Multidisciplinary Design Optimization of the Actuation System of a Hybrid Electric Aircraft Powertrain

Abstract

In the context of hybrid electric and full electric powertrains for future less-pollutant aircrafts, this paper focuses on the multidisciplinary design optimization (MDO) of the actuation system, including a surface-mounted PMSM in order to maximize the power density of the device: this study is a preliminary approach before integrating the whole powertrain. After an introduction of the MDO context, the analytical model of the electric motor is detailed. It integrates multi-physical aspects (electric, magnetic, mechanical, thermal, partial discharges and insulation, control and flight mission) and takes several heterogeneous design constraints into account. The optimization method involves a genetic algorithm allowing the reduction of the actuation weight with regard to a wide set of constraints. The results show the crucial sensitivity of the electro-thermal coupling, especially the importance of transient modes during flight sequences due to thermal capacitance effects. Another major point is related to the performance of the thermal cooling, which requires the introduction of an “internal cooling” in the stator slots in addition to the “base cooling” for stator and rotor. Gathering these analyses, the MDO leads to high power density actuators beyond 15 kW/kg with high-voltage–high-speed solutions, satisfying all design constraints (insulation, thermal, magnet demagnetization) over the flight mission.

Integrated Optimal Design for Hybrid Electric Powertrain of Future Aircrafts

“…Upstream of the gearbox, the electromechanical actuator design model detailed in [35,36] has been achieved through an analytical model. The Emotor is a surface-mounted permanent magnet synchronous motor (SM-PMSM) combining high efficiency and specific power.…”

“…Based on that complete study, a meta-model has been built to simply verify the feasibility constraint related to windings. This surrogate model for partial discharge constraints is integrated in the motor design model and permits a system-oriented optimization of the actuation device [36] (see Figure 7). Two different issues have been considered: first, the turn-to-turn voltage is assessed depending on the power electronics structure.…”

“…Finally, an adapted winding involving PD tolerance is derived fulfilling a filling factor constraint. Readers may find details on that model in [35,36].…”

“…The work has been performed in the frame of the Clean Sky II EU project called "HASTECS" for "Hybrid Aircraft: Academic Research on Thermal and Electric Components and Systems." In HASTECS, several innovative technologies have been assessed [35][36][37][38][39][40][41][42][43][44][45][46][47][48] for power electronics with high performance cooling by involving high voltage and partial discharges constraints. These innovative concepts are applied to a regional hybrid aircraft integrating a series hybrid architecture beyond the "MW" and beyond the "kV" for the bus voltage range.…”

Aerodynamic Uncertainty Quantification for Tiltrotor Aircraft

“…Based on the FFNI results, Sobol's sequence [19,20] is constructed to represent the uncertainties in the aerodynamics of the tiltrotor, which is used to form an N × 2D sample matrix, where N and D = 4 represent the number of sampling and uncertainty inputs, respectively. The first D columns of the matrix form matrix A and the remaining D columns are regarded as matrix B.…”