Experimental Investigation of Operating Characteristics of a Micro Gas Turbine Turbogenerator Hybrid Electric Propulsion System

In this study, a turbogenerator rig was developed using a JetCat SPT15-RX micro gas turbine turboprop engine. This system is proposed as a primary power source for electric propulsion systems to overcome the low energy density limitations of current battery-only configurations. The operational characteristics were investigated by varying two key parameters: the DC bus voltage and the power lever angle (PLA). Three performance metrics—output shaft rotational speed, DC current, and DC power—were analyzed. The results demonstrated that at a constant DC voltage, all three metrics increased as the PLA increased. Conversely, for a given PLA, an increase in DC voltage resulted in a higher output shaft speed but a decrease in DC current and power. Notably, a maximum DC power of 10 kW was achieved at DC voltages of 45 V and 50 V. Furthermore, a hybrid system was constructed by integrating a 12-cell battery with the turbogenerator. Analysis of voltage and current transients revealed the battery’s effectiveness as a power buffering mechanism, stabilizing the system by absorbing or supplying power during rapid electrical fluctuations, while also identifying its operational limits. To prevent system instability, it is suggested that the battery’s state of charge (SOC) be maintained with a sufficient margin. These experimental results provide critical foundational data for the further development and optimization of hybrid electric propulsion systems.