Experimental Research of High-Energy Capabilities of Material Recognition by Dual-Energy Method for the Low- Dose Radiation

The algorithm to produce primary radiographs, its transformation by dual energy method and recognition of the object materials were enhanced based on the analysis of experimental results. The experiments were carried out at the inspection complex with high X- ray source - betatron MIB 4/9 in Tomsk Polytechnic University. For the reduced X -ray dose rate, the possibility of recognition of the object materials with thickness from 20 to 120 g/cm{2} was proved under the condition that as the dose rate is reduced by the defined number of times, the segment of the image fragment with the reliably identified material will increase by the same number of times

Adequacy Criteria of Models of the Cargo Inspection System with Material Discrimination Option

Generalized adequacy criteria for mathematical models in order to discriminate materials in X-ray inspection systems by the dual-energy method were developed. Two main approaches of the examination systems to produce the adequacy criteria by the final and the intermediate parameters of the dual-energy method were analyzed. The criteria were specified in respect to the discrimination by the effective atomic number and by the method of level functions. Experimental and theoretical estimates of the discrimination parameters of the test object constituents scanned by fan beams of X-ray radiation with the maximal energies of 4.5 and 9 MeV are given

About accuracy of the discrimination parameter estimation for the dual high-energy method

A set of the mathematical formulas to estimate the accuracy of discrimination parameters for two implementations of the dual high energy method - by the effective atomic number and by the level lines is given. The hardware parameters which influenced on the accuracy of the discrimination parameters are stated. The recommendations to form the structure of the high energy X-ray radiation impulses are formulated. To prove the applicability of the proposed procedure there were calculated the statistical errors of the discrimination parameters for the cargo inspection system of the Tomsk polytechnic university on base of the portable betatron MIB-9. The comparison of the experimental estimations and the theoretical ones of the discrimination parameter errors was carried out. It proved the practical applicability of the algorithm to estimate the discrimination parameter errors for the dual high energy method

Betatron Application in Mobile and Relocatable Inspection Systems for Freight Transport Control

Accelerators with energy level up to 4 MeV having high level of penetration ability by steel equivalent are the popular to control oversize cargo transported by road, by railway and by river. Betatron's usage as cyclic induction accelerator has some advantages in comparison with linear accelerators and other sources. Tomsk Polytechnic University has developed many types of betatrons, most of them are being produced by separate affiliated company " Foton ". Article is shown the results of application of the betatrons in inspection custom systems

Boost type resonant LCL-T converter for autonomous power supply system from renewable sources

Relevance. Autonomous electrical supply from renewable sources in oil-gas equipment is considered more and more due to ecology concerns. The requirements set by the power supply system to the converter include high efficiency and wide load range including idle. The latter is quite serious taking into account intrinsic property as a current source of photovoltaic. Direct conversion is impeded and required high loop gain as well as high speed in a control circuit. Current work examines resonant converter topologies for solar sources assuring soft commutation as well as parametric stabilization of the output voltage in full load range due to load impedance transformation. The aim of the research is the analysis of electrical properties of boost resonant LCL-T converter for photovoltaics along with efficiency of the one. Methods: basic electric circuit theory, algebraic equations, computational solving as well as modern instrumental systems and numerical simulation. Results. It is shown that current fed resonant LCL-T converter needs active rectifier to achieve parametric output voltage stabilization by recuperation energy out of output filter into resonant tank. That solution has high static losses because they are determined by the photovoltaic's current. Use of boost topology allowed divert source's current between bridge converters thus less static losses to achieve 98 % efficiency at nominal load. The authors have examined the properties of boost type resonant LCL-T converter controlled by PWM. Current and voltage values within the full control range do not exceed nominal ones due to mitigation of gain rise by declining source (solar battery) current. The gain increase is caused by the phase shift between current and voltage. LCL-T converter assures soft commutation of the transistors without frequency adjustment needed in typical series resonant converter. Validation of the result obtained is provided, conclusions are given

Boost type series resonant converter with flexible structure for power supplies

Relevance. Geophysical research quality highly depends on power supply system, which, in its turn, has to provide uninterrupted power, for instance by means of accumulator battery. Specifically, continuity of supply is important for borehole logging during directional drilling which requires autonomous (self-powered) equipment. Converter powering geophysical equipment operates at high temperatures, where heat removal is impeded, makes the enhancement of the converter efficacy of utter importance. In that regard boost type topologies converting a part of a total power flow are preferred, especially in non-isolated power supply systems. However hard commutation in such topologies impairs an efficiency thus justifying development of boost type resonant converter. The aim of the research is to develop resonant boost type converter of high efficiency and to investigate one's power and control properties. Methods: electrotechnique fundamentals, linear equations theory, along with the modern simulation software, computational and mathematical modeling techniques. Results. The authors have analysed DC-DC resonant bridge converter with the boost link in voltage regulation mode powered by the battery as well as in a battery charge mode. The paper demonstrates high efficiency of a narrow battery voltage range. The control mode has substantial influence on operating parameters. Variable frequency PWM keeps relatively low value of operating current thus providing maximum efficiency. Frequency variation required to stay in soft commutation mode by guaranteeing current direction at turn-on instance. Soft commutation transitions are however different for the inverter and synchronous rectifier. Inability of boost topology to limit output current at overload is shown and topological solution is proposed to overcome it using auxiliary switches. The results are proven using hardware prototype. The paper introduces the conclusions as well as discussion of the results

Boost type resonant LCL-T converter for autonomous power supply system from renewable sources

Актуальность. Проблеме автономного электропитания нефтегазового оборудования на возобновляемых источниках энергии оказывается все большее внимание ввиду экологической чистоты этого вида энергии. Требования, предъявляемые системой электропитания к преобразователю энергии солнечной батареи, заключаются в первую очередь в высоком КПД и широком диапазоне изменения нагрузки, меняющейся вплоть до холостого хода. Последнее требование является серьезной проблемой, учитывая, что солнечная батарея по своей природе является источником постоянного тока. При применении непосредственных преобразователей изменение нагрузки вызывает существенные затруднения и приводит к глубокому регулированию, необходимости формирования быстродействующих контуров обратной связи. В работе рассмотрены топологии резонансного преобразователя энергии солнечной батареи на основе LCL-T контура, обеспечивающего не только мягкое переключение транзисторов, но и параметрическую стабилизацию выходного напряжения в полном диапазоне изменения нагрузки за счет преобразования импеданса нагрузки. Цель работы: анализ энергетических характеристик вольтодобавочного резонансного LCL-T преобразователя энергии солнечной батареи и оценка его КПД. Методы исследования основаны на общих положениях теории электрических цепей, теории алгебраических уравнений, вычислительных методах и использовании современных инструментальных систем и методов математического моделирования. Результаты. Показано, что при питании от источника тока для реализации параметрической стабилизации выходного напряжения резонансным LCL-T преобразователем необходим активный выпрямитель, обеспечивающий рекуперацию энергии выходного фильтра в резонансный контур. При этом статические потери в преобразователе существенны, так как ток инвертора определяется током солнечной батареи. Построение резонансного преобразователя по вольтодобавочной топологии позволяет разделить ток солнечной батареи между мостовыми преобразователями и существенно уменьшить статические потери, что, учитывая одновременную реализацию мягкого переключения транзисторов, позволяет получить высокий КПД преобразования, свыше 98 % в номинальном режиме. Исследованы характеристики вольтодобавочного резонансного LCL-T преобразователя при широтно-импульсном регулировании. Во всем диапазоне регулирования параметры схемы не превышают номинальных значений, так как их увеличение за счет фазового сдвига тока относительно напряжения, неизбежного в процессе регулирования, компенсируется уменьшением тока солнечной батареи. Преобразователь с LCL-T контуром обеспечивает мягкую коммутацию транзисторов без частотной подстройки, необходимой в классическом последовательном преобразователе. Проведена экспериментальная проверка полученных результатов, сделаны выводы.Relevance. Autonomous electrical supply from renewable sources in oil-gas equipment is considered more and more due to ecology concerns. The requirements set by the power supply system to the converter include high efficiency and wide load range including idle. The latter is quite serious taking into account intrinsic property as a current source of photovoltaic. Direct conversion is impeded and required high loop gain as well as high speed in a control circuit. Current work examines resonant converter topologies for solar sources assuring soft commutation as well as parametric stabilization of the output voltage in full load range due to load impedance transformation. The aim of the research is the analysis of electrical properties of boost resonant LCL-T converter for photovoltaics along with efficiency of the one. Methods: basic electric circuit theory, algebraic equations, computational solving as well as modern instrumental systems and numerical simulation. Results. It is shown that current fed resonant LCL-T converter needs active rectifier to achieve parametric output voltage stabilization by recuperation energy out of output filter into resonant tank. That solution has high static losses because they are determined by the photovoltaic's current. Use of boost topology allowed divert source's current between bridge converters thus less static losses to achieve 98 % efficiency at nominal load. The authors have examined the properties of boost type resonant LCL-T converter controlled by PWM. Current and voltage values within the full control range do not exceed nominal ones due to mitigation of gain rise by declining source (solar battery) current. The gain increase is caused by the phase shift between current and voltage. LCL-T converter assures soft commutation of the transistors without frequency adjustment needed in typical series resonant converter. Validation of the result obtained is provided, conclusions are given

Boost type series resonant converter with flexible structure for power supplies

Актуальность. Качество геофизических исследований во многом определяется системой электропитания геофизических приборов, которая, в частности, должна гарантировать бесперебойность энергообеспечения за счет питания от аккумуляторной батареи. Особенную актуальность бесперебойность питания имеет при исследовании наклонных и пологих скважин, требующих применения автономных геофизических приборов. Эксплуатация силового преобразователя, питающего геофизический прибор, производится в условиях высоких температур, при существенно затрудненных условиях отвода тепловых потерь, что ставит задачу увеличения КПД преобразования в ряд наиболее актуальных. В этой связи применение вольтодобавочных топологий, преобразующих неполный поток энергии, является энергетически оправданным, так как система энергоснабжения не требует гальванической развязки. Однако жесткая коммутация транзисторов в такой схеме приводит к существенному росту динамических потерь, что делает актуальной разработку резонансного вольтодобавочного преобразователя. Цель работы: создание резонансного вольтодобавочного преобразователя с повышенным КПД и исследование его энергетических и частотных характеристик. Методы исследования: основаны на общих положениях теории электрических цепей, теории алгебраических уравнений, вычислительных методах и использовании современных инструментальных систем и методов математического моделирования. Результаты. Рассмотрен резонансный мостовой DC-DC преобразователь с вольтодобавочным звеном в режиме стабилизации выходного напряжения при питании от аккумулятора и режиме заряда аккумулятора в реверсном режиме. Показана эффективность схемы вольтодобавочного преобразователя при узком диапазоне изменения напряжения аккумулятора. Существенное влияние на характеристики преобразователя оказывает способ регулирования; установлено, что широтно-импульсное регулирование инвертором с частотной подстройкой обеспечивает минимальные значения рабочих токов, а соответственно, максимальное значение КПД. Подстройка рабочей частоты необходима для обеспечения мягкого включения транзисторов, так как формирует необходимое направление тока, отпирающее обратные диоды включаемых транзисторов. При этом коммутационные процессы, протекающие в инверторе и выпрямителе резонансного преобразователя, и условия обеспечения мягкого включения различны. Показана невозможность вольтодобавочной схемы ограничивать выходной ток при перегрузках, для чего предложено изменение структуры вольтодобавочного преобразователя при помощи дискретных ключей. Проведена экспериментальная проверка полученных результатов, сделаны выводы, обсуждены полученные результаты.Relevance. Geophysical research quality highly depends on power supply system, which, in its turn, has to provide uninterrupted power, for instance by means of accumulator battery. Specifically, continuity of supply is important for borehole logging during directional drilling which requires autonomous (self-powered) equipment. Converter powering geophysical equipment operates at high temperatures, where heat removal is impeded, makes the enhancement of the converter efficacy of utter importance. In that regard boost type topologies converting a part of a total power flow are preferred, especially in non-isolated power supply systems. However hard commutation in such topologies impairs an efficiency thus justifying development of boost type resonant converter. The aim of the research is to develop resonant boost type converter of high efficiency and to investigate one's power and control properties. Methods: electrotechnique fundamentals, linear equations theory, along with the modern simulation software, computational and mathematical modeling techniques. Results. The authors have analysed DC-DC resonant bridge converter with the boost link in voltage regulation mode powered by the battery as well as in a battery charge mode. The paper demonstrates high efficiency of a narrow battery voltage range. The control mode has substantial influence on operating parameters. Variable frequency PWM keeps relatively low value of operating current thus providing maximum efficiency. Frequency variation required to stay in soft commutation mode by guaranteeing current direction at turn-on instance. Soft commutation transitions are however different for the inverter and synchronous rectifier. Inability of boost topology to limit output current at overload is shown and topological solution is proposed to overcome it using auxiliary switches. The results are proven using hardware prototype. The paper introduces the conclusions as well as discussion of the results