Electromechanical Coupling Modeling and Torsional Vibration Analysis of Helicopter Electric Propulsion System

The electric powered helicopter has the benefits of energy saving, emission and noise reduction, which has opened a door to the innovation and technical reform in aviation field. electric propulsion system (EPS) is a key system of electric powered helicopter, and its performance directly affects the safety and mission endurance of electric powered helicopter. In order to accurately evaluate the EPS's working performance, a electromechanical coupling model is established in this study. In the proposed model, the physical details such as the shaft flexibility and time-varying meshing characteristics of the gear transmission system, the harmonic and saturation effects of the permanent magnet synchronous motor (PMSM), and the dead zone and switching characteristics of the inverter are taken into consideration. Compared with the models that are used to study gear transmission system or motor system separately, this electromechanical coupling model can be used for analyzing the gear transmission system and motor system as a whole, thus laying the foundation for realizing the electromechanical integration design and miniaturization of the EPS. Based on the proposed electromechanical coupling model, the torsional vibration and PI control under variable speed and variable load conditions of the EPS is studied. The results show that: 1) the flexibility of shafts increase the torsional vibration of the EPS, and main rotor torsional vibration is more sensitive to the stiffness of main rotor shaft than to the stiffness of other shafts; 2) open loop control of PMSM generates higher dynamic load than closed loop control when external load is constant, but open loop control has adaptability to external load changes; 3) the torsional vibration of the EPS can be reduced by changing the PMSM control methods and control parameters. © 2023 The Authors.