AC Converter Research Articles

An Isolated Identical Bipolar Buck-Boost AC–AC Converter With Step-Changed Frequency Operation and Reduced Active and Passive Components

An Isolated Identical Bipolar Buck-Boost AC–AC Converter With Step-Changed Frequency Operation and Reduced Active and Passive Components

Common-Mode EMI Noise Reduction With Improved Balance Technique for DC–AC Converters

Common-Mode EMI Noise Reduction With Improved Balance Technique for DC–AC Converters

Energy injection and free resonance converter for AC–AC inductive power transfer

Energy injection and free resonance converter for AC–AC inductive power transfer

A New Single-Phase Isolated Improved Quasi Z-Source AC–AC Converter

A New Single-Phase Isolated Improved Quasi Z-Source AC–AC Converter

Input and Output Harmonic Suppression Strategy of Single-Phase AC–DC–AC Converter

Input and Output Harmonic Suppression Strategy of Single-Phase AC–DC–AC Converter

Topology and Corresponding Modulation Strategy of AC–AC Converters With Multiple Decoupled Outputs

Topology and Corresponding Modulation Strategy of AC–AC Converters With Multiple Decoupled Outputs

The implementation of a cost‐efficient damped AC testing methodology for transmission cables based on DC–AC conversion and distributed partial discharge detection

AbstractThis research introduces a novel damped alternating current (DAC) testing methodology, which integrates an enhanced DAC generator with a pulse‐based distributed partial discharge (PD) detection technique. The advanced DAC generator is designed without the need for high voltage (HV) solid‐state switches, thereby offering a cost‐effective solution for field‐testing voltage generation through a direct current–alternating current conversion approach. To meet the demand for high instantaneous power, a capacitor bank is employed as the power supply. Furthermore, the implementation of a distributed PD detection technique enhances sensitivity and eliminates limitations associated with cable length. To minimize the construction costs of the distributed PD‐detection system, a pulse synchronization technique has been employed. Efforts to reduce the system's weight were informed by simulations, resulting in the design and development of a prototype weighing 850 kg for a 64/110 kV power cable. The reduction in the number of HV solid‐state switches contributes to significant cost savings, amounting to tens of thousands of dollars, when compared to conventional DAC generators. Laboratory and field tests validated the effectiveness of the cost‐efficient DAC testing methodology.

Application of Artificial Intelligent Techniques for Power Quality Improvement in Microgrid System

This paper focuses on modeling, control and power quality improvement of a microgrid connected system. This last was designed as a multi-converter system with Wind Turbine driven Permanent Magnet Synchronous Generator, and lithium ion Battery Storage Energy System. These sources are connected by a continuous bus to a nonlinear load through a DC /AC converter and three-phases multi-functional voltage source inverter. Where, wind systems are considered as primary power resource, and the grid is used for the effect of consumption of the overage power available from sources, when the battery has been fully charged. Multi Functional Voltage Source Inverter is used to ameliorate the performance of the proposed system, guaranteeing both reactive power and harmonic compensation. Moreover an intelligent control by fuzzy logic control algorithm are managed In order to extract the maximum power from wind turbine, to guarantee an effective storage management, this about the DC side. For the AC side a direct power control strategy with fuzzy logic algorithm have been used. The simulation of the system solution is carried out in Matlab/Simulink. The obtained simulation results show that the technique of fuzzy logic furnish the best solution in term of robustness, optimization performance, low THD and fast dynamic response.

Bio-inspired MPPT and advanced control for grid-connected solar photovoltaic systems with flyback converter

ABSTRACT This paper presents an enhanced approach for grid-connected photovoltaic (PV) systems using a flyback converter and Sovereign Butterfly Optimization for advanced Maximum Power Point Tracking (MPPT). The focus is on improving energy extraction efficiency from PV panels by dynamically adjusting system parameters. A flyback converter ensures reliable grid integration, while the Butterfly Optimization Algorithm, inspired by butterfly foraging, provides real-time MPPT to rapidly and accurately track the maximum power point, even under varying environmental conditions. A novel voltage harmonic mitigation technique processes three-phase currents through dq0 frames for closed-loop control, reducing harmonics and optimising voltage precision. The DC/DC flyback converter stabilizes AC conversion, minimizing high-frequency harmonics. Additionally, a Subsystem Synchronization Control Strategy synchronizes active and non-active grid currents, improving system stability. Simulations show a 99.3% tracking accuracy, 2% power oscillation around the maximum power point, and a Total Harmonic Distortion (THD) of 1.78%, meeting IEC 61,727 standards.

Techno-economic Analysis of Hybrid Renewable Energy System for Hydrogen Production in the Demnate Region of Morocco

This paper investigates the techno-economic feasibility of producing electrical energy for three villages in the mountains in the Demnate region. The community needs were determined based on the site visit to identify the electrical load demand in reality. In addition, a site description was done to evaluate the suitable system to produce the electrical energy. Using the Homer software, two systems were selected to produce electricity and hydrogen which are described as follows: The first system is constituted of a PV-Generator with 3759 kW, an Autosize Genset generating 300 kW, a DC/ AC converter supplying 317 kw, 800 kW produced by the electrolyzer, and a hydrogen storage tank with 900 Kg as a capacity. The second system is composed of PV modules with 3743 kw, seven G3 wind turbines with 3kW, an Autosize Genset generating 300 kw, 323 kW of power converters, a generic electrolyzer with an output power of 800 kW, and a hydrogen tank with 900 Kg as capacity. In addition, the financial analysis gives 1.56$/kWh and 1.57$/kWh as the Levelized Cost of Energy and 15.6 M$ and 15.7 M$ as the Net Present Cost for the first and second systems respectively.

An Isolated Three-Phase AC–AC Converter With Bipolar Output Voltage

An Isolated Three-Phase AC–AC Converter With Bipolar Output Voltage

Dual-Buck Bipolar Buck–Boost AC–AC Converter With Reduced Semiconductor Devices

Dual-Buck Bipolar Buck–Boost AC–AC Converter With Reduced Semiconductor Devices

PWM Strategy for the Cancellation of the Common Mode Noise Generated in a Multicell DC–AC Converter

PWM Strategy for the Cancellation of the Common Mode Noise Generated in a Multicell DC–AC Converter

Empowering the solar energy landscape: The techno-economic analysis of grid-connected PV power plants in Uganda

Solar PV power is still under-utilized despite the abundance of solar radiation in Uganda. There is need for empowering renewable energy landscape through unlocking the technical and economic feasibility of solar photovoltaic power. We analyzed data from 56 locations for the techno-economic and environmental assessment of photovoltaic power facilities in Uganda. This was based on weather data availability and accessibility to the national power grid. Analysis of the energy generation and different input factors was done using PVsyst 7.2. A three stage approach to losses was adopted: absorption of sunlight, conversion to DC and DC to AC conversion. Findings indicate that most of the countryside is suitable for construction of large scale grid-connected photovoltaic power facilities. Due to longer sunshine duration and stronger Global Horizontal Irradiance (GHI) which are associated with high energy yield, northern Uganda performed better than the rest of the country, making it a preferential siting for large scale grid-connected photovoltaic facilities. South western Uganda performed the poorest. After a thorough energy accounting and a list of all performance metrics, the viability of investing in grid-connected photovoltaic power facilities was assessed.

Single‐stage single‐phase multiport DC–AC inverter suitable for standalone applications due to its notable performance in different operation modes

AbstractA new multiport DC–AC converter is proposed for standalone and off‐grid tied applications. The configuration converts power from DC to AC form in a single stage with suitable voltage gain. To increase the certainty of supporting power, the converter is designed to operate in four modes, including battery‐alone mode. The other advantage of the presented work is supplying the output power during unbalanced voltage conditions of the input ports. The advanced features of the converter for being used in standalone applications are related to the suitable placement and structure of the bidirectional port. In addition, the configuration is designed in a way to contain appropriate structural properties such as the existence of a common ground between the DC section and inverter, continuity of input currents, configured by an acceptable number of components, and low‐voltage stress on the DC–DC section's switches. Furthermore, it has an impedance network to protect the inverter's switches in a shoot‐through state. To confirm the converter advantages from the mentioned points of view, it has been compared with similar configurations. A prototype rated at 110 V is prepared to demonstrate the advantages of the converter performance per different conditions. The results of the steady‐state and transient experiments validate the suitability of the presented converter.

Highly Efficient Three-Level AC–AC Converter With Identical In-Phase and Antiphase Buck–Boost Operations

Highly Efficient Three-Level AC–AC Converter With Identical In-Phase and Antiphase Buck–Boost Operations

Buck–Boost DC–AC converter based on coupled inductors

In this paper, a single stage buck–boost DC–AC converter based on coupled inductors is presented for renewable energy and electric vehicle applications. The proposed topology works with only three semiconductor switches, two diodes, and three coupled inductors to transfer input DC voltage to a high gain or low gain output AC voltage. A coupled inductor is used instead of normal inductors, which will reduce core and size requirements. The sinusoidal pulse width modulation strategy is used in this paper for controlling the main switch. There are many merits in the presented topology, like high gain up to five times of input voltage, compact size, less number of components, which results in reducing the overall cost, reducing switching loss, and increasing the converter efficiency. The simulation study is carried out using MATLAB/SIMULINK to simulate the operation of the proposed converter. Also, an experimental setup is built up to examine the actual operation of the proposed converter. There is a good agreement between simulation and experimental results which increases the validation and confidence of the model.

Grid-Connected Single-Stage DC–AC Converter for Solar PV Applications

Photovoltaic (PV) has become an important alternative because of the increased demand for electricity and the limited supply of traditional energy sources. Harmonic distortion (HD) on the grid-connected PV can lead to several undesirable outcomes, including overheating of connected equipment, frequent grid interruptions, reduced accuracy of electrical meters, and an increase in the required current. This manuscript proposes the novel use of the Sunflower Optimization (SFO) Algorithm in grid-connected single-stage DC–AC converter with minimizing Total HD (THD) and enhancing the efficiency of the system as its primary objective. The SFO algorithm is used to maximize the system's features and control the switched inductor boost converter. The proposed technique is then simulated using MATLAB and its performance is contrasted with other existing technologies Recurrent Neural Network (RNN), Garra-Rufa Fish Optimization-Student Psychology Optimization Algorithm (GRFO-SPOA), and Fuzzy Logic Control (FLC). The proposed method attains an efficiency of 97% with a low THD of 3.1%. The findings suggest that the proposed method outperforms the existing approaches.

Neural learning fault-tolerant control of fuel cell–battery–ultracapacitor-based hybrid electric vehicle

This article investigates the energy management and control of a fuel cell hybrid electric vehicle (FCHEV) with parametric uncertainties and sensor faults. The FCHEV in this study consists of a fuel cell, battery, and ultracapacitor connected to the DC-bus via DC–DC power converters, while the DC-bus is connected to the AC motor which drives the electric vehicle via a DC–AC converter. To control the power transfer from the energy sources to the drivetrain, a finite-time fractional-order control is proposed to coordinate the DC–DC power converters. A radial basis function neural network (RBFNN) is employed to estimate and compensate for sensor faults and parametric uncertainties. A minimum learning parameter scheme is used to minimize the computational burden on the RBFNN. The main tasks of the proposed scheme are; tolerating faults and parametric uncertainties, delivering the required power to the load, voltage regulation of the DC-bus, tracking the reference currents for the battery, fuel cell, and ultracapacitor in a short finite time. The closed-loop system is guaranteed to be stable in finite time using the Lyapunov function. The simulation results highlight the validity of the presented control.

Design and implementation of an innovative single-phase direct AC-AC bipolar voltage buck converter with enhanced control topology

Direct AC–AC converters are strong candidates in the power converting system to regulate grid voltage against the perturbation in the line voltage and to acquire frequency regulation at discrete step levels in variable speed drivers for industrial systems. All such applications require the inverted and non-inverted form of the input voltage across the output with voltage-regulating capabilities. The required value of the output frequency is gained with the proper arrangement of the number of positive and negative pulses of the input voltage across the output terminals. The period of each such pulse for low-frequency operation is almost the same as the half period of the input grid or utility voltage. These output pulses are generated by converting the positive and negative input half cycles in noninverting and inverting forms as per requirement. There is no control complication to generate control signals used to adjust the load frequency as the operating period of the switching devices is normally greater than the period of the source voltage. However, high-frequency pulse width modulated (PWM) control signals are used to regulate the output voltage. The size of the inductor and capacitor is inversely related to the value of the switching frequency. Similarly, the ripple contents of voltage and currents in these filtering components are also inversely linked with PWM frequency. These constraints motivate the circuit designer to select high PWM frequency. However, the alignment of the high-frequency control input with the variation in the input source voltage is a big challenge for a design engineer as the switching period of a high-frequency signal normally lies in the microsecond. It is also required to operate some high-frequency devices for various half cycles of the source voltage, creating control complications as the polarities of the half cycles are continuously changing. This requires at least the generation of two high-frequency signals for different intervals. The interruption of the filtering inductor current is a big source of high voltage surges in circuits where the high-frequency transistors operate in a complementary way. This may be due to internal defects in the switching transistors or some unnecessary inherent delay in their control signals. In this research work, a simplified AC–AC converter is developed that does not need alignment of high-frequency control with the polarity of the source voltage. With this approach, high-frequency signals can be generated with the help of any analog or digital control system. By applying this technique, only one high-frequency control signal is generated and applied in AC circuits, as in a DC converter, without applying a highly sensitive polarity sensing circuit. So, controlling complications is drastically simplified. The circuit and configuration always avoid the current interruption problem of filtering the inductor. The proposed control and circuit topology are tested both in computer-based simulation and practically developed circuits. The results obtained from these platforms endorse the effectiveness and validation of the proposed work.