The paper deals with induction motor speed control systems in sensor and sensor-less cases. Firstly, the passivity of the rotor flux error subsystem (in d-q reference frame), and the corresponding passivity-based scheme are respectively shown; secondly, a passivity-based sensor-less scheme is presented; at last, a simulation experiment example is also given to illustrate that the excellent tracking performance of the rotor flux and speed, and the performance robustness w. r. t. uncertain rotor resistances.