Simulation of a Seven-Phase Air-Core Pulsed Alternator Driving the Electromagnetic Rail Gun

As the most efficient and compact sources in pulsed power supply for electromagnetic launchers, the air-core pulsed alternator can supply a current as high as 1 MA with a voltage reached several kilovolts. The machine performs various functions, such as kinetic energy storage, electromechanical energy conversion, and power conditioning, making the electromagnetic launch system compact and lightweight. But due to the short history of the machine and the absence of fabrication experience in China, the air-core pulsed alternator is still in an exploratory stage, and there are lots of key technologies and problems needed to be researched deeply. Taking technical risks and manufacturing costs into consideration, a seven-phase air-core pulsed alternator has been proposed and the machine is under development. In this paper, operation principles of the electromagnetic launch system are presented in detail. The mathematical models of the seven-phase alternator and the rail gun are introduced. Based on the mathematical models, a simulation model about the electromagnetic launchers is built, and it is useful to help us figure out the operation characteristic when the self-excitation machine drives the electromagnetic rail gun with a 200-g projectile. As a result, it is convincing by simulation to prove the drive current can be as high as 1 MA and the projectile is with a velocity of 2 km/s at the exit. Simultaneously, violent transient situations will be illustrated in this text, such as the electromagnetic torque and the rotor speed. Meanwhile, simulation results can verify the analytical method and present the current and voltage straightforwardly. They also have great significance on choosing the proper high power switching devices.