AC Converter Research Articles

A Single-Phase Z-Source AC–AC Converter With Continuous Input Current and Without Commutation Issue

A Single-Phase Z-Source AC–AC Converter With Continuous Input Current and Without Commutation Issue

Analysis Of Voltage and Current Performance of 100 WP Solar Panel Using Matlab Simulink R2021a

The growing population increases the need for electrical energy. Development of renewable energy that is environmentally friendly and sustainable to replace fossil energy sources that are almost depleted and have an impact on global warming. Indonesia is on the equator where there is potential for the application of photovoltaic technology. However, the high cost of implementing a solar power system must be considered, as the energy supply is intermittent and highly dependent on environmental factors such as solar radiation and temperature. Therefore, it is necessary to design a solar power generation system using MATLAB Simulink 2021a software simulation method to avoid the implementation error rate and determine the success, especially the system performance. The MATLAB Simulink 2021a simulation method uses a 10 Wp monocrystalline Photovoltaic (PV) and a 12 V 20 Ah Lead-Acid battery. PV array design, PV Array, Buck Converter, Inverter, PV Controller, Battery Controller and Metering. To find out the value of the output voltage and current from solar panels, batteries, and the results of the DC to AC conversion by the inverter and using a load of 17 watts. The simulation results of a 100 Wp solar panel at MATLAB Simulink in the South Jakarta area with an intensity of 131W/m2 and a temperature of 27.99 °C produce a PV array output voltage and current of 17.6 V and 5.8 A, respectively. The battery voltage and current show the highest values are 12.58 V and 4.8 A. The actual voltage and current are close to the values of Vmp 17.8 V and Imp 5.2 A, so that the results of this system design can be stated to have maximum performance. Meanwhile, the inverter output has the highest voltage and current values of 218 V and 0.085 A.

Sliding modecontrolled PV-based bootstrap converter system with enhanced response and voltage stability

<p><span lang="EN-IN">In this paper, a straightforward method for locating the controller in a PV-based bootstrap converter system is presented. Recent developments in control strategies and power electronics have made it possible to create PV-based DC-to-AC converters for AC drives that are connected to 3-phase loads. High voltage gain is intended to be produced by the bootstrap converter (BSC). The BSC's purpose is to control load voltage. This study compares the time specification performance of the proportional resonant controller (PRC) and the sliding mode control (SMC) for photovoltaic systems with bootstrap three phase inverter (PV-BSTPI). For the delicate loads, steady voltage is typically more important. The BS-TPI system incorporates a closed loop control to fast achieve constant voltage. Choosing the best control approach is the aim. It is observed that the steady state error of SMC is 1.67 which is better when compared to PRC.</span></p>

Highly Efficient Dual-Buck Structured Buck–Boost AC–AC Converter With Versatile Identical Inverting/Noninverting Operations

Single-phase dual-buck ac-ac (DBAC) converters are gaining attention due to their intrinsic protection from shoot-through and open-circuit problems of conventional ac-ac converters. However, researches on DBAC converters are mainly concentrated around unipolar topologies. In a few developed bipolar topologies till date, the inverting buck-boost operations (for series voltage injection and step-variable frequency outputs) are inefficient and burdened by large voltage and current stresses ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v_in + v_o</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_in</i> + <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_o</i> ) of switching devices and ripples of passive elements. In this article, an efficient dual-buck structured buck-boost ac-ac converter is proposed, with the following features: no voltage source shoot-through and inductor open-circuit problems, natural attainment of safe-commutation without additional protection circuitry or complex control, no need of PWM dead-times, and elimination of high-frequency conduction of MOSFET's body diodes and related slow reverse recovery issues. The proposed converter provides distinct type efficient inverting and non-inverting buck (EINIBu) and boost (EINIBo) operations, with smaller switch voltage/current stresses ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v_in</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">v_o</i> and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_in</i> / <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">i_o</i> ) and passive component ripples. Combined inverting and non-inverting buck-boost (CINIBB) operations are also proposed with separate tuning of buck and boost voltage transfer ratios. A simple adaptable switching strategy provides the switch control pulses for all circuit operations by modulating the buck and boost control reference signals. The proposed converter provides sustained input/output currents and performs well with non-resistive loads. Extensive theoretical analysis is presented followed by practical verifications on a 400-VA laboratory circuit.

Integrated Control and Optimization for Grid-Connected Photovoltaic Systems: A Model-Predictive and PSO Approach

To propel us toward a greener and more resilient future, it is imperative that we adopt renewable sources and implement innovative sustainable solutions in response to the escalating energy crisis. Thus, renewable energies have emerged as a viable solution to the global energy crisis, with photovoltaic energy being one of the prominent sources in this regard. This paper represents a significant step in the desired direction by focusing on detailed, comprehensive dynamic modeling and efficient control of photovoltaic (PV) systems as grid-connected energy sources. The ultimate goal is to enhance system reliability and ensure high power quality. The behavior of the suggested photovoltaic system is tested under varying sun radiation conditions. The PV system is complemented by a boost converter and a three-phase pulse width modulation (PWM) inverter, with MATLAB software employed for system investigation. This research paper enhances photovoltaic (PV) system performance through the integration of model-predictive control (MPC) with a high-gain DC–DC converter. It improves maximum power point tracking (MPPT) efficiency in response to the variability of solar energy by combining MPC with the traditional incremental conductance (IN-C) method. Additionally, the system incorporates a DC–AC converter for three-phase pulse width modulation, which is also controlled by predictive control technology supported by Particle Swarm Optimization (PSO) to further enhance performance. PSO was selected due to its capability to optimize complex systems and its proficiency in handling nonlinear functions and multiple variables, making it an ideal choice for improving MPC control performance. The simulation results demonstrate the system’s ability to maintain stable energy production despite variations in solar irradiation levels, thus highlighting its effectiveness.

Review of Fault Diagnosis and Fault-Tolerant Control Methods of the Modular Multilevel Converter Under Submodule Failure

Modular multilevel converters (MMCs) have attracted extensive research interests in various ac and dc conversion applications due to their modular structure and excellent harmonic performance. However, the large number of power switches increases the potential risk of submodule (SM) failure, which greatly challenges the safe and reliable operation of the MMC. This paper presents a detailed review of fault diagnosis and fault-tolerant control methods of the MMC under SM failures. On this basis, comprehensive comparisons are conducted among different fault diagnosis methods, and verification results are provided to analyze the advantages and disadvantages of the popular fault-tolerant control methods. Finally, the review is concluded, and future trends and research opportunities are discussed.

Switching Modulation Optimization for Efficiency Maximization in a Single-Stage Series Resonant DAB-Based DC–AC Converter

Switching Modulation Optimization for Efficiency Maximization in a Single-Stage Series Resonant DAB-Based DC–AC Converter

Active Power Decoupling by Closed-Loop Control of Power Oscillations for a Bidirectional Single-Phase DC–AC Converter

Active Power Decoupling by Closed-Loop Control of Power Oscillations for a Bidirectional Single-Phase DC–AC Converter

Designing a Model of Solar Photovoltaic Water Pumping System for Off-Grid Localities in Tanzania

Modeling of photovoltaic (PV) water pumping system for rural water localities is vital especially in these modern days, in Tanzania. This is due to the rise of high number of solar-powered rural water projects constructed lacking appropriate design. The fate result into poor and substandard projects delivering below expectations. Kikombo Solar Water Project situated in Dodoma; Tanzania is one among poorly designed solar project chosen as a case study to validate proposed model. The main problem of Kikombo project is unsatisfactory amount of water from domestic points to satisfy population demand. This matter has been raised by pumping-station attendants and the Kikombo village community. The Kikombo water project can only deliver 14.21 m3/day while required demand is 50 m3/day. In order to solve the existing problem, solar water pumping model was developed. It consists of PV array, a motor-pump (AC), inverters (DC–AC converter), maximum power point tracker (MPPT) integrated with a controller and a storage water tank. Analysis was done in MATLAB to estimate which parameters should be upgraded to meet the water requirements. Moreover, the input and output variable for each model component were identified and simulated in MATLAB software. Finally, PV model was validated and system capacity improvement to rectify designs limitation for Kikombo is proposed. The model results were validated through real measurement data at Kikombo water pumping station. The differential error of 0.04062 was observed as a system error. PV model displayed an error of 0.0509 for power output, 0.0383 for current and 0.0131 for voltage; inverter displayed error of 0.0686 and 0.0406 for motor pump. In order to acquire sufficient water demand of 50 m3 /day, the PV panel and pump capacities should be increased to 8.82 kW and 7.35 kW respectively from the existing PV panel’s power of 2.5 kW and motor-pump of 4 kW.

A Novel Design and Development of Multilevel Inverters for Parallel Operated PMSG-Based Standalone Wind Energy Conversion Systems

AbstractThe article presents the new power conversion for parallel-operated wind energy conversion systems. It has been formulated by new multilevel inverter (MLI) topologies with reduced switch counts, lowered conduction losses and a very good output voltage spectrum. The wind energy conversion systems included permanent magnet synchronous generator (PMSG), a diode bridge rectifier, a conventional boost converter and a novel multilevel inverter connected to an isolated load. The power conversion utilizing a novel multilevel DC to AC converter has been proven for its better efficiency, voltage utilization and power quality. The integration of wind energy conversion systems has been explored in MATLAB Simulink, and the hardware setup does the authentication of the MLI structure.

A Five Level SC Inverter with reduced switch count and self balancing capability

Multilevel inverters (MLIs) have become a favoured option for medium voltage and high power DC to AC conversion applications to assure high power level cascade type inverter which accepts multiple/single DC sources and offers combined AC output for appropriate voltage and frequency. MLIs provide various benefits over two-level inverters, including lower dv/dt, the capacity to handle greater voltage levels, a quasi-sinusoidal output waveform, and lower Total Harmonic Distortion (THD), among others. The biggest problem in adopting the MLI is the increasing number of switches and it's design. MLIs based on switched capacitors (SC) for boost-type DC-AC converters often demonstrate a trade-off among switch voltage rating and switch count. This work introduces a new 5-level(5L) SC inverter by adding a switched capacitor module into the usual 3L neutral point clamped inverter leg(NPC). The SC unit consists of one bidirectional switch and two capacitors capable of withstanding one-quarter of the DC voltage. When compared to typical 5L inverters, such as standard NPC and active NPC designs, the new approach in addition reduces the amount of switches but also shorten the topology. The proposed FLSCI has been examined by using several PWM techniques. The simulation and hardware results showed that the presented FLSCI is ideal for a broad variety of applications.

Three-phase bidirectional active split source inverter for automotive traction application

The Split Source Inverter (SSI) is an attractive single-stage boost DC–AC converter topology. It requires fewer components than the Z-source inverter to achieve the boost function and also maintains a continuous input current. However, a significant drawback of this topology is its limited DC-bus voltage utilization. This paper introduces a new inverter topology derived from the SSI, aimed at addressing the DC voltage utilization issue and assessing its viability for traction applications. The new three-phase single-stage boost DC–AC inverter topology is named B-ASSI, and a potential modulation scheme is proposed to accompany it. To verify their functionality, the proposed converter and modulation scheme are simulated using Matlab/Simulink. Furthermore, a Proof of Concept (POC) is executed to experimentally validate the performance of the proposed inverter topology.

Three-Phase Single-Stage Three-Port High-Frequency Isolated DC–AC Converter

Three-Phase Single-Stage Three-Port High-Frequency Isolated DC–AC Converter

Three-Level Isolated Direct AC–AC Converter and its Closed-Loop Control Strategy

The isolated direct AC-AC converter has the advantages of high power density and long life time, however, suffering from the high cost and relatively low efficiency. In this paper, a three-level isolated direct resonant AC-AC converter is proposed, thus the voltage stress of power switches reduce to half of the input voltage amplitude and as a result, the voltage rating of the power switches is reduced. A hybrid modulation strategy for the proposed converter is proposed to realize the AC-AC conversion and reduce the switching power loss. Furthermore, in order to obtain a good control of the output voltage based on the proposed converter, the closed-loop control strategy of the output voltage combining a linear controller with the repetitive controller is proposed and the detailed parameters design rule is discussed. The proposed control strategy not only realizes the sinusoidal output voltage waveforms and good dynamic performance, but also effectively eliminates the effect of input voltage harmonics. The corresponding proposed topology, modulation and closed-loop control strategy are all verified by the detailed experimental results.

Modeling and design of PV grid integration for GA-PSO based on fluctuating power quality

Grid integration of renewable energy systems with majority of which is variable dc and variable ac. For example, solar systems output variable dc, while wind systems output variable ac. Power electronics now plays a significant role in the DC and AC conversion required for the grid. Power electronics now allows dc-coupled systems to be controlled for both active and reactive power, making inductively controlled for improving power quality and synchronizing renewable energy systems. The presence of harmonics in electrical systems indicates that current and voltage are distorted and deviate from sinusoidal waves; odd and even harmonics are the result of a nonlinear load. Voltage and sag and swell are examples of power quality issues, as are filters whose primary purpose is to reduce harmonics, voltage, and current in alternating-current power systems to an acceptable level. The maximum power point tracking is based on maintaining temperature and irradiance variables. We use both proposition and Maximum power point tracking (MPPT) to maximize PV power with oscillation tracking. The genetic algorithm with partial swarm optimization (GA-PSO) algorithm based on various optimization control techniques. Control techniques are proposed for systems with various unbalanced voltages to maintain control operation during fault conditions.

Dual Band Metasurface Integrated With Wideband Power Combiner for RF Energy Harvesting

This letter presents a novel dual-band metasurface (MS) structure with a Chebyshev transformer-based wideband power combiner for RF energy harvesting (RFEH). The unit cell (UC) of MS formed by embedding an electric-inductive capacitive resonator (EICR) in a single square loop (SSL) provides dual-band characteristics at 2.2 and 4.6 GHz, respectively. The wideband power combiner in corporate feed architecture, represented by the circuit schematic, channels the power to a 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> load, mimicking the input impedance of any standard rectifier. The system is studied using numerical simulation followed by fabrication of the prototype and its validation with experiment. The proposed system provides close to 90% radiation to ac conversion efficiency at 50- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega$</tex-math> </inline-formula> load in dual-band.

Converter valve-level fault location method based on the temporal differences among horizontal and longitudinal valve states

AC fault or converter fault could lead to LCC-HVDC converter protection operation, and converter protection outlet involves a random bypass pair scheme, which would expand the fault. To address this issue, a converter valve-level fault location method based on temporal differences among horizontal and longitudinal valve states is proposed. The research focuses on the inverter as the object, and analyzes the circuit state characteristics at the different fault locations within converter. In the horizontal direction of converter structure, conduction widths of AC current are constructed based on the location of commutation groups. In the converter longitudinal direction, temporal features of conduction widths are constructed based on single bridge or two bridges. Firstly, fault area is identified based on the amplitude characteristics of converter terminal currents and the abnormal characteristics of valve states. Secondly, converter internal fault is located by using the difference in the horizontal conduction width and the longitudinal temporal features between two bridges. Thirdly, the faulty phase or faulty valve is located as the valve that has the greatest virtual conduction width within the time window interval. Finally, simulations and field record data verify the validity of the proposed fault location method, and show that the proposed method has strong adaptability.

Low-Cost Real-Time Control Platform with Embedded Isolated Electrical Sensors for Power Electronics

This paper presents a versatile, low-cost real-time control platform with embedded isolated inputs and outputs for direct usage in electrical applications. The inputs correspond to voltage and current measurements, while the outputs are digital signals with isolated power supply. The validation for the platform considers the implementation of the power electronics topologies where the control algorithms are implemented in Simulink. The topologies are the interleaved three-phase buck converter, push–pull converter, H-bridge, and thyristor-based AC load controller. The control for them involves voltage feedback, current feedback, linear control algorithms, and the implementation of a discrete PLL algorithm for the last topology. Hence, the platform demonstrates the effectiveness of performing real-time control for some power electronics topologies.

Hybrid Energy Storage System Based on a Multioutput Multilevel Converter

Energy Storage Systems (ESSs) allow improving the stability and efficiency of the electrical grids with a high penetration of renewable energy sources. Moreover, the use of Hybrid Energy Storage Systems (HESSs) enable storage solutions with both high-energy and high-power densities, by combining different storage technologies such as diverse battery chemistries, ultracapacitors, or hydrogen fuel cells to name a few. In this paper, an HESS-based Multi-Output Multilevel Converter is presented. The proposed topology enables decoupled control of each AC converter voltage outputs. The internal switching states further allow the use of different storage units and high-quality multilevel voltage in each AC outputs. The mathematical model of the proposed topology and the defined operation region of the system, besides a model-predictive control strategy are developed. Finally, simulation and experimental results validate the performance of the proposed topology.

Guest Editorial: Special Issue on Emerging Topics of High-Frequency High-Power Density DC–AC Conversion Technologies

Guest Editorial: Special Issue on Emerging Topics of High-Frequency High-Power Density DC–AC Conversion Technologies