Multiphase Transformer Research Articles

Enhancement Design of Multi-phase Transformer for Cascaded H-Bridge Motor Driver

Enhancement Design of Multi-phase Transformer for Cascaded H-Bridge Motor Driver

Multi-phase features interaction transformer network for liver tumor segmentation and microvascular invasion assessment in contrast-enhanced CT.

Precise segmentation of liver tumors from computed tomography (CT) scans is a prerequisite step in various clinical applications. Multi-phase CT imaging enhances tumor characterization, thereby assisting radiologists in accurate identification. However, existing automatic liver tumor segmentation models did not fully exploit multi-phase information and lacked the capability to capture global information. In this study, we developed a pioneering multi-phase feature interaction Transformer network (MI-TransSeg) for accurate liver tumor segmentation and a subsequent microvascular invasion (MVI) assessment in contrast-enhanced CT images. In the proposed network, an efficient multi-phase features interaction module was introduced to enable bi-directional feature interaction among multiple phases, thus maximally exploiting the available multi-phase information. To enhance the model's capability to extract global information, a hierarchical transformer-based encoder and decoder architecture was designed. Importantly, we devised a multi-resolution scales feature aggregation strategy (MSFA) to optimize the parameters and performance of the proposed model. Subsequent to segmentation, the liver tumor masks generated by MI-TransSeg were applied to extract radiomic features for the clinical applications of the MVI assessment. With Institutional Review Board (IRB) approval, a clinical multi-phase contrast-enhanced CT abdominal dataset was collected that included 164 patients with liver tumors. The experimental results demonstrated that the proposed MI-TransSeg was superior to various state-of-the-art methods. Additionally, we found that the tumor mask predicted by our method showed promising potential in the assessment of microvascular invasion. In conclusion, MI-TransSeg presents an innovative paradigm for the segmentation of complex liver tumors, thus underscoring the significance of multi-phase CT data exploitation. The proposed MI-TransSeg network has the potential to assist radiologists in diagnosing liver tumors and assessing microvascular invasion.

Optimizing the Connection Diagram and Turns Number for the Three-Phase to Multiphase Transformer Converter Secondary Winding Coils

An approach to determining the optimal connection diagram and the number of turns for secondary winding coils of a three-phase to multiphase transformer-type converter is considered. Each phase of the device’s multiphase winding comprises three coils placed on different core limbs and connected in series with each other. To determine the connection diagram and the number of turns in the multiphase winding coils, it is necessary to solve an optimization problem with taking into account certain constraints that will make it possible to obtain the same number of turns in the series-connected coils of each secondary winding phase, a symmetrical multiphase EMF system, and uniformly distributed symmetrical multiphase load among the three primary winding phases. The formulated optimization problem with constraints is solved using the numerical interior point method. The application of the proposed approach is illustrated by an example of calculating the minimum number of turns in the coils of a three-phase to seven-phase converter, and the converter windings connection diagram is presented. The article gives the calculated apparent power values of the secondary winding coils with a symmetrical resistive-inductive load for a converter with different numbers of coil turns evaluated from solving the optimization problem with various constraints. A prototype three-phase to seven-phase converter has been fabricated on the basis of a three-phase transformer of a standard series. As a result of experimental studies of the prototype, the seven-phase winding instantaneous voltage waveforms, r.m.s. values of currents and voltages, and the primary winding power for no-load and symmetrical load modes have been obtained. The experimental study results have confirmed the calculation results adequacy. By using the proposed approach, it is possible to design a three-phase to multiphase converter with the number of multiphase secondary winding phases more than two. The designed secondary winding coils will have the minimal number of turns, which will make it possible to manufacture a device with smaller mass and dimension indicators and decrease the consumption of expensive electrical materials.

PERANCANGAN TRANFORMASI DAYA LISTRIK DARI SISTEM 3 PHASA KE 9 PHASA MENGGUNAKAN TRANSFORMATOR BERINTIKAN BESI

Regarding the harmonics of AC current, when the AC phase is connected to the rectifier it will cause harmonics to appear on the AC line. In addition, this rectification process requires a large enough capacitor if you want to reduce the voltage ripple from the rectification result. The larger the capacitor, the smaller the ripple, but the higher the cost of the capacitor. So the author chose the title of the final project «Design of Electrical Power Transformation from 3 Phase to 9 Phase System Using an Iron Core Transformer. Problem Formulation How to design a multi-phase transformer, especially a 3-phase to 9-phase transformer. How to design a multi-phase transformer construction. For multiphase transformers, especially transformers from 3 phases to 9 phases, 3 single phase transformers can be used which have one coil on the primary side and 5 coils on the secondary side. To get a voltage on phase 2 with the same amplitude of 100 volts with phase 1 only 40 degrees different in phase, then a voltage of 113 volts on phase 1 with a phase angle of 0 degrees, plus a voltage on phase 4 of 74 volts with a phase angle 120 degrees. Then to get a voltage on phase 3 with the same amplitude of 100 volts, it takes a voltage of 74 volts on phase 1 with an angle of 0 degrees, plus a voltage on phase 4 of 113 volts with a phase angle of 120 degrees. trying to make this 3 phase to 9 phase transformer by using the construction of 1 3 phase transformer. do the calculation of the transformer power that will be designed.

New Methodology to Calculate DC Voltage Signature in N-Phases TRUs Under Supply Voltage Sags

A new methodology based on the shadow projection has been developed to study any multipulse rectifier’s dynamic behavior under balanced and unbalanced conditions. The proposed methodology calculates the DC average voltage and instantaneous values under balanced and unbalanced supply voltage conditions for multiphase Transformer Rectifier Units (TRUs). The calculation of the developed algorithms is more practical than the classical methods and other approaches based on Fourier series or symmetrical components that are difficult to apply under unbalanced conditions. Furthermore, classical methods are not simple to determine the limits of the integrals and calculate them to obtain the average value, so a more friendly and practical methodology has been developed to analyze rectifiers operating under supply voltage sags. This new methodology has been validated by simulation for a 12-pulse TRU in series and parallel connections, and it has also been validated for a 36-pulse TRU in parallel connection using interphase inductors. The accuracy of the calculations is validated by the experimental results for 12-pulse TRUs, series, and parallel connection, and 18-pulse TRU in series connection.

Power Conversion Techniques Using Multi-Phase Transformer: Configurations, Applications, Issues and Recommendations

Recently, the superiority of multi-phase systems in comparison to three-phase energy systems has been demonstrated with regards to power generation, transmission, distribution, and utilization in particular. Generally, two techniques, specifically semiconductor converter and special transformers (static and passive transformation) have been commonly employed for power generation by utilizing multi-phase systems from the available three-phase power system. The generation of multi-phase power at a fixed frequency by utilizing the static transformation method presents certain advantages compared to semiconductor converters such as reliability, cost-effectiveness, efficiency, and lower total harmonics distortion (THD). Multi-phase transformers are essential to evaluate the parameters of a multi-phase motor, as they require a multi-phase signal that is pure sine wave in nature. However, multi-phase transformers are not suitable for variable frequency applications. Moreover, they have shortcomings with regard to impedance mismatching, the unequal number of turns which lead to inaccurate results in per phase equivalent circuits, which results in an imbalance output in phase voltages and currents. Therefore, this paper aims to investigate multi-phase power transformation from a three-phase system and examine the different static multi-phase transformation techniques. In line with this matter, this study outlines various theories and configurations of transformers, including three-phase to five-, seven-, eleven-, and thirteen-phase transformers. Moreover, the review discusses impedance mismatching, voltage unbalance, and per phase equivalent circuit modeling and fault analysis in multi-phase systems. Moreover, various artificial intelligence-based optimization techniques such as particle swarm optimization (PSO) and the genetic algorithm (GA) are explored to address various existing issues. Finally, the review delivers effective future suggestions that would serve as valuable opportunities, guidelines, and directions for power engineers, industries, and decision-makers to further research on multi-phase transformer improvements towards sustainable operation and management.

Equivalent circuit modelling of a three-phase to seven-phase transformer using PSO and GA

Impedance mismatching between different phases of a multiphase transformer is generally observed e.g., in a three-phase to seven-phase transformer, due to an unequal number of turns in different coils. This mismatching introduces error in the study of per phase equivalent circuit diagrams as well as induces an imbalance in output voltages and currents. Therefore, it is a challenging task to develop a per-phase equivalent circuit for the secondary and primary sides (In some cases) too. This paper proposes an artificial intelligence optimization technique like PSO based modeling of the per-phase equivalent circuit of the secondary side. This paper deals with the modeling and simulation of a three-phase to seven-phase power transformer using Artificial Intelligence technique like particle swarm optimization (PSO) and Genetic Algorithm (GA). The proposed model is optimized through PSO and GA algorithms and tested for minimum voltage error in each phase. The proposed model is designed and the objective function is optimized by PSO & GA in MATLAB environment. It is found that the optimized model can be effectively implemented as a per-phase equivalent circuit for the secondary side.

Analysis of a three-phase to seven-phase transformer under unbalanced input

In the recent past, multiphase power generation, power transmission, and multiphase drive system are the main focus of research due to their several advantages over existing three phase system. Multiphase drives have better performance over three-phase drives. A multiphase transformer is required at the input of a fixed frequency multiphase drive, rectifier circuit for HVDC applications and multiphase generation and transmission systems. This paper investigates an static three-to seven-phase conversion technique and presents a design of transformer and control strategy to analyze the effect of unbalanced supply on a three-phase to seven-phase transformer. The transformer presented in this paper takes three phase input and a seven-phase output is obtained at the secondary terminals. The paper also discusses input–output unbalancing. A complete design, analysis and simulation of the proposed transformer is presented and experimental validation is also reported in this paper. Experimental and simulation results show that the presented transformer can produce a seven-phase power from three-phase ac power. Input unbalance is reflected at the output of the transformer but is less than the input unbalance. It is also shown that seven-phase output is not produced if one phase of input is open and the transformer has more than three limbs for flux to flow. But a balanced seven-phase output in steady state is produced even in one phase open condition for a three limb core type transformer. A new definition of sequence components of an unbalanced seven-phase system is required for unbalancing study so it is also defined in this paper.

Analytical Expressions to Link SCNF and OCNF of Transformer Windings to Their Inductances and Capacitances for 1-$\Phi$, 3-$\Phi$ Y and $\Delta$ Configurations

Recently, the present authors’ research group derived an analytical expression to link the harmonic sum of the squares of short circuit natural frequencies (SCNFs) of a single, isolated winding to its elementary inductances and capacitances. Also, it was demonstrated how this expression could be practically used for locating radial and axial displacements, along with assessing its severity on a single, isolated, actual transformer winding. The next logical task was to extend the derived expression to multi-phase windings, viz., star/delta connections and for any terminal condition of the neutral. Actually, it would be desirable to have a similar expression for open circuit natural frequency (OCNF) as well. A major highlight of this paper is that it presents a single, unified approach (using salient features of coefficients of the numerator and denominator polynomial of driving-point impedance) by which compact analytical expressions can be simultaneously derived for both SCNF and OCNF, for any multi-phase transformer configuration, and for any condition of the neutral terminal. Complete derivation details of the proposed method are presented, and then, the expressions for SCNF and OCNF are derived for 1- $\Phi$ isolated windings as well as 3- $\Phi$ (Y, $\Delta$ ) configurations. Finally, simulation results for all the cases are reported.

Design and Simulation of Power Converting Three-Phase to Multi-Phase Transformer

Design and Simulation of Power Converting Three-Phase to Multi-Phase Transformer

Design and Simulation of Power Converting Three-Phase to Multi-Phase Transformer

Design and Simulation of Power Converting Three-Phase to Multi-Phase Transformer

A Novel Scheme of Three to Eleven Phases Transformer Connection by using MATLAB Software

A novel scheme of three to eleven AC multiphase transformer to convert into DC power through modeling. The whole modeling has been simulated by using MATLAB Software. Multi-winding transformer block was taken from the sim-power system block library and turn ratios set in the dialog box then simulated. The complete design and simulation of the proposed work is presented in this paper. Now we have mentioned the simulation results only for RL load. Eleven phase transmission system can be developed for the generation of bulk power transfer. As per need of the induction motor under a loaded condition is used to proof the viability of transformation system. In eleven phase's, each phases shifted from the order by 32.73° (360°/11) and got the sin wave voltage/current. The connection scheme was expanded by using the modeling and simulation approach to prove the viability of the implementation.

A Novel Three Phase to Seven Phase Conversion Technique Using Transformer Winding Connections

This paper proposes a novel multiphase transformer connection scheme which converts three phase balanced AC input to seven phase balanced AC output. Generalized theory to convert a three phase utility supply into any number of phases is presented. Based on the proposed generalized principle, a three phase to seven phase power converting transformer design is presented with connection scheme, analysis and simulation and experimental results of the proposed three phase to seven phase conversion transformer. The proposed transformer in this paper is analyzed and compared with the connection scheme for seven phase available in the literature. The connection scheme is found to have higher power density, lower core area and lower core requirement as compared to the available connection scheme of the same rating. Impedance mismatching between different phases of the transformer is observed in the three phase to seven phase transformer available in the literature. As this mismatching introduces error in study of per phase equivalent circuit diagrams as well as imbalance in voltage and currents. The present design also addresses the impedance mismatching issue and reduces mismatching in the proposed transformer design. A prototype of the proposed system is developed and waveforms are presented. The proposed design is verified using simulation and validated using experimental approach.

Generation of Dc-dc Converters With Wide Conversion Range Based on the Multistate Switching Cell

This paper presents the conception of six nonisolated dc-dc converters with wide conversion range based on the multistate switching cell (WCR-MSSC). In order to achieve wide conversion range, the multiphase transformer that is part of the multistate switching cell (MSSC) aggregates coupled secondary windings with controlled rectifiers, which are then connected in series. Then, it is possible to minimize the voltage stresses across the switches, allowing the use of MOSFETs (metal oxide semiconductor field effect transistor) with reduced on-resistance RDS(on), thus implying the significant improvement of the converter efficiency. The operation principle, qualitative analysis, quantitative analysis, and design procedure are properly presented. An experimental prototype is also developed, whose ratings are: output power PO=3 kW, input voltage VIN=84 V and output voltage VO=400 V. Some important results are then discussed in order to validate the theoretical assumptions.

Analysis of pulse transformer voltage ripple of invert type of modular structure

The mathematical models of voltage ripple in input and output circuits of pulse converters of DC modular structure with power channels of the inverting type are obtained and analyzed. The mathematical model is focused on the power of channels in the boundary mode operation that can reduce energy loss in the transformation. The mathematical model is generalized to the single-phase and multiphase transformation principles, auto-transformer and transformer connection of storage chokes of power channels. The methods and algorithms for calculating the voltage and current ripple in the input and output circuits of these converters are presented. The simulation results of the electrical processes in input and output converters with autotransformer turning of the choke are presented. It was established that the principle of multi-phase transformation reduces the magnitude of both fluctuations in the input and output circuits. This allows developing the converters with improved mass-dimensional and cost indicators.

ANALYSIS OF MULTIPHASE TRANSFORMER FOR STATIC LOAD

In the year of 1970 saw the starting invention of the five phase motor as the milestone in advanced electrical motor. Through the years, there are many researchers who passionately worked towards developing for multiphase drive system. They had developed a static transformation system to obtain a multiphase supply from the available three phase supply. This idea gives an influence for further development in electric machines as an example; an efficient solution for bulk power transfer. This paper presents the ability of Finite Element Method to proof the theory and concept in design multiphase transformer before proceeds to the fabrication stages. Identifying of specification on a real transformer had been done before applied in software modelling. The final part of this paper deals with the hardware construction of multiphase system with the static load to see the effect of phase current on variation of load.

Design of Five-Phase Transformer through Finite Element Simulation

The interests in multiphase (more than three) system are escalating recently especially in the motor drive applications. Thus, this paper introduces the graphical phasor diagram method in designing the multiphase transformer connection. The proposed method eases the design process of the static multiphase transformer that produces multiphase output from the standard three phase input. The transformer connection was simulated in ANSYS Maxwell and the multiphase waveform with appropriate phase angle was obtained. The design of five-phase transformer using graphical phasor and simulation results from the finite elements software are presented in this paper.

A static three-phase to five-phase transformer based on Scott connection

Multiphase machines have become challenging candidates for safety-critical applications that require wide fault tolerant capabilities and higher system reliability. However, this adds more complexity to the adopted power converters. In applications such as electrical submersible pump (ESP) systems, motor electric power is commonly fed using a three-phase low voltage variable frequency drive system (VFD) followed by a step-up transformer and a medium voltage long feeder. Application of multiphase machines in such applications was recently shown to provide possible benefits, however, this necessitates a more complex multiphase power converter and a multiphase transformer. Alternatively, a passive transformation is a viable and more economical solution to step up the three-phase output of a standard off-the-shelf three-phase inverter and convert it into n-phase secondary voltages. This paper investigates the existing connections of passive transformation and proposes a transformation, based on the well-known Scott connection, to convert the three-phase grid voltages to an n-phase supply. In comparison with other connections in the literature, the proposed connection uses only two magnetic cores and less number of total coils, hence less transformer volume. The paper also introduces the general per-phase equivalent circuit for three-phase to n-phase transformer, and the required modifications to conventional open-circuit and short-circuit tests to estimate the transformer parameters. A case study is carried out for a three-to-five-phase transformer to validate the proposed connection. Simulations as well as experimental investigations are presented.

Power quality improvement in DC electric arc furnace plants utilizing multi-phase transformers

SUMMARY Conventional feeding systems for DC electric arc furnace steel making plants usually include a 12-pulse rectifier that is fed by Δ/Δ and Δ/Y three-phase transformers. In this paper, with the use of the PSCAD/EMTDC software (Developed by Manitoba HVDC Research Center Inc., Canada), the advantages of applying multi-phase transformers for supplying such loads are evaluated and compared with the traditional three-phase power supply systems. A well-designed secondary winding for multi-phase transformer is proposed, and then the modeling of such transformers is discussed. With some proper power quality indices applied, it is shown that utilizing multi-phase transformers can lead to power quality improvement such as current/voltage harmonic reduction and unbalance mitigation. Copyright © 2012 John Wiley & Sons, Ltd.

Multiphase Transformer Effect and Harmonic Response Analysis of Accelerator Power System

Accelerator main dipole magnet system magnetic field regulation depends on its transmission line characteristic properties and its power supply system regulations. In addition, the main magnet AC power transformer configuration has indirect impact on the field quality of dipole magnet. A large accelerator main magnet system consists of hundreds, even thousands, of dipole magnets. They are linked together under selected configurations to provide uniform dipole fields when powered. When all dipole magnets are linked together in a synchrotron, they become a coupled pair of very high order complex ladder networks due to magnet parasitic capacitance, leakage resistance, and conductor resistance. In this study, we present multiphase transformer effect and harmonic response analysis of AGS main magnet system.