Design and Experimental Investigation of BLDC Motor for Aircraft Electromechanical Actuator

Abstract

Among the electric motors used in the aircraft industry, brushless direct-current (BLDC) ones have the highest power density and efficiency. This paper presents the BLDC motor design and electromagnetic analysis for use in direct-drive aircraft electromechanical actuator. An experimental BLDC motor prototype has been made to test the output. Finite-element analysis (FEA) has been applied to finalize and investigate the characteristics of the BLDC motor design. Then, FEA output has been compared to experimental results in order to validate the latter. The high specific torque has been attained by the 12-slot, 8-pole configuration. Segmenting the rotor magnetic pole has reduced loss to eddy currents in permanent magnets, while double-layer concentric winding has reduced loss to copper and more effective dissipated heat. The BLDC motor presented herein has short response time and high rotor rotational angle precision thanks to the high torque to rotor moment-of-inertia ratio. For evaluating BLDC motor performance assessment, experiments have been run stand-alone, i.e. with no integration in a gearless EMA. Rotational speed vs torque, as well as the holding torque vs phase current at a given BLDC motor rotor position fit well the FEA output at a maximum difference of 10%. Post-test residual magnetization readings of the permanent magnets proved the BLDC motor operable.