In this paper, we treat a control strategy of the permanent magnet synchronous generator (PMSG) for a small size wind turbine in isolated site. The direct drive PMSG is connected to the dc link through a PWM rectifier. The dc voltage is kept constant at its reference value using a sliding mode control approach, under wind speed and load variations. To ensure the reaching and sustaining of the sliding mode, the Lyapunov direct method is used. The logic control signals (Sa, Sb, Sc) are calculated by using the space vector modulation (SVM) technique. To alleviate chattering phenomenon, a tangent hyperbolic function is used in the dc voltage loop instead of a conventionally used sign function. The simulation results have been performed using Matlab/Simulink environment, they show good tracking performances as well as robustness against external disturbances.

Keywords: Permanent magnet synchronous generator (PMSG), Wind turbine, Pulse width modulation (PWM) rectifier, Sliding mode control (SMC), Dc link voltage