Abstract

Electric power generation for fixed-wing unmanned aerial vehicles (UAVs) is often generated with the aid of brushless DC (BLDC) motors mechanically coupled to the engine. Conventional alternators and generators are usually unsuitable for this purpose due to the weight concerns of the UAV. Moreover, by using a BLDC motor for power generation, the engine of the UAV can be started by rotating the starting ring gears on the flywheel of the engine with the aid of this motor, thereby serving as an autostart mechanism for the engine. This work considers the design of a BLDC motor based starter-generator for an experimental medium-range, medium-endurance UAV at reduced weight while meeting the performance specifications of the UAV in terms of range and endurance. The design comprises of a belt driven A2212 BLDC motor which serves as a starter-generator, a 12v LiPo battery and a microcontroller based battery management system to increase the endurance of the UAV by ensuring that the battery operates only within acceptable conditions. Results from numerous simulations indicate that this design is capable of generating sufficient power at 12volts for the avionics components of the UAV whenever the engine rotated at 4500RPM or above.