Design and finite element analysis of external rotor motor for ornithopter
WANG Ke
LI Xintao
WANG Bo
SHI Lei
LI Siyu
Abstract：To the demand for efficient and lightweight drive systems in large flapping wing aircraft,this paper proposes an optimized design scheme for an external rotor permanent magnet brushless motor.Based on the total weight of 20 kg and the power requirement of 200 W for the flapping wing aircraft,the key parameters of the motor were determined through classical motor theory calculations:using a 12 pole 16 slot combination,a surface mounted structure with neodymium iron boron permanent magnets,a rated power of 340 W,and a speed of 1 500 r/min.We focused on optimizing the stator slot parameters(hs0=2.5 mm,hs1=1 mm)and pole arc coefficient(0.7),and conducted electromagnetic simulation analysis using Maxwell software.The results showedthatafter optimization,the motor efficiency reached 88.6%,the rated torque was 10.5 N·m,the cogging torque was reduced to 0.867 N·m,and the distribution of unilateral magnetic pulling force was balanced.Finite element analysis verified the reasonable distribution of magnetic flux density(peak value 1.860 1 T)and the stability of back electromotive force waveform(25 V amplitude).This design provides a solution for flapping wing power systems that combines high power density and low vibration characteristics,and has significant engineering application value.
Keywords：ornithopterexternal rotor motorsembracecogging torque
Publication Date：2025-11-20
Online Publishing Date：2026-01-06(First online date of this platform, not the publication date of the document)
Pages：6( 97-102 )