Fuel-economy-optimal power regulation for a twin-shaft turboshaft engine power generation unit based on high-pressure shaft power injection and variable shaft speed

Due to the high power-to-weight ratio characteristic of turboshaft engines, the power generation unit based on it holds immense potential in the hybrid electric propulsion system (HEPS) of flying cars. To mitigate environmental pollution and reduce fuel consumption, while enhancing the fuel economy of turboshaft engine power generation unit (TEPGU) across the entire power output range, this paper investigates a dual-motor electronic regulation architecture for twin-shaft TEPGU. According to the different variable combinations of TEPGU architecture, two modes and their respective fuel-economy-optimal power regulations are proposed. Initially, by considering the efficiency distribution of motors, we construct an Extended co-working balance model based on the Newton-Raphson method. Subsequently, different operating modes are proposed and discussed, studying the characteristic laws of the power generation unit under each mode. For the variable speed mode and the power split mode, this article proposes a shaft-speed-feature-projective searching (SFPS) method and a multi-dimensions-feature-projective searching (MFPS) method based on characteristic dimensionality reduction projection. Finally, a comparative analysis of the fuel-saving effects of the SFPS and MFPS regulation methods is conducted, and the reasons for enhancing fuel efficiency are discussed. The simulation results show that the model of TEPGU is in good agreement with the experimental data, and the error of specific fuel consumption(SFC) in the full power range is less than 5.7 %. Besides, comparative results indicate that the strategies based on MFPS and SFPS can achieve a maximum instantaneous fuel consumption reduction of 14.38 % and 10.82 %, respectively. The MFPS strategy exhibits a fuel consumption saving of 12.69 % throughout the driving cycle, demonstrating superior performance in fuel economy.