Analysis of Coupled Thermal and Electromagnetic Processes in Linear Induction Motors Based on a Three-Dimensional Thermal Model

The article describes a mathematical model of interconnected electromechanical and thermal processes in a linear induction motor (LIM). Here, we present the structure of the thermal model and provide the calculation formulas of the model. The thermal model consisted of eight control volumes on each tooth pitch of the LIM. Moreover, we also present a model of electromechanical processes and its interaction with the thermal model. The electromechanical model was based on the detailed magnetic and electrical equivalent circuits of the LIM. Model verification was performed using a model based on the finite element method and using experimental data. We also conducted a study focused on the necessity of considering the influence of various features of the thermal processes. We herein discuss the application of the model implemented in the MATLAB/Simulink, which was used to analyze the thermal performance of linear transport and technological induction motors. For the traction single-sided linear induction motor, we determined limits of safe operation by considering the unevenness of heating along the length in two cases: natural cooling and forced cooling. For forced cooling, required values of air flow were determined. For the arc induction motor of the screw press, the influence of various factors (i.e., reduction of the stroke, the use of a soft start, and the use of a forced cooling) on heating was evaluated.

Design Optimization of Secondary Element of Single-Sided Linear Induction Motors Using a Genetic Algorithm

The article focuses on the use of genetic algorithms for the design of linear induction motors. Comparison of genetic algorithm with classical methods in the context of electrical machines designing has been carried out. The results of solving an optimization problem for two designs are presented, viz. a laboratory linear induction electric motor based on a three-phase SL-5-100 inductor and a traction single-sided linear induction electric motor of an urban transport system. The optimality criterion included maximizing the power factor and efficiency, as well as the rigidity of the mechanical characteristic while ensuring a starting traction force of at least a set value. The results of optimization of such parameters of the secondary element as the width and thickness of the conductive strip as well as the thickness of the magnetic circuit are described. The relevance of the problem of optimizing the parameters of the secondary element with unchanged parameters of the inductor is due to the fact that the same inductor can be used to build various structures, while the secondary element is created for each specific application and integrated directly into the working body of the mechanism or is a driven product. To calculate the traction and energy characteristics of linear induction electric motors, an electromagnetic model based on detailed equivalent circuits was used, taking into account longitudinal and transverse edge effects and providing a calculation time for one set of parameters of about 1 s. In accordance with this model, the electric motor is reduced to a set of three detailed equivalent circuits: a magnetic circuit, primary and secondary electrical circuits. The result of the optimization of these electric motors was an increase in the efficiency by 1.6 and 1.4 %, respectively, an increase in the power factor by 0.9 and 0.2 %, and an increase in the rigidity of traction characteristics and starting traction force.

Investigation of high current electron beam dynamics in linear induction accelerator for creation of a high-power THz radiation source

The work addresses the use of electron beam produced by the linear induction accelerator to generate terahertz radiation pulses of 100 MW power level based on a free electron laser scheme. The beam parameters required for efficient generation are given. The features of transverse beam dynamics when transporting the beam through the linac are investigated. Emphasis is put on the electron injector which geometry and operation parameters mainly determine the beam characteristics at the linac exit. Most of the possible factors contributing to the beam emittance gain in the accelerator are considered. The obtained analytical estimates are compared to the numerical simulation results. The experimental results on compressing and transporting the beam having the electron energy of 5 MeV and the current of 1 kA in the transport system of free electron laser are presented.

Maglev Technology and the World Scenario

In this growing world when cities and towns continue to become more crowded , the modes of transportation that are currently available to us will not be able to handle the demands of these overpopulated areas. This problem can be solved by the concept of electromagnetism. Electromagnets and superconducting magnets have allowed us to create a magnetic levitating train nicknamed “Maglev” which reduces friction between track and train by floating over it instead of directly being in contact. This has a lot of potentials to create trains that require a high initial investment but later on low maintenance and helps in fast transportation thus saving time. The magnetic levitation system used by these trains play an important role in suspending the Maglev train stably and following the track quickly with the adequate gap from the side walls thus highly reducing chances of damage. This paper gives an idea about the tech aspects of maglev projects worldwide such as Germany, Japan, and USA and also discusses about various idea to bring Maglev trains in developing countries like India. Keywords: Maglev, superconducting magnets, magnetic levitation, Transrapid, lateral guidance, linear induction morot, frictionless travel.

Electromagnetic design method of linear induction motor considering lateral end effect

Due to the complex end effect, it is difficult for the linear induction motor to design and analyze with the "road" calculation and two-dimensional field calculation. Considering the end effect, skin effect and secondary leakage reactance of the eddy current of the secondary induction plate, a linear induction motor electromagnetic design and calculation program was programmed via VB language. A two-dimensional finite element analysis method was proposed to approximate the lateral end effect on linear induction motor performance by multiplying the two lateral end effect coefficients into secondary induction plate resistivity and air-gap relative permeability. The accuracy for both calculation of end effect coefficients by "road" calculated program and considering lateral end effect in two-dimensional finite element analysis was validated by using the experiment and three-dimensional full model finite element, respectively. This work proposes the calculation method of the lateral end effect, which is faster and more accurate for the electromagnetic design as well as the finite element simulation of linear induction motor.

Energy efficiency comparison of three-phase transverse and longitudinal field inductors

The paper presents the results of energy efficiency and traction evaluation of linear induction machines for with molten aluminum recycling furnaces. Ansys Maxwell software was used for the synthesis of 3D parametric models of electromagnetic fields for a large air gap furnace. Interchangeable modules of three-phase transverse and longitudinal field inductors were used as a subsystem of a parametric model. Both inductor models include invertor low frequency power supply. Transverse and longitudinal field inductors have been designed with similarity principles. A stationary electromagnetic mode and power parameters has been modeled without taking melt hydrodynamics into account. Linear induction transverse-field machines have demonstrated higher efficiency.