MAGNETIC LEVITATION TRAIN TECHNOLOGY II BLOCK DIAGRAM BRADLEY UNIVERSITY DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING NOVEMBER 18, 2003 BY: TONY PEDERSON AND TOBY MILLER ADVISOR: DR. WINFRED ANAKWA
INTRODUCTION: This project will consist of levitating a model size train and propelling it around a track. The train will make no physical contact with the track that causes levitation during operation. It will only make contact with the guide track when the train is accelerating from a stop and slowing down, coming to rest on its wheels. The speed of the train and height of levitation will have to be controlled. The height will be a function of the speed and will be a maximum of.75cm above the track for our model. The user will adjust the speed for the train manually. Figure 1 below shows the inputs and different subsystems of the MAGLEV system. FIGURE 1 BLOCK DIAGRAM OF SYSTEM SUBSYSTEMS: Train The train will have one sensor on it to measure speed. This sensor may or may not be attached to the train. This will be determined later. (See figure 4) Changes in the frequency of the signal in the track will change the speed of the train. Four Halbach Arrays will be on the train to provide levitation and to keep it centered on the track. (See FIGURE 2)
FIGURE 2 Drawing of Track and Train Track The track will have the propulsion motor in the track. The dimensions and shape of track is still being researched and will be determined later.[2] Controller Consists of an analog or digital system with one speed sensor. It will have some hardware with it, to change the frequency of the three-phase power, but that will be determined later. The change in frequency will change the speed and height of the train. FIGURE 3 DIAGRAM OF THE CONTROLLER
TECHNOLOGIES FOR LEVETATION: Electrodynamic suspension (EDS) The magnets on the train produce currents while traveling in the guide way. This uses repulsion to guide and support the train, but will need a support for landing and takeoff since EDS does not work below 25 mph on a full size train. [2] Halbach Array This special type of magnet array will levitate and propel the train. Figure 4 shows an example of the Halbach Array. The Halbach Array will be attached to the bottom and sides of the train to maintain it levitating and centered on the track. The array will also be used to slow down and stop the train. This array cancels most magnetic fields on three side of it and produces a steady magnetic field on the fourth. This is what will be pointed at the track to make the train levitate. We will use another set of arrays to stabilize the train so the height and lateral sensors are no longer needed. The setup of this array on the train is shown in figure 2. FIGURE 4 HALBACH ARRAY TECHNOLOGIES BEING RESEARCHED FOR PROPULSION: "Short-stator" propulsion A linear induction motor winding on the train and a passive guide way (aluminum plate installed along the rail surface) is used to propel the train. [3] "Long-stator" propulsion An electrically powered linear motor winding in the guide way is used instead of a passive system like the short-stator [3]
Linear electric motors A power source that provides electric traction in a straight line, instead of rotary fashion in a conventional motor. [3] POWER REQUIREMENTS: Three-phase power will be required to run the MAGLEV system. The coils used for propulsion could draw large amounts of current, so the power requirements could be substantial. The size of the train will determine how much current the coils draw. In an actual train, the power required to run the train is less than to run the air conditioner for the train. [1] Figure 5 Control Block Diagram of MAGLEV System REFERENCES: [1] http://www.dom.com/about/companies/vapower/maglev/index.jsp [2] http://www.lanl.gov/superconductivity/train.shtml [3] http://www.howstuffworks.com/maglev-train.htm