Magnetik askılı taşıma sisteminin kontrolü

Abstract

Magnetik kaldırma teknolojisinin özellikleri üzerine yapılan çalışmalar etraflıca incelenerek, bu çalışmada İ. T. Ü Kontrol Proses Laboratuarında bulunan magnetik kaldırma sistemi (Maglev) prototipinin modellenmesi, simülasyonu ve kontrolü incelenmesine çalışılmıştır. Kontrol düzenin elemanları elektromagnetik enerji dönüşümü ve Newton yasalarına göre davrandıklarından, dinamik davranışlarını tanımlayan matematik modelleri de bu yasalar kullanılarak elde edilir. Elektromagnet ve magnetik cisimden oluşan sistem hem konum, hem de akım değişkenine göre lineer olmadığından, kontrol edilen her konum denge noktasında, kontrolörün başka parametre değerlerine ayarlanmasını gerektirmektedir. Ele alınan bu sistemin deneysel olarak hava aralığına göre indüktans değişim grafiği deneysel olarak çıkartılmış ve sistem MATLAB-SIMULINK ile simüle edilmeye çalışılmıştır.

The magnetic levitation technique makes contactless and frictionless bearing of linear movements possible. A magnetically levitated vehicle system is currently being developed as the high speed transport system of the future. Besides, this technology has been widely applied for the benefits of its non-contact feature. When the bogie runs at a high speed, it moves laterally and vertically from its belanced position at low frequencies. If the propulsion is performed by a linear drive transportation of persons or goods is totally contactsless. For the effective operation of a magnetically levitated (maglev) vehicle using electromagnetic suspension, it is necessary that the airgap between the guideway and the levitating magnets is maintained. Such system. Where the output is required to remain strictly within bounds, are known as critical systems. The concept of a magnetically levitated which is briefly called MAGLEV vehicle is not new. The development of this MAGLEV transportation system was started about 30 years ago. The recent advances in technology have made it possible for maglev vehicles to be successfully implemented. The two most effective suspension techniques are the electrodynaics suspension EDS and electromagnetic EMS. EDS systems rely on the fact that a repulsive force is generated when a magnet is moved over a conducting sheet. Of course MAGLEV vehicle has some non-linearities because of its nature. Therefore system has some non linear para-meters such as mutual inductances. Therefore, scientists haven't managed occured some problems in running of the MAGLEV system such as heating, noise, vibration and friction. Concentrated researchs are on getting rid of these problems for developing of a robust control. Running of the MAGLEV transportation vehicle based on electro-magnetic propulsive effect. The coils on a MAGLEV vehicle vibrates and heats up inside under the influence of various distrubances in running. These magnetic disturbances have a frequency component ranging widely from 0 Hz to several hundred Hz whic is proportional to the speed of the MAGLEV wehicle. The magnetically levitated vehicles with Electrodynamic Suspension (EDS- MAGLEV) are propolled by aircored long-stator linear synchronous motors (LSM). Researchers have tried to s olve these problems by using some kinds of methods. There are many studies to solve these problems. MAGLEV device had to have been to take into account as a time- variant system. MAGLEV vehicle system consists of bogie, coils mounted symmetrical and a guide-way and on-board magnets. In this system, in according to running of linear synchronous motor, rotor is vehicle drived by DC and stator is guide-way drived by AC. In the same time, guide way is called as ground-coils and coils mounted onto bogie is called on-board coils. When coils are excited by means of interaction repulsive forces between guide-way and on-board coils or AC and DC. Therefore system has some non-linear parameters such as mutual inductances. By depending upon this subject, system is required on active control method for stable levitating. Besides, various electromagnetic or mechanical disturbances can couse the change of gap length and the displacement or oscillation of the bogie. So, it is very important to analyze the characteristics of bogie motion by numerical simulation and verify them in the test running as well. New design techniques have been developed for maglev vehicle by scientists. For a long time in recently years, an important applying in this area is made with superconducting magnets. Sometimes these superconducting elements is symmetrically laidout in-guide way and used instead of on-board coils. Using advanced technology material superconductor is required various design methods. This is why, realization of the superconductive maglev system in stability takes a lot of materials with various characteristics such as light weight, superconductivity resistance to low temperature, thermal insulation, magnetic shielding, non-magnetism, electrical insulation weatherability, large power conversion. The development of magnetically-levitated (maglev') vehicles offer a number of advantages over the conventional wheel-on-rail system. A major operational advantage is the elimination of wheel and track wear giving a consequent reduction in maintenance costs. The absence of wheels also eliminates much of the noise produced by rail vehicles and this is an advantage of the maglev system is that it offers the prospect of operation at speeds much higher than those abtainable with propulsion and guidance being provided by flanged wheels. In the maglev system there is no mechanical contact between the vehicle and the track. The traction motors must therefore produce both motoring and braking by direct electromagnetic interaction with the track. Maglev systems are classified into two categories, repulsive and attractive Repulsive system using permanent magnets has simple configuration, and power is not required to levitate a carrier. However, it is difficult to dump motions of the carrier and to precisely locate the carrier, which are serious problems as a clean-room transportation system. Compared to the repulsive type, attractive system using feed-back control is complicated and power is required to levitate a carrier. However, motions and location of the carrier are highly controllable. Therefore, maglev systems for clean-rooms which have been developed so far are the attractive systems. Since the maglev vehicle is utilized as a transportation, the vehicle is imposed on a disturbance. When a disturbance puts on the vehicle, it causes a steady devitation Therefore, its nature is very complex. For understanding its very complex nature, the examinations of Maglev device had to taken high carefully into account. That feature can be yield by means of some Mathematical Methods. In addition to these, some proper control methods can be examined for controlling the Maglev Vehicle. So the best control method can be detected for Maglev Vehicle by comparing them to each other. In fact, there are some proposed control methods for controlling it. For the application one of many forms of the linear electric machine is appropriate. It is seen that, although there are some research concentrated on its control, researchers haven' t managed some problems like cooling of the magnets, yielding of equal attractive and /or repulsive force etc.. Specially, Japanese researchers have examined its controlling. They have very wide application area for understanding its nature under different conditions. And also, in Japan, there are some special test guide-lines. On these test lines, Japanese researchers have developed new control techniques. In this study, a simple magnetical levitation vehicle system which is in Control Laboratory in Technical University of Istanbul, Maslak, is used. It is goaled modelling, simulating and controlling it, by means of this model obtained. Where the body is near to the equilibrum point, reference position is changed as a step function and then current-time, position-time and velocity-time responses of the process are obtained with simulation by means of the MATLAB-Simulink Programm. In according to block diagram configurated by Simulink, some kinds of simulation working of the maglev coil are examined under some different conditions like with a reference velocity with respect to the coil and without a reference velocity. For this simulation, first the voltages and currents of coil are measured with an avo-meter by applying the sine waves of 10 Hz, 15 Hz, 20 Hz and 30 Hz. That measuring is done by disconnecting the coil from the controller and by laying some glass plates of 2 mm. And by means of that measured values, the inductances of coil are calculated. An average value sequence of the inductances for all four frequencies with respect to changing the distance of the body from the coil excited is calculated by talcing the arithmetics average of that calculated values of the inductances. For fitting a proper function in order to average value sequence calculated, EUREKA Mathematics Program is used. Some kinds of functions proposed are examined with EUREKA Program with solutions including their maximum approximation error ranges. VI In according to obtained results, the most proper function is chosen for simulation process. It was T T T 1 T 1 L = L0 + L, -7 =r- + L2 H) ki The simulation is realized with MAT-LAB SIMULINK simulater Program by taking into account first two terms of this function. Simulation process is examined for some different conditions. That process is realized by changing the values of derivative constant ( Kd ) and the values of reference position ( Xref ). So, results are seen in Results and Suggestions Chapter of this thesis. Results show that an Adaptive PID or a Robust PID Controller is necessary for better controlling of the Maglev. By mathematical model developed in this studying, these controllers first can be modelled and after designed.