Inter turn short circuit fault detection using PWM ripple currents in Brushless DC motor.

Inter-turn short circuit (ITSC) faults are common issues in motor drive systems, primarily arising from the degradation of winding insulation. An ITSC fault begins with shorted turns in the winding, progresses rapidly, and can eventually lead to a complete short circuit, causing the system to halt. Therefore, an ITSC fault diagnosis technique is critically important for ensuring the reliability of the target application. Pulse Width Modulation (PWM) is widely used for speed control in BLDC motor drives, introducing high-frequency (HF) components in the stator currents. These components are inversely proportional to the winding inductance. ITSC faults create asymmetry in the stator currents due to unbalanced inductance, which is more pronounced at high frequencies. By Leveraging this characteristic, the proposed method extracts high-frequency current components, identifying asymmetry in three-phase currents for fault detection. Notably, the proposed technique remains unaffected by resistive asymmetry and symmetrical inductive asymmetry across phase windings. The proposed technique is evaluated through experimental studies on a $48 \mathbf{V}, 0.5 \mathbf{k W}$ BLDC motor drive setup.