Increased Frequency Alternating Current Systems for the Electrothermal Processing of Composite Materials

In recent years, considerable attention has been given to find the compact and low cost power converter topology for Switched Reluctance Motor (SRM) drive to meet the emerging applications such as plotters, fans, pumps, screw rotary compressor drives, high speed application drives above 30,000 RPM. This paper is concerned with such as attempt to formulate a new compact power converter for SRM drive. The proposed power converter has reduced number of power electronic components which makes the converter compact and also reduce the switching losses. The power factor plays a vital issue in the usage of power electronic converters. The power boost converter and PI controller. A Simulink system is developed for 3Φ SRM by using MATLAB software. The proposed converter performance is compared with the classical converter and analysis results are presented.

Dispersion-strengthened composite materials belong to the group of promising structural materials characterized by a diverse combination of properties. The work presents examples of the creation and heat treatment of composite materials based on aluminum alloys, strengthened by a dispersed phase of titanium carbide, and characterized by high hardness, elastic modulus and good wettability by the melt. The most accessible, inexpensive and effective way to obtain them is self-propagating high-temperature synthesis (SHS).The work shows the possibility of obtaining new aluminum matrix composite materials based on industrial aluminum alloys AM4.5Kd and AK10M2N by reinforcing them with 10 wt.% highly dispersed titanium carbide or AM4.5Kd–5.95 vol.% TiC and AK10M2N–5.78 vol.% TiC. The reinforcing phase is formed in alloy melts using the technology of SHS from the initial elemental components—titanium powder and carbon black. Using the obtained samples, an assessment was made of the uniformity of the ceramic phase distribution over the volume of the matrix alloys, which amounted to 0.15 and 0.12 for the samples AM4.5Kd–10%TiC and AK10M2N–10%TiC, respectively, which constitutes a high degree of uniformity.An assessment was made of physical properties such as porosity, density, electrical conductivity, as well as the coefficient of thermal linear expansion. Analysis of the data allows us to say that the final composite materials AM4.5Kd–10%TiC and AK10M2N–10%TiC have a slightly higher density (↑~4%) than the matrix alloys, due to the presence of a ceramic phase, low porosity values (~1%), lower TCLE (↓~6%) than matrix alloys and low electrical conductivity (~25% IACS). This article also presents data on the values of the mechanical properties of composite materials AM4.5Kd–10%TiC and AK10M2N–10%TiC. It has been shown that reinforcement with a ceramic phase contributes to a significant increase in hardness by 15 and 42 HB, as well as higher values of the compressive yield strength by 31 and 17 MPa, respectively, while maintaining a high level of relative deformation. The results obtained allow us to conclude that the developed composite materials can be recommended for products used under conditions of elevated temperatures and significant wear.

Existing laboratory furnaces for high-temperature heat treatment of materials at around 3000°C, which have graphite heaters, allow samples to be heated at a rate two orders of magnitude lower than in electrothermal fluidized bed furnaces. This makes it impossible to use them in the research into the heat treatment of carbon materials because they do not meet the conditions of shock heating and do not allow to keep accurate residence time. The paper presents the research into the use of low-density composite carbon materials as heaters. Based on the results obtained, a high-temperature chamber furnace was designed, studied, and the temperature field in the heater was simulated. As a result, a high-temperature laboratory furnace was created with a sample heating rate of 20 °C/s - 100 °C/s, which made it possible to use it to simulate the heating process in the electrothermal fluidized bed furnace. Comparison of energy consumption in the furnace with a traditional graphite heater and a low-density carbon composite heater showed that heat loss in the furnace is reduced by 1.7 to 1.8 times.

Early diagnosis of Alzheimer's and epilepsy requires monitoring a subject's development of symptoms through electroencephalography (EEG) signals over long periods. Wearable devices enable convenient monitoring of biosignals, unlike complex and costly hospital equipment. The key to achieving a fit and forgettable wearable device is to increase its operating cycle and decrease its size and weight. Instead of batteries, which limit the life cycle of electronic devices and set their form factor, body heat and environmental light can power wearable devices through energy-scavenging technologies. The harvester transducers should be tailored according to on the application and the sensor placement. This leaves a wide variety of transducers with an extensive range of impedances and voltages. To realize an autonomous wearable device, the power converter energy harvester, has to be very efficient and maintain its efficiency despite potential transducer replacement or variations in environmental conditions. This thesis presents a detailed design of an efficient integrated power converter for use in an autonomous wearable device. The design is based on the examination of both power losses and power transfer in the power converter. The efficiency bound of the converter is derived from the specifications of its transducer. The tuning ranges for the reconfigurable parameters are extracted to keep the converter efficient with variations in the transducer specifications. With the efficient design and the manual tuning of the reconfigurable parameters, the converter can work optimally with different types of transducers, and keeps its efficiency in the conversion of low voltages from the harvesters. Measurements of the designed converter demonstrate an efficiency of higher than 50% and 70% with two different transducers having an open-circuit voltage as low as 20 mV and 100 mV, respectively. The power converter should be able to reconfigure itself without manual tunings to keep its efficiency despite changes in the harvesters' specifications. The second portion of this dissertation addresses this issue with a proposed design methodology to implement a control section. The control section adjusts the converter's reconfigurable parameters by examining the power transfer and loss and through concurrent closed loops. The concurrent loops working together raise a serious concern regarding stability. The system is designed and analyzed in the time domain with the state-space averaging (SSA) model to address the stability issue. The ultra-low-power control section obtained from the SSA model estimates the power and loss with a reasonable accuracy, and adjusts the timings in a stable manner. The entire control section consumes only 30 nW dynamic power at 10 kHz. The control section tunes the converter's speed or its working frequency depending on the available power. The frequency clocks the entire architecture, which is designed asynchronously; therefore, the power consumption of the system depends on the power available from the transducer. The system is implemented using 0.18 µm CMOS technology. For an input as low as 7 mV, the converter is not only functional but also has an efficiency of more than 40%. The efficiency can reach 70% with an input voltage of 50 mV. The system operates in a range of just a few of millivolts to half a volt with ample efficiencies. It can work at an optimal point with different transducers and environmental conditions.

The research carried out is aimed at developing the scientific basis for obtaining new composite materials based on high-entropy alloys, as well as developing the basic principles of processing and operation of such materials. It was necessary to conduct a theoretical and experimental study of the physical-chemical processes occurring during the interaction of high-entropy alloys with reinforcing TiC particles, as well as to study the effect of temperature and composition of interacting phases on the interaction process and its results. Thermodynamic and kinetic modeling of the interaction processes of the matrix components of high-entropy alloys based on the Cantor alloy (FeCoCrNiMn), including titanium and carbon with the formation of titanium carbide was carried out. Modern modeling approaches were used, which makes it possible to implement modern software. In particular, thermodynamic modeling using methods developed within the framework of the Calphad approach was carried out. Thermo-Calc software (includingTC-PRISMA kinetic modeling software) and FactSage software were used in the research process. An experimental study of the composition and structure of samples of TiC-reinforced metal matrix materials (using electron microscopy, X-ray spectral microanalysis and XRD) was also carried out. The distribution of various elements in the microstructure of materials and their phase composition were investigated. Comparison of the simulation results with experimental data allowed to make conclusions about the qualitative adequacy of thermodynamic and kinetic models of phase equilibria and phase transformations occurring during the formation, possible heat treatment and operation of TiC-reinforced metal matrix materials at high temperatures to the observed experimental data.

Thanks to the inherent features of small volume and light weight, high frequency power transformers are widely used as the key module for DC power supply. With the increasing prevalence of DC power technologies, high frequency power transformers are widely implemented in large scale DC conversions. However, conventional iron-core materials used in high frequency power transformers inhibit the raising of power capacity and frequency because the ideal iron core materials with excellent high frequency performance and low power loss are not readily available. In this paper, a new type of power transformer is proposed using magnetic resonance coupling and air-core techniques. Theoretical analysis is conducted based on π-shape model of iron-core high frequncy and circuit theory of resonant coupling wireless power transfer. After that simulation models are built using the parameters fulfilling the mentioned voltage ratio with Pspice software package. And output power as well as transfer efficiency are calculated. We observed that the stray capacitors which are very small compare to coupling capacitor have little impact on tranfer property. Meanwhile, the stray capacitor C01 and C02 have stronger impact than C12. To get the same voltage ratio, the Series-Series and Series-Parallel model have different parameters. Besides, the two type models have different property to load resistance and coupling coefficient.

The paper addresses the problem of predictive maintenance in high power supply systems. According to FMECA (Failure Mode, Effects and Criticality Analysis) study key issues for power system reliability are the faults occurring in 3-phase high power transformers. With respect to the state of art where typically only thermal and electrical faults are monitored this work proposes a distributed network of measuring nodes where also vibration-based mechanical stress diagnostic is implemented. Mechanical degradation is tracked through multichannel vibration measures with sensitivity down to 0.5 mg and local processing in the transformed frequency (100 Hz–1 kHz) domain. A compact hardware-software implementing platform is also presented whose performances are assessed through experimental measurements on real high power transformers used in railway applications.

In this article, an improved Multistage Switched Inductor (M-SI) based power converter or Improved Multistage Switched Inductor Boost Converter (Improved M-SIBC) is proposed for renewable applications which provides a key to enhancing the voltage conversion ratio. In the last decades, Switched Inductor (SI) and M-SI are the popular network/technique employed in DC-DC converter to achieve a high voltage conversion ratio. An improved SI and M-SI network/technique is proposed to enhance the existing the voltage conversion capabilities of SI and M-SI by replacing central uncontrolled switches by polarized capacitor. The anticipated power converter configuration combines the feature of the conventional boost converter and improved M-SI. The voltage conversion a capability is depends on the number of stages of M-SI and ON time of the control switch. The operation modes and characteristics of the proposed converter with steady state mathematical analysis for N-stages are discussed in detail. Moreover, the proposed converter compared with the existing converter in terms of the voltage conversion ratio and the detail of the number of components is also provided. Matrix Laboratory R2016a simulation results of 100W proposed improved M-SIBC with considering three stages are provided and the results always show a good agreement with theoretical analysis and also validates the improved M-SI network concept.

The construction industry has experienced the hugest number of changes during all century’s history. Today in construction there is a huge set of scientific completions and innovative solutions that many times increase quality of works and process reliability of construction in general. This publication is devoted to an innovative element for strengthening building constructions and elements - to high-strength composite materials. Due to inevitable exhaustion of natural resources and increase in energy cost in the world the process of composite materials production in industrial is becoming more relevant, important and popular, such as fibreglass, basaltplastic, carbonoplastic. These composite materials possess sufficient characteristics on reliability, durability, profitability and that is the most important - environmental friendliness in comparison with the metal reinforcing elements. It is important that source replenishment of raw materials in modern production is possible due to processing of secondary raw materials and technogenic waste. Experience of using composite materials during strengthening building constructions, the comparative analysis from the point of ecology production and using materials, advantages of composite materials is reflected in this publication. The purpose of this publication is to show validity of using composite materials for strengthening building constructions from the point of view of reliability, profitability and also environmental friendliness in comparison with other reinforcing elements.

The article is dedicated to improving the quality of apple puree with xylitol for dietetic nutrition due to the development and implementation of a new technological process. This is microwave boiling of apples, rather than traditional steaming using saturated steam before chopping, with the development of a device for its implementation and multilevel high-temperature sterilization modes with prebake of apple puree in glass jars in microwave EMF. The analysis of research and technical data proved that pre-heat treatment of apples with saturated steam and traditional sterilization modes have a considerable duration, which impairs the finished products quality and has an adverse effect on the nutrient composition of the raw material during processing. Substituting the traditional method of pre-heat treatment of apples for their short-time processing in microwave EMF reduces the process by more than twice, which, in turn, contributes to an increased preservation of the nutrient composition of apples, while enhancing the yield of apple puree. For the implementation of microwave processing method of raw materials, a new design of the device for electromagnetic treatment of plant roughage has been developed, providing a uniform and more intensive heat treatment of raw materials in a continuous flow. Rapid multilevel high-temperature sterilization modes with the application of apple puree in glass jars in microwave EMF, liquid high-temperature heat devices and an autoclave basket, providing the opportunity for thermal sterilization of the product without creating reverse pressure in the machine, generally contribute to reducing heat costs and increasing the nutritional value.

The use of induction heating for pasteurization of food raw materials is proposed. (Purpose of the study) Creation of an energy-efficient method of heat treatment of food raw materials using a pasteurization tank heated by induction currents. (Materials and methods) The pasteurization container is made of AISI 304 stainless steel. Plates made of AISI 430 ferritic stainless steel are welded on the tank to localize the induction heating site. The frame for the inductor was developed using the Fusion 360 automated programming system and printed on a 3D printer made of a polymer material, the choice of which is determined by the maximum operating temperature. A litecenter is selected as the winding of the inductor. Attention is paid to the constructive solution of the location of inductors. The design of the basic electrical circuit of the power part of the prototype device was carried out in the multifunctional program for computer-aided design of electronic circuits Proteus 7.10. (Results and discussion) A prototype induction type installation for pasteurization of food raw materials has been developed. The proposed solution for the arrangement of inductors leads to uniform and rapid heating of the container material and, accordingly, the raw materials in contact with it. The choice of a litzendrate in the manufacture of an inductor made it possible to increase the quality factor at the operating (resonant) frequency of the power unit. Using a thermal imager, thermographic images show a change in the thermal field when the container is heated by different devices. At the same time, the time to reach the required heating temperature with the help of the developed inductor system increases. To control the operation of the prototype pasteurization device, a hardware and software complex has been developed that allows you to set pasteurization parameters, control the process and create a report on the pasteurization session. Thanks to the developed control system, the electromagnetic field can be precisely controlled, which makes it possible to easily heat a small area of the material to a high temperature without affecting the surrounding space. (Conclusions) The proposed pasteurization method is more energy efficient than other methods such as resistive heating, since less energy is required for the same amount of material. The use of induction heating for pasteurization plants of raw materials allows them to be made energy efficient, less bulky, and more environmentally friendly.

On the evolution of welding residual stress after milling and cutting machining

This paper presents an isolated battery charger which is configured by a seven-level AC-DC power converter and an isolated DC-DC power converter. The seven-level AC-DC power converter is composed of a diode rectifier and a three-port DC-DC power converter. The three-port DC-DC power converter generates a four-level voltage at the DC bus of the diode rectifier by controlling its power electronic switches. Accordingly, the voltage at the AC input terminals of the diode rectifier is an AC voltage with seven levels, and the input current is sinusoidal and in phase with the utility voltage to perform unity power factor. The inductance of the filter inductor and the capacity of the EMI filter can be reduced due to the seven-level AC voltage at the input AC terminals of the seven-level AC-DC power converter. The isolated DC-DC power converter is a two-level forward power converter to regulate the voltages of the three-port DC-DC power converter and generate an isolated output power to charge the battery set. A prototype is developed and tested to verify the performance of the isolated battery charger. The experimental results show the isolated battery charger performs as expected.

This paper proposes a practical control circuit design of power converter for energy transducer with high output impedance. In conventional control circuit systems, the input voltage of the power converter is set so that the output power becomes maximum. However, this operating point voltage can be lower than the lower limit of the supply voltage at which the power converter can work. The proposed control circuit enables the power converter to operate when the output voltage is lower than a target voltage V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">pp</sub> and the input voltage is higher than a specified voltage V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> . As a result, the input impedance Z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CPin</sub> of the power converter can be low enough to extract power from the energy transducer via a power supply capacitor C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> when the power converter is enabled. On the other hand, Z <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CPin</sub> can be high enough to charge up C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> via the energy transducer when the power converter is disabled. As a result, 1) the operating point of the input voltage can be controlled to be higher than the minimum supply voltage, 2) a maximum power can be extracted, and 3) the output voltage is controlled to be the target voltage. The proposed circuit system was fabricated in 65nm 1V CMOS and its operation was verified. The proposed integrated circuit converts an output power of 50μW at an output voltage of 2.5V from a thermoelectric energy transducer with an open circuit voltage of 0.9V and an output impedance of 400Ω.

Rapid development of automotive, aviation, aerospace and defense industries are necessitated the use of lightweight and high strength materials. For this purpose, glass fiber reinforced plastic composite materials are began to be produced and widely used. These materials are in proportion to weight have higher strength and rigidity so that has found wide usage. In this study, glass fibre reinforced plastic composite materials were produced with hand lay-up as different number of layers of glass fibre. Mechanical properties of produced composite materials were investigated. Avarage strength values of produced composite materials are obtained with three point bending and tensile tests. In addition to these tests, impact strength of materials were investigated by low speed impact test. Macro and micro photographs of samples were taken before and after the tests. Samples were characterized by metallographic respect. The damage zones of resin and glass fibre materials were examined in detail in the test images. The variation of mechanical properties depending on the number of fibre layers were identified considering the experimental results. Mechanical properties of GFRP materials were investigated; mechanical properties of fibre composite materials had a good outcome, depending on the number of layers. When impact test results are examined, between the number of fibre layers and the values of the energy absorbed by GFRP were observed approximately linearity.