Use of Halbach Arrays in Axial and Radial Flux Permanent Magnet Machines for Aerospace Applications

Abstract

The need for reductions in global greenhouse gas emissions, coupled with rising fuel prices, has motivated intense research in the area of hybrid and fully electric crafts for commercial applications in the aviation sector. This thesis explores implementation of Halbach arrays in high-speed radial flux machines (RFMs) and low-speed axial flux machines (AFMs) for aerospace applications. Highly accurate analytical equations are developed for quickly predicting the magnetic field in the latter (both for coreless and steel core stators) due to the complex three dimensional axial flux paths which make traditional finite element analysis time-consuming. Electromagnetic design and optimization of two aerospace machines that use Halbachs are detailed. The first is a ~14 kW AFM intended to replace an existing high lift motor RFM concept in NASA’s Maxwell X57 all-electric plane. Two design variants are selected which achieve a 10 % increase in torque/power and a 10 % decrease in mass/volume, respectively. The second machine is a 20,000 RPM surface permanent magnet RFM capable of 150 kW peak power output that is intended as a proof-of-concept for the later development of a megawatt machine for a hybrid and/or all-electric aircraft.