This paper proposes a sensorless fault-tolerant control technique solving the tracking problem of the maximum delivered power characteristic for a wind energy conversion system equipped with a permanent magnet synchronous generator. A previously published control scheme ensuring the achievement of maximum power efficiency of the wind turbine, not requiring feedback information about rotor speed and position, and about wind velocity, is here extended to make the control scheme fault-tolerant with respect to possible faults affecting the equations of the PMSG in the original (α,β) frame. The control law is based on a number of interconnected nonlinear observers, and closed loop asymptotic vanishing of the observation errors is proved, as well as boundedness of the observer variables.