Three-phase Bridge Research Articles

VERIFICATION OF ENERGY CHARACTERISTICS OF A THREE-PHASE BRIDGE COMPENSATION CONVERTER WITH ONE COMMUTATING LINK

The article considers the issue of reliability of the results of analytical calculation of the feedforward control angle of power electric valves and the commutate angle of a three-phase bridge compensating converter of electric energy with one commutating link. It is noted that the value of these angles determines the capabilities of the converter regarding the generation of reactive energy together with the power supply of the consumer of direct current electric energy. Based on the complexity of the analytical calculation of these characteristics, the issue of verification of the obtained results is relevant, which also confirms the adequacy of the applied research methodology. As a tool for achieving the goal of the work, the authors use circuit simulation in the Micro Cap package. The modeling technique is described in detail, the results of modeling several modes of converter operation are presented, and these results are analyzed. A comparative analysis of the numerical values ​​of the control and commutating angles obtained as a result of analytical calculation and circuit modeling of the same modes of converter operation showed that the discrepancy does not exceed 5%. This indicates the adequacy of the applied modeling technique and the acceptable accuracy of the results of analytical calculations. Refer. 3, fig. 3, table 3.

A New Proposed Triple Active Bridge Converter for Fuel Cell Applications

This paper deals with a new proposed three port converter structure dedicated for two-input source hybrid systems especially for fuel cell applications. This converter is made up of three-phase triple active bridges which are galvanically isolated by means of three single phase high frequency transformers. The present converter integrates a fuel cell as the primary power source with a battery that stores energy, harnessing the unique benefits of both sources to deliver reliable power to a DC load through a single power conversion stage. In order to control the power flow between the ports, a phase shift control technique has been carried out to generate the control signals of the load and battery side bridges in reference with those of the fuel cell bridge. A detailed analysis of the proposed converter has been presented in this paper. A novel proposed energy management algorithm has been developed. This algorithm provides a robust solution for managing and distributing power flow between the converter's ports, ensuring an optimal balance of power delivery. The algorithm has been rigorously validated through simulations and experimental test, using Dspace 1104 board.

Research on fault diagnosis for three-phase rectifier device in direct current transmission system based on continuous wavelet transform and vision transformer

Abstract As a core component of photovoltaic power generation systems, the three-phase rectifier device plays a crucial role, and its failure can potentially reduce energy conversion efficiency and output quality. Presently, the performance of fault time-domain signal diagnosis methods based on three-phase rectifier circuits is challenging to enhance. This paper proposes a novel fault detection method for three-phase rectifier devices based on Vision Transformer, referred to as CWT-ViT, to address this issue. This method transforms time-domain fault signals into images through Continuous Wavelet Transform (CWT), subsequently inputting these images into a Vision Transformer model. Relying on its powerful self-attention mechanism and fully connected layers, it realizes the extraction and learning of rectifier device image features. A Simulink simulation model of a three-phase bridge controllable rectifier circuit is established for fault injection to collect fault signals. Fault diagnosis experiments demonstrate that the proposed diagnostic method achieves a prediction accuracy of 98.6%, maintaining a relatively high precision level. In comparison to four excellent classification models currently available: AlexNet, RepVGG, ResNet, and GoogLeNet, the proposed method demonstrates superior diagnostic performance. Additionally, this paper conducts ablation experiments to meticulously analyze the impact of each module in the fault diagnosis process. This research achieves more precise and efficient fault diagnosis in photovoltaic power generation systems, thereby reducing downtime and maintenance costs for actual equipment and enhancing the stability of photovoltaic power generation systems. This research provides an innovative, intelligent solution for the intelligent operations and maintenance of photovoltaic power generation.

Evaluation of the effectiveness of incomplete phase pulse width modulation algorithms in the converter-electric motor system

Aim. This study evaluates the effectiveness of incomplete-phase algorithms for pulse width modulation of three-phase voltages in frequency control of electric drives, using integral current dispersion in the load as the criterion. Materials and methods. This study examines pulse width modulation processes in frequency-controlled electric drives, focusing on the converter-electric motor system. Methods from electric circuit theory are used, with proposed algorithms illustrated through drawings, and these drawing can be implemented in the matrix laboratory software. Results. The process of pulse width modulation in the converter-electric motor system is considered. It is demonstrated that to minimize the number of switching keys in the frequency converter, incomplete-phase pulse width modulation algorithms are beneficial. Expressions for local dispersion of the interphase current in single-phase and two-phase modulation are analyzed. An expression for local current dispersion in a three-phase bridge circuit load is derived, and the concept of integral current dispersion in a three-phase load is derived. Indicators for evaluating the effectiveness of algorithms for incomplete-phase pulse width modulation are proposed. Graphs the efficiency coefficient, characterizing incomplete-phase pulse width modulation with a minimum number of switching of key elements in the function of the amplitude coefficient and in the function of the relative frequency of modulation are constructed. Conclusion. The results aid in developing algorithms for controlling frequency converters in asynchronous electric drive systems.

Перемодуляция в трехфазных электронно-ключевых мостах системы преобразователь–электродвигатель

To ensure the operability of a circuit with three-phase pulse width modulation, it is necessary to meet the conditions of operability. One of the most important conditions is to exclude the phenomenon of overmodulation. To obtain the boundary values of the variables that determine the quality of modulation, it is necessary to study the phenomenon of overmodulation in various modes of operation of a three-phase converter. New modulating functions with constraints have been introduced to analyze the phenomena associated with overmodulation. Methods of analysis of electrical circuits have been used. The processes of three-phase pulse width modulation in the overmodulation mode have been studied. An assessment of the effect of overmodulation on the variables that determine the quality of the modulation process has been made. The boundary amplitude coefficient of a three-phase bridge has been determined, at which a three-phase overmodulation mode occurs. The results can be used to develop algorithms for controlling frequency converters in frequency control systems of electric drives.

A Novel Shunt Zigzag Double-Tap Low-Harmonic Multi-Pulse Rectifier Based on a Three-Stage Power Electronic Phase-Shifting Transformer.

To solve the problem of the large size of traditional industrial frequency phase-shift transformers and the harmonic distortion of multi-pulse wave rectifier systems, this paper proposes a three-stage shunt zigzag power electronic phase-shift transformer based on a double-tap multi-pulse wave rectifier, which combines the power factor correction (PFC) converter with the voltage-type SPWM inverter circuit to form a power electronic converter to realize the frequency boost and power factor correction. Through AC-DC-AC conversion, the frequency of the three-phase AC input voltage is increased, the number of core and coil turns in the transformer is reduced to reduce the size of the phase-shifter transformer, a zigzag structure of the phase-shifter transformer is used to solve the unbalanced distribution of current between the diode bridges, and a passive harmonic suppression method on the DC side is used to generate a loop current by using a group of single-phase rectifier bridges to regulate the input line current of the phase-shifter transformer. The phase-shifted voltage is input into two three-phase diode rectifier bridges to rectify and supply power to the load. Simulation and semi-physical test results show that the proposed method reduces the total harmonic distortion (THD) value of the input current of the phase-shifted transformer to 7.17%, and the THD value of the grid-side input current is further reduced to 2.49%, which meets the harmonic standard and realizes the purpose of power factor correction as well as being more suitable for high-power applications.

Optimization Study of High-Efficiency Rectifier Circuits for Uninterruptible Power Supply Systems

Uninterruptible Power Supply (UPS) is a kind of equipment that can supply power to other equipment’s in an uninterrupted way, which can ensure that the key equipment’s can continue to operate stably in the face of power grid failure. Therefore, uninterruptible power supply system is of utmost importance in the modern power system. The aim of this paper is to optimize rectifier circuits in uninterruptible power supply system that rely on three-phase bridge full-wave rectifier circuits. Build a model using LTspice and simulate it, compare and analyze the waveform characteristics of the output voltage of the load under different filtering schemes, and propose optimization strategies based on actual production. As one of the key components of the UPS system, the rectifier circuit can directly affect the efficiency with stability of the whole system. Hence, it is important to optimize the high efficiency rectifier circuit to improve the overall performance of the UPS system.

APPLICATION OF SOFT SWITCHING IN THREE-PHASE VOLTAGE INVERTERS OF TRACTIONAL ROLLING STOCK

Autonomous voltage inverters with PWM, which are used in electric drive systems with brushless motors, occupy an important place in the complex of electrical equipment of modern traction rolling stock of railways. The article presents the results of the research of the traction three-phase bridge voltage inverter with soft switching of power switches. Using the soft switching mode allows you to reduce the switching losses in the power transistors of the keys, increase the PWM frequency and improve other performance indicators of the converter. It is advisable to implement soft switching in the key transistors of the three-phase voltage inverter using soft switching nodes with fast-acting four-quadrant switches based on IGBT. It is proposed to consider the possibility of using transistor switches of a voltage inverter with capacitive non-dissipative snubbers at high PWM frequencies. For this purpose, a synthesis of the scheme and algorithm for the implementation of soft switching in a three-phase bridge voltage inverter with bipolar sinusoidal PWM with soft switching nodes with high-speed four-quadrant switches based on IGBT was performed. An analysis of the characteristics of the three-phase voltage inverter was carried out when using high-speed switches in the soft switching nodes to implement soft switching in the power transistors of the inverter switches.On the basis of the study, it is proposed to modernize the scheme of the soft switching unit in order to provide better preparation for the switching of the power transistors of the keys at large load currents. The improved soft switching unit includes low-voltage sources of constant voltage, which will compensate for energy losses in the recharging circuit of the snubber capacitors and contribute to the soft switching on of the power transistors of the voltage inverter keys. The performance test was carried out and the characteristics of the converter were analyzed when using a modernized soft switching node using simulation modeling in the MATLAB package.

Fault-tolerant Integration of Charge and Discharge Information Security for Multi-Scale Time Series Models

In this paper, the power mode of winding and converter topology are integrated. Considering the filter characteristics and electromagnetic torque control of the system during charging/discharging, the integrated structures of one-phase full bridge, three-phase full bridge and three-phase four-arm bridge are studied. The single-phase all-bridge integrated structure can completely suppress the electromagnetic torque generated by the motor during charging and discharging, and make the filtering effect of the system better. In this project, a multi-scale full convolutional deep neural network method based on time series is studied. The multi-scale full convolution time series model is used for training, and the future continuous signals can be monitored according to the trained model based on the power signal data collected from high-voltage power lines. Experiments show that the proposed method can effectively extract the required data.

A grey wolf optimization-based modified SPWM control scheme for a three-phase half bridge cascaded multilevel inverter

The Multilevel inverter (MLI) plays a pivotal role in Renewable Energy (RE) systems by offering a cost-effective and highly efficient solution for converting DC from Photovoltaic (PV) sources into AC at high voltages. In addition, an innovative technology holds immense significance as it not only enables the seamless integration of PV systems into the grid but also ensures optimal power generation, thereby contributing to the widespread adoption of RE and fostering a sustainable future. This paper presents a modified sinusoidal pulse width modulation (SPWM) control scheme for a three-phase half-bridge cascaded MLI-powered PV sources. The selection of the MLI configuration is motivated by its reduced number of switching components, which enhances system reliability and simplifies experimental implementation. Compared to the SPWM schemes which require (m−1) carriers that make the generation of the pulse circuit very complex, the proposed control scheme requires only three signals: a carrier signal, a triangular waveform, and a modulating signal. This approach significantly reduces the complexity of control and facilitates practical implementation. The proposed control scheme simulation is verified using MATLAB/SIMULINK Software. The grey wolf optimization (GWO) algorithm is implemented to determine the optimal switching angles of the proposed control scheme. The Total Harmonic Distortion (THD) objective is selected to be the fitness function to be minimized for improving the quality of the output waveforms. For verification, the results of the proposed GWO-based modified SPWM control scheme are compared with those obtained using both the Particle swarm Optimization (PSO) and Genetic algorithm (GA) used in the literature. Simulation results declared that the proposed control scheme improves performance, especially THD which is minimized to 6.8%. Experimental validation has been conducted by building a laboratory prototype of the proposed system. The experimental and simulation results gave acceptable and limited convergent results considering the experimental difficulties.

Minimum current stress control strategy for three degree of freedom three-phase dual active bridge DC-DC converter

Compared to single-phase dual active bridge (1p-DAB) DC-DC converters, three-phase dual active bridge (3p-DAB) DC-DC converters have advantages such as high single machine power, high power density, small filtering capacitance, and are more suitable for high-voltage situations. Therefore, they have good application prospects in DC transmission and industrial high-power DC-DC converters. However, under traditional single-phase shift (SPS) control, especially in the low power range, there is a large reactive current and severe soft switch loss. This article adopts an asymmetric modulation strategy for its larger reactive power, which reduces its reactive power in the low power range with more degrees of freedom and improves the efficiency of power transmission. Taking current stress as the optimization objective, the KKT algorithm is used to solve, and the corresponding analytical solution is ultimately obtained. Finally, a simulation is built by using MATLAB software to verify the feasibility of the proposed solution.

Reduced Losses in PV Converters by Modulation of the DC Link Voltage

The efficiency of a PV system has improved by the fact that the researchers have used different techniques to enhance their efficiency. This paper aims to present how the PV converter losses can be reduced by employing a polypropylene capacitor in the DC link and to modulate that DC voltage. A problem of controllability and stability arises. Two current control methods, constant off time and a PWM type with second order high pass filter DC-link feedback are presented. Polypropylene capacitors in the PV converters do have lower losses and a lower cost. The PV converter simulation and lab experiment is based on a three-phase bridge APTGF50X60T3G, used to combine a step-up/step down and H-bridge in one package.

A 12-pulse rectifier using coupled reactors for supplying three-inverters

The paper presents a proposal of an auspicious multi-pulse rectifier convenient for supplying three-level inverters. The rectifier consists of two three-phase bridges. Their outputs are connected in parallelwhile inputs are connected to the line by use of coupled reactors These reactors are connected and work in an exceptional variant 3CRλ. The application of 3CRλ makes that the diodes conduction angle in rectifiers achieves 180°. Simulation and experimental works prove that multi-pulse rectifier gives a worthy performance and has some respectable properties.

Fault Current Control of Three-Phase Dual Active Bridge DC–DC Converter Employing Modified Asymmetrical Duty Cycle Control Modulation

Fault Current Control of Three-Phase Dual Active Bridge DC–DC Converter Employing Modified Asymmetrical Duty Cycle Control Modulation

Quasi-Z-Source Three-Phase Voltage Source Inverter with Virtual Space Vector Modulation to Increase the Voltage Gain and for the Reduction of Common Mode Voltage

Abstract A quasi-Z-source network is used to boost the DC bus voltage of a voltage source two-level H-bridge inverter to increase the voltage gain. With the increase in the DC bus voltage, the common mode voltage (CMV) also increases. The CMV is reduced using virtual space vector pulse width modulation (SVPWM). Due to the presence of a quasi-Z-source network, the expression of the CMV changes significantly with respect to the conventional voltage source two-level H-bridge inverter fed from a pure DC supply. In this paper, a detailed analysis of the origin of the CMV for the quasi-Z-source two-level H-bridge inverter is presented. Additionally, it is shown how the CMV is affected for a DC input supply taken from a three-phase diode bridge rectifier. The work also details the scheme for suitable placement of shoot-through time intervals required for boosting within the non-active time intervals in virtual SVPWM. The simulation and experimental results show the scheme is effective in increasing the voltage gain and reducing the CMV arising at the third harmonic of the desired output frequency by at least 33.33%.

FEA simulation of harmonics generation from 6-pulse rectifier and their impact over rectifier’s transformer

In the present work, the operation of a 6-pulse three-phase rectifier supplying a powerful DC consumer is simulated using the finite element method (FEM). The purpose of the simulations is to research the generation of harmonics from the rectifier circuit and to investigate their influence on the transformer supplying the three-phase bridge rectifier. For this purpose, two co-simulations were made. The first of them is realized with the help of the professional Finite Element Analysis (FEA) software - Ansys Electromagnetic Suite. The voltage-driven model of the rectifier transformer for FEA was built and was used in the Ansys Twin Builder software simulation. The resulting current harmonics from the FFT analysis of the current waves with their amplitudes and phases are input into the primary and secondary windings of the transformer current-driven model in the second electromagnetic-thermal co-simulation in Ansys Workbench to calculate the losses in the transformer. These losses are used in the thermal model to account for transformer heating from higher harmonics.

MoS2 Self-Switching Diode-Based Low Power Single and Three-Phase Bridge Rectifiers

MoS₂ Self-Switching Diode-Based Low Power Single and Three-Phase Bridge Rectifiers

An Energy-Feed Type Split-Capacitor Three-Phase Four-Wire Power Electronic Load Compatible with Various Load Demands

Energy-feed power electronic loads can precisely control the phase and magnitude of the power supply output current, achieving the emulation of loads. Moreover, they can feed energy back to the grid for energy regeneration, demonstrating significant research value. This article proposes an energy-fed power electronic load topology and control method that can realize the static and dynamic simulation of linear and non-linear loads and take into account the simulation needs of single-phase, three-phase three-wire, and three-phase four-wire loads. The main circuit uses a two-stage back-to-back AC/DC/AC structure: the front side is a three-phase four-wire split capacitor PWM rectifier bridge, which is used to simulate loads under various operating conditions; the back side is a three-phase three-wire PWM inverter bridge, which realizes the energy feeding back to the grid and reduces the waste of energy; and the intermediate side uses a split capacitor to equalize the voltage and achieve voltage stabilization. The topology is analyzed under the simulation demands of three-phase balanced, three-phase unbalanced, single-phase and non-linear loads. Finally, a MATLAB(R2022a)/Simulink simulation platform is built for a power electronic load with a rated capacity of 200 kVA. The simulation results verify the effectiveness, feasibility, and advancement of the power electronic load proposed in this article.

Practical Dead-Time Control Methodology of a Three-Phase Dual Active Bridge Converter for a DC Grid System

An effective dead-time control strategy for the three-phase dual active bridge (3P-DAB) converter of a distribution system is studied to reduce the switching losses of power switches and improve the under-light-load power conversion efficiency. Because of the advantages of a dual-active bridge converter, such as an inherent zero-voltage switching (ZVS) capability without any additional resonant tank and a seamless bi-directional power transition, this is an attractive topology for bi-directional application. The 3P-DAB converter is apt for high-power applications such as aircraft due to an interleaved structure, which can reduce conduction losses. However, the design of the dead time depends on engineering experience and empirical methods. In order to overcome the conventional practicality of the dead-time design method, the effective control of dead time is proposed based on the theoretical analysis. In this paper, the overall explanation of the 3P-DAB converter is shown with operation principles. In addition, the dead-time effect of the 3P-DAB converter is examined and the practical variable dead-time control strategy is studied. Finally, experimental results validate the proposed variable dead-time control strategy using a 25 kW prototype 3P-DAB converter.

VOLTAGE ON THE POWER ELECTRIC DIODES OF A THREE-PHASE BRIDGE COMPENSATION CONVERTER WITH ONE COMMUTATING LINK

The operating conditions of power electric diodes of a three-phase bridge compensation converter with one commutating link, which consists of a three-phase capacitor battery and a three-phase group of fully controlled devices, are investigated. This technical solution makes it possible to ensure the recharging of the capacitors of the commutating link and the control of the energy process of the converter. At the same time, the operating conditions of its power equipment also change. The main content of the study is the analysis of the components of the reverse voltage of the power electric diodes of the compensation part of the converter and the dynamics of its change during the regulation of the electromagnetic process by transistors of the commutating link. This is required when determining the class of diodes in the case of introducing a converter according to the scheme under study into production. The study of the magnitude and form of the reverse voltage was carried out for two modes: the transistors of the commutating link are controlled within the framework of the operation of the power electric diodes of their phase and the next one. The volume of research is limited to the analysis of processes at a single frequency of control pulses. As a result, it was proved that on the power electric diodes of the compensation part of the converter, the reverse voltage is less than on other valves. The reason for this is the commutating voltage of the capacitors, which, superimposed on the line voltage of the secondary winding of the converter transformer, reduces the maximum value of the reverse voltage curve of the electric diodes.