Digital Twin of a DC Brushless Electric Motor-Propeller System with Application to Drone Dynamics

Abstract

A digital twin of a direct current brushless (BLDC) electric motor and propeller is developed for predicting the generated thrust when there is no motion of the system (static conditions). The model accounts for the back electromotive force, the propeller drag force, and the finite response time arising from the electromagnet winding inductance and DC resistance. The model is compared to a textbook model of BLCD dynamics and to experimental measurements on a KDE Direct KDE2315XF-885/885 Kv motor with a 945 propeller and a Holybro electronic speed controller (ESC) driving an AIR 2216/880 Kv motor with a 1045 propeller. These systems are typically found on Group 1 uncrewed quadcopters (drones). Both the steady-state and transient dynamics depart substantially from linearized models found in the literature. This study is a starting point for disentangling the dynamics of the motor and the change in propeller dynamics due to complex airflow conditions.