters or changing the switching frequency. This article includes decoupling equivalent analysis of coils, topologies analysis of CC mode and CV mode, calculation of equivalent input ac voltage source, design of magnetic coupler, and circuit parameters. Finally, a 1-kW experimental prototype is built to verify the theoretical analysis; the maximum efficiency can reach up to 92.5%.

Measurements and Analysis of Partial Discharges at HVDC Voltage with AC Components

This paper presents the methodology for phase-resolved partial discharge measurements in HVDC systems with a DC voltage containing trace AC harmonics or a DC voltage ripple. The measurement result of partial discharges is an indicator of the current condition of the high-voltage power devices’ insulation system. The voltage waveforms in HVDC systems are not ideal DC, because different disturbances occurring naturally in these systems can affect the DC voltage. The AC harmonics related to the AC source voltage, and the voltage ripples provided by the power converter topology, can be found in the HVDC voltage. This paper proposes a novel approach to partial discharge measurement in DC networks. The synchronization to the particular AC harmonics appearing in DC voltage was applied to the PD measurements. The analyses were performed on the model sample containing a void inclusion, which was placed between electrodes fed by the DC voltages with the imposed chosen AC harmonics. Two scenarios were analyzed at a constant DC level: one with a variable AC magnitude and the second with a variable frequency of an AC source adjusted to the harmonics: 50, 150, 300, and 350 Hz. It was observed that the superimposed AC voltage component resulted in an intensification of PDs.

DBD System Operating in Ambient Air for Surface Treatment of Polyethylene Terephthalate Films

Abstract Polymers are materials widely used in many important technologies and applications because of their optical, physical, mechanical, thermal and chemical properties. Polyethylene terephthalate (PET) foil is often used as an insulating material in printed electronics, flexible circuitry, displays, industrial applications, graphic films, or for clinical and healthcare applications. A big inconvenience of PET film is the low surface tension which also implies a low wettability, resulting in poor coating adhesion and poor printing properties. In order to eliminate this disadvantage, a surface treatment was used by means of a dielectric barrier discharge (DBD) operating in ambient air at atmospheric pressure which consisted of a high voltage AC source and two circular metal electrodes 60 mm in diameter. The paper aims are to treat two different PET film substrates designed in this work as PET 1, without thermal treatment, and PET 2 which is heat stabilized. The effect of plasma exposure was assessed by determining the water contact angle by means of an Ossila goniometer and by measuring the surface tension with a special ink. The considered foils were exposed to different DBD treatment times (0.2, 0.5, 1, 5, 10, 30 s) and the evolution of the water contact angle overtime after treatment up to 96 hours was monitored. It was found that the water contact angle of the untreated PET 1 and PET 2 was 74° and 73.5°, respectively, and after 30 s DBD treatment time it decreased to 30.9° and 30°, respectively.

Reduction of the auto seismic component of error of a ballistic laser gravimeter by excitation of an induction-dynamic catapult from an AC voltage source

The purpose of the study is to analyse the influence of the excitation of an induction-dynamic catapult of a ballistic laser gravimeter from an AC voltage source at different frequencies on electromechanical indicators that provide a reduced value of the auto seismic component of error in measuring the gravitational acceleration g due to a decrease in the recoil force. A mathematical model of the gravimeter catapult when excited from an AC voltage source is proposed, taking into account the interrelated electrical, magnetic and mechanical processes. The nature of the electromechanical processes in the catapult of the gravimeter with such excitation has been established. It is shown that a phase shift occurs between the currents in active elements, as a result of which positive (repulsive) pulses of the electrodynamic force alternate with negative (attractive) pulses of force. A criterion for the efficiency of the gravimeter catapult has been introduced, taking into account the maximum value of push of the test body at the smallest values of the electrodynamic force and current of the inductor winding. It was found that the highest efficiency of the gravimeter catapult is provided at a frequency of 250 Hz, at which the catapult efficiency is 3.5 times higher than at a frequency of 50 Hz. It is shown that the transition from the method of excitation of an induction-dynamic catapult with one short pulse to excitation from an AC voltage source makes it possible to reduce the uncertainty in measuring the gravitational acceleration.