A method for controlling an induction motor using an equivalent circuit model, the equivalent circuit having a real component and an imaginary component, is disclosed. The method instead of measuring a plurality of induction motor parameters, the real and the imaginary component of the induction motor impedance are calculated based on the measured phase currents and voltages. The invention calculates a first control function based on the real component of the induction motor impedance, and a second control function based on the imaginary component of the induction motor impedance, and adjusts the induction motor excitation frequency until the first control function is approximately equal to the second control function. After the excitation frequency is determined, the motor torque is calculated by taking the square of motor voltage in the d-q reference frame. Working with a few control parameters, the present invention achieves a desired maximum torque or a desired peak efficiency with a high tolerance of variation in the control parameters.