Comparison of inherent saliency tracking methods for zero speed sensorless control of standard induction machines

Sensorless control of induction machines around zero frequency can only be achieved by evaluating inherent saliencies of the machine. The signals resulting from signal injection based sensorless control methods are composed of components caused by saturation, slotting, or anisotropy saliencies, as well as inter-modulation effects. In addition there is a strong influence of the load level on some components. Depending on how the different disturbing components are treated and modeled the performance of the resulting sensorless control is influenced. A comparison between the two methods for both rotor position estimation (tracking of rotor-position-dependent saliency) and flux position estimation (tracking of flux-dependent saliency) is experimentally verified for both methods at zero mechanical and electrical frequencies with high load level under sensorless control technique.