An analysis of properties of the BLDC motor for unmanned aerial vehicle hybrid drive

The paper presents an analysis of a brushless dc motor (BLDC) design solution to be used in the hybrid drive for an unmanned aerial vehicle (UAV), where the designed machine can be operated as the combustion engine starter, generator, and motor. Solutions with external rotor are preferred due to necessity of minimization of the machine weight. Relatively low value of the supply voltage requires that parallel connections within each of the motor phases should be adopted. When selecting optimum pole-arcs of permanent magnets, the relevant analysis concerns not only their influence on the generated cogging torque, electromagnetic torque, and induced voltage, but also circulating currents resulting from the assumed configuration of stator windings. Waveforms of currents, voltages, and the electromagnetic torque are determined for a selected motor working point. Finally, conclusions concerning the analyzed motor are presented.