Inter-turn fault tolerant control system in brushless DC motor by using yoke winding

A fault tolerant control is mightily important in industrial and electrical vehicles. A shutdown of these motors should not happen due to its direct relationship to enormous loss to life and property, even if inter-turn fault of a winding occur. This paper proposed an inter-turn fault (ITF) tolerant control system using new-design brushless DC (BLDC) motor, which has teeth and yoke winding connected in parallel for fault tolerant control. The special point of new-design BLDC motor is that back electromotive force of teeth and yoke winding have nearly similar value and phase. In addition, we used a fault detection using input impedance algorithm. It can distinguish the ITF condition using variation of input impedance, which is obtained by monitoring of input voltage and current. After that, a fault tolerant control can prevent the spread of the fault by cutting off the three-phase winding and maintain partial output characteristics in proposed BLDC motor. The system has a special advantage that can use existing inverter without additional control device. Finally, we analyzed characteristics of the ITF tolerant control system in proposed BLDC motor using finite element method.