Abstract

Abstract: Brushless dc motors are getting more attention in many areas owing to its compactness, maintenance, high efficiency and low cost. Precise detection of rotor position is essential to achieve high efficiency. Mechanical sensor based methods increase size and inaccuracy. Back EMF method is one of the most popular control method for sensorless brushless dc motor. But this method is not suitable for high-speed operation, for the pulse width of zero-vector may be very short. Z-source inverter based approach to zero-crossing point detections during the shoot-through vectors for sensorless brushless dc motor is discussed here. This approach separates the zero crossing point detections from speed adjustment, and makes the shoot-through vector not influence the motor speed-adjustment directly. With this approach, the sensorless drive can operate in a wide speed range. It not only provides boost voltage for sensorless brushless dc motor drive system, but also improves the utilization rate of dc source voltage and the safety of the drive system.

Keywords: Brushless dc motor, sensorless, zero-crossing point detection, Z-source inverter

Abstract: Induction machines are the widely used machines in many industrial applications. Enlistment machines are generally utilized as a part of enterprises because of its ease and least upkeep. In more electric aircraft (MEA), both ac and dc electric power with different voltage levels is required for different airplane loads. This paper introduces an enlistment generator-based ac/dc crossover electric power age framework for MEA. In the proposed system design, a fast enlistment starter/generator and a low-speed acceptance generator are introduced on the high pressure (HP) and low pressure (LP) spools of the motor, separately. In creating method of activity, the bigger part of the steady voltage variable recurrence ac power is produced by the HP generator while the dc control request is shared by both HP and LP generators. A control conspire is produced to manage the ac stack voltage and organize dc control age between the two generators. The proposed induction generator based ac/dc hybrid generation system outcomes in reduced hardware requirement compared with both ac and dc primary generation systems.

Keywords: Aircraft, distributed power generation, generators, induction motors, power generation control..

Abstract: An image is worth more than ten thousand words. The two principle application area of digital image processing methods (a) improvement of pictorial information for human interpretation and, (b) processing of image data for storage, transmission, and representation for autonomous machine perception. Here we propose a flexible method to enhance contrast of medical images by using modified adaptive gamma correction with a provision to correct the illumination. This proposed transformation technique may enhance the brightness of the darker areas of the image modality. The experimental results shows that the proposed image enhancement technique produces enhanced images of comparable or even higher quality than those produced via conventional methods.

Keywords: Contrast enhancement, medical image

Abstract: Permanent magnet synchronous motors (PMSM) are extensively used in many applications including robotics, precision machining etc. because of their good features such as, high efficiency, light weight, better accuracy, and low maintenance requirements compared to induction motors. Because of the increasing demand for energy efficiency, PMSM replaces the traditional induction motors. The main problem with this motor is the formation of torque ripples at low-speed which may cause mechanical vibrations and induces oscillations in speed. So low-speed applications of this motor have some limitations. Vector controlled PMSM drives can be used to supply lesser torque ripples and better dynamic response. Conventionally Proportional integral (PI) controllers are used for this. But the performances of the PI controllers are affected by load disturbances, speed variations and parameter variations due to its constant proportional gain and integral time constant. The novelty of this work is implementing a new control technique by using a PI-resonant (PI-RES) controller by paralleling a variable frequency resonance controller with the conventional PI controller.

Keywords: Permanent magnet synchronous motors, Proportional integral (PI) controllers, PI-resonance (PI-RES) controllers, Torque ripples, Field oriented control

Abstract: A system to facilitate the collision avoidance capabilities for marine vessels during ocean navigation is presented in this project. This proposed concept also helps to safeguard the ship crossing the border and guides them to go in a right path and save their life. This idea helps in locating the ships and fishing boat using GPS system. This information is transmitted using wireless mode to the control system. The Bluetooth technology helps us to communicate from both the end that is the ship and the control system .Similarly the temperature and humidity is also calculated using respective sensors. Ultra sound sensors is used to avoid ship collision .All the information related to the process is sent to the micro controller unit and process take place .Microcontroller is pre-programmed in such a way to undergo the process .Similarly the border crossing alert is sent to the coast guards from the controller section through the Bluetooth module.

Keywords: GPS, Ultrasound sensor, Microcontroller, Bluetooth

Abstract: The proposed system is an alternative to the conventional hardware section of the interlocking and signalling methodologies adopted by Indian Railways, which are largely composed of relays and cables. In this paper, sensors, controllers and Wi-Fi modules, made to work in an integrated fashion to replace these otherwise inefficient (both in terms of energy and space) systems is presented. The presence of trains in railway tracks, detected by sensors, is used to control the railways signals, via microcontrollers. Further, this information is used to switch the siding tracks and level crossing gates through various motors. The utility of microcontrollers in this area also warrant several other additional features like pre-acknowledging loco pilots about upcoming signals, stopping the trains directly from control rooms in case of emergency, etc., which also adds to the security aspect of the entire system.

Keywords: Indian Railways; signalling; interlocking; energy efficiency; safety factors in railway; embedded systems.