In Ac motor drive systems asynchronous motors are normally powered by VSIs (voltage source inverters). The control strategy of these drives is the vector control by orientation of the direct type rotor flux (RFOC). The combination of the induction motor and the voltage source inverters is sensitive to several types of faults, if a fault touching an organ of this combination directly it affects these electrical quantities and causes the shutdown of the system. In recent years, there has been a great deal of interest in the development of methods for diagnosing open-circuit faults in IGBTs (insulated-gate bipolar transistors) of the voltage source inverters. In this paper, a new diagnostic method has been proposed to detect and locate faults in real time using only three-phase motor currents. We used MATLAB/SIMULINK to build our system. Under distinct operating conditions, the simulation results show the performance and robustness of this diagnostic method.