The Design And Control Of The Propeller On HTS Maglev System In Evacuated Tube

Security issues, energy issues and noise issues are the three most important problems in transportation with the improvement of vehicle’s speed. High-speed transportation is always the tireless pursuit of mankind. When the speed is improved, such previously listed problems will appear more or less. When the train is running, the drag contains two components. The one is generated by the friction between the wheels and the rail and the other is the aerodynamic drag. In air transportation the gravitational potential energy of the plane and the carried objects must be provided with corresponding plane height. So the energy consumption in these two ways is obvious. The evacuated tube transportation with maglev technology will be the best one to solve the problems previously listed above in the future.The evacuated tube transportation with maglev technology contains several problems. The propelling and control mode, the structure of the evacuated tube, the precision of each component and the run economic problem and etc. are the main problems in evacuated tube transportation. The propelling and control mode is the most aspect in this system. An excellent one could compensate some minor deficiencies in design.The levitated mode that is adopted in evacuated tube in this thesis is to use the high temperature superconducting bulks and the permanent guidway. For getting a continuous running state, the guidway is designed as an annulus. The arrangement of the propellers in this system could be designed as two patterns. The one is installing the propellers in several points and the other is installing the propellers along the guidaway. The linear induction motor is adopted to propel the system in this thesis. The factors that affect the linear induction motor’s performance contain the field in the gap, the frictional drag and the power supply and etc. The purpose of this thesis is to study these factors.At first, the mathematical model of the linear induction motor was discussed base on the basic principle of the electrical machine for this special evacuated HTS maglev system. A kind of novel coordinate system called the translational coordinate system is presented. It is difficult to comprehend when the traditional rotating coordinate systems are used in linear motor for there is no rotating part in this system.Then the basic problems of the power supply in this system are discussed based on the vector control. The equivalent circuit of the linear induction motor used in this system is also discussed.The characters of the field in the gap are discussed in detail considering the method of arranging the windings on the primary. A new approach to analyze the electromagnetic theory in linear induction motor is presented. This method is called the instantaneous current analysis. Base on this method the arrangement of the windings is discussed.In this thesis the relationship between the aerodynamic drag and the block ratio, the pressure in the tube and the speed of the train is discussed. The frictional drag between the primary and the secondary of the linear motor in this evacuated tube system contains two main parts. The one is the aerodynamic drag and the other is the magnetic drag that generated for the unbalanced distribution of the field above the permanent guidway.At last, the vector control strategy was used for constant speed with neglecting some unessential factors. This is verified by experiment on this evacuated levitated system. The translational coordinate system is used and its rationality and effectiveness are testified.