Rotor time constant updating scheme for a rotor flux oriented induction motor drive

This paper presents a simple online rotor time constant identification scheme of an indirect field oriented induction motor, for the purpose of improving the performance and robustness of the drive. The proposed technique neither requires any special test signal nor any complex computations. This scheme is based on a special switching technique of the current regulated PWM (CRPWM) voltage source inverter (VSI), which allows the measurement of the induced voltage across the stator phase. The rotor time constant is then identified directly from this measured voltage. This proposed technique provides six windows within one electric cycle to update rotor time constant, which should be sufficient for all practical purposes. Simulated results are presented to validate the effectiveness of the proposed technique