Abstract
This paper presents a novel staggered-teeth cylindrical transverse-flux permanent-magnet linear machine (TFPMLM), which aims to improve the power factor and force density. Due to the compact structure and high performance requirement, thermal problems should be seriously considered. The three-dimensional (3-D) temperature field model is established. The determination of convection heat transfer coefficients is discussed. Equivalent thermal conductivities of stator core and winding are given to simplify the analysis. With the thermal effect of the adhesive coatings among permanent magnets (PMs) and mover yoke taken into account, the temperature field distribution and variation rules of the TFPMLM are obtained using the finite volume method (FVM). The influences of slot filling factor and air flow velocity on the temperature field distribution are analyzed. It is found that the hottest spot of the TFPMLM appears in the middle of the end winding; and there is no risk of demagnetization for PMs.
Highlights
In the past decade, transverse-flux permanent-magnet linear machine (TFPMLM) has been widely employed in the applications of electrical power generation [1,2,3,4,5], magnetic levitation [6,7], electromagnetic launcher [8,9], etc. [10]
Many scholars have been dedicated to the analysis, design and optimization of TFPMLM using the approaches of equivalent magnetic circuit network (EMCN) [11,12], finite element method (FEA) [1,2], modern intelligent algorithms [10,13]
The TFPMLM generally has the disadvantages of low power factor and complex structure leading to difficult manufacturability
Summary
Transverse-flux permanent-magnet linear machine (TFPMLM) has been widely employed in the applications of electrical power generation [1,2,3,4,5], magnetic levitation [6,7], electromagnetic launcher [8,9], etc. [10]. A novel staggered-teeth TFPMLM is proposed in order to solve the problems of high flux leakage and low power factor existing in the conventional TFPMLM [14,15,16]. For the staggered-teeth TFPMLM, the three phases can be arranged in axial direction or circumferential direction, and cylindrical topologies are competitive for free-piston energy converter applications. Compared with the TFPMLM employing soft magnetic composite (SMC) to achieve the complex structure and three-dimensional (3-D) flux path, the stator core of staggered-teeth TFPMLM is laminated by electrical-steel sheets, which results in a relatively simple manufacturing process and high reliability [17,18]. 2. Transverse-Flux Permanent-Magnet Linear Machine (TFPMLM) Temperature Field Model. The permanent magnets (PMs) of two adjacent phases are arranged by 2/3 pole pitch displacement in the axial direction.
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