The application of the research is towards brushless ac permanent magnet machine drives of the type deployed in aerospace actuation systems. These drives tend to utilise motor designs having concentrated windings with a low slot to pole ratio and thus are not ideal sinusoidal machines. In addition, these machines are often required to operate both below base speed and in the field-weakened region. The proposed sensorless technique, based on two flux models, avoids the need for differentiation in the position and speed estimation, is computationally efficient and is robust to temperature dependent motor parameter variation.