Primary Linear Induction Motor Research Articles

Electromagnetic field calculation and analysis of short primary linear induction motor for electromagnetic launch

AbstractThe aim of this study is to determine the electromagnetic field spatial distribution and longitudinal end effect characteristics of short primary linear induction motor (SPLIM) in the field of electromagnetic launch. First, in accordance to the electromagnetic model assumption of SPLIM and one‐dimensional electromagnetic field theory, the analytical expression of the whole‐region magnetic flux density of air‐gap is derived using electromagnetic field boundary conditions in line with the actual physical meaning. Second, the finite element method used in comparing the analytical calculation values of key physical quantities, such as air‐gap flux density and secondary eddy current in a multidimensional manner under various static and dynamic working conditions and verifying the correctness of the analytical calculation of the electromagnetic field. On this basis, the air‐gap flux density of SPLIM is decomposed according to the different generation mechanisms, and the spatial distribution of each part of the flux density is studied. Spatial Fourier analysis of flux density is conducted, the end effect coefficient is defined, and the change rule of the end effect coefficient with the design parameters of the motor is studied. Finally, a megawatt‐class high thrust prototype test platform was built, and the measured electromagnetic force was compared with the electromagnetic force calculated by air gap magnetic field and secondary eddy current. The steady‐state error of the two was less than 2%, which verified the accuracy of the analysis and calculation.

MagLev-Cobra Operational Tests

The Brazilian project MagLev-Cobra proposes a superconducting levitation vehicle for urban transportation in highly populated cities. The levitation technology is based on the diamagnetic behavior and flux pinning property of Y-Ba-Cu-O blocks in the proximity of the magnetic field of Nd-Fe-B magnets. The traction is given by a short primary linear induction motor. In previous editions of EUCAS conference, laboratory tests were presented to validate the levitation method and vehicle design. In this paper, recent operational results of the MagLev-Cobra traveling along an outdoor 200-m test facility constructed in the university campus will be reported. The full-scale vehicle is composed of four modules, interconnected by mechanical links. The transportation capacity is equivalent to 5 passengers/m 2 , a limit of transportation comfort and quality. Acceleration, braking, and also cruising speed conditions were analyzed. A data acquisition system monitored the levitation gap and other parameters along the track. This effort is an important step to certificate the operational safety, an indispensable condition before industrialization and commercialization.

Linear Motor Powered Transportation [Scanning the Issue

This special issue on linear-motor powered transportation covers both supporting technologies and innovative transport systems in various parts of the World, as this technology moves from the lab to commercial operations. There are many types of linear motors, but most of those discussed in these papers are the short primary linear induction motor (LIM) and the long primary linear synchronous motor (LSM). They are similar to their rotary counterparts, but the linear versions represent a more complex design challenge.

Characteristics of short primary linear induction motor with a partially adopted wound secondary member

AbstractThis paper describes single‐sided linear induction motors (LIMs) with a short primary member. In these machines a solid‐plate conductor is usually used for the secondary. We here propose the partial adoption of wound secondary members in LIMs. The characteristics of such machines are summarized as follows.1. Basic characteristics: The wound secondary shortens the magnetic clearance and makes the characteristics of the machine superior to those of the solid‐plate conductor version. In addition, we can improve the thrust and efficiency characteristics by applying the proportional shifting method.2. Primary and secondary winding scheme: Parallel connection is appropriate for the primary and independently shorted‐circuit scheme in order to obtain stable performance.3. Transient phenomena at the boundary between the wound secondary and the solid‐plate secondary: Undesirable phenomena develop at the boundary, especially at the end of the solid‐plate conductor. Thus, we propose a novel boundary structure that yields stable transient performance. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 48–55, 2001

Characteristics of the Short Primary Linear Induction Motor with the Partially Adopted Wound Secondary Member

Characteristics of the Short Primary Linear Induction Motor with the Partially Adopted Wound Secondary Member

Evaluation of fixed and moving primary linear induction motor systems

Linear induction motors being proposed for high-speed ground transportation may have their primaries carried on board the vehicle or embedded in the guideway. This paper evaluates various aspects, such as power requirements, power switching and controls, utilization factor, efficiency and cost, etc., for these two alternatives and provides the basic format on which relative merits of various systems can be readily evaluated. The analysis shows that, in the fixed primary system, it is economically impractical to energize sections of the roadbed substantially longer than the vehicle. Even when the primaries in the roadbed are energized in sections of minimum length, the cost of the linear induction motor and additional switching and power network for the fixed primary system is an order of magnitude higher than that for the moving primary system.