A back EMF-based rotor position prediction in Permanent Magnet machines for survivable wind generator systems

In wind power generators, position information is often required for tracking maximum power point as well as implementing control strategies for the Permanent Magnet (PM) generator. For such a system, failure of position sensor could potentially lead to major fault or require the system to be shut down. This could cause significant economic losses and also require unscheduled maintenance. This paper proposes a new sensorless position estimation approach to track position of the PM machine using the back EMF if the position sensor fails. This technique can also be used to provide initial rotor position for the proper implementation of a fall-back strategy. This technique can also be extended to detect position information at low speeds. Simulation and experimental results have been presented showing the effectiveness the proposed scheme and validate the claims presented.