Design of a Pulsed Alternator to Drive a Single-Stage Induction Coilgun

Pulsed alternators (PAs) are ac generators which are specifically designed to generate pulsed currents of very high magnitudes for a given duration. An induction coilgun is being designed and developed in the author's laboratory to propel projectiles of different sizes. The scope of this work is to design and develop a PA for the same. A single-phase, iron core, slotted stator, cylindrical rotor, and no-compensation topology of the PA has been selected for this application. For the parametric analysis, a coupled circuit model of the PA has been used by considering the correction factors which include the skin effect and the magnetic saturation of the iron parts of the alternator. Eddy currents induced in the rotor core have been modeled as one circuit on each axis. A number of designs have been modeled and simulated and their performances have been analyzed for different design variables of the PA. Peak current, projectile velocity, and the temperature rise of the coil per current pulse are the output parameters which have been analyzed for every design. From the parametric analysis, PA with a particular configuration has been selected which results in the desirable performance of the PA-coilgun system. The design has been validated by modeling the same in finite element method (FEM)-based software. The performance of the PA driving the coilgun has been compared with that driven by the capacitor bank, and the feasibility of the multistage operation using the PA has been studied.