A New Longitudinal End Effect Factor for Linear Induction Motors

The longitudinal end effect in a linear induction motor (LIM) is analysed assuming two travelling magnetic flux density waves in the airgap: the wave travelling with synchronous velocity and the wave representing end effect [1]. A simple equation for the end effect factor which modifies the airgap EMF is obtained, and a simple equivalent circuit incorporating the end effect factor is established. Analysis is compared with measurements from two largescale single-sided LIM's. The equation for the end effect factor is sufficiently accurate to be used for design studies of LIMs. Since end effects are negligible at low speeds, the end effect factor has application for medium and high-speed LIMs.     

Performance calculation for single-sided linear induction motors with a double-layer reaction rail under constant current excitation

A method for computing the performance of a single-sided linear induction motor (SLIM) with a double-layer reaction rail, under constant current excitation, is presented. This method takes into account the reaction of secondary eddy currents on the airgap field, transverse edge and longitudinal end effects, together with skin effect, saturation, nonlinear magnetic permeability, and hysteresis in the solid steel core of a reaction rail. In an equivalent circuit of the machine, the mutual and secondary impedances are found from a solution of the two-dimensional electromagnetic field distribution. Modifying factors account for configurations in which the width of the secondary conductive layer is different from that of the steel core, and in which the thickness of the conductive overhand is different from that over the steel core. Good correlation is obtained between analysis and test results from a large-scale linear induction motor (LIM) at Queen's University. The developed expressions are appropriate for small and large LIM's and may also be used for constant voltage excitation conditions.     

Analytical approach to cogging torque calculation of PM brushless motors

This paper discusses the approach to analytical calculation of the cogging torque in permanent-magnet (PM) brushless motors. Magnetic field energy in the air gap has been used to obtain the cogging torque equations. Two equations have been derived: with the PM circumferential width taken into account, and a simplified equation, i.e., without the effect of the finite width of the PM. The effect of eccentricity has also been included. Calculation results have been compared with laboratory test results.     

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

Contents 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.

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Berechnung von Zusatzverlusten bei einem einseitigen linearen Induktionsmotor

Übersicht Der Artikel beschreibt eine Methode zur Berechnung von Zusatzverlusten bei einseitigen, linearen Induktionsmotoren. Die Zusatzverluste, die durch höhere räumliche Oberwellen der Primärwicklung und die primärseitige Nutung entstehen, werden besprochen. Berechnungsbeispiele für einen kleinen sowie einen großen Linearmotor sind beigefügt.

     

Design of Linear Induction Drives by Field Analysis and Finite-Element Techniques

Two-dimensional field and finite-element analyses are complementary in evaluating the performance of single-sided linear induction machines, and can be used to develop a machine design for a given drive application. Electromagnetic analysis leads to an equivalent circuit of the machine with speed-and frequency-dependent parameters, in which top cap geometry, core hysteresis and saturation, skin effect, eddy current reaction, and both transverse-edge and longitudinal-end effects can be included. Finite-element analysis provides detailed information on the magnetic field distribution to aid in machine design.     

高速永磁同步电机在多物理场和变流器约束下的设计

高速电机中多物理场是强耦合的,其影响是甚至相互矛盾的.因此,高速电机的设计受到多物理场的强制约.此外,变流器的电压和电流都受限,由此也制约了高速电机的设计.当电机功率较大时,所有这些约束变得更加显著,因此较难获得一个很好的优化设计方案.该文以一台350kW、13.5kr/min的大功率高速内置式永磁同步电机作为案例,阐...     

Performance analysis of a shaded-pole linear induction motor usingsymmetrical components, field analysis, and finite element method

The performance analysis of a shaded-pole linear induction motor using symmetrical components, field analysis and finite element methods is presented. Calculated results and measurements are compared and discussed