MODELING AND EXPERIMENTAL CHARACTERIZATION OF A PERMANENT MAGNET LINEAR ALTERNATOR FOR FREE-PISTON ENGINE APPLICATIONS

Sandia National Laboratories is developing a prototype 30 kW free-piston internal-combustion-based linear generator for vehicular applications. This paper describes the development and experimental validation of a mathematical model for the permanent magnet linear alternator that will be used by the prototype. A magnetic-flux versus mover-position function is used to correlate individual coil fluxes to the motion of the mover This function is derived from a finite element electromagnetic simulation of the linear alternator The mathematical model of the alternator is compared to experiments with prototype hardware driving 0.5-2 kW loads; excellent correspondence to measured voltage and current waveforms is found.