Single-sided Linear Induction Motor Research Articles

Characteristics analysis of linear induction motor with two types of secondary structure based on electromagnetic field and electric circuit analysis

In this study, we attempt to analyze characteristics of single-sided Linear Induction Motor with a short primary member and a complicated secondary structure, which consists of solid-plate conductor section and a winding one. For this purpose, electromagnetic field analysis by 3-D FEM is combined with electric circuit analysis and motion equation. Here, electric circuit analysis involves the primary and secondary windings. Focusing on the distributions of secondary induced current and thrust force, we discuss various transient phenomena that develop at the boundary between different secondary structures. Finally, to suppress the aggravation of characteristic caused by the secondary structural transition, we improve the boundary.

Investigation of equations for calculation of secondary resistance and secondary leakage reactance of single-sided linear induction motors

In the linear induction motor, the original equations of the secondary equivalent circuit quantities derived from the two-dimensional electromagnetic analysis were expressed in combination with hyperbolic functions and trigonometric functions of complex numbers. In this paper, we attempt to deduce the equations for calculation of the secondary resistance and the secondary leakage reactance referred to the primary. These equations are approximated by a Maclaurin expansion and are expressed by polynomial approximation. This paper also shows the variation of those equivalent circuit parameters with slip and the change of the operating characteristics with the thickness of the secondary conducting plates. © 1998 Scripta Technica. Electr Eng Jpn, 122(1): 60–67, 1998

An investigation on the characteristics of a single-sided linear induction motor at standstill for Maglev vehicle

This paper presents the single-sided linear induction motor (SLIM) developed as electrical drives for the EXP0'93 magnetic levitation vehicle with a cruising speed of 40-100 km/h, in Taejon, Korea. The SLIM is designed to produce a 2440 Newtons thrust from an active area of 2836 mm long by 235 mm wide at the airgap of 14 mm. In order to investigate its performance characteristics both experimentally and theoretically, the static test facilities was designed and equipped. At standstill, the experimental results are compared with the analytical ones.

Change of Equivalent Circuit Parameters and Performance Characteristics of Single-sided LIMs with Various Secondary Conducting Plates.

This paper describes the equations for calculation of the equivalent secondary resistance and the equivalent secondary reactance referred to the primary of single-sided linear induction motor (SLIM) and shows the change of those equivalent circuit parameters and the operating characteristics with various secondary conducting plates.Usually, a composite conductor slab which is consisted of an aluminum plate backed with a solid steel plate is used. In order to simplify the calculation, we have assumed that the back-iron plate consists of a laminated core instead of a solid steel core.Firstly, the computed results of the performance characteristics of a SLIM with the secondary aluminum plate backed with either solid steel plate or laminated core are shown comparatively.It was confirmed that the characteristics curves in the case of laminated core give close agreement with the curves in the case of solid steel:In practice the reaction rail backed with a solid steel is better than that backed with a laminated core from the point of view of economy, robustness and corrosion.Next, the calculated results of the performance characteristics of a SLIM with a single secondary aluminum plate or a single secondary iron plate are shown.

A method of optimal design of single-sided linear induction motor for transit

An optimal design method for a single-sided linear induction motor (SLIM) for transit applications is described. The authors propose a method which determines the overall parameters of an SLIM for transit using only the rated mechanical output. When the optimization is carried out, the slot depth is used as the initial value so that the exact slot depth is calculated iteratively from the circuit equation. The optimization problem of a SLIM design is approached by use of the sequential quadratic programming (SQP). The influence of design variables is analyzed by the rated thrust and the rated velocity respectively.

Investigation of Equations for Calculation of Secondary Resistance and Secondary Leakage Reactance of Single-sided Linear Induction Motors.

In the linear induction motor, the original equations of the secondary equivalent circuit quantities derived from the two-dimensional electromagnetic analysis was expressed in combination with hyperbolic function and trigonometric function of complex number.In this paper, it has been successfully investigated to deduce the equations for calculation of the secondary resistance and the secondary leakage reactance referred to the primary.These equations are approximated by the Maclaurin's expansion and are expressed by polynomial approximation. This paper also shows the variation of those equivalent circuit parameters with slip and the change of the operating characteristics with various thickness of the secondary conducting plates.

Linear Drive Systems and their Related Technologies. On the Design of Single Sided Linear Induction Motors for Urban Transit Using a Nonlinear Optimization Technique.

The urban transit with single-sided linear induction motor (SLIM) propulsion and wheel on rail support and guidance have been in the stage for practical application.This paper presents a method of optimizing the design parameters of the SLIM using nonlinear optimization technique. In the formulation of the optimization problem, the performance characteristics are estimated using space harmonic analysis taking into account the end effect, skin effect and air gap leakage. The transformation method and the simplex method are applied to solve the problem. As the transformation methods, the exterior point transformation are used. Seven parameters are chosen as the independent variables, such as the number of poles, the pole pitch, the stack height, the secondary aluminium sheet thickness, the overhang length, the slot width/slot pitch and the rated slip. The output KW/input KVA, the maximum flux density in teeth, the temperature rise, the primary length, the stack height, overhang length, the maximum thrust and the vertical force are selected as the constraint function.The SLIM design is analyzed under four objective functions; the primary weight, the input KVA, the cost of secondary materials and energy consumption. Furthermore, the design is regarded as the multi-objective programing problem and the computed design example is shown.

Linear Drive Systems and their Related Technologies. Investigation of Equivalent Circuit Quantities and Equations for Calculation of Characteristics of Single-sided Linear Induction Motors.

It is expected to establish an analytic method and performance equations more suitable for estimation the characteristics and design a reasonable LIM. An approximation for simplified computing the performance of single-sided linear induction motor is presented. The original equations was derived from the two-dimensional electromagnetic analysis and the equivalent circuit quantities, such as magnetizing reactance, secondary resistance and secondary reactance, was expressed in combination with hyperbolic function and trigonometric function of complex number.In this paper, these functions are approximated by the Maclaurin's expansion and the equivalent circuit quantities are expressed by polynomial approximation. Both computed thrust, primary current, power factor and efficiency-slip curves for the test SLIM for urban transit at Kyushu university calculated by the original equation and the new approximation show a close agreement. Even without the former complicated calculation, we can use the proposed convenient approximation. The magnetizing reactance plays an important role in the LIM performance and the larger, the better. The ratio of air gap length to pole pitch holds the key to goodness of LIM.

Finite element force calculation of a linear induction motor taking account of the movement

This paper presents a finite element force calculation method for a single sided linear induction motor (SLIM) taking account of the movement. To avoid the distortion of air gap elements caused by the movement, moving band is used and the edge parts are renewed at each time step keeping the boundary conditions. In this way, the number of total nodes and elements is not changed. Finally, an example which is the application of the method is given to compute the thrust and normal force of SLIM by Maxwell stress tensor. >

Flow Control of Molten Tin Surface Sloping by a Single-sided Linear Induction Motor.

This paper presents a flow control of molten tin surface sloping by a Single-sided Linear Induction Motor (SLIM) in a float process that is a typical forming method of flat glass. Flow pattern in the molten tin bath is quite important to keep the good quality of float glass.The following results are obtained:(1) It is verified in experiments that the SLIM can maintain a whole surface of molten tin sloping with molybdenum-made bus-bars.(2) The 80 millimeter-wide bus-bars for the SLIM with pole pitch of 156 millimeters is enough to get the desirable flow direction of molten tin adjacent to the bus-bars.(3) It is theoretically discussed that the distribution of the secondary current density in molten tin can be controlled with bus-bar conditions.

Design of single‐sided linear induction motors using a nonlinear optimization technique

AbstractBoth low‐speed wheel‐on‐rail and the medium‐speed Maglev transport system with single‐sided linear induction motor (SLIM) propulsion have been in practical application.This paper presents the method of optimizing the design parameters of SLIMs using the nonlinear optimization method. The optimization problem is formulated by the use of the design formulas taking into account the end effect, skin effect and airgap leakage, and the transformation method and the simplex method are applied to solve the problem.Seven parameters, such as the number of poles, the pole pitch and the stack height, are chosen as the independent variables. The output kW/input kVA, the maximum flux density in the core teeth, the temperature increase, the primary length, the stack height and the maximum thrust are selected as the constraint functions. The performance characteristics are estimated using space harmonic analysis as well as the approximate equations.The method is applied to the SLIM design for urban transit, and the maximum speed is about 70 km/h. As the transformation methods, the interior point transformation and the exterior point transformation are compared from the viewpoints of accuracy and CPU time. The design is analyzed under several objective functions, the primary weight, the input kVA and the cost of secondary materials.

Design of single-sided linear induction motor using the finite element method and SUMT

The optimization of the design variables of a single-sided linear induction motor (SLIM) using the finite-element method (FEM) and the sequential unconstrained minimization technique (SUMT) is presented. Thrust is taken as an objective function in order to maximize thrust under a constant current drive, and seven independent design variables and nine constraints are chosen. As a result, pole pitch/airgap and pole pitch/aluminum depth for the best design are determined. Thrust is increased by 30% under a constant current of 12 A, so that the input current can be reduced to 10.5 A for necessary starting thrust because thrust is proportional to I/sup 2/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Method of Calculating Asymmetrical Constants Based on Lock Test for Single-Sided Linear Induction Motor.

The constants of each phase of linear induction motor(LIM) are different, because of it's structure. It is important that the method of calculating asymmetrical constants is established, because the asymmetrical constants cause the thrust pulsation. In this paper, a new method of calculating asymmetrical constants of LIM is proposed. Moreover, the results of simulation performed by the calculated constants are compared with the experimental results.The test machine of LIM is single-sided, short-primary-type, three-phase and 4-poles. The primary winding wires are double layer winding, concentrated winding and full pitch winding. In this paper, first, the asymmetrical equivalent circuits and voltage equations of LIM are showed on suitable d-q axis. Next, the asymmetrical constants are obtained by the calculations based on d axis equivalent no-load test, q axis equivalent no-load test, three-phase equivalent no-load test, d axis lock test and q axis lock test. Here, the equivalent no-load test is the lock test removed the non-magnetic conductor plate from LIM. Finally, it is showed that the simulations results of thrust containing pulsation and primary currents performed by the calculated constants are satisfactorily agreed with experimental results.

Local Velocity Measurement of Magnetic Fluid Flow Using Semiconductor Laser and Optical Fiber.

A new method is developed, using a semiconductor laser and optical fiber, to measure the local velocity of magnetic fluid flow. In this method, the local flow velocity is obtained by measuring the time taken for a tracer particle to pass between two sets of optical fiber probes. After this method is calibrated with a rotational flow in a rotating channel, it is applied to magnetic fluid flows in an open channel under the influence of a traveling magnetic field which is produced with a stator of a single-sided linear induction motor. As a result, it is clarified that the flows are mainly induced opposite to the traveling direction of the magnetic field and the magnitude of induced velocity is almost proportional to the frequency of the magnetic field, increasing especially near the free surface. The velocity distributions are quite different from those of nonmagnetic fluid flow in an open channel.

Modeling and performance of linear induction motor with saturable primary

This work presents a 2-D electromagnetic field analysis of the single-sided linear induction motor (LIM), taking into account saturation in both primary and secondary cores. An analytical layer model has been developed in which the primary core is modeled by two different layers representing the yoke and teeth-slot regions. Such representation facilitates the evaluation of the magnetic state of the primary yoke and teeth separately. A generalized mathematical formulation of a multilayer model is presented. The analytical computation results from a seven-layer model correlate very well with experimental results obtained from an intermediate-capacity transit system LIM. The model is well suited for sensitivity analysis and design studies.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Single-sided linear induction motor controlling the surface shape of molten tin (glass formation)

Presents theoretical analyses and experimental results on molten-tin control using a 1.5-m-wide single-sided linear induction motor (SLIM) to improve the float process of forming sheet glass. First, a mathematical model of molten tin controlled by a SLIM is derived. It is shown that theoretical predictions agree with experimental results within 5% error. Second, the vibration of the molten tin surface is vibratory under the condition that the initial height of the molten tin is greater than 0.6 dimensionless height (the ratio of height to the specific wavelength of SLIM). Two locations of SLIM are compared from the standpoint of application to the actual float process. It is theoretically demonstrated that the lower location to molten tin is superior to the upper location.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Calculation of stray losses in a single-sided linear induction motor

The paper describes a method of the stray losses calculation in single-sided linear induction motors (LIMs). The stray losses produced by the higher space harmonics of the primary winding and by the primary slots are discussed. Examples of calculations for a small and a large-scale LIM have been included.

Method of Maintaining a Slope Surface of Molten Metal by Using a Single-Sided Linear Induction Motor.

This paper presents a method of maintaining a slope surface by using a Single-sided Linear Induction Motor (SLIM). The points discussed are as follows:(1) It is clarified in principle that a slope surface of molten metal can be generated by supplying electromagnetic force of SLIM in the transverse direction to the gravity force. This technology will have great potentiality to improve the float process of flat glass production.(2) A mathematical model of a surface shape of molten metal controlled by SLIM is derived. It is shown that the calculated values of the surface shape of molten metal agree with the measured values within 5% error.(3) The experiments using a 0.3 meter-wide SLIM verify that the SLIM can maintain a slope surface of molten metal in the width of SLIM excluding the bus bar width. It is also demonstrated that SLIM can prevent an overflow of molten metal even if the level of molten metal is higher than the fence of molten metal bath.

On the design of a single-sided linear induction motor for urban transit

Single-sided linear induction motor (SLIM) propulsion and wheel-on-rail support and guidance for urban transit has been developed in Canada and Japan. The maximum speed for urban transit is about 70 km/h, with the trains repeatedly performing powering, coasting, and braking operations within relatively short distances between stations. In the design of SLIM's operating under such conditions, we must take into account energy consumption as well as motor weight, input KVA, and performance characteristics. In this paper, we conduct a theoretical examination of such a SLIM design, estimating its performance characteristics in using space harmonic analysis. Energy consumption is reduced by decreasing the mechanical clearance. The flux density, then, should be a low value of from 0.5 T to 0.6 T. A motor length of from 2 to 2.5 m and pole pitch of about 300 mm are advisable.

On the Design of Single-Sided Linear Induction Motors Using a Nonlinear Optimization Technique.

On the Design of Single-Sided Linear Induction Motors Using a Nonlinear Optimization Technique.