Advanced control methods are nowadays increasing in interest for power electronics devices. This paper proposes a nonlinear control law for a DC/DC boost converter dedicated to extract the maximum power from a photovoltaic (PV) array, taking into account the constraints of the control action. System stability analysis is provided by a proper Lyapunov function. Simulations on SimPowerSystems validate how the developed control strategy is able to properly control the converter with good performances.