Absolute stability of fuel cell-super capacitor hybrid power source using Lure Lyapunov formulation for load variations

Fuel Cells have emerged as one the most efficient energy conversion devices which convert chemical energy into electricity. It is a common practice to use supercapacitor or battery with a fuel cell to compensate for a high instantaneous power requirement during transients in applications such as hybrid electric vehicle, smart grids etc. This paper presents a non-linear controller design method for a fuel cell-supercapacitor hybrid structure. We identify the Lure form of the dynamic model of fuel cell-supercapacitor hybrid power source. A class of control laws is proposed to ensure the absolute stability of the system. The feedback control law satisfies the necessary and sufficient conditions for stability which are established using a Lure type Lyapunov function. This method offers more degrees of freedom in choosing controller parameters hence providing more flexibility in controller design. The performance of the proposed control scheme is tested via simulations.