In the low speed range, indirect stator-quantities control of circular stator flux linkage was adopted and the stator voltage vector was obtained by calculating the periodic variation of stator flux. Flux observer model was established according to mathematical model of induction motor. Electromagnetic torque ripple theory analysis showed that the indirect stator-quantities control was applicable to the low speed range. In high speed range, the torque control of eighteen-corner stator flux linkage was adopted to realize all speed control of AC induction motor. The experimental results verified the effectiveness of the method.