In this paper an adaptive rotor flux observer is developed. This observer performs a real-time correction of the mutual inductance and rotor resistance of the motor using data from the DC-link voltage sensor, the inverter state and the phase current and position sensors. The observer compares the behavior of two independent observers (sensorless and sensored observers) in order to correct the parameters of the sensored observer. The adaptation algorithm corrects the mutual inductance, which can vary due to change of the magnetization current, and the rotor resistance, which can change due to variation of the rotor temperature. Computer simulation results are presented to validate the proposed method.