In the field of electric vehicles driven by induction motor with indirect filed oriented control method, the motor is usually operated in torque mode. In order to achieve precise control of torque, it is crucial to estimate the rotor flux. Low pass filter(LPF) with compensation system is usually applied in the voltage model based stator flux estimator. In this paper, the performance of two realizations of LPF scheme are compared. Moreover, an optimized implementation of the band pass filter(BPF) based voltage model is proposed. With the proposed scheme, not only the DC offset in the estimated flux is eliminated, but also the dynamic performance is improved and the unsatisfied high-frequency noise is reduced. Based on the estimated rotor flux, estimation and closed-loop control of torque is achieved. The simulation and experimental results verify the feasibility of the proposed scheme.