Fault diagnosis on a pwm rectifier ac drive system with fault tolerance using the average current Park´s Vector approach

Motor drives reliability is becoming a fundamental aspect of their general performance due to the widespread use of motor-drive systems in numerous critical applications. Therefore, strategies able to operate under faulty conditions are of extreme importance. However, for them to operate there is the obvious need of detecting, identifying and locating the fault. Several methods of diagnosis applied to rectifier and inverter systems have been recently researched. This paper proposes the use of the average current Park´s vector approach, to make possible the diagnosis of the inverter power switches open circuit faults. The simulated AC drive model uses a PWM rectifier, to feed the DC link of the AC drive, that permits near sinusoidal input current and unity power factor and gives, simultaneously, regenerative capabilities to the drive. The active rectifier also improves the drive fault tolerance capabilities. The diagnostic method used in this paper, can be readily integrated into the drive control system. Further, with the rapid detection of the fault, corrective steps can be initiated immediately after system breakdown, thereby enhancing the reliability and maintainability of the system.