Abstract: Electromagnetic torque is one of the feasible variables to model reference adaptive systems（MRASs） for online rotor time constant updating in indirect field oriented induction motor drives. However, the effective range of the torque model is limited to the heavy-load operation. In this paper, the stability of the torque model was further analyzed based on the established small-signal model of the estimation system. It was concluded that the torque model was characterized by the desired equilibrium point（EP） and the false EP. Moreover, the root cause of the constraints of the torque model was coming from the false EP. Then, an improved torque based MRAS was proposed through a simple modification of the traditional reference torque model. With the proposed method, the false EP was naturally avoided in practice. Besides, design strategy of the adaptation proportional-integral（PI） gains was proposed to achieve stability and optimized dynamic performance over the whole operation range. The effectiveness of the proposed theory is validated through experiments.