Design of a Multidisk Axial Flux Machine for drones

Axial flux machines are useful when the weight of the device is an important constraint as in drones. Due to their bigger power density, they are more suitable, then the radial flux ones [1]. For the analysed application we considered two different operating phases: one at nominal torque and nominal speed, and the other, longer then the first one, where the desired torque is less than 50% of the nominal one. Between the several possible architectures of axial flux machines we choose the R-S-R-S-R one (see Figure 1) that guarantees the following advantages: - The radial dimension of the machine can be restrained due to the distribution of the torque in several disks, reducing the mechanical stress at high speed. - The whole motor is equivalent to two semi-motors on the same shaft. Each motor could be designed for developing the 50 % of the nominal torque. In this way, we can satisfy both of the two operating condition, feeding one stator, or both of them. Nevertheless, in case of failure, the second semi-machine will allow enough torque to ensure a better landing.