Fields and Inductances of the Sectioned Permanent-Magnet Synchronous Linear Machine Used in the EMALS

Some intriguing advantages of permanent-magnet linear synchronous machines (PMLSMs), such as simple structure, high thrust, high efficiency, ease of maintenance, and controller feedback, make it possible to take the place of steam catapults in the future. The conventional PMLSM is renowned for its simple structure and high efficiency, whereby the high reactive power resulted from great leakage inductances during the long stator. Thus, great concern is paid to the section structure of the PMLSM. A sectioned permanent-magnet linear synchronous machine (SPMLSM) used in the EMALS is introduced in this paper, whose stator core is continuous but the armature winding is divided into two sectioned parts. First, the electromagnetic fields of the SPMLSM are investigated analytically. Then, the fields are computed by the finite-element method (FEM) and measured experimentally. Not only are the self-inductances and mutual inductances in one section studied but also the mutual inductances between the two sections. These inductances are then calculated by the FEM and measured experimentally. Good correlation among the results was obtained by these three methods.