Simulation and Analysis of Stirling Alternators With Sage and COMSOL

A new modeling initiative is under way to develop government designed alternators in support of small Radioisotope Power Systems (RPS) applications. Modeling is a crucial tool for alternator design and optimization for moving magnet and moving coil linear alternators. Typical software that has been utilized to model both alternator types by NASA and industry are Sage and COMSOL Multiphysics®. In the case of moving coils Stirling alternators, an initial design geometry is arrived at by performing a Sage optimization based on maximizing alternator efficiency subject to mechanical constraints. Furthermore, in this work, the Maxwell’s equations are discussed in relation to how a moving coil alternator produces power. In addition a general Sage and COMSOL Multiphysics® alternator methodologies are used to illustrate a systematic construction and development for each model type. Finally, transduction force (motor coefficient), AC current, AC voltage, and AC force results from a general design of a moving coil alternator were extracted from both Sage and COMSOL Multiphysics® models, and were super imposed in four plots. Plots show that for each model parameter result, model comparisons are within a 10% agreement.