Dynamic model of a free piston tubular linear generator for vehicle auxiliary power supply

The paper deals with the modelization of a Stirling free piston engine coupled to a linear electric generator to be adopted as auxiliary power unit to supply vehicle electric loads. In particular, a simplified model of the thermodynamic cycle is defined, taking into account the influence of various thermodynamic and mechanical parameters on the thermomechanical conversion of the heat provided by the exhaust gases of a primary internal combustion engine. By integrating such model with the linear generator one, overall dynamic performances and in particular power output can be evaluated for different design parameters and operating conditions. In addition, by implementing the complete mathematical model in a numerical code, a profitable control strategy on the linear generator current can be assessed. The paper presents the analysis of typical operating conditions to evidence the solution suitability and the effectiveness of the proposed procedure.