Brushless direct-current (BLDC) motors are used in various applications where maintaining high reliability and safety is a major concern. Therefore effective fault diagnosis is becoming increasingly essential for such systems. This paper presents an inter-turn short circuit fault detection approach for BLDC motors with trapezoidal back electromotive forces (back EMFs). This kind of fault is one of the common electrical faults in motors stators. As the motor back EMFs are considered as bounded uncertainty, a sliding mode observer, which is suitable for uncertain parametric systems, is used to estimate the phase currents. After the phase currents estimation, fault residual is generated and compared to a preset threshold for fault detection. Simulation results are given to demonstrate the efficiency of the proposed method.

Keywords: Diagnosis, Sliding mode observer, Brushless direct-current (BLDC) motor, Trapezoidal back EMF, Short circuit fault