by João Miguel Trindade, João Paulo N. Torres, António Baptista and Mª João Martins
Original Research
Satellite communication systems are increasingly more used by the society in many applications, and its development is a high priority for the scientific community. The need for increasing bandwidth to satisfy the users’ needs, makes inter-satellites Free Space Optics (FSO) communication preferred instead of traditional radio frequency links. The inter-satellites communication links with high bit rates and low power is a determining factor in the performance of these systems. As such, communications occur over long distances and high altitude orbits, which requires optical sources with highly collimated and coherent beams in order to ensure a better link between the transmitter and the receiver with low emission power. This paper involves the development of two experimental blocks for implementing an inter-satellite optical communication system using a semiconductor laser type. It aims at the definition and analysis of the elements of the two circuits, at the transmitter subsystem and includes the design for the production of printed circuit boards (PCB). Moreover, experimental tests were performed to validate the results obtained in the simulations.
American Journal of Electrical and Electronic Engineering. 2017, 5(3), 108-119. DOI: 10.12691/ajeee-5-3-6
Pub. Date: July 01, 2017
23131 Views2104 Downloads
by LingZhi Yi, Yue Liu, WenXin Yu and Weihong Xiao
Original Research
Neural networks have many advantages, such as parallel processing, self-suit, associated memory and classify ability strongly which can be used to analog circuit fault diagnosis. But it is very easy to trap the local minimum if the initial network weights are randomly generated. To solve this problem, the cuckoo search algorithm is used to optimize the initial weights of the neural network. A novel method for analog circuit fault diagnosis is proposed in this paper, based on BP neural network as classifier optimized by cuckoo search algorithm. The feasibility and effectiveness of the proposed method are verified by the simulations of Sallen-Key low-pass filter circuit. Compared with other methods, the results show that the proposed method is effective to identify and classify faults.
American Journal of Electrical and Electronic Engineering. 2017, 5(3), 102-107. DOI: 10.12691/ajeee-5-3-5
Pub. Date: June 02, 2017
16372 Views3231 Downloads
by E.A. Anazia, E. S Ugochukwu, J. C. Onuegbu and Onyedikachi S.N
Original Research
This paper examined and presented a simplified approach to power transformer design. Analyzed possible losses associated with power transformers through computational techniques and crucial design diagram.
American Journal of Electrical and Electronic Engineering. 2017, 5(3), 94-101. DOI: 10.12691/ajeee-5-3-4
Pub. Date: June 01, 2017
13580 Views2234 Downloads
by Serge Raoul Dzonde Naoussi, Charles Hubert Kom and Jean-Philippe Blonde
Original Research
This paper presents an unusual Field Programmable Gate Array (FPGA) development platform for power systems control. This platform is made up of two FPGA boards with a hardware and software communication interface. The one initially realized for direct torque Motor control is now dedicated for analog and digital signals input/output and the other card of much important density is specialized in data processing. A fully digital modules have been developed inside FPGAs from synthesis tools Quartus 2 and Maxplus 2, and a physical link have been realized to manage the communication between the cards. The control strategy takes advantage of the parallelism of the FPGA technology to share in real-time the controller’s information with its environment. Simulations and experimental results validate the feasibility of a simple handshaking communication protocol between both cards. On the other hand, with the proposed implementation solution it was shown a safe operation in a power grid switching station, a successful instantaneous frequency measurements used for grid synchronization and Active Power Filter control, followed by a production of Pulse Width Modulation (PWM) gating signals used for inverter in motor control and power quality applications.
American Journal of Electrical and Electronic Engineering. 2017, 5(3), 85-93. DOI: 10.12691/ajeee-5-3-3
Pub. Date: May 18, 2017
16950 Views2380 Downloads
by Abd Ulsamad Ibn Omer, Mohamed Nasr Eldin, Mohammed Siddig and Nisreen Ibrahim
Original Research
Now wireless communications growing very fast, in their applied techniques and equipment. Hardware reduction became a main objective for less cost and less complexity wireless communication devices and systems. One of the most efficient solutions for the hardware complexity reduction in wireless communication systems is Software Defined Radio (SDR), it’s modulation and demodulation execute through software in a Field Programmable Gate Array (FPGA), stored in a USB Dongle used to reduce the hardware by using software, that’s enable the radio system to be multi-functions instead of one function as in the classic radio systems. This paper shows the software demodulation of FM broadcast (88 – 108 MHz) by using RTL2832 USB dongle which capture from monopole antenna to the RF Front-end ( E4000chip) then to Digital Signal Processor (DSP) for demodulation and channel decoding through (RTL2832U) chip, As shown in the plotted received (demodulated through software) signals, Signals are so smooth (no ripples) which shows the high resolution of received signals. Furthermore the channel can be tune many channels simultaneously which cannot be done by the classical radio systems.
American Journal of Electrical and Electronic Engineering. 2017, 5(3), 78-84. DOI: 10.12691/ajeee-5-3-2
Pub. Date: May 16, 2017
22439 Views3757 Downloads
by Mohammad Amin Jokar
Original Research
This paper presents the tropology of direct conversion of AC-AC with step down frequency operation. Due to, the higher order harmonics AC conversion always arises difficulty and complex calculation, which effect the output response. Precise controlling and harmonics reduction is much easier using frequency control strategy, in this regards cycloconverter has drawn higher attention in terms of frequency conversion. In this paper, an approach for designing of single phase and three phase cycloconverter is reported. The gating sequence has been designed for desired frequency conversion. Again the performance of the designed converters is evaluated using Matlab/Simulink software for different types of loads. The rotor speed of Induction motor (IM) is observed here as a dynamic AC load .The complete description of the models for the frequency conversion is provided and simulation results for resistive, inductive and motor validate the developed strategy.
American Journal of Electrical and Electronic Engineering. 2017, 5(3), 69-77. DOI: 10.12691/ajeee-5-3-1
Pub. Date: May 10, 2017
17820 Views2330 Downloads