This paper presents a new approach for broken rotor bars detection in induction motors. When broken rotor bar occurs, the rotor resistance will increase. Furthermore, thermal effects of rotor resistance are considered to address practical aspects. Therefore, a suitable method to detect broken rotor bar is rotor resistance estimation. An applicable method in state estimation is Cubature Kalman Filter (CKF). To display the advantages of the CKF, simulation results are compared with Unscented Kalman Filter (UKF). In addition to not needing setting parameters, this filter is more accurate in rotor resistance estimation compared to the UKF.