Energy harvesting from the FC stack that operates using the MPP tracking based on modified extremum seeking control

In this paper, a Maximum Power Point (MPP) tracking technique is proposed for the Fuel Cell (FC) stacks based on a modified Extremum Seeking (mES) control that slightly improves the performances of the classical ES control schemes. A higher value of the search speed obtained for the same tracking accuracy is demonstrated for the proposed mES control in comparison with the classical ES control schemes. The analysis made for the mES control in frequency domain reveals interesting relationships to design the control parameters, the values of closed loop gain and the dither amplitude, to obtain the imposed performance related to the search speed and tracking accuracy. The search speed will increase proportionally with the product of both control parameters, so it is practically limited for safe reasons. Finally, in the dynamical operation of the FC stack, a higher loop gain means a shorter time to catch the next MPP. Simulations show that the performances mentioned above are effective for the mES control based on a band pass filter scheme. (C) 2012 Elsevier Ltd. All rights reserved.