scholarly journals Systems mutual loadings of traction asynchronous cars

2019 ◽  
Vol 294 ◽  
pp. 05009
Author(s):  
Andriy Afanasov ◽  
Oleksandr Shapovalov ◽  
Maryna Voitenko
Keyword(s):  
Power Supply ◽  
Power Efficiency ◽  
Reactive Power ◽  
Capital Expenditure ◽  
Wide Frequency Range ◽  
Electrical Machines ◽  
Rolling Stock ◽  
Frequency Range ◽  
Wide Range ◽  
High Level

The review of methods of post-repair tests of traction asynchronous motors under conditions of locomotive depot is carried out.The necessity of introducing special stands for post-repair tests is shown in order to improve their quality, reduce the number of failures of service equipment, improve safety of the railway transport. Let’s consider a question of power supply of the research asynchronous engine in wide frequency range and also a possibility of creation of the universal stand for testing important asynchronous engines of the electrorolling stock. Survey of possible versions of the scheme mutual loadings of asynchronous electrical machines which can be used for testing traction asynchronous engines of the rolling stock is executed. Such systems can be constructed both with use of the static converter of frequency, and without it. The given short characteristic of each alternative, certain advantages and shortcomings of each of system options. It is shown that systems with use of static converters of frequency differ in high power efficiency, allow to carry out tests in the wide frequency range of power supply, however have higher prime cost. Schemes without converters of frequency differ in smaller power efficiency, impossibility to carry out tests in the wide range of frequency of power supply, high level of consumption of reactive power . The results of the carried-out analysis can be used when choosing rational option of a system mutual loadings of asynchronous electric motors which will differ in higher functionality and power efficiency. Use of such systems will allow to lower capital expenditure for creation new and modernization of traction electrical machines that exist at the station for test.

scholarly journals The Effect of Exposure to Noise during Military Service on the Subsequent Progression of Hearing Loss

2021 ◽  
Vol 18 (5) ◽  
pp. 2436
Author(s):  
Brian C. J. Moore
Keyword(s):  
Hearing Loss ◽  
Longitudinal Studies ◽  
Military Service ◽  
Noise Exposure ◽  
Hearing Threshold ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Threshold Levels ◽  
Wide Range ◽  
High Level

This paper reviews and re-analyses data from published studies on the effects of noise exposure on the progression of hearing loss once noise exposure has ceased, focusing particularly on noise exposure during military service. The data are consistent with the idea that such exposure accelerates the progression of hearing loss at frequencies where the hearing loss is absent or mild at the end of military service (hearing threshold levels (HTLs) up to approximately 50 dB HL), but has no effect on or slows the progression of hearing loss at frequencies where the hearing loss exceeds approximately 50 dB. Acceleration appears to occur over a wide frequency range, including 1 kHz. However, each of the studies reviewed has limitations. There is a need for further longitudinal studies of changes in HTLs over a wide range of frequencies and including individuals with a range of HTLs and ages at the end of military service. Longitudinal studies are also needed to establish whether the progression of hearing loss following the end of exposure to high-level sounds depends on the type of noise exposure (steady broadband factory noises versus impulsive sounds).

Experimental Analysis on the Operating Performance of Induction Motor with Unbalance Power Supply Conditions

2014 ◽  
Vol 635-637 ◽  
pp. 1404-1407
Author(s):  
Yuan Xing Zhang ◽  
Fei Li ◽  
Ya Li Shen ◽  
Lei Juan Yang ◽  
Jie Li ◽  
...  
Keyword(s):  
Induction Motor ◽  
Power Supply ◽  
Power Efficiency ◽  
Single Phase ◽  
Reactive Power ◽  
Phase Voltage ◽  
Three Phase ◽  
Unbalanced Voltage ◽  
Negative Sequence Current ◽  
Domestic Appliances

Problems of power quality have been increasingly concerned by the researchers, as the domestic appliances we are usually used are single-phase load, which mainly causes the unbalance of three-phase voltage of power supply. If the induction motor is supplied by three-phase unbalanced voltage, the currents, active and reactive power, efficiency, and losses are affected as the negative-sequence current appears, this paper is emphasized on the induction motor’s characteristics when its’ power supply is three-phase unbalanced voltage by experimental research.

Solid State Sintering and Microstructural Evolution on Wide Frequency Range Dielectric Responses of Mechanically Activated CaTiO3 Ceramics

2015 ◽  
Vol 1107 ◽  
pp. 38-44
Author(s):  
Wong Yick Jeng ◽  
Hassan Jumiah ◽  
Mansor Hashim
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Sintering Temperature ◽  
Microstructural Analysis ◽  
High Energy ◽  
Wide Frequency Range ◽  
Milling Process ◽  
Frequency Range ◽  
Wide Range

The CaTiO3samples were prepared by high-energy ball milling process followed by sintering process from 1040 to 1200°C. X-ray diffraction (XRD), microstructural analysis, and dielectric properties over a wide range of frequency varying from 0.01 Hz to 1 GHz at room temperature were investigated. The formation of a single phase CaTiO3with orthorhombic structure was achieved at 1120°C and above. From a morphological point of view, sintering temperature promoted grain growth. Dielectric properties in the frequency range 0.01 Hz - 1 MHz revealed a relaxation-type process. Interfacial phenomena were the possible physical mechanisms that gave rise to these relaxation-type plots. Extending the frequencies above ~1 MHz yielded a frequency-independent characteristic of dielectric constant (ε'). These turned out to the relatively small dielectric loss (tan δ) values. The origin of the dielectric responses in the frequency range 1 MHz - 1 GHz was attributed to the domination of dipolar polarization. The grain size effect in sintered CaTiO3samples was prominent, notably in dielectric responses above ~1 MHz. Increase in sintering temperature remarkably led to an enhancement in dielectric constant values and reduction in dielectric loss values. Therefore, a significant correlation existed between microstructural features and dielectric properties.

Dynamic Bridge Piezoelectric Amplifiers with Signal Generator

2012 ◽  
Vol 182-183 ◽  
pp. 374-377
Author(s):  
Hai Tao Xin
Keyword(s):  
Frequency Response ◽  
Piezoelectric Actuator ◽  
Power Supply ◽  
Dynamic Performance ◽  
Wide Frequency Range ◽  
Slew Rate ◽  
Frequency Range ◽  
High Demand ◽  
Positioning Accuracy ◽  
New Type

Piezoelectric amplifier is a very important part of the piezoelectric actuator. Not only positioning accuracy, but also dynamic performance and power are demanded more and more highly. At present piezoelectric amplifier are mainly used in static applications, power and frequency response are usually incompatible. This paper developed a new type of piezoelectric amplifier to meet high demand for dynamic, which takes dual-power supply, bridge-output to achieved slew rate, power were doubled, and maintain a wide frequency range at the same time. Controller implements DDS unit through FPGA, which could achieve sine, triangle, square and sawtooth.

scholarly journals Designing an uninterruptible power supply based on the high efficiency push–pull converter

2013 ◽  
Vol 16 (3) ◽  
pp. 29-40
Author(s):  
Phuong Minh Le ◽  
Dzung Quoc Phan ◽  
Huy Minh Nguyen ◽  
Phong Hoai Nguyen
Keyword(s):  
Power Supply ◽  
High Efficiency ◽  
Harmonic Distortion ◽  
Original System ◽  
Uninterruptible Power Supply ◽  
Switching Power ◽  
Wide Range ◽  
Uninterruptible Power ◽  
Modulation Control ◽  
High Level

This paper presents an implementation of the DC/DC push–pull converter for an uninterruptible power supply (UPS). Some classical DC/DC converters are presented and analyzed for pointing out their advantages and drawbacks. Besides, an original system based on a push-pull converter associated with a dynamic modulation control is chosen. The main advantage is the possibility to control the delivered electric power in a wide range from very low level to high level of voltage within the same basic architecture. It can reduce the switching power losses and increase the power conversion efficiency. This paper proposed a new control scheme of the DC/DC converter and DC/AC inverter. The suggested system consists of a high efficiency DC/DC converter and a singlephase DC/AC inverter has been simulated using Matlab/Simulink and designed basing on the DSP TMS320F28027. Both results show high performances of the DC link and AC load voltages, when load changes from zero to rated. The performance of the proposed system has been verified through a 1kW prototype of the system for a 50 Hz/220-230 VAC load sourcing by two series connected batteries of 12V. The proposed DC/DC converter achieves a high efficiency of 93.0%. The system including the DC/DC converter and DC/AC inverter achieves an efficiency of 91.2% and Total Harmonic Distortion (THD) of AC load voltage reached 1.9%.

scholarly journals THE EFFECTIVENESS OF VALIDATION MEASUREMENTS IN AUTOMATED SYSTEMS OF THE POWER SUPPLY SYSTEMS CONTROL IN ACCORDANCE WITH LIMIT VALUES

2017 ◽  
Vol 60 (5) ◽  
pp. 407-416 ◽  
Author(s):  
V. A. Anishchenko ◽  
T. V. Pisaruk
Keyword(s):  
Power Supply ◽  
Operational Reliability ◽  
Probability Of Detection ◽  
Measured Variable ◽  
Operating Personnel ◽  
Limit Values ◽  
Technological Processes ◽  
Wide Range ◽  
High Level ◽  
Supply Systems

A high level of operational reliability of power supply systems is virtually impossible to provide without operational control of the reliability of the measurement variables (currents, voltages, powers, energies, temperatures, pressures) that characterize the condition of power equipment and technological processes. Reforming the power engineering and its transition to market relations necessitate one to toughen the requirements for the reliability of the measuring information. Inaccurate measurements are a potential source of misdiagnosis of malfunctions of equipment and they cause incorrect operation of emergency control equipment and erroneous actions of operating personnel in the control of technological processes. Operational methods of reliability control that enhance the operational reliability of the measuring information are based on the usage of the semantic value of the measured data, their consistency, process consistency, and consistency of balance. These methods use technological sense of the measured variables and they complement the methods of hardware status monitoring of automated control systems based on digital codes. That improves the overall operational reliability of the transmission, collection and processing of information. The most common semantic method of control is the method of limits (“fork”) that compares the numeric value of the measured variable with the upper and lower boundaries of valid values. The disadvantage of limit values in many cases is its poor resolution, due to the wide range of appearance of results of measurements. This reduces the probability of detection of gross and systematic errors of measurements more than it may be accepted. With this regard, the objective of a reasonable narrowing of the range of valid values of the variables, that uses the theory of statistical decisions, acquires high relevance.

scholarly journals Design of Digital Control System for DC/DC Converter of On-Board Charger

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Haijun Tao ◽  
Guopeng Zhang ◽  
Zheng Zheng ◽  
Changshun Du
Keyword(s):  
Power Supply ◽  
Power Efficiency ◽  
Dead Time ◽  
Dynamic Performance ◽  
Soft Switching ◽  
Current Phase ◽  
Voltage Oscillation ◽  
Wide Range ◽  
Subharmonic Oscillation ◽  
The Dead

Vehicle charging power supply is widely used because of its small size and portability. Aiming at the problems of slow dynamic response, subharmonic, oscillation and limited soft-switching range of phase-shifted full-bridge DC/DC converter, the paper proposed a modified PSFB converter by introducing clamp diodes at the primary side of the transformer to suppress voltage oscillation of the transformer’s secondary side. Also, digital peak current phase-shifting control and slope compensation are introduced to avoid subharmonic oscillation. Dynamic dead-time control technology introduced adjust the dead-time in different load ranges through the dead-time adjustment subroutine. Finally, an experimental platform of on-board charging phase-shifted full-bridge DC/DC converter is established. The experimental results show that the power supply eliminates subharmonic oscillation, achieves a wide range of soft-switching, improves the dynamic performance and antiinterference ability of the system, and optimizes the power efficiency.

Bromine NQR and Crystal Structures of Tetraanilinium Decabromotricadmate and 4-Methylpyridinium Tribromocadmate

1994 ◽  
Vol 49 (1-2) ◽  
pp. 213-222 ◽  
Author(s):  
Hideta Ishihara ◽  
V. G. Krishnan ◽  
Shi-qi Dou ◽  
Helmut Paulus ◽  
Alarich Weiss
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Negative Temperature ◽  
Wide Frequency Range ◽  
Frequency Range ◽  
Temperature Dependent ◽  
Positive And Negative Coefficients ◽  
Temperature Coefficients ◽  
Wide Range ◽  
Group D

AbstractThe 79,81Br NQR spectra of tetraanilinium decabromotricadmate (1) and 4-methylpyridinium tribromocadmate (2 ) were studied as function of temperature and their crystal structures were determined. (C6H5NH3)4Cd3Br10 (1): Space group D1 52h - Pbca , Z = 4, a = 2507.8(7) pm, b = 1985.4(5)pm, c = 763.0(2)pm. Characteristic for the structure are trioctahedral units [Cd3Br10] condensed to planes. Within the units the octahedra are face connected and further condensed to planes via common corners. Two types of hydrogen bonds are observed. The 81Br NQR lines with frequencies (MHz, 298 K) of 62.98, 52.59, 43.39, 41.82, and 40.71 are little temperature dependent with positive and negative coefficients. The wide frequency range of the NQR lines is reflected by the wide range of the intraionic distances, 263 ≤ d(Br-Cd)/pm ≤300. (4-(CH3)C5H4NH)CdBr3 (2): C52h - P21/n, Z = 4, a = 1228.8(5}pm, b= 1168.5(5)pm, c = 758.3(3)pm, β = 95.30(1)°; the CdBr⊖3 ions are condensed to chains. The 81Br NQR spectrum is a triplet with frequencies (MHz, 298 K) of 66.01, 55.39, and 50.75. The temperature dependence is small, with positive and negative temperature coefficients. The distances d(Cd-Br) are 256 pm (Cd-Br(2)), 261 pm (Cd -Br(1)), and 284 pm (Cd-Br(3)) and in the chain [CdBr3]Br(1) and Br(3) are bridging atoms. The relations between Br-NQR and crystal structures are discussed.

scholarly journals Linear Ultrasound Transmitter Based on Transformer with Improved Saturation Performance

Electronics ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 107
Author(s):  
Stefano Ricci ◽  
Dario Russo
Keyword(s):  
High Voltage ◽  
Magnetic Core ◽  
Wide Frequency Range ◽  
Portable Devices ◽  
Power Network ◽  
Frequency Range ◽  
Power Sources ◽  
Ultrasound Waves ◽  
Test Board ◽  
Wide Range

Ultrasound methods are currently employed in a wide range of applications. They are integrated in complex electronics systems, like clinical echographs, but also in small and compact boards, like industrial sensors, embedded systems, and portable devices. Ultrasound waves are typically generated by energizing a piezoelectric transducer through a high-voltage sequence of small sinusoidal bursts. Moreover, in several applications, the ultrasound board should work in a wide frequency range. This makes the transmitter, i.e., the electronics that drives the transducer, a key part of the circuit. The use of a small transformer simplifies the electronics and reduces the need of high-voltage power sources. Unfortunately, the transformer magnetic core, when subjected to the sequence of bursts employed in ultrasound, is particularly prone to saturation. This phenomenon limits the maximum voltage and/or the minimum frequency the transformer can be employed for. In this work, a transmitter based on a transformer is proposed. Inspired by the technique currently employed in the power network transformers, we added a prefluxing circuit, which improves the saturation performance 2-fold. The proposed transmitter was implemented in a test board and experimented with two commercial transformers at 80 Vpp. Measurements show that the proposed prefluxing circuit moves down the minimum usable frequency 2-fold: from 400 to 200 kHz for one of the two transformers, and from 2.4 to 1.2 MHz for the other.

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