A Simplified Fixed Switching Frequency Model Predictive Control for an AFPM Motor Drive in a Distributed Electric Aircraft Propulsion System

The growing focus on aircraft electrification has led to a great emphasis on distributed electric propulsion (DEP). This paper proposes a simplified fixed switching frequency model predictive control (SFSF-MPC) for an axial flux permanent magnet (AFPM) motor drive fed by a three-level T-type inverter in a DEP system. This inverter has multiple performance benefits for DEP applications due to providing more voltage vectors; however, its use in the conventional finite control set MPC (FCS-MPC) leads to an increased computational burden and hinders using higher sampling frequencies. The proposed SFSF-MPC aims to reduce the computational burden in the conventional two-step FCS-MPC by offering a set of candidate voltage vectors, which are determined based on the spatial position and magnitude of the reference voltage vector. Only the voltage vectors close to the reference voltage vector participate in optimizing the cost function. Meantime, a switching frequency regulation strategy is applied based on the gate signal edge detection to maintain a fixed switching frequency. Counting the gate signal edges can predict the switching frequency and optimize it within the cost function. Moreover, the neutral point potential is balanced by equalizing the voltages of the DC-link capacitors based on the compensated stator currents. The performance of the proposed SFSF-MPC is evaluated in the cruise mode of an electric aircraft mission profile.