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    Analysis of Output Voltage Power Spectrum of High Voltage Power Supply

    , M.Sc. Thesis Sharif University of Technology Nouri Jevinani, Hadi (Author) ; Kaboli, Shahriyar (Supervisor)
    Abstract
    Some microwave tubes can function as a narrowband power amplifier and their output power spectrum is an indicator of their amplification and efficiency. One of the factors affecting its power spectrum is the noise and ripple of its HVDC power supply. To reduce the negative effects of power supply, first there should be an exact measurement of ripple and noise in the output of the HVDC power supply. Destructive factors which affect voltage ripple measurement in the case of high DC voltage are follows as conductive interference, radiative interference, intrinsic noise of electrical elements, and nonideal frequency response of voltage divider. After identifying and suppressing the mentioned... 

    Robusting Series Structure of Semiconductor Switches for High Voltage Applications

    , Ph.D. Dissertation Sharif University of Technology Mohsenzadeh Hedesh, Sadegh (Author) ; Kaboli, Shahriyar (Supervisor)
    Abstract
    The series structure of semiconductor devices has a wide application in the industry and research field. The most critical issue in the series structure of series switches is the safe operating condition provision. Hence many kinds of research have been intensively focused on this topic to overcome this necessity. However, many existing aspects relevant to the series stacking of the semiconductor switches have not been pointed out. These include, the power loss must be accepted for the series devices and recovery of this power, providing balanced voltage for the series devices through a simple and easy implementing structure and providing a safe voltage condition for the series devices under... 

    Analysis and Improvement of Output Voltage Ripple in High Voltage DC Power Supply

    , M.Sc. Thesis Sharif University of Technology Ziaoddini, Mojtaba (Author) ; Kaboli, Shahryar (Supervisor)
    Abstract
    The TWT is highly sensitive to the ripple amplitude of its power supply output voltage. If the amplitude of the output voltage's ripple exceeds a certain limit, the amplitude of the undesired harmonics in the power spectrum of the TWT is greatly increased. Increasing the amplitude of undesired harmonics in the TWT output power spectrum reduces the accuracy and performance of the TWT. Therefore, for optimum TWT performance, a low-ripple power supply is essential. Typically, a low-frequency rectifier or high-frequency switching structure is used to build a high-voltage DC power supply. In this thesis, the different structures of high voltage DC power supplies are studied. Next, by focusing on... 

    Reliability Improvement of the High Voltage Power Supply Based on Interleaved Inverters

    , M.Sc. Thesis Sharif University of Technology Keshtkar Teeula, Afshin (Author) ; Kaboli, Shahriyar (Supervisor)
    Abstract
    In some high voltage applications it is necessary for high voltage power supply (HVPS) to operate over a wide load and gain range. For instance a HVPS may be used to supply various microwave tubes. Our goal in this thesis is to design a HVPS which can provide a DC voltage between 0-15 KV and 0-5 KW. In convetional approaches, operating over wide load and gain range necessitates the switching frequency or duty cycle to swing over a wide range. This approach may disturb soft switching, consequently switching loss will increase. The control process will be more complex too. the wide swing range of switching frequency means that the HVPS needs to operate with low switching frequency too.... 

    Analysis and Optimal Design of High-Voltage High-Frequency Transformer with Parasitic Elements Consideration for Microwave Power Module

    , Ph.D. Dissertation Sharif University of Technology Aghaei, Morteza (Author) ; Kaboli, Shahriyar (Supervisor)
    Abstract
    Applications of high voltage power supplies is increasing. Microwave power module is one of the applications. In microwave power module, the dimensions of the power supply are very important. On the other hand, the parasitic elements of the transformer of a high voltage power supply are significant because of high insulation distances and transformer high turn ratio. These elements including stray capacitance and leakage inductance change the converter behavior. In this thesis, a method for dimensional efficient design of high voltage power supply used in microwave power module is presented considering and analyzing the transformer parasitic elements. Beforehand, at first, the transformer... 

    Analysis and Solution Proposal for Improving the Resiliency of High Voltage Cathode Power Supply

    , M.Sc. Thesis Sharif University of Technology Pouresmaeil, Kaveh (Author) ; Kaboli, Shahriyar (Supervisor) ; Safdarian, Amir (Co-Supervisor)
    Abstract
    High voltage power supplies (HVPS) are widely used to supply the vacuum tubes. The function of this power supply is disturbed by some internal and external faults. One of the external faults is the arc fault in the tube. The amount of delivered energy from the HVPS to the tube is an important issue during the arc fault in the tube. The conventional protection mechanism consists of a shunt crowbar device which divert the fault current from the tube arc. The crowbar circuit is usually built with thyristor in most cases. This type of crowbar cannot be turned off simply by protection command. It is a drawback since if the fault is transient such as arc in the load or false fault detection is... 

    On the effect of disorder on stray capacitance of transformer winding in high-voltage power supplies

    , Article IEEE Transactions on Industrial Electronics ; Volume 64, Issue 5 , 2017 , Pages 3608-3618 ; 02780046 (ISSN) Aghaei, M ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2017
    Abstract
    Stray capacitance of transformer winding is an important parasitic element influencing the behavior of the switching power converters, especially for high-voltage transformers. There are various methods for calculating the stray capacitance in transformers and inductors with ordered windings. However, an ordered winding is less likely with an increased number of turns and layers. In this paper, it is shown that a slight disorderliness in winding leads to a considerable difference between the value of winding stray capacitance of the former ordered winding and its slightly disordered scheme. Therefore, regular methods for calculating the stray capacitance have significant errors in a... 

    On the performance of high voltage electrospray echnique for producing nanoparticles

    , Article 26th Iranian Conference on Electrical Engineering, ICEE 2018, 8 May 2018 through 10 May 2018 ; 2018 , Pages 283-288 ; 9781538649169 (ISBN) Kaboli, S ; Naghibi Nasab, J ; Elyasi, M ; Zarrabi, R ; Vosoghi, M ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2018
    Abstract
    Electrospray technique is one of the commonly used methods for generating nanoparticles. In this method, the chemical solution which consists of a polymer and its solvent are injected into an electric field via a nozzle. At the end of this nozzle, due to electric forces, a certain part of this liquid is separated. Then, the separated part is divided into smaller particles and the solvent is evaporated and hence, the nanoparticles are acquired. Produced nanoparticales are collected in deionized water placed under the certain distant from nozzle. However, construction of this method is generally based on practical results. In this paper, modeling and performance evaluation of high voltage... 

    A reopened crowbar protection for increasing the resiliency of the vacuum tube high-voltage DC power supply against the vacuum Arc

    , Article IEEE Transactions on Plasma Science ; Volume 47, Issue 5 , 2019 , Pages 2717-2725 ; 00933813 (ISSN) Pouresmaeil, K ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    High-voltage power supplies (HVPSs) are widely used to supply vacuum tubes. The amount of delivered energy from the HVPS to the tube is an important issue during the vacuum arc in the tube. The conventional protection mechanism consists of a shunt crowbar which diverts the fault current from the tube to itself as a parallel path. The crowbar circuit is usually built of the devices without the turn-off capability. It is a drawback since the output of the power supply is shortened for a long time. Thus, the restoration time of these power supplies is excessive. This demerit can have detrimental effects on mission-critical applications. In this paper, the insulated-gate bipolar transistor... 

    A high voltage variable inductor LCC resonant converter with high power factor over wide load range

    , Article 10th International Power Electronics, Drive Systems and Technologies Conference, PEDSTC 2019, 12 February 2019 through 14 February 2019 ; 2019 , Pages 279-284 ; 9781538692547 (ISBN) Aghaei, M ; Ayoubi, R ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    High voltage power supplies (HVPS) are widely used to supply vacuum tubes. Regarding to their high efficiency, resonant converters are a choice of HVPS structure. In this application, HVPS is faced with wide variation of the load power. On the other hand, output voltage regulation over wide load range is essential. However, there are several problems dealing with resonant converters such as output voltage regulation and low-efficient performance in a light load. In this paper, a control scheme for a series-parallel resonant converter is presented. This scheme regulates the output voltage of the converter over load variation range. A variable inductor placed as the series inductor in the... 

    A Vacuum arc diagnosis method for the high voltage power supply of vacuum tubes

    , Article 2019 International Vacuum Electronics Conference, IVEC 2019, 28 April 2019 through 1 May 2019 ; 2019 ; 9781538675342 (ISBN) Ayoubi, R ; Rahmanian, M ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2019
    Abstract
    Vacuum tubes are widely used for various applications. These vacuum tubes are supplied by high voltage power supplies. The amount of delivered energy from the high voltage power supply to the vacuum tube is an important issue during the vacuum arc in the tube. The protection mechanism consists of a shunt crowbar which diverts the fault current from the tube to itself as a parallel path. Detection of the vacuum arc is crucial and only one sensor is usually employed to detect the vacuum arc. This characteristic intensifies the interference susceptibility of the vacuum arc diagnosis system in a noisy environment. As a result of the noise, the arc detection system can report false alarms. False... 

    A low loss linear voltage regulator for high voltage dc power supplies based on adjustable inductors

    , Article 11th Power Electronics, Drive Systems, and Technologies Conference, PEDSTC 2020, 4 February 2020 through 6 February 2020 ; 2020 Osanlo, M ; Pouresmaeil, K ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    High voltage power supplies are widely used in telecommunication systems. To better utilize these power supplies, voltage should be stabilized at a certain level. In this application, in case of changing voltage, the desired output parameters will change, such as RF output power quality. Various methods have been proposed to stabilize the voltage at acceptable levels. One of the most commonly used methods is use of switching regulators that are considered for high efficiency in comparison with linear regulators. But the use of these regulators also has problems. One of these problems is electromagnetic interference which is very important in telecommunication systems. Therefore, the need for... 

    A comprehensive design of the thyristor-based crowbar for vacuum tube high-voltage dc power supplies

    , Article IEEE Transactions on Plasma Science ; Volume 48, Issue 6 , 2020 , Pages 2202-2209 Pouresmaeil, K ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    High-voltage power supplies (HVPSs) are widely used to drive vacuum tubes, inherently susceptible to vacuum arc faults. Owing to the considerable cost of vacuum tubes, the HVPS should enjoy a reliable, fast protection mechanism. A common protection mechanism against vacuum arc faults is the shunt crowbar. The crowbar diverts the energy stored in the elements of the HVPS through itself as a parallel path, thereby protecting vacuum tubes from irrecoverable damages. Among all types of the shunt crowbar, the thyristor-based crowbar along with the fault current limiter (FCL) resistors attracts more attention because of its more reliable operation. The absence of the comprehensive design procedure... 

    An Extremely low ripple high voltage power supply for pulsed current applications

    , Article IEEE Transactions on Power Electronics ; Volume 35, Issue 8 , 2020 , Pages 7991-8001 Zarghani, M ; Mohsenzade, S ; Hadizade, A ; Kaboli, S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Abstract
    This article describes the development of an 18 kV, 30 kW power supply for a pulsed current load with the maximum current of 20 A and a di/dt equal to 100 A/μs. The achieved output ripple is less than 0.01%. In such a high level of precision, the most important issues are considerable difference between the instantaneous and average output powers, as well as insufficient reaction speed of the converter to the fast load change. Very low level of the voltage feedback and its sensitivity to the noise. The first issue necessitates a notable overdesign of the converter switches if the output voltage precision is dedicated to the converter. The second issue raises the problems relevant to...