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2. Supply Of Capacitors, Switches, Joints, Filters, Electronic Modules, Switches, Presentation Paper, Signal Converters, Phase Sequence Indicator And Chemical Analysis Instruments For Bam Deployed In Omp (sophia)
- Subjects
Capacitors ,Switches ,Budgets ,Email ,Business, international - Abstract
Tenders are invited for supply of capacitors, switches, joints, filters, electronic modules, switches, presentation paper, signal converters, phase sequence indicator and chemical analysis instruments for bam deployed in omp (sophia) [...]
- Published
- 2019
3. Hybrid Analog and Digital Control of a High Current Converter Based on an EDLC Bank for Rapidly Decreasing Input Voltage.
- Author
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Baek, Ji-Eun, Rhee, Jae-Ho, and Ko, Kwang-Cheol
- Subjects
VOLTAGE control ,POWER resources ,DC-to-DC converters ,CAPACITORS ,ENERGY storage ,PULSE width modulation transformers - Abstract
This paper proposes unconventional control techniques for a portable power supply consisting of electric double-layer capacitors (EDLCs), a dc–dc converter, and a low-impedance load such a plasma load. Between the EDLCs and the plasma load consuming high power, a dc–dc converter is required to control the output voltage from the rapidly decreasing voltage of EDLCs. In addition, the dc–dc converter should maintain a set point by responding to arcs occurred in plasma process. This paper proposed hybrid analog and digital controls for a nonideal boost converter which was setup by theoretical analysis. The proposed system is verified with experiment and simulation. As a result, the proposed control method can maintain the constant output voltage longer than a traditional analog pulsewidth modulation control. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
4. A 0.6-V 10-bit 200-kS/s SAR ADC With Higher Side-Reset-and-Set Switching Scheme and Hybrid CAP-MOS DAC.
- Author
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Zhang, Hongshuai, Zhang, Hong, Sun, Quan, Li, Jijun, Liu, Xipeng, and Zhang, Ruizhi
- Subjects
COMPLEMENTARY metal oxide semiconductors ,SUCCESSIVE approximation analog-to-digital converters ,ELECTRIC capacity - Abstract
This paper presents a low-power and area efficient 10-bit SAR ADC with higher side-reset-and-set (HSRS) switching scheme and hybrid capacitive-MOS (CAP-MOS) DAC. The HSRS switching scheme consumes zero switching energy for the two most-significant bits and skips unnecessary switching without using any auxiliary circuit. It is further verified in this paper that the HSRS switching scheme shows lower nonlinearity compared with the conventional CDAC structure with the same unit capacitor size and matching condition. This additional advantage permits using DAC topologies with lower total capacitance under given linearity requirement. A hybrid CAP-MOS DAC is adopted to reduce the total capacitance of the DAC, which consumes lower static current and chip area than the conventional hybrid capacitive-resistive DAC under the same settling requirement. The prototype 10-bit SAR ADC is implemented in a 0.18- $\mu \text{m}$ CMOS technology, showing an SNDR/SFDR of 56.43 dB/71 dB at 90-kHz input, under a 0.6-V power supply, while consuming $1.01~\mu \text{W}$ at 200 kS/s for a figure of merit of 9.32 fJ/conv.-step. The ADC occupies only a small active area of 0.0675 mm2. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
5. Ultra-Voltage Gain Step-Up DC-DC Converter for Renewable Energy Micro-Source Applications.
- Author
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Bekkam, Krishna and Karthikeyan, V.
- Subjects
DC-to-DC converters ,RENEWABLE energy sources ,CAPACITOR switching ,MOTOR drives (Electric motors) - Abstract
In renewable energy micro-source applications, a wide range of voltage conversion of the step-up converter is an essential part to equalize the typical low voltage of micro-source with DC-bus voltage of Inverter or motor drives. In order to meet this purpose, an ultra-voltage gain step-up DC-DC converter is proposed in this paper. The proposed converter has made an arrangement of the regenerative-boost fed switched inductor and capacitor configurations. Thereby, due to such an organization of structure, the proposed converter can develop an extremely high voltage-gain even at lower duty ratios. In addition, it has the advantage of lower switching stress across all power semi-conductive diodes. Furthermore, this paper describes the steady-state analysis and comparative features of the converter with existing recent literature. Finally, to validate theoretical analysis and test the feasibility and suitability of the proposed ultra-gain converter, the experimental results were observed by a 500 W fabricated prototype. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
6. Analysis of Nonideal Behaviors Based on INL/DNL Plots for SAR ADCs.
- Author
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Huang, Chun-Po, Ting, Hsin-Wen, and Chang, Soon-Jyh
- Subjects
SUCCESSIVE approximation analog-to-digital converters ,ELECTRONIC equipment ,COMPARATOR circuits ,DATA conversion ,NONLINEAR theories ,SAMPLE & hold circuits - Abstract
This paper presents a comprehensive investigation of several important error sources for the successive-approximation register (SAR) analog-to-digital converters (ADCs). The error sources that we discuss in this paper include the dynamic comparator offset, the dynamic gain error of digital-to-analog converter (DAC), the capacitor mismatch of capacitive DAC, the incomplete settling of DAC, the undershoot of reference voltage, and the input signal coupling. The integral/differential nonlinearities (INL/DNL) of SAR ADCs that are resulted from these error sources are analyzed and addressed. A diagnostic procedure is presented to identify the possible error sources based on the INL/DNL plots. In addition, design suggestions for overcoming these problems are also offered and recommended in this paper. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
7. A Highly Integrated Tri-Path Hybrid Buck Converter With Reduced Inductor Current and Self-Balanced Flying Capacitor Voltage.
- Author
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Wang, Chuang, Lu, Yan, and Martins, Rui P.
- Subjects
CAPACITORS ,VOLTAGE ,PRIVATE flying ,AC DC transformers ,LOW voltage systems ,DC-to-DC converters ,CAPACITOR switching - Abstract
This paper presents a single-stage tri-path buck converter with reduced inductor current and self-balanced flying capacitor voltage. The proposed converter introduces capacitor paths to reduce the average inductor current and inductor current ripple, hence decreasing the conduction loss. Operating with two states per conversion cycle, it exhibits a relatively low voltage conversion ratio of ${D}$ /(1 $+\,\,2{D}$). Besides, it realizes a self-balanced flying capacitor voltage in the charge redistribution phase. Similar to the conventional buck converter, the proposed converter in continuous-current mode only has two complex poles. Therefore, we design a Type-III compensator to obtain a good transient response. Moreover, the circuit does not require extra supplies for gate drivers due to the reutilization of the flying capacitor voltages, eliminating additional circuit and power overheads. The proposed converter, validated in a 65-nm standard CMOS technology, regulates a 0.7 V – 1 V output voltage from a 3.3 V – 4 V input voltage, delivering a maximum output power of 270 mW. The peak efficiency is 84%, with a switching frequency up to 5 MHz. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
8. On Capacitor Switching Transient Immunity of Inverter-Based Renewable Generations.
- Author
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Li, Chun
- Subjects
ELECTRIC inverters ,CAPACITOR switching ,ELECTRIC transients ,POWER capacitors ,POWER supply quality - Abstract
This paper highlights an immediate need for renewable generation developers, manufacturers, utilities and industry standardization institutes to jointly address a challenge of capacitor switching transient immunity in inverter-based wind or solar farms. The need was identified from wide-area operation records which showed partial or full generation loss in coincidence with routine utility-owned capacitor switching. The lack of a clear industry guideline has caused confusion to all involved parties. This paper recommends all entities to address this challenge collaboratively through enhanced equipment specification, design, and test before a well-defined industry guideline becomes available. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
9. Extending Protection Selectivity in DC Shipboard Power Systems by Means of Additional Bus Capacitance.
- Author
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Kim, Seongil, Kim, Soo-Nam, and Dujic, Drazen
- Subjects
BUSES ,ENERGY storage ,ELECTRIC potential ,ELECTRIC capacity ,ENVIRONMENTAL regulations - Abstract
DC shipboard power systems have been considered as a promising solution for stricter environmental regulations on ships due to their main benefits in fuel savings with variable speed engines and easy integration of energy storage systems. In order to employ the dc solution in the shipboard power systems, the dc power systems have to be protected from a system fault with protection selectivity to minimize impacts of the fault or to avoid other undesirable situations in the system. For low-voltage dc shipboard power systems, a three-level protection has been proposed: 1) fast action (first)—bus separation by solid-state dc bus-tie switch; 2) medium action (second)—feeder protection by high-speed fuse; and 3) slow action (third)—generator–rectifier fault controls. This paper proposes a new method by means of additional bus capacitance added in main dc buses to help reliable operation of the three-level protection. The principle of the proposed method is introduced and the sizing of the additional bus capacitance is addressed in this paper. With the modeling of the dc shipboard power systems, the analyses of voltage drops for the bus separation failure and fault clearing time for the feeder protection are carried out to verify the proposed method. The results show that the proposed method not only mitigates the voltage drop for the bus separation failure, but also achieves the selectivity and the sensitivity for the feeder protection. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
10. Topology and Control of a Four-Level ANPC Inverter.
- Author
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Wang, Kui, Zheng, Zedong, and Li, Yongdong
- Subjects
HIGH voltages ,TOPOLOGY - Abstract
Four-level hybrid-clamped inverter is a newly proposed topology that can operate under a wide voltage range without switches connected in series. However, when it is applied in medium voltage high power conversions, the flying capacitors in each phase will occupy a huge volume and a high switching frequency is required to restrain the voltage ripples. In order to overcome this drawback, a four-level active neutral-point clamped inverter is discussed in this paper, which consists of only six switches and no diodes or flying capacitors are required. In order to balance the neutral-point voltages under the full power factor and modulation index range, a capacitor voltage balance method based on carrier-overlapped pulsewidth modulation is proposed in this paper. The upper and lower dc-link capacitor voltages are balanced by zero-sequence voltage injection and the central dc-link capacitor voltage is balanced by adjusting the duty cycles of switching signals slightly. Simulation and experimental results are presented to confirm the validity of this method. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
11. A Four-Switch Three-Phase AC–DC Converter With Galvanic Isolation.
- Author
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Khodabakhsh, Javad and Moschopoulos, Gerry
- Subjects
GALVANIC isolation ,AC DC transformers ,ELECTRIC current rectifiers ,IDEAL sources (Electric circuits) ,VIRTUAL private networks ,PULSE width modulation - Abstract
A new single stage three-phase ac–dc converter with four switches and galvanic isolation is proposed in this paper. The new converter is simple and uses fewer switches than previously proposed ac–dc converters of the same type. It is a bridgeless converter that can operate with continuous input current and with any pulsewidth modulated method suitable for a standard three-phase six-switch voltage source rectifier. In this paper, the operation, control, analysis, and design of the proposed converter are explained and its features are discussed. Experimental results obtained from a prototype that confirm the feasibility of the converter are presented as well. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
12. A Seven-Level VSI With a Front-End Cascaded Three-Level Inverter and Flying-Capacitor-Fed H-Bridge.
- Author
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Abhilash, Tirupathi, Annamalai, Kirubakaran, and Tirumala, Somasekhar Veeramraju
- Subjects
RENEWABLE energy sources ,VOLTAGE control - Abstract
Multilevel inverters (MLIs) are playing a pivotal role in the power sector with potential applications, such as interfacing renewable energy sources with the grid and several industrial drive applications. MLIs with a smaller number of switching devices are more promising due to their compact size, reduced cost, and higher efficiency compared with their traditional counterparts. This paper, therefore, presents a new three-phase seven-level inverter. This topology is a combination of two cascade-connected two-level voltage-source inverters (VSIs) and H-bridge cells with flying capacitors (FCs). This paper presents the operating principle and the balancing technique for the dc-link capacitors and FCs. The generation of various output voltage levels and the limitation of the sinusoidal pulsewidth modulation control for FC voltage balancing is also presented. The number of components in the proposed circuit configuration and their voltage ratings are considerably lower compared with the recently proposed topologies. The behavior of the proposed circuit configuration is first assessed with simulation studies and is then tested with a laboratory prototype. The simulation and experimental results validate the effectiveness of the proposed topology and the voltage balancing technique. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
13. A High-Frequency High Voltage Gain Modified SEPIC With Integrated Inductors.
- Author
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Gao, Shanshan, Wang, Yijie, Guan, Yueshi, and Xu, Dianguo
- Subjects
ZERO voltage switching ,VOLTAGE multipliers ,HIGH voltages ,DC-to-DC converters ,VOLTAGE-frequency converters ,PHOTOVOLTAIC cells ,POWER density - Abstract
With the rapid development of photovoltaic and fuel cell stacks, high voltage gain converters are urgently demanded. Conventional boost is limited by the exaggerated duty cycle, it is impossible to obtain a high voltage gain while ensuring efficiency. Therefore, a zero-voltage switching (ZVS)-modified SEPIC converter that combines a voltage multiplier cell with traditional SEPIC is proposed in this paper. With detailed parameters design process, this presented converter works at zero voltage switching (ZVS), while obtaining high voltage gain without extremely high duty cycle. Besides, voltage stress is also reduced and low-voltage component with lower parasitic parameters can be used, thus efficiency is maintained. In order to further improve the power density, an integrated inductor scheme is adopted in this paper without changing intrinsic working states of the two inductors. A 36-W prototype is built, and experiments are conducted to verify the advantages of the proposed converter. The efficiency is up to 91.5% at full load. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
14. Overload and Short-Circuit Protection Strategy for Voltage Source Inverter-Based UPS.
- Author
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Wei, Baoze, Marzabal, Albert, Perez, Jose, Pinyol, Ramon, Guerrero, Josep M., and Vasquez, Juan C.
- Subjects
IDEAL sources (Electric circuits) ,OVERCURRENT protection ,SHORT circuits ,UNINTERRUPTIBLE power supply ,VOLTAGE control - Abstract
In this paper, an overload and short-circuit protection method is proposed for voltage source inverter-based uninterruptible power supply (UPS) system. In order to achieve high reliability and availability of the UPS, short circuit and overload protection scheme are necessary. When overload or short circuit happens, using the proposed control method, the amplitude of the output current can be limited to a constant value, which can be set by the customer to avoid the destruction of the power converter, and to obtain a faster recovery performance as well. The detailed principle of the proposed protection method is discussed in this paper. It mainly contains three parts in the control diagram for current limit, first is the anti-windup in the voltage and current controllers, then the feedforward of the capacitor voltage to the current control loop, the last is the fast reset of the resonant part of the current controller when overcurrent happens. The procedure of developing the control method is also presented in the paper. Experimental results on a commercial UPS system are presented to verify the effectiveness of the control method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
15. Nonlinear Analytical Model for Switched-Capacitor Class-D RF Power Amplifiers.
- Author
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Luo, Wei, Yin, Yun, Xiong, Liang, Li, Tong, and Xu, Hongtao
- Subjects
POWER amplifiers ,CAPACITOR switching ,SPECTRAL energy distribution ,POWER density - Abstract
This paper presents a nonlinear analytical model for an inverter-based switched-capacitor Class-D RF power amplifier (SCDPA). The root causes of the SCDPA AMAM and AMPM nonlinearities are studied. The major factors affecting SCDPA nonlinearities are identified as the unequal on-resistances of selected cell and unselected cell. Specifically, time-varying resistance of the switch, different transistor responses during the transition and parasitic resistance on the supply path (IR drop) are analyzed. Then, the system-level result, like EVM and power spectral density, can be obtained with nonlinear behavior of PA. The results of model calculation, schematic simulation, and measurement are presented and compared with validate the model both on transistor level and system level. This paper, for the first time, provides an accurate design guidance to enable fast architecture study and quick circuit-level prototype with close-to-optimum component initial parameters. It can be expanded to more architectures, therefore helps to pave the path to future design automation for highly linear SCDPAs. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
16. Noise Filtering and Linearization of Single-Ended Sampled-Data Circuits.
- Author
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He, Tao, Kareppagoudr, Manjunath, Zhang, Yi, Caceres, Emanuel, Moon, Un-Ku, and Temes, Gabor C.
- Subjects
ANALOG integrated circuits ,NOISE ,ANALOG circuits ,HARBOR management - Abstract
The performance of analog integrated circuits is often limited by the noise generated in its components. Several circuit techniques exist for mitigating the effects of the low-frequency noise. In this paper, a novel approach is described, which can also reduce even-order distortion, another major limitation of analog circuits. It may also allow the use of single-ended circuits in applications where usually differential structures are needed. In most cases, the resulting single-ended circuit will be much simpler than the fully or pseudo-differential one. It does not require common-mode feedback circuitry, nor single-ended-to-differential and differential-to-single-ended conversions at the input and output ports. The amplifiers may be single-ended, using, e.g., inverter-based circuits, and the use of baluns can be avoided. The number of pins and pads of the chip can be reduced. In addition, the single-ended opamps of the circuit may require less power than differential ones. These factors and the omission of the common-mode feedback circuits as well as the single-ended/differential converters will usually allow significant power savings. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
17. Non-Isolated n -Stage High Step-up DC-DC Converter for Low Voltage DC Source Integration.
- Author
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Shanthi, T., Prabha, S. U., and Sundaramoorthy, Kumaravel
- Subjects
DC-to-DC converters ,IDEAL sources (Electric circuits) ,VOLTAGE-frequency converters ,LOW voltage systems ,HIGH voltages ,SEMICONDUCTOR devices ,ELECTRIC current rectifiers - Abstract
The dc-dc converters with high step-up DC-voltage gain play a vital role in integrating low voltage DC sources. Though several converter topologies are reported in the recent past, attempts have been made to reduce the components, especially the switching devices, passive elements, converter losses, etc., of the converter. A novel DC-DC converter topology, viz., single switched impedance network (SSIN)-based converter with n-stage is proposed in this paper. The operation of the SSIN based converter in continuous and discontinuous conduction modes are discussed. The effect of parasitic elements on DC-voltage gain and efficiency of the SSIN is carried out. The small-signal model of the SSIN converter is derived. The performance of the SSIN converter is compared with the similar converter topologies. The 500 W prototypes of the SSIN with n = 1 and n = 2 are fabricated, and the experimental results are presented in this paper. To improve the converter performance, SiC-based semiconductor devices are used. The SSIN converter with two-stage has low switch loss at 500 W load, improved efficiency during high power and high output voltage operation, the switch stress of Vo/2, etc. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
18. A Three-Level Neutral-Point-Clamped Inverter Synchronous Reluctance Machine Drive.
- Author
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Masisi, Lesedi, Pillay, Pragasen, and Williamson, Sheldon S.
- Subjects
ELECTRIC inverters ,RELUCTANCE motors ,CAPACITORS ,ELECTRIC power ,CLAMPING circuits - Abstract
This paper is concerned with the use of a three-level inverter for a synchronous reluctance machine (SynRM). The SynRM suffers from a poor power factor due to poor machine saliency. This makes it harder to operate the three-level neutral-point-clamped inverter due to a strict requirement to have the two dc-link capacitor voltages balanced. This paper proposes a new nearest three vector modulation algorithm which can balance the two dc-link capacitors even at poor machine saliency ratio (poor power factor). In this paper, a method of sizing the two dc-link capacitors based on the machine power is also proposed. A comparison between two- and three-level inverters was conducted. The SynRM registered lower $d$-axis current ripple with a three-level inverter, indicating lower core losses in the machine. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
- Full Text
- View/download PDF
19. A Scalable Bandwidth Mismatch Calibration Technique for Time-Interleaved ADCs.
- Author
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Park, Yunsoo, Kim, Jintae, and Kim, Chulwoo
- Subjects
DIGITIZATION ,BANDWIDTHS ,ANALOG-to-digital converter calibration ,SINE waves ,MONTE Carlo method - Abstract
This paper presents a foreground calibration method for both a sampler and a track-and-hold (T/H) buffer bandwidth mismatch in highly time-interleaved analog-to-digital converters (TI-ADCs). The T/H buffer bandwidth mismatch stems from the length difference of interconnect lines between the buffer and the channel ADC, while the sampler bandwidth mismatch arises from the mismatch in a switch and a sampling capacitor. To address both mismatches along with other mismatches residing in TI-ADCs, this papers utilizes least-squares (LS) minimization technique in order to extract mismatch parameters while injecting a sinewave at two distinct frequencies. Programmable capacitor arrays (PCAs) are used to tune the bandwidth of sampler, and correcting buffer bandwidth mismatch is performed in digital-domain. The method presented here is scalable to arbitrary number of interleaved paths, and can easily be combined with existing calibration methods for gain, offset, and timing-skew mismatches. Numerical experiment via Monte-Carlo simulations demonstrates significant performance improvement in the spurious-free dynamic range (SFDR) from 38 dB to 75 dB for a 32-channel time-interleaved ADC model that includes all major mismatches. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
20. A New Coupled-Inductor-Based High-Gain Interleaved DC-DC Converter With Sustained Soft Switching.
- Author
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Li, Bo, Wang, Ping, Wang, Zhishuang, Ma, Xiaochen, and Bi, Huakun
- Subjects
DC-to-DC converters ,ZERO current switching ,FUEL cell vehicles ,ZERO voltage switching - Abstract
This paper presents a new soft switching high voltage gain interleaved dc-dc converter with a three-windings coupled inductor for a fuel cell vehicle. Two interleaved and intercoupled boost cells are connected by the input parallel and output series (IPOS) configuration, realizing low input current ripple and high voltage gain simultaneously. All power switches can operate under soft switching conditions by only adding a simple auxiliary circuit composed of one auxiliary inductor and one power switch. Besides, the auxiliary inductor is coupled with the main inductors, which results in a rapid zero convergence of the auxiliary current and a small conduction loss of the auxiliary circuit. The operating principle, steady state characteristic, comparison with other converters, and parameter design are analyzed in this paper. Finally, the main characteristics of the proposed converter are verified by a 1-kW laboratory prototype. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
21. Investigation of the Interaction Between Substation Transients and Transformers in HV and EHV Applications.
- Author
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McBride, Jim, Melle, Tom, Lopez-Fernandez, Xose M., Coffeen, Larry, Degeneff, Robert, Hopkinson, Phil, Poulin, Bertrand, Riffon, Pierre, Rocha, Angelica, Spurlock, Mike, and Wagenaar, Loren
- Subjects
ELECTRIC transients ,TASK forces ,TASKS - Abstract
This paper summarizes the work performed by the Task Force —within Performance Characteristic Subcommittee of IEEE PES Transformers Committee— to investigate potential revisions to IEEE Std C57.142-2010. Although the scope of this document does not implicitly exclude HV and EHV systems, the existing document primarily includes examples and information on distribution voltage systems. A Task Force was formed to investigate the need to include information about power system transient events on HV systems more explicitly in this existing document. The Task Force was charged with the following tasks:-Establish system voltages encompassed by C57-142-2010 Guide. -Gather field data, reports, and literature on HV and EHV failures related to substation transients and transformer interaction. -Solicit input from the other technical committees on this subject. -Review IEC and CIGRE work in this area. -Recommend course of action on revision of the present Guide. -Recommend high level changes to the Guide. -Prepare final paper for the Subcommittee. In the course of this work several failure scenarios were identified. These are categorized and the failures are described in this paper. The final recommendations to the Subcommittee are summarized and recommendations are presented for the course of action on the revision/addition of HV and EHV material to the current C57.142 Guide. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
22. Improved Average-Value and Detailed Equivalent Models for Modular Multilevel Converters With Embedded Storage.
- Author
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Herath, Nuwan and Filizadeh, Shaahin
- Subjects
MULTILEVEL models ,ELECTRIC transients ,RENEWABLE energy sources ,STORAGE - Abstract
The paper develops two computationally efficient models, namely a detailed equivalent model and an average-value model, with provisions for representation of the critical state of converter blocking, for modular multilevel converters with embedded storage. These models are indispensable in the simulation of dc faults. The developed detailed equivalent model provides accuracy that matches electromagnetic transient (EMT) simulations, with much reduced computational burden; the developed average-value model represents the averaged behavior of the converter by neglecting switching transients. Both models are extensively evaluated in the context of an HVDC system against benchmark results form a detailed switching model developed in PSCAD/EMTDC. The results confirm the validity and accuracy of the models for steady state, transient, and faulted operating conditions including when the converter is blocked in response to a dc fault. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
23. A Single-Stage Wireless Power Transfer Converter With Hybrid Compensation Topology in AC Input.
- Author
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Zhang, Shuo, Wang, Chunfang, and Chen, Daolian
- Subjects
WIRELESS power transmission ,ZERO voltage switching ,TOPOLOGY - Abstract
Miniaturization and low cost contribute to the development and popularization of wireless power transfer (WPT). Reducing the number of power conversion stages can reduce the volume and cost of the WPT converter, and even make it possible to improve the efficiency. A single-stage WPT converter with constant current (CC) and constant voltage (CV) output and its asymmetric modulation method are proposed in this paper. A direct AC-AC converter is applied to the primary side of the WPT converter to directly convert line-frequency AC to high-frequency AC. The applied direct AC-AC converter that can replace the commonly used multi-stage primary converter reduces the number of circuit devices, thereby reducing the volume and cost of primary converter. The proposed WPT converter can realize zero voltage switching (ZVS) and power factor correction (PFC). In order to achieve CC and CV output, a switchable hybrid compensation topology is applied to the proposed WPT converter. A 720-W experimental prototype was manufactured to verify the rationality of the proposed WPT converter and the correctness of the theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
24. An Improved Model of Voltage Source Converters for Power System Harmonic Studies.
- Author
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Gao, Bo, Wang, Yang, and Xu, Wilsun
- Subjects
VOLTAGE-frequency converters ,IDEAL sources (Electric circuits) ,IMPEDANCE matrices ,HARMONIC analysis (Mathematics) ,RENEWABLE energy sources ,HARMONIC distortion (Physics) - Abstract
Voltage source converters (VSCs) have been extensively used in power systems for interfacing renewable energies and other modern loads. Because of their nonlinear nature, a proper harmonic model of VSC devices must be established when conducting harmonic analyses in power systems. This is especially true for low-order harmonics, which are routinely encountered in present power systems. To this end, an analytical harmonic model that represents the low-order harmonic characteristics of VSCs is developed in this paper. The new model takes both the control loop and power loop (i.e., DC-link capacitor) of the VSC into account through rigorous mathematical derivations. The final result has shown that the VSC can be represented by a harmonically coupled impedance matrix at harmonic frequencies, which can be easily used for harmonic analyses of large-scale power systems. It also shows that the DC-link capacitor has a more noticeable impact on the harmonic impedance of VSCs with a smaller DC-link capacitance and low-order harmonics. The appropriateness of the new model was verified using EMT simulations and lab experiments. A complete procedure to construct the proposed VSC model is also established based on the research findings. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
25. Analysis and Control of Neutral-Point Deviation in Three-Level NPC Converter Under Unbalanced Three-Phase AC Grid.
- Author
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Jung, Kyungsub and Suh, Yongsug
- Subjects
AC DC transformers ,PULSE width modulation ,ELECTRIC potential ,VOLTAGE control - Abstract
This paper presents a neutral-point deviation and ripple compensating control method applied to a three-level neutral-point-clamped (NPC) converter. The neutral-point deviation and its harmonic components are analyzed with a focus on the average current flowing through the neutral-point of the dc link. This paper also proposes a control scheme compensating for the neutral-point deviation and dominant harmonic components under generalized unbalanced grid operating conditions. The positive and negative sequence components of the switching functions and ac input currents are employed to accurately explain the behavior of three-level NPC converter. Simulation and experimental results are presented to verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
26. A High-Frequency High Voltage Gain DCM Coupled-Inductor Boost LED Driver Based on Planar Component.
- Author
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Gao, Shanshan, Wang, Yijie, Guan, Yueshi, and Xu, Dianguo
- Subjects
ZERO voltage switching ,AIR gap (Engineering) ,HIGH voltages ,LIGHT emitting diodes - Abstract
A high-frequency high voltage gain discontinuous conduction mode coupled-inductor boost LED driver based on planar component is presented in this paper. GaN switch is adopted with lower conducting resistance and higher switching speed. Zero voltage switching (ZVS) is achieved at the same time to reduce high switching loss caused by high switching frequency. Compared with the previous work, the voltage gain is higher and efficiency is higher because of ZVS. This paper focuses on high efficiency; therefore, resonant gate driver is adopted and efficiency is increased by 0.6%. In terms of the coupled-inductor, planar component is used and parameter optimization is also proposed to realize lower loss, including wingding loss and fringing loss caused by the air gap. A 500 kHz 36 W prototype has been designed to demonstrate theoretical analysis. In addition, comparison of drive loss between the resonant gate driver used in this paper and conventional driver implemented by Si8271 is made, revealing advantages of the resonant driver. Obtained efficiency was up to 92.1% at full load. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
27. Balancing Algorithm for a Self-Powered High-Voltage Switch Using Series-Connected IGBTs for HVDC Applications.
- Author
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Chivite-Zabalza, Javier, Trainer, David R., Nicholls, Jonathan C., and Davidson, Colin C.
- Subjects
INSULATED gate bipolar transistors ,OVERVOLTAGE ,POWER semiconductor switches ,DIRECT currents ,CLAMPING circuits - Abstract
This paper presents a balancing algorithm for the so-called Director Switch, a controlled, reverse conducting, self-powered, high-voltage switch, using series-connected insulated gate bipolar transistors (IGBTs). This is a key component on two new voltage-source, high-voltage direct current (HVDC) converter topologies. These, which promise efficiency, cost, and size reductions, are an alternate arm converter and a series bridge converter. One of the main design challenges of the director switch is how to supply the IGBT gate drivers, and other auxiliary electronics while overcoming the high-voltage insulation barrier to ground level. In this paper, this is achieved by using the energy stored in a capacitive clamp snubber circuit, which also helps with the overvoltage mitigation during rare hard-switching events. However, the clamp capacitor and by proxy the IGBT voltages become highly unbalanced during operation, compromising the integrity of the switch. This paper presents a balancing strategy that consists in applying a controlled delay in the switching of the IGBT levels, in a way that forces a voltage balance on all the switch levels. The paper explains the unbalance. Then, the balancing strategy is explained and validated on simulation and on a high-voltage experimental rig, on switches comprising two and three series-connected IGBTs, respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
28. Monte Carlo Simulation of Switching Dynamics in Polycrystalline Ferroelectric Capacitors.
- Author
-
Alessandri, Cristobal, Pandey, Pratyush, Abusleme, Angel, and Seabaugh, Alan
- Subjects
FERROELECTRIC capacitors ,DISTRIBUTION (Probability theory) ,LATTICE dynamics ,PREDICTION models ,CAPACITORS ,MONTE Carlo method - Abstract
Ferroelectric (FE) materials are being studied for a variety of applications in memory, logic, and neuromorphic computing, for which predictive models of FE polarization are essential. In this paper, we present a Monte Carlo simulation framework capable of predicting the dynamic, history-dependent response of an FE under arbitrary input waveforms. The simulation is developed by generalizing the physics-based nucleation-limited switching model for polarization reversal in a polycrystalline FE. Measured polarization reversal data from fabricated FE Hf0.5Zr0.5O2 capacitors are used to extract the statistical distribution of FE grains. After parameter extraction, the model is able to predict the dynamics of the FE capacitor without further calibration. Finally, the model is applied to characterize the dynamic response of FE–dielectric bilayer structures and quantify the reduction in memory window due to device variability. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
29. Condition Monitoring of Circuit Switchers for Shunt Capacitor Banks Through Power Quality Data.
- Author
-
Bastos, Alvaro Furlani and Santoso, Surya
- Subjects
CAPACITOR banks ,DATA quality ,CAPACITOR switching ,MAINTENANCE costs ,CAPACITORS ,TRANSIENT analysis - Abstract
Aging of power system assets challenges utilities to maintain reliable service while minimizing their maintenance costs. Although malfunction of devices in the transmission or distribution networks can have catastrophic consequences, their failure is seldom unforeseen. Typically, the device aging occurs gradually over time until its health condition reaches a point of complete breakdown. The overall objective of this paper is to devise a non-invasive, online condition monitoring technique of circuit switchers for shunt capacitor banks. It aims to detect abnormal operation of these devices based on features derived from raw voltage and current waveforms, such that a predictive maintenance strategy may be employed before a complete failure occurs. The data analyzed in this paper are collected at a transmission capacitor bus, where the banks are equipped with pre-insertion impedance. Through a baseline range of values for selected parameters, the proposed technique is able to detect missing pre-insertion impedance during the capacitor energizing and failure of pre-insertion impedance switch out a few cycles after the energizing operation. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
30. A Modular Step-Up High-Voltage Bipolar Pulse Generator.
- Author
-
Gholamalitabar, Hossein, Adabi, Jafar, and Rezanejad, Mohammad
- Subjects
PULSE generators ,IDEAL sources (Electric circuits) ,BUILDING operation management ,LOW voltage systems ,POWER electronics ,CAPACITOR switching - Abstract
In this paper, a modular topology is presented for generating high-voltage pulsed power. The proposed structure consists of Marx-type modules, which are based on the switched-capacitor (SC) concept. This module receives an input voltage and, depending on the requirement of the user, produces an output voltage either equal to the input or twice as much as the input voltage, which shows the flexibility of our model. The capability of the module to produce a doubled output makes it appropriate for applications with low input voltage sources. Also, the topology has the capability of generating combined wide and narrow pulses. The topology was simulated in MATLAB Simulink and a laboratory setup was built to test its operation. The results validate the theoretical basis of the structure. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
31. Field-Based Evaluation of the Effects of Shunt Capacitors on the Operation of Distribution Transformers.
- Author
-
Korunovic, Lidija M., Jovic, Aleksandar S., and Djokic, Sasa Z.
- Subjects
CAPACITORS ,ELECTRIC potential ,ELECTRIC transformers ,ELECTRIC currents ,PERFORMANCE - Abstract
This paper analyzes the effects of shunt capacitors installed on the low voltage sides of 10/0.4 kV distribution transformers on the operation of these transformers. Using the results of an extensive measurement campaign, this paper compares: real and reactive power losses, secondary-side current, and primary-side apparent power before and after the installation of transformer capacitors. The following four cases of reactive power compensation are considered and discussed: adequate, conditionally adequate, and total compensation, as well as overcompensation. The presented analysis helps to identify transformer substations where the initial compensation should be changed or adjusted, in order to improve transformers’ operational performance. Voltage dependencies of real and reactive power demands of the transformer-supplied loads are taken into account, based on the previously identified load characteristics in the considered networks as well as voltage dependence of reactive power of shunt capacitors. The result with and without including these voltage dependencies in the analysis is compared and discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
32. The Predictive Closed-Loop Averaging Control of MMC Phase-Unit Losses Under Unbalanced Conditions.
- Author
-
Xu, Jianzhong, Yu, Yongjie, and Zhao, Chengyong
- Subjects
ELECTRIC potential ,ELECTRIC current converters ,CLOSED loop systems ,PHASE-locked loops ,ELECTRIC power systems - Abstract
This paper introduces an averaging control strategy of the phase-unit losses of modular multilevel converters (MMCs). The quantitative analysis of the MMC phase-unit loss distribution under unbalanced ac conditions is carried out by investigating the individual component of the MMC arm currents. It shows that the unbalanced arm currents will result in unbalanced phase-unit losses. To address this issue, this paper proposes a predictive closed-loop-control-based zero-sequence voltage injection method that results in much averaged loss distribution under unbalanced ac conditions. The essence of the new method is that it adjusts the three-phase sinusoidal references so that the unbalanced arm currents are fully utilized to average phase-unit losses. This paper shows the effectiveness of the new approach by electromagnetic transient simulations on PSCAD/EMTDC. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
33. A Zero-Sequence Voltage Injection-Based Control Strategy for a Parallel Hybrid Modular Multilevel HVDC Converter System.
- Author
-
Qin, Jiangchao and Saeedifard, Maryam
- Subjects
HIGH-voltage direct current converters ,HIGH-voltage direct current transmission ,ELECTRIC power system harmonics ,ELECTRIC circuits ,ELECTRICAL engineering - Abstract
A parallel hybrid modular multilevel converter (PHMMC) belongs to the class of modular multilevel converters, which have become potential candidates for high-voltage direct-current (HVDC) transmission systems. Due to the circuit topology of a PHMMC, the dc bus voltage contains low-order harmonics and cannot be fully regulated at a constant dc voltage. The dc bus voltage, if not properly controlled, leads to improper power transfer and increases the magnitude of dc current ripple on the dc transmission line. This paper proposes a zero-sequence voltage injection (ZSVI)-based model predictive control (MPC) strategy to control the dc current/power flow and simultaneously minimize the dc current ripple. The proposed strategy takes advantage of a cost function minimization technique to determine and inject the optimal zero-sequence voltage components into the dc- bus voltage of a PHMMC system. This paper derives a discrete-time dynamic model of the dc transmission-line current and, correspondingly, develops a predictive model. The predictive model is used to inject the appropriate amount of zero-sequence voltage components to the dc bus reference voltage waveform. Compared with the existing triplen harmonics injection method, the proposed ZSVI-MPC strategy improves the performance of a PHMMC system in terms of minimization of the dc current/voltage ripple. Performance of the proposed strategy for a 21-level PHMMC-based HVDC station system is evaluated based on time-domain simulation studies in the PSCAD/EMTDC software environment. The reported results demonstrate superior performance of the PHMMC-HVDC station operating based on the proposed ZSVI-MPC strategy, under various operating conditions, as opposed to the existing triplen harmonics injection method. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
34. The Use of Averaged-Value Model of Modular Multilevel Converter in DC Grid.
- Author
-
Xu, Jianzhong, Gole, Aniruddha M., and Zhao, Chengyong
- Subjects
CASCADE converters ,HIGH-voltage direct current transmission ,SMART power grids ,IDEAL sources (Electric circuits) ,ELECTRICAL engineering - Abstract
This paper investigates the applicability of averaged-value models (AVMs) for modular multilevel converters (MMCs) operating in a voltage-sourced converter-based-high-voltage dc (VSC-HVDC) grid. The AVM models are benchmarked by comparison with a detailed electromagnetic transient model of the grid, including a fully detailed MMC model. Analysis results show that the AVM is only effective as long as the capacitors are large enough to maintain nearly constant voltage across each MMC submodule. This paper also shows that previously developed MMC averaged models are not able to accurately simulate the transients under dc fault conditions. This paper introduces topology changes to a previously proposed averaged model that results in much improved simulation for such conditions. This paper also shows that the model can be used effectively to study HVDC grids with significant time savings. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
35. Independent Control of Two Permanent-Magnet Synchronous Motors Fed by a Four-Leg Inverter.
- Author
-
Ito, Shigeru, Moroi, Takayuki, Kubo, Yuji, Matsuse, Kouki, and Rajashekara, Kaushik
- Subjects
PERMANENT magnets ,ELECTRIC inverters ,ELECTRIC potential ,VECTOR control ,ELECTRIC switchgear ,INDUCTION motors - Abstract
This paper proposes a vector control strategy for independent control of two permanent-magnet synchronous motors (PMSMs) using a single four-leg inverter (4LI). An expanded two-arm modulation to obtain a balanced three-phase output voltage is described. This paper also proposes a method to compensate for the fluctuations in the neutral point voltage of two split capacitors in the dc link. The experimental results show that independent speed and position control of two PMSMs can be achieved using a single 4LI with the proposed vector control method. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
36. Multiple Objective-Based Optimal Energy Distribution for Wireless Power Transfer.
- Author
-
Zhang, Zhen, Pang, Hongliang, and Wang, Jiang
- Subjects
WIRELESS power transmission ,MAGNETIC coupling ,MAGNETIC energy storage ,PHYSICAL constants ,WIRELESS communications - Abstract
This paper presents a multi-coupling wireless power transfer (WPT) system aimed at dealing with various charging requests simultaneously. The proposed WPT system is able to distribute the energy more reasonably based on the top priority principle applying a novel distribution algorithm. Besides, the proposed system has the ability to charge the load in both the constant current mode and constant voltage mode while detecting the state of charging without using the bidirectional wireless communication. Moreover, this paper also puts forward a current injection topology named capacitance buffer rather than the traditional capacitor array in order to alleviate the large demand of the capacitors with different values under different resonant frequencies. Both simulation and experimental results are provided to demonstrate the feasibility and the performance of the proposed system. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
37. Analysis and Design of N-Path RF Bandstop Filters Using Walsh-Function-Based Sequence Mixing.
- Author
-
Agrawal, Abhishek and Natarajan, Arun
- Subjects
RADIO frequency ,BAND-stop filters ,WALSH functions ,SEQUENCY theory ,COMPLEMENTARY metal oxide semiconductors ,RADIO frequency integrated circuits - Abstract
Impedance translation using passive N-path mixers has been used to achieve local oscillator (LO)-defined series bandstop and shunt bandpass filtering. In this paper, we generalize N-path filtering using a correlator-based approach and propose N-path passive mixers driven by orthogonal sequences. Such sequence-driven N-path filters can potentially reject or select signals based on their properties in the spectral, spatial, and code domains. Specifically, a Walsh-function (WF) sequence (WF-seq)-based N-path shunt filter is implemented, demonstrating the feasibility of shunt bandstop filtering using LO sequences other than nonoverlapping pulses. The WF-seq approach enables reconfigurable concurrent filtering at two different frequencies with shunt operation avoiding penalties due to the switch drive overlap. A 65-nm CMOS implementation achieves 20-dB rejection at one frequency and 14-dB rejection concurrently at two frequencies between 0.3 and 1.4 GHz. The reconfigurable bandstop filter is implemented using analog gyrators and consumes 35–62.5 mW and achieves 2.9-dB noise figure and −2.5–5-dBm IIP3. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
38. Rise-Time Improvement in Bipolar Pulse Solid-State Marx Modulators.
- Author
-
Canacsinh, Hiren, Silva, J. Fernando, and Redondo, L. M.
- Subjects
ELECTRONIC modulators ,CAPACITORS ,INSULATED gate bipolar transistors ,DIODES ,SWITCHING circuits - Abstract
This paper presents the effect of stray capacitances in bipolar (negative and/or positive) pulses generated by the two different topologies of the solid-state Marx modulators. According to the analysis, the stray capacitances influence the energy transfer from the Marx modulator capacitors to the load affecting the bipolar (negative and/or positive) pulse rise time. This paper deals with the structure design to reduce the influence of the stray capacitance and to improve the pulse rise time of these bipolar solid-state Marx modulators. A four-stage laboratory prototype of the two topologies has been assembled using 1200-V insulated gate bipolar transistors and diodes, operating with 1000-V dc input voltage and 1-kHz frequency, producing 4-kV bipolar pulses, with 5- \mu \texts pulse duration and 120-ns rise time, into a resistive load. [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
39. Adaptive Modular Multilevel Converter Model for Electromagnetic Transient Simulations.
- Author
-
Stepanov, Anton, Mahseredjian, Jean, Karaagac, Ulas, and Saad, Hani
- Subjects
MULTILEVEL models ,COMPUTATIONAL electromagnetics ,VOLTAGE control ,INTEGRATING circuits ,INTEGRATED circuits - Abstract
This paper proposes an adaptive model of modular multilevel converter (MMC) for electromagnetic transient (EMT) simulations. The model is applicable to MMCs with arbitrary numbers of half-bridge and full-bridge submodules. The proposed design includes average value model, arm equivalent model, and detailed equivalent model. It allows smoothly transitioning from one model to another during time-domain simulations depending on the desired accuracy and execution time constraints. Modifications required in conventional MMC models to achieve smooth transitions are presented in the paper. Time-domain initialization methods are developed for each constituting model, including initialization of the appropriate control system blocks. Validity and effectiveness of the proposed adaptive model is demonstrated using EMT simulations of 401-level MMC-HVDC system. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
40. Adaptive Control for Three-Phase Power Converters With Disturbance Rejection Performance.
- Author
-
Yin, Yunfei, Liu, Jianxing, Luo, Wensheng, Wu, Ligang, Vazquez, Sergio, Leon, Jose I., and Franquelo, Leopoldo G.
- Subjects
ADAPTIVE control systems ,ELECTRIC current rectifiers ,SLIDING mode control - Abstract
This paper presents voltage regulation and current tracking control strategies for three phase two-level grid-connected power converters. By using power-invariant Park’s transformation, an averaged mathematical model of power converters is obtained in dq synchronous reference frame. Then a novel control strategy using adaptive control and ${H}_{\infty }$ technique is proposed to regulate the dc-link output voltage as well as track a desired current reference for three-phase power rectifiers. More specifically, an efficient adaptive controller is established in the external loop for regulating dc-link output voltage in the presence of external disturbances. A set of ${H}_{\infty }$ controllers are designed in the internal loop to force the input currents track their desired values. Finally, simulation results obtained from the proposed control method are presented, analyzed, and compared with that of sliding mode control, and the superiority of the proposed control laws is verified. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
41. Optimal Switching of DC–DC Power Converters Using Approximate Dynamic Programming.
- Author
-
Heydari, Ali
- Subjects
DC-to-DC converters ,DYNAMIC programming ,CAPACITORS ,ELECTRIC leakage ,SWITCHING circuits - Abstract
Optimal switching between different topologies in step-down dc–dc voltage converters, with nonideal inductors and capacitors, is investigated in this paper. Challenges including constraint on the inductor current and voltage leakages across the capacitor (due to switching) are incorporated. The objective is generating the desired voltage with low ripples and high robustness toward line and load disturbances. A previously developed tool, which is based on approximate dynamic programming, is adapted for this application. The scheme leads to tuning a parametric function approximator to provide optimal switching in a feedback form. No fixed cycle time is assumed, as the cycle time and the duty ratio will be adjusted on the fly in an optimal fashion. The controller demonstrates good capabilities in controlling the system even under parameter uncertainties. Finally, some modifications on the scheme are conducted to handle optimal switching problems with state jumps at the switching times. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
42. An Improved Submodule Topology of MMC With Fault Blocking Capability Based On Reverse-Blocking Insulated Gate Bipolar Transistor.
- Author
-
Song, Yonghui, Luo, Yongjie, Xiong, Xiaofu, Blaabjerg, Frede, and Wang, Wei
- Subjects
BIPOLAR transistors ,GRABENS (Geology) ,TRANSISTORS ,FAULT currents ,TOPOLOGY ,HIGH voltages - Abstract
The missing capability of DC fault current limitation is an inherent disadvantage in the typical half-bridge modular multilevel converter (MMC), which restricts its application in long-distance high voltage direct current (HVDC) systems. The full-bridge submodule (FBSM) and clamped double submodule (CDSM) topologies allow for fault current self-clearing, but also suffer from additional hardware cost and power losses. In this paper, an improved submodule topology utilizing the new reverse-blocking insulated gate bipolar transistor (RB-IGBT) is proposed to improve system economy without compromising its performance. The operating principles and DC fault characteristics of the proposed topology are analyzed in details, including comparison with various topologies in terms of cost, losses, fault current clearing speed and thermal. Compared with the traditional CDSM topology, the proposed RBSM can clear DC faults faster with reduced cost of switching devices. A DC fault protection strategy for MMC-HVDC system is also presented. Simulation results under normal operating, permanent and transient fault conditions are carried out to verify the effectiveness of the proposed topology. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
43. A Novel High-Gain DC-DC Converter Applied in Fuel Cell Vehicles.
- Author
-
Wu, Xiaogang, Yang, Mingliang, Zhou, Meilan, Zhang, Yu, and Fu, Jun
- Subjects
STATE-space methods ,FUEL cell vehicles ,LOW voltage systems - Abstract
The DC-DC converter for fuel cell vehicles should be characterized by high-gain, low voltage stress, small size and high-efficiency. However, conventional two-level, three-level and cascaded boost converters cannot meet the requirements. A new non-isolated DC-DC converter with switched-capacitor and switched-inductor is proposed in this paper, which can obtain high-gain, wide input voltage range, low voltage stresses across components and common ground structure. In this paper, the operating principle, component parameters design, and comparisons with other high-gain converters are analyzed. Moreover, the state-space averaging method and small-signal modeling method are adopted to obtain the dynamic model of converter. Finally, simulation and experimental results verify the effectiveness of the proposed topology. The input voltage of the experimental prototype ranges from 25 V to 80 V. The rated output voltage is 200 V and rated power is 100W. The maximum efficiency is 93.1% under rated state. The proposed converter is suitable for fuel cell vehicles. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
44. A Novel Oscillation Wave Test System for Partial Discharge Detection in XLPE Cable Lines.
- Author
-
Zhu, Guangya, Zhou, Kai, Zhao, Shilin, Li, Yuan, and Lu, Lu
- Subjects
PARTIAL discharges ,TEST systems ,OSCILLATIONS ,CABLES ,CAPACITORS ,ELECTRIC capacity - Abstract
This paper presents a novel oscillation wave test system (OWTS) to detect the partial discharge (PD) of mounting defects in power cable insulation. In the proposed system, a charging capacitor is added to the circuit topology based on the traditional OWTS. The charging capacitor is charged to the desired voltage by a high-voltage DC power source. After the charging process, the test cable sample is charged by the capacitor. The resonant circuit is formed by the charging capacitor, the test cable, and the resonant reactor to create an oscillating decay voltage. With this novel method, no space charge is injected into the cable insulation. The effect of the charging capacitance on the charging efficiency is calculated with the Multisim software. This paper describes the working principle and the assembly of a laboratory prototype for the PD detection of a 500 m cable circuit. The test results show the feasibility of the novel OWTS method. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
45. A Switched Capacitive Filter-Based Harmonic Elimination Technique by Generating a 30-Sided Voltage Space Vector Structure for IM Drive.
- Author
-
R, Rakesh, Ramachandran, Krishna Raj, Yadav, Apurv Kumar, Gopakumar, K., Umanand, Loganathan, and Matsuse, Kouki
- Subjects
VECTOR spaces ,SPACE frame structures ,INDUCTION machinery ,HARMONIC analysis (Mathematics) ,ELECTRIC potential ,TORQUE - Abstract
This paper proposes a novel polygonal voltage space vector structure (SVS) having 30 sides, for a star-connected induction motor drive. The SVS eliminates the presence of harmonics up to 25th order from motor phase voltage throughout the entire modulation range, providing a torque profile devoid of lower order pulsations. Linear modulation is extended till 99.63% of base speed without exceeding the motor phase voltage rating. Topology consists of a dc-link fed primary inverter and two equal low voltage modular capacitor fed secondary inverters. Here the harmonics generated by the primary inverter is canceled by the secondary inverter which acts as a switched capacitive filter. Detailed description of the SVS generation and timing calculations are provided in this paper. Effectiveness of the proposed scheme is validated using experimental results, inverter loss calculations, and harmonic analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
46. Optimization of High-Density and High-Efficiency Switched-Tank Converter for Data Center Applications.
- Author
-
Lyu, Xiaofeng, Li, Yanchao, Ren, Na, Nan, Chenhao, Cao, Dong, and Jiang, Shuai
- Subjects
DATA conversion ,SERVER farms (Computer network management) ,POWER density ,PRINTED circuit design ,ZERO current switching ,CORE materials - Abstract
In this paper, the design methodology of switched-tank converter (STC) is presented. The power loss breakdown analysis is conducted to point out the directions and paths for components optimization. It is revealed that the switching device conduction loss, printed circuit board (PCB) loss, and inductor loss become significant when output power is >150 W. Power loss of four switches is calculated and compared for switching device selection. The resonant capacitor is carefully designed to meet both current stress and ripple requirements. On the other hand, optimal design of the resonant inductors and PCB layout are fully investigated. The core loss model is provided, and different core materials are compared to minimize the core loss. Besides, a fine-tuned inductor winding structure is designed to achieve the lowest winding loss. Furthermore, PCB layout is optimized to get short loop length for each operation state. In addition to the hardware level optimization, an improved control method is proposed, in which the conduction time of switching devices is tuned to mitigate the circulating power. To verify the optimization work, a prototype of STC is built and tested. The experimental results indicate that a state-of-the-art performance of 98.71% efficiency and a 1000 W/in3 high power density is achieved. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
47. A New and Modular Active Snubber Cell for Inverters.
- Author
-
Bodur, Haci, Akboy, Erdem, and Yesilyurt, Huseyin
- Subjects
ZERO current switching ,ZERO voltage switching ,IDEAL sources (Electric circuits) - Abstract
In this paper, a new modular and active snubber cell, easily applicable, and attractive for converters, especially have many switches proposed. This snubber cell is implemented on the single phase of a grid-connected three-phase T-type three-level inverter (T-3LI). In this new converter, the main switches turn-on under zero-voltage transition and turn-off under zero-voltage switching (ZVS). Also, auxiliary switches turn-on under zero-current switching and turn-off under ZVS. All snubber diodes operate under soft switching (SS). There are no additional current and voltage stresses on the main switches. During an SS operation, the switching energies are transferred to a dc voltage source. Then, these energies are processed to input with an independent dc–dc converter. Thus, all switching energies are recycled. In this paper, the principle operation and steady-state analysis of the modular and active snubber cell for a single-phase T-3LI are presented and experimental results, rated 1 kW and 100 kHz, are provided to verify theoretical analysis. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
48. An Isolated Multilevel Quasi-Resonant Multiphase Single-Stage Topology for 380-V VRM Applications.
- Author
-
Rizzolatti, Roberto, Saggini, Stefano, Ursino, Mario, and Jia, Liang
- Subjects
DIGITAL modulation ,VOLTAGE regulators ,TOPOLOGY ,POWER resources ,ANALOG-to-digital converters - Abstract
In order to increase the efficiency of modern microprocessor power supplies used in data centers, 380-V dc power distribution systems have been attracting attention due to their high efficiency and high reliability. This paper presents an innovative single-stage approach for 380-V voltage regulator modules (VRMs) based on a quasi-resonant multilevel topology constant on-time operation. The proposed topology inherently integrates the multiphase approach, providing fast phase shedding and flat high-efficiency curves even at light-load conditions. This is a unique advantage, which is not possible to establish in the two-stage approach, which is very important in server architectures, and where high efficiency is required even at light-load conditions. This paper analyzes the circuit topology and proposes a control architecture for fast transient response, including current-sharing capabilities. The digital controller has been implemented in 0.16- $\mu$ m lithography together with a digital pulsewidth modulation with a 195-ps resolution and a 40-MS/s 7-bit analog-to-digital converter. Experimental results show an efficiency of 93% for a 120-A 380–1.8-V VRM power supply. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
49. Theoretical Analysis and Improvement on Pulse Generator Using BJTs as Switches.
- Author
-
Li, Zi, Li, Pan, Rao, Junfeng, Jiang, Song, and Sakugawa, Takashi
- Subjects
JUNCTION transistors ,PULSE generators ,ELECTRIC switchgear ,ELECTRIC circuit analysis ,ELECTRIC resistors - Abstract
Bipolar junction transistors (BJTs) have been widely studied and used in nanosecond high-voltage pulse generators due to the advantages of fast switching speed and high repetitive frequency. Usually the Marx-type circuit is used to raise the peak value of output pulses. In this paper, a traditional BJT-Marx circuit using charging resistors is analyzed theoretically and experimentally. Based on the results, the structure of a circuit is changed to decrease the isolation voltage across the resistors, and diodes are used to replace charging resistors to block capacitors discharging to resistors. Experimental results showed that the three Marx generators proposed in this paper output pulses with higher voltage amplitude, and the last improved circuit outputs pulses with faster fall times at a higher efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
50. Analysis of the Integrated SEPIC-Flyback Converter as a Single-Stage Single-Switch Power-Factor-Correction LED Driver.
- Author
-
Poorali, Behzad and Adib, Ehsan
- Subjects
LIGHT emitting diodes ,ELECTRIC power factor correction ,ELECTRIC power factor ,ELECTROLYTIC capacitors ,SWITCHING circuits - Abstract
This paper proposes a new isolated single-stage single-switch power-factor-correction (S4 PFC) driver for supplying light-emitting diodes (LEDs) without electrolytic capacitor. In the proposed LED driver, the switch turns on under zero current switching (ZCS) condition. Also, it turns on at a voltage less than its nominal voltage stress, and therefore, the switch capacitive turn-on loss decreases too much extent. The leakage energy is absorbed, so there are no voltage spikes across the switch when the switch turns off. In this paper, operating principles of the proposed driver are discussed, and design considerations are presented. Also, a laboratory prototype for supplying a 21 W/30 V LED module from 220 Vrms/50\,\rm Hz ac mains is implemented, and experimental results are presented to verify the theoretical analysis. [ABSTRACT FROM PUBLISHER]
- Published
- 2016
- Full Text
- View/download PDF
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