Abstract: The principle of indirect torque control based on quiescent coordinate is analyzed.The stator flux and motor torque are calculated in stator coordinate,and the stator flux increment vector is obtained,including phase increment and range increment.The space voltage vector of asynchronous motor stator is calculated according to the stator flux increment vector.A new full order flux state observer of induction motor is established by choosing appropriate state variables of stator flux and rotor flux,and the rotor speed can be adaptively estimated.Experiment results show that the stator current is a sine curve with little harmonics,the electromagnetic torque has good dynamic and steady response performance,and the estimated speed can accurately track the actual speed.