Low-power Transformers Research Articles

Designing Power Transformer Using Particle Swarm Optimization with Respect to Transformer Noise, Weight, and Losses

The increased use of electrical energy will encourage the installation of more power transformers in residential areas as well as in industrial areas. Each power transformer, in its operation, will generate noise that can interfere with comfort and, at some level, cause health problems. The design of the power transformer currently focuses on optimizing its economic side, so noise has not been considered at this design stage. This research is about optimizing the low noise transformer design. The main goal is to obtain a low noise power transformer with low production costs. The method used in this optimization is particle swarm optimization with a multi-objective function. The objective function consists of the minimization of load noise, core weight, and winding weight. In this study, 11 optimized variables were used. Some variables that are optimized must be in the form of integers. Therefore, the optimization process needs a mechanism for mapping variables. The results showed that a low noise power transformer could be designed at optimal cost. Design validation was performed analytically and numerically with COMSOL software. The optimization results showed a decrease in load noise, core, and winding weight by 0.86 dB, 2.12%, and 47.46%, respectively. The results of this optimization are better than the designs used regularly in the industry.

Conditions for distortion-free voltage transfer in the transformer

The optimal design of low-power transformers, sonic and ultrasonic transformers, pulse transformers, differential transformers, etc. requires an in-depth study of their theory and design calculation. In this article, the influence of transformer parameters on the voltage transfer ratio is discussed, and recommendations are given for the selection of values of these parameters to reduce possible distortions. The calculation methods are illustrated by an example.

A Modified Phase Shift Control of the Dual Active Bridge-Based Modular Power Electronic Transformer to Minimize the LVdc Side Voltage Ripples Under Unbalanced Load Conditions

Power Electronic Transformers (PETs) are considered as an emerging solution for power conversion due to their benefits over the low frequency power transformers (LFPTs) such as lower size, multi-port structure and different control functionalities. However, unbalanced load conditions may limit the reduction of size due to using bulky capacitors to absorb the resulting 2^nd harmonic voltage oscillations. This paper aims to provide a solution to this problem in the Dual Active Bridge (DAB)-based Modular Multilevel Converter Power Electronic Transformers (MMC-PET). In this study, a modified phase shift control strategy for the DAB isolation stage is presented. In this strategy, the duty cycle is allowed to change sinusoidally around the operating point. This consequently transfers the power oscillations to the HV side where their effect is less significant. The system is simulated using Matlab-Simulink under different unbalanced load conditions. Besides, the theoretical analysis and the simulation results are experimentally validated using a laboratory prototype. According to the obtained results, the proposed controller succeeded to reduce the voltage ripples from 7.5% to 0.2% and this helps in replacing large Aluminum electrolytic capacitors with low size film capacitors and consequently reducing the system overall size and volume which is a great benefit.

Автономный инвертор для однофазного активного фильтра гармонических искажений судовой сети

The article focuses on the problem of documentary control of the level of harmonic distortions in the ship power network. It has been proposed to use active filters to improve the quality of electric flow on board a ship. There is given a block diagram of the active filter. The methods of designing power electronic devices have been studied. A device for converting DC voltage into sinusoidal AC was designed on the platform of the STM32F4 debug board. The device includes a control system, power amplifiers, short circuit protection and power switches. A low power transformer is provided to convert voltage levels. The controller software was developed using the MATLAB / Simulink software package, and the board was debugged and flashed. Comparison of the device stability and the generated signal quality at different carrier frequencies has been made. It has been stated that the software for the device operation consists of two levels: the lower (code to the microcontroller) and the interface (which communicates and transfers data in real time to a personal computer). Oscillograms of voltages and currents at key points of the converter's electrical circuit are shown. The data obtained from the operation of the device made it possible to evaluate the assembly quality and to determine the scope of application of the developed device. The device is capable of generating a signal of a given frequency and amplitude including interharmonic components, which makes it possible to use it as an active current filter for power systems on ships.

ENERGY EFFICIENT WATER-COOLED ELEMENTS FOR FOUNDRY CLASS ELECTRIC ARC STEELMAKING FURNACES

Low energy efficiency of foundry class electric arc steelmaking furnaces (EAF) mainly is caused by heat loss by massive lining during forced downtime. A low-power transformer doesn’t allow, in the conditions of classical technology, practice of traditional water-cooled elements in order to replace partially the lining, what determines increased refractory consumption. The aim is energy and refractory savings. On the basis of numerical modeling of heat exchange by radiation in the EAF working space, taking into account capacity, bath shape factor, duration of technological period of heat, a multiple regression equation for power of heat loss with cooling water was obtained. Three-row water-cooled wall panels with a spatial structure are elaborated, which provide a decrease in heat loss by 14 %, in comparison with two-row ones. Estimates of optimal relative cooled surface of the EAF working space, providing refractory savings up to 25-30%, are substantiated.

Development of a Module for Measuring Electrical Variables in Power Transformers Based in IoT, to Manage and Monitoring by Telemetry Mechanism

This work shows the development of a module that performs measurements of electrical variables in a low voltage power transformer. These variables are sent by means of the IEEE802.11 standard, connecting to a database stored in the cloud; associating with the meter IoT concepts, this to allow a client to perform an analysis, monitoring and management of their electrical network. For the construction of this module, non-invasive current sensors connected to a three-phase meter are used and a communication card is used that allows data to be extracted from the meter and sent to the cloud database. This module, to convert a conventional electrical power transformer into a smart electrical power transformer, making it a Smart Object and thus extract information from it telemetrically in real time.

Evaluation of errors of the wattmeter method for determining magnetic losses in transformers

The problem of the influence of the accuracy of dividing magnetic losses into components in transformers on the efficiency of minimizing these losses is considered. Various methods of studying and evaluating the magnetic properties of electrical steels and the power of magnetic losses are described. It is shown that the use of the wattmeter method for determining the components of magnetic losses in a specific transformer, in contrast to the currently used methods for determining the power of specific magnetic losses, does not require special equipment and software. An assessment of two specific errors of the wattmeter method for determining the magnetic losses in the transformer core is carried out. The first error is associated with the errors of the measuring devices (wattmeter and frequency meter), the second – with electrical losses during an idle experiment. The dependences of the errors of these losses on the accuracy class of the devices (wattmeter and cymometer) are obtained. It was found that for a dry single-phase transformer, the error of hysteresis losses is 19 times higher than the accuracy class of devices, and the error of eddy-current losses is 32 times. For low-power transformers (up to 5 kVA), taking into account electrical losses in the no-load experiment underestimates the losses due to hysteresis and overestimates the losses due to eddy currents, the error in determining which can significantly exceed the total error in determining the magnetic losses. It is shown that for transformers with a capacity of over 25 kVA, the error associated with taking into account electrical losses in the no-load test is negligible.

ОЦЕНКА ЭНЕРГЕТИЧЕСКОЙ ЭФФЕКТИВНОСТИ И ВОЗМОЖНОСТИ ИСПОЛЬЗОВАНИЯ В СЕТЯХ ПРОМЫШЛЕННЫХ ПРЕДПРИЯТИЙ СТАБИЛИЗАТОРА НАПРЯЖЕНИЯ С ФУНКЦИЕЙ ЭНЕРГОСБЕРЕЖЕНИЯ

The energy-saving voltage stabilizer belongs to the field of electrical engineering and can be used to supply power to electrical equipment, drives, motors, lighting networks, power supplies for communication systems, automation and telematics in order to optimize the operation of electrical equipment and energy saving. Reducing power consumption can be achieved by eliminating the consumption of the load unnecessary for normal operation of energy, and by reducing the amount of current and energy losses in the supply network. In addition, the service life of lighting and household electrical appliances will increase, which will operate at normal and not increased voltage. When the voltage decreases and the load consumes the same power, the current in the network increases in proportion to the decrease in voltage, which will cause overheating of the network elements to the place where the stabilizer is installed, the operation of automatic devices, fuses and other protection elements, i.e. interruption in power supply to consumers. Any stabilizer is not a source of energy, and its use with a significant decrease in the voltage in the network (power shortage) does not give the desired result. ECE of such stabilizers is 95-97%, that is, up to 5% of energy is lost in the regulating device, which limits their use in order to save energy, as well as increase the weight, dimensions and cost. The proposed device is based on the use as a regulating body of a low-power transformer operating in the autotransformer mode with a transformation ratio close to 1. By switching the high-voltage winding of the transformer under load without breaking the circuit, 3 operating modes of the device are obtained. Control devices are used: to reduce electricity consumption by up to 20% in residential and public buildings, shops, outdoor lighting networks; to ensure the normal operation of numerically controlled machines, technological lines, etc. It has no analogs in terms of simplicity of the scheme, payback (about two years), and reliability of operation. It will reduce the unnecessary energy consumption allowed worldwide by at least 10% and network losses by up to 40%.

Researching and modelling of unbalanced regimes in systems of household electric power consumers

The modelling of the operation modes of the 0.38/0.22 kV power supply systems by the Monte Carlo method using the Electronics Workbench computer program is considered, and statistical processing of simulation results and testing of the Pearson distribution law hypothesis using the Mathcad program are carried out. An analysis of existing power supply systems has been carried out and an alternative, economically feasible version of the power supply system is proposed, where consumers are powered by low power transformers mounted on supports. The performed studies showed that the variation of the load currents in the segments and the losses of electric energy in an asymmetrically loaded network of 0.38/0.22 kV are subject to the normal distribution law and that the consumers who feed on the traditional power supply system have unsatisfactory quality of electrical energy.

Comparison of three-phase transformers with rectangular and circular conversion of laminated magnetic cores (active power losses)

Purpose. In the mass production of low-power transformers, magnetic cores and windings are used with rectangular sections of rods and forming the contours of the coils turns. The contours of medium and high power transformers active elements are circles. The cross sections of the magnetic cores form rectangular steel packages of various widths with filling coefficients of circular circuits 0,786–0,925 at a power of 16–10000 kV·А. In recent decades, rectangular contour generators of planar electromagnetic systems have also been used in the transformers manufacture with a more than 250 kV·A capacity. The use of rectangular sections instead of rods circular cores changes the consumption of materials and active power losses. Therefore, it is of theoretical and practical interest an analytical substantiation of the expediency of such a replacement. Methodology. A comparative analysis of hree-phase transformer variants is performed by the method of generalized invariant structural-parametric synthesis. Target functions are used with a component of the source data and electromagnetic loads and dimensionless components. The dimensionless optimization components of mass and cost are functions of relative geometric controlled variables. The loss component additionally depends on the relative electromagnetic controlled variable. The values of optimization components are indicators of the objective function, and their minima represent the technical level indicators of transformer. Results. The indicators are determined with same source data and loads, which corresponds to electromagnetic power of the compared options identity. Calculations are performed in real range of electromagnetic controlled variable variation of dry and oil transformers. This eliminates the dependence of loss indicators on power, method of heat removal and other factors. Originality. It has been established that, in addition to improving the mass-carrying indices, a reduction in losses of three-phase transformers is achieved when replacing circular forming circuits to rectangular circuits. Practical value. The reduction of loss of transformers of voltage range 1–110 kV with rod laminated magnetic cores, copper and aluminum windings with rectangular generating circuits relative to analogs with circular circuits is 6,3–8,9 % and 2,64–3 % with the rods filling factor 0,786 and 0,925.

Research on resonance parameters matching based on partitioned operation method of atmospheric pressure plasma reactor array

Matching optimization of resonant parameters among the high power inverters, low power transformers and plasma reactors have significant effects on the performance and output of the reactor array when applying the partitioned operation method. In this paper, the Matlab/Simulink electrical model was established based on the method of partitioned operation. The matching relation between resonant parameters is analyzed on the basis of experimental result. As a consequence, transformer leakage inductance and working frequency are the important parameters influencing the operational efficiency of system, leakage inductance of transformer should be adjusted based on the equivalent capacitance of plasma reactor to realize the matching optimization of resonant parameters.

Investigation on Mechanical Resonance Induced by Magnetostriction in a Structure Based on Si-Fe Sheets

The noise generated by rotating machines and electrical transformers is harmful and its reduction has been the subject of several studies. Such systems are likely to come into resonance and become noisier. This resonance may come from mechanical or magnetic forces. The phenomenon of resonance is usually studied only if the frequency and the known spatial distribution of the excitation force are consistent with the natural frequency and the shape of the corresponding mode of the structure. We demonstrate in this paper that magnetostriction can induce resonance without, however, knowing its spatial distribution. A ferromagnetic frame made of a stack of non-oriented electrical steel (e.g., low-power transformers for railway applications) is used to confirm that mechanical resonance can be induced by magnetostrictive strain at a very low magnitude in in-plane and out-of-plane directions. Finite-element calculations are performed with laminated model and vibratory measurements are presented. A numerical model based on homogenization technique is also detailed. Then, experimental and computation results are analyzed and compared. Finally, results of resonance under magnetization when double the magnetizing frequency matches the resonance frequency of the ferromagnetic frame are described as well as the corresponding spectrum.

A 60 GHz low power direct‐conversion quadrature‐phase transmitter in 130 nm CMOS with low profile cavity backed antenna

ABSTRACTThis article presents the analysis, design, and implementation of a 60 GHz transmitter in 130 nm bulk CMOS, focusing on low power and high performance applications. The low power transmitter lineup consists of two double‐balanced Gilbert‐cells with dynamic current injection, on chip FGCPW meandering ring‐hybrid balun, Lange coupler, combiner, preamplifier, and low power transformer coupled power amplifier. A planar antenna with above 6 dB gain is also implemented. The measured output −1 dB compression point of the power amplifier is 9.6 dBm with 8.6 dB gain, and the 3 dB bandwidth is from 47 to 67 GHz (power amplifier) while drawing 90 mA from a 1.2 V supply. The mixer, preamplifer, and drive amplifier consume 12, 26, and 68 mA, respectively. The transmitter up‐converting an IF of 200 MHz to RF at 60.2 GHz achieve a total gain of 17.17 dB (simulated 21.09 dB) and saturation power higher than 9.53 dBm. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:785–789, 2015

Unequal Wilkinson power divider with wide range of arbitrary power division based on recombinant technology

An arbitrary ratio Wilkinson power divider with large power dividing ratio is analysed and demonstrated in this study. This kind of Wilkinson power divider is constructed by incorporating equal (or unequal) power divider cells, recombinant structures, extra low power branches and transformers for matching the circuits. The proposed structure is compatible with single-layer printed circuit board fabrication process. The structure is analysed in detail, while the formulas are given as design guidelines. Moreover, this method is extended to unequal power dividers based on three-way Wilkinson power divider with larger dividing ratio. To verify the proposed design approach, the prototypes of 5:1, 7:1 and 11:1 unequal power divider are optimised, fabricated and measured. The measured bandwidth of 20 dB return loss are about 10, 10 and 6%, respectively, while the isolations of the output ports are better than 20 dB. Good agreements can be observed between the simulated and measured results. The phase differences of output ports are within ±3° over 10% fractional bandwidth.

A Study of Waste-Heat Recovery Unit for Power Transformer

This study discussed the feasibility of developing a system to circulate the heat loss from the coil and iron core of the power transformer equipped for buildings during power supply to the heat recovery unit. This study affixed a copper tube into the transformer insulating oil, allowing the water to circulate at normal temperature in the coil tube, and absorb the heat energy generated by the transformer coil and iron core. The heat energy was then recovered and stored. A low tension power transformer (7.5 KV) was used in the experiment. The operation was carried out in transforming power supply mode to seek for the most suitable recovery unit for various occasions. The test results showed that if the hot water recovery efficiency is 50%, in the course of producing hot water, the mean temperature of 17.5 L normal temperature water can be increased from 20°C to 50°C, thus producing 12.5 kJ heat only spends about 34 min. The results proved that the recovery unit for the heat from the power transformer can benefit from heating, prolong the transformer's lifetime, increase the power supply efficiency, and reduce the air conditioning load to save energy and to reduce global warming.

Dedicated Rewriting: Automatic Verification of Low Power Transformations in Register Transfer Level

We present dedicated rewriting, a novel technique to automatically prove the correctness of low power transformations in hardware systems described at the Register Transfer Level (RTL). We guarantee the correctness of any low power transformation by providing a functional equivalence proof of the hardware design before and after the transformation. We characterize low power transformations as rules, within our system. Dedicated rewriting is a highly automated deductive verification technique specially honed for proving correctness of low power transformations. We provide a notion of equivalence and establish the equivalence proof within our dedicated rewriting system. We demonstrate our technique on a non-trivial case study. We show equivalence of a Verilog RTL implementation of a Viterbi decoder, a component of the DRM SoC, before and after the application of multiple low power transformations. We further demonstrate the application of our technique on a completely different kind of hardware circuit, viz. microprocessors. We show the correctness of instruction-driven slicing algorithm as applied to the OR1200 microprocessor.

Design and implimentaton of a model (ATLC-2007DNM) of an automated traffic light controller

In this work, a model of an automated traffic light controller (ATLC –2007DNM) had been designed and implemented, using electronic instrumentation and experimental techniques in electronic engineering and physics, to manage the traffics at the busy four- ways junctions along Sahuda road in Mubi North,Adamawa State, Nigeria. The designed was achieved with the help of low power transformer rating of 3.6 watts, time base (555 timer), decade counter, D-flip-flop, timing sequence selector for red, green, amber and yellow light and relay circuit for switching the appropriate light. The average volume of vehicular traffics observed for the period of one week (4/4/07 – 11/4/07) for Masalachi, Stadium, Sahuda and Sarki roads are 2368, 1996,1982 and 138, respectively which prompted the development of the model (ATLC – 2007DNM) to allowed 17.50s, 14.00s, 10.50 and 7.00s accordingly. This model is capable of eliminating the inefficiency and likely error associated with human traffic controller by minimizing accident and unnecessary traffic jams at the junction. Key word: Traffic light, four-way junction, traffic jam.

On the development of a core for a low-power transformer on a basic of wasteless technology

Innovations in critical technology for the production of magnetic materials is considered. On the basis of these innovations, a new design of a low-power transformer is proposed. The operating characteristics of transformers of the pilot and analog design are studied.

Case-based reasoning approach to concurrent design of low power transformers

In current practice, product design and process design of low power transformers are done sequentially in which quite a number of activities are mainly performed by engineers. Therefore, the time for the development of low power transformers and the quality of the product and process design are largely dependent on the experience of the engineers. In this paper, an artificial intelligence technique, case-based reasoning, is introduced to perform the concurrent product and process design of low power transformers from which a prototype concurrent design system for low power transformers, named CBS-TX, was developed. The prototype system aims to assist design engineers in formulating a configurable design of low power transformers in short time and provide the process information in the early design stage. In the system, the previous successful design cases and their corresponding process solutions are stored in a case library. After the input of design problems, the case-based system performs the case retrieval, and similarity analysis. A number of the closest matching cases are then selected and adapted. After the adaptation, case evaluation is then performed on them based on techniques for order preference by similarity of ideal solution (TOPSIS) algorithm and hence a concurrent design solution of low power transformers can be obtained.

Leakage flux in a single phase transformer

The effects of aluminium magnetic shielding and mild steel magnetic shunts on the leakage flux in the steel tank of a single-phase 50 Hz low power transformer have been investigated.