Study of Operation Principle of a Novel Brushless Self-Excited Air-Core Compensated Pulsed Alternator

Air-core compensated pulsed alternator (ACPA) has been applied to the field of pulsed power technology, especially electromagnetic launch. The high-field current and the rotating speed of the ACPA bring the benefits of high power and energy density, but also make it suffer from low reliability and poor performance due to the serious heat and wear in the slip rings and brushes. To solve this problem, a novel brushless self-excited ACPA (BSACPA) is presented in this paper. It consists of two submachines in cascade, namely, an exciter and a generator, for which the air-gap flux rotation directions are opposite. The rotor windings are specially arranged and adopt the principle of negative sequence alternate current excitation, thus eliminating brushes and slip rings, and no rotary rectifier diode is needed. First, the structure and the operation principle of the BSACPA are described. Second, the magnetic field distribution and the coupling between the two submachines are analyzed. Third, the mathematical model of BSACPA is established. Finally, the validity of its operation principle is verified by finite-element and circuit analyses. In conclusion, BSACPA achieves the brushless structure and provides a new solution to improve the performance and the reliability of a conventional ACPA.