A Hybrid Model of a Brushless DC Motor

This paper presents a novel approach to modeling of a brush-less direct current motor (BLDCM) driven by an inverter using hybrid systems theory. Hybrid systems combine continuous and discrete (event-based) dynamics, which is exactly the case in an inverter-driven BLDCM. The model presented in this work consists of a general automaton with discrete states, combined with a set of continuous dynamic equations describing the electro-mechanical behavior of the motor. One of the significant benefits of this strategy is that the model describes the motor under all possible operating conditions. The model is derived for the common case of a BLDCM in wye-connection with a three-leg inverter. The model is verified on a real BLDCM drive and shows good agreement with experiments.