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In previous studies, the field winding of the brushless pulsed alternator (BPA) is embedded in the stator slots, which is supplied by dc power or variable frequency power. The advantage is that the field current can be independently adjusted. It means that the BPA system needs a standalone excitation system, which will increase the volume and cost of the system. If we substitute electric excitation for permanent magnet excitation, not only the volume and cost of the BPA system can be decreased but the efficiency and flexibility can be enhanced. In this paper, the design schemes for electric excitation and permanent magnet excitation BPA are presented. For comparison, the stator and rotor dimensions of the two kinds of BPA are both the same. The characteristics of electric excitation and permanent magnet excitation BPA are analyzed by the finite-element method and field-circuit coupling method. Finally, the BPA systems with a resistive load are established, the performances of both the two excitation modes are compared. According to the simulation results, we conclude their advantages and disadvantages. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]