Improved drift-free P&O MPPT method to enhance energy harvesting capability for dynamic operating conditions of fuel cells

Abstract

The current study introduces an improved MPPT algorithm to enhance energy harvesting capacity for momen-tary operating situations of FC. The proposed drift-free MPPT is employed to eliminate the situation caused by an incorrect decision of the classical P&O method during rapid changes in dynamic conditions. The traditional P&O method is based on slope characteristics of the Delta P/Delta V (power change/voltage change). Dynamic temperature/ pressure changes in an FC system affect the system's operational point. In addition to Delta P and Delta V in the classical P&O algorithm, it is aimed to eliminate drift problem that occurs in FC systems by using the current change (Delta I) information in the decision process of the proposed algorithm. The proposed method is tested in a stand-alone FC system, including PEMFC with a rating of 100 W, a dc-dc boost converter, and a constant impedance load. In the operating system, the PEMFC stack is designed and implemented according to the actual working situations of Horizon H-100 PEMFC. The proposed algorithm is compared with conventional method and two other methods in literature. The PEMFC system with the drift-free P&O method has been operated for dynamic temperature/ hydrogen pressure variations. The power of PEMFC settles to almost 98 W at 0.11s with the proposed method, while FC power is 90 W at the same time as the conventional P&O method. In addition, in the temperature variation case, the extracted powers from the FC unit between 2.8s and 3.3s are 96.5 W, 95.8 W, 96 W, and 96 W for the proposed algorithm, classical P&O, IC, and the other one, respectively. Furthermore, successively, the powers between 3.3s and 3.7s are 97.3 W, 96.9 W, 97 W and 97.1 W for the methods. In the pressure variation case, the proposed technique has a faster response to drift phenomena at 1.5s time than the existing methods.