Due to reduction of fossil fuels and environmental pollutions, renewable energies are currently raising a great attention for obtaining electric power. Wind energy is the most growing renewable resource in the world; it is renewable, infinite and environmentally clean. Recently, due to developments in power electronics, variable speed wind turbines became more attractive because of its ability of operation at its maximum power coefficient, which results in larger energy capture from the wind. Permanent magnet synchronous generator (PMSG) is a popular generator in variable speed wind turbines. The Energy captured from wind depends not only on wind conditions but it also depends on the ability of control system to track maximum power points. Because of nonlinear inherent of electrical machines, the excellent performance of their control system could be achieved by nonlinear control techniques. In this paper some nonlinear control techniques adopted to be implemented on PMSG in wind turbines. Firstly input-output feedback linearization control scheme is introduced and implemented to track maximum power points. The adaptive backstepping control system is then designed in presence of resistor uncertainty as well as mechanical torque disturbance, which is the most concerned uncertainty in wind turbines. It is a Lyapunov based nonlinear adaptive controller which is adopted in order to implement MPPT algorithm for permanent PMSG based wind turbines. This approach is based on newly developed adaptive backstepping controller which gains a great attention in nonlinear control systems, due to its capability to derive the control law and a stable Lyapunov function, step by step. Finally a justify; TEXT-INDENT: 18pt; MARGIN: 0cm 0cm 0pt; unicode-bidi: embed; DIRECTION: ltr" dir=ltr Keywords: Adaptive backstepping control, MPPT, Permanent Magnet synchronous Generator, Wind Turbine, Input Output Feedback Linearization, Adaptive Backstepping, Pi-Sliding
