Search

Tubular-switched reluctance linear launcher (TSRLL) with novel structure is proposed in this paper. The structure of switched reluctance motor is simplified, and the unbalanced force of common types of switched reluctance linear launcher is alleviated in TSRLL. The structure of the single-phase TSRLL with transverse flux is introduced thoroughly. The 3-D finite-element (FE) model of the proposed TSRLL is constructed, and electromagnetic analysis is performed by the FE method (FEM). To improve the electromagnetic force of the proposed launcher, the sensitivity analysis is conducted by means of 3-D FEM. The stator yoke thickness, mover cylinder’s thickness, stator pole arc, and pole width ratio of TSRLL are optimized, and the results of the sensitivity analyses are presented. TSRLL with two different polarity distribution patterns is compared via static FE analysis. The dynamic simulation of TSRLL with optimal specification and polarity distribution is carried out and demonstrated, of which the results agree well with the static analysis by FEM. [ABSTRACT FROM AUTHOR]

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]

In this paper, a tubular permanent magnet linear launcher (TPMLL) is proposed. Its basic structure is introduced, and initial dimensions are given. Devoted to improve the performance of TPMLL, an optimization method combined weight determination algorithm based on fuzzy optimization iteration is presented. Based on this, average electromagnetic thrust, electromagnetic force smoothing coefficient, and electromagnetic force copper loss ratio are selected as optimization objectives. The finite-element (FE) models are set up for the sensitivity analysis. The sensitivity analyses of key structural parameters are executed for these three optimization objectives. The final optimization results are obtained by calculation, and the performance of optimized launcher is compared with the initial one. It can be concluded that the proposed algorithm greatly improves the performance of TPMLL. [ABSTRACT FROM AUTHOR]

Pulsed power technology is widely used in medical treatment, military, and scientific research, such as laser burst and electromagnetic launch. Compensated pulsed alternator (CPA) is a kind of device generating that pulsed power. One of the shortages for the air-core pulsed alternator is the huge excitation loss. In order to solve the problems, a multidisk axial flux CPA (MAFCPA) is proposed, which replaces the excitation windings with permanent magnets, saving the self-excitation process. In addition, multidisks are designed, especially to reduce subtransient reactance when the CPA discharges, which contributes to increasing the discharging current. This paper mainly focuses on researching the feasibility of MAFCPA in aspects of thermal issues, rotor statics, and dynamics problems. First, the topology and principle of MAFCPA are introduced, and the properties of the materials are listed as well. Second, the loss of discharging is calculated and the temperatures of both stator and rotor are solved. Then, the maximum stresses of different materials are obtained. Afterward, the critical speeds are researched in order to avoid resonance. Finally, the conclusion is made that MAFCPA can work safely under a speed of 10000 r/min and supply a pulse of over 50 ms. [ABSTRACT FROM AUTHOR]

In electromagnetic launch (EML) applications, a compensated pulsed alternator is an effective form of pulsed power supply because of its high energy density and power density. The basic advantages of compensated pulsed alternators for EML applications are their higher energy density than capacitors and their export ac output that is suitable for transmission and transformation. In general, external excitation is adopted as a form of self-excitation or pulse excitation in compensated pulsed alternators with an iron core or air core. Using this form not only results in heavy and bulky components but also complicates and reduces the reliability of the system. This paper proposes a novel compensated pulsed alternator that is excited by permanent magnets (PMs) and equipped with an iron core or air-core stator. This system does not require any excitation converter or brush–slip ring, thereby making it more reliable, less massive, and less voluminous than the system with self-excitation or pulse excitation. In addition, analytical models are introduced to simulate the air-gap magnetic distribution, back-electromotive force, pulsed current wave, discharge torque, and energy exchange of this machine. A scale-model prototype of the PM-compensated pulsed alternator is designed, fabricated, and tested. The actual output voltage waveform and pulsed current waveform are sampled and compared with the predicted ones. The results show that the design of the PM compulsator is feasible and reliable. [ABSTRACT FROM PUBLISHER]