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This 35 system deployment has shown that fuel cells systems are now a credible backup power solution for critical telecom sites. The commercially available fuel cell with an integrated fuel reformer and HydroPlus methanol/water fuel is an increasingly popular, highly reliable, and cost-effective backup power source for remote and/or extended run power outages for the telecom industry.
In this paper, the preliminary EMC analysis process between the Communication, Ocean and Meteorological Satellite (COMS) and Geostationary Earth Orbit (GEO) launch vehicles in the frequency range [1 MHz-47 MHz] is described. The considered launch vehicle is delta IV. The COMS satellite Radiated Emission (RE) specifications have been compared to delta 4 launch vehicle Radiated Susceptibility (RS) limits...
Many countries are making strong harmonic current regulations for high power consuming equipments to reduce power loss and voltage distortion in power distribution. To comply with the regulation, the PWM converter is receiving more interest due to the low harmonic current generation compared with diode rectifier and unity power factor. This paper introduces a design of PWM converter inverter system...
This paper is focused on implementing an online monitoring system that checks power facility status by applying network based technology to Urban Transit substation power facilities and the results of its on-field tests. This system is composed of a sensor part, a measurement part, a transceiver part, a host computer, and a power source part. The system is designed to collect, save, analyze, and display...
By analysis on the power of motor and the voltage of system in various hybrid cars, the up-to-date trend was analyzed; as the power of motor increases, the DC link voltage of inverter goes up. The voltage of system was analyzed in a view point of the loss of power device and the copper loss of motor according to the DC link voltage. Moreover, the DC link voltage was defined as the power of motor by...
This paper reviewed the development of a 3-phase 125 kW grid connected PV inverter and changes in the conversion performance of the inverter based on the gain of the low frequency isolation transformer for isolation between solar and the grid. The 125 kW PV inverter consists of a transformer with the grid frequency for isolation between input and output (galvanic isolation) and it has the output power...
As the grid-connected photovoltaic power conditioning systems (PVPCS) are installed in many residential areas, this has raised potential problems of network protection on electrical power system. One of the numerous problems is an Island phenomenon. There has been an argument that because the probability of islanding is extremely low it may be a non-issue in practice. However, there are three counter-arguments:...
Cogging torque results from the interaction of the rotor magnets acting on the stator teeth or poles independent of any current. It is desirable to reduce the cogging torque since it may cause speed ripple and vibration, particularly at light load and low speed. When the motor equipped ring magnet, it is very effective to reduce the cogging torque as changing only the magnetization patterns of the...
In this paper, the nonlinear observer based controller will be developed for PEM fuel cell system. Nonlinear model of PEM fuel cell system is introduced to study the design problems of observer. Sliding mode observer and nonlinear state observer are designed to estimate the system states such as supply manifold pressure, Oxygen pressure, Hydrogen pressure, return manifold pressure, etc. These states...
This paper presents a current-mode control non-inverting buck-boost converter. The proposed circuit is controlled by the current mode and operated in three operation modes which are buck, buck-boost, and boost mode. The operation mode is automatically determined by the ratio between the input and output voltages. The proposed circuit is simulated by HSPICE with 0.5 ??m standard CMOS parameters. Its...
This paper presents the influence of flatness of the secondary reaction plate on performance of a linear induction motor. Construction tolerance of the plate affects directly to the cost and performance of the Linear metro. Detailed simulation of the flatness has been done by using FEM.
In this paper, a wireless power transmission system was designed and demonstrated using an optimized rectenna circuit. To use wireless power transmission, the most important factor is the microwave-DC conversion efficiency. To improve the microwave-DC conversion efficiency, matching circuits from antenna to rectifier and rectifier to load were designed and fabricated in this research. And also, printed...
In this paper, a robust self-tuning controller for a velocity control of permanent magnet type stepping motor is proposed.. The self-tuning theory provides a nonlinear modeling of a stepping motor drive system and could provide the controller with information regarding the reference variation, system noise, and parameter variation of the stepping motor through the on-line estimation. Thus, the proposed...
In this paper, power quality control (PQC) using a Goertzel algorithm for single phase grid-connected photovoltaic power conditioning system (PV-PCS) is proposed. The Goertzel algorithm is a kind of discrete Fourier transform (DFT) that extracts magnitude and phase of required frequency from the input signal, with minimum computation. The proposed PQC is formed based on the Goertzel algorithm. Also...
Magnetic field coupling is the best candidate for the communication in a harsh environment, for example, under water and ground. However, the magnetic coupling at low frequency and high frequency range is limited by its short communication range. To obtain the maximum communication range between aggregator and sensor node, several main parameters such as number of turns, thickness and diameter of...
The usual way to avoid a computer shutdown during a mains failure is to connect an ac uninterruptible power supply (UPS). Alternatively, in this paper, a simple and high efficiency dc UPS is presented by proposing an isolated bidirectional soft-switching dc-dc converter. The bidirectional dc-dc converter operates under zero-current switching (ZCS) condition by utilizing the leakage inductor of the...
This paper describes the overview of the COMS (communication ocean meteorological satellite) telecommand (TC) processing. On-board command function receives, verifies and executes commands from ground, which are addressed to the flight software. In order to process the commands using the unique format, command messages (CMs) are generated by the flight software from received telecommand sent by the...
It is to make motors more efficient because of the higher conductivity of copper. In addition, reduced tosses in such motors may lead to better design flexibility and motors are more compact. However, copper price and weight is higher than aluminum so, copper wire motor has disadvantage compared with aluminum wire in manufacturing cost. This paper presents aluminum wire motor design to reduce motor...
There are several levels of software (i.e. flight software) performance testing in spacecraft development. For example, unit test, integration test and system test. Especially the integration test is one of the key phases because in this phase the flight software performance with respect to HW and SW compatibility is validated. Also throughput analysis shall be performed at the integration test level...
In general, solar array is used for primary power source of satellite. For solar array design, required power and voltage are considered to perform the mission successfully. Also, solar cell degradation and string failure at EOL (End of Life) are considered for its design. In this paper, solar array design that is reflected design consideration for Korea LEO (low earth orbit) satellite is introduced...
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