Linear Reluctance Machine Research Articles

Quantitive Harmonic Analysis and Force Ripple Suppression of a Parallel Complementary Modular Linear Reluctance Machine

Considering the fluctuating price of permanent magnet, magnetless machine is a new trend in development. Variable reluctance linear machines (VRLM) with simple structure, good robustness, and high dynamic performance, is one of the potential candidates for linear direct-drive wave energy conversion (WEC) application replacing PM-excited linear machine. To ameliorate the fault-tolerance performance of VRLM, the researchers have come up with modular or segmented design, denoted as modular variable reluctance linear machines (MVRLM) However, suffering from large thrust ripple, the design of MVRLM still needs to be improved. To relieve the force ripple of MVRLM, a novel H-shaped modular variable-flux linear reluctance machine (HMVF-LRM) is proposed in this paper. The principle of force ripple suppression by using parallel-complementary structure is analyzed deeply. In this paper, the analytical calculation of induced voltage is developed quantitively with equivalent magnetic circuit method (EMC) and harmonics analysis. Then the design mechanism of HMVF-LRM is illustrated. Further, the performance and fault-tolerant capability of the proposed machine are simulated and evaluated by finite element analysis (FEA), and the prototype is tested to verify the effectiveness of the machine design.

Analysis and Performance Evaluation of a High Thrust Force Density Segmental Stator Linear Switch Reluctance Machine for Low Cost Conveyor Applications

This paper presents a novel linear switch reluctance machine (LSRM) with segmental stator. The principle of the presented machine is given and compared to the well-known teeth type linear switch reluctance machine. Because the presented machine incorporates a simple concentric winding and concrete ferrite-magnetic segmentations, it features unique magnetic circuit compared to teeth type linear reluctance machine. It is found that the presented linear reluctance machine gains favorable superiority over the teeth type linear reluctance machine in terms of high force density, high reliability and low cost. Different topologies of the presented machine are given and both their merits and demerits are discussed.

Comparison of a High Thrust Force Density Segmental Stator Linear Switch Reluctance Machine for with Different Topologies

Linear switch reluctance machine (LSRM) has been an alternative to linear permanent magnet synchronous machine and linear induction machine. However, the nature of reluctance force production, together with the air gap which is always much larger than rotary SRM, result in low propulsion force density in LSRM. This is an inherent demerit of LSRM, limiting its applications where the machine size is strictly set. This paper presents a novel linear switch reluctance machine with segmental stator, which consists of series of ferrite-magnetic segments. The principle of the proposed LSRM featuring high force density has been introduced. A variety of topologies of the proposed machine have been presented including single stator, dual stator and non-stator yoke structure. This paper deals with the comparison of the proposed segmental stator linear switch reluctance machine and traditional teeth type linear reluctance machine in terms of the propulsion force, normal force and force ripple as well as the force density and active pay load ratio. Finite Element Method is implemented to obtain the correlated results. Some conclusions are drawn to verify the analysis above.

A generalized 3-D dynamic modelling for transverse flux homopolar linear machines based on statistical saliency-effect superposition method

This paper presents a prototype of a transverse flux homopolar linear machine system, along with a systematic and generalized 3-D approach which is capable of analyzing three kinds of these linear machines: the transverse flux linear induction machine; the homopolar linear synchronous machine; and the transverse flux linear reluctance machine; all in one compact mathematical model. A novel methodology which combines the state-space technique with the statistical saliency effect superposition method is proposed. With such a detailed and generalized modelling approach, the capability of analyzing the saliency effects induced by the distributed windings in practical linear machine systems is enhanced, and the representations of all the related linear machine system equations can be manipulated in compact matrix forms. Experimental verifications confirm that this comprehensive theoretical approach is a convenient and reliable mathematical basis for computer-aided analysis and design studies on linear machine systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A control algorithm for reluctance accelerators

A brief review of the theory of linear reluctance machines is presented, followed by the derivation of a control algorithm capable of tailoring the acceleration-versus-time profile of the device to user specifications. This control algorithm is based on finite element techniques, numerical integration, and the solution of nonlinear equations. Finally, practical implementation considerations are addressed, and an intuitive picture of the operation of the control algorithm is presented. >

Experimental investigation of the operating behaviour of linear synchronous motors

Linear machines can be derived from the various types of rotating synchronous machines.On the basis of cost, however, only the types having reaction systems (secondaries) without windings are suitable for high-speed vehicles. Of these types, the homopolar- machines and reluctance machines are distinguished by their simpler construction. In both of these cases, the reaction system consists of single ferromagnetic parts laid along the rail bed, e.g. in concrete.The primary carries the moving-field winding, usually 3-phase, and in the case of homopolar machines, also a d.c. excitation winding. With the linear reluctance machine, the disadvantages are that the thrust developed is relatively low, and that the magnetization current is taken from the grid. For this reason only the linear synchronous machine having homopolar constant field excitation can be considered as an alternative to the linear induction machine. In order to investigate the operating characteristics of high-speed machines of this type having a solid type of reactor, a model in the form of a sector machine was designed and built in the Department for Electrical Machines and Apparatus of the Technical University of Munich. The recently obtained experimental results are presented here.