Design of Model Based Control Strategies for a Novel MISO PEM Fuel Cell Control Structure

Abstract

Nowadays, the application of the proton exchange membrane fuel cells (PEMFCs) is advancing as a popular renewable energy source. PEMFCs must operate at low temperatures, have high power density, and be easily implemented. These features contorted them into the most compelling type of fuel cell. However, PEMFCs need a strategy for maintaining the voltage at a desired operating point, specifically during the current variation. The present study proposes a novel Multiple-Input-Single-Output (MISO) control structure for a PEMFC system to improve its performance. This study focuses on airflow optimization and hydrogen consumption optimization, as the literature focuses more on airflow optimization for compressor or pump performance. To give an outlook, a two-input-two-output PEMFC system, with air and hydrogen flow rates as inputs and cell voltage and load current as outputs, is considered a two-input-single-output system by fixing the output resistance. The fractional order model is realized from the existing integer order MISO PEMFC system using a genetic algorithm as the optimization technique. The proposed control structure aims to control the output cell voltage by regulating the air and hydrogen inlet rates by designing various model-based controllers like PI, PID, MPC, and Predictive PID. The control performance is evaluated for set point tracking, disturbance rejection, inverse response rejection, and time delay compensation for the best combination of controllers based on ISE, IAE, and TV values. From the simulation results, the fractional-order system is observed to give better results than the integer-order system, with MPC showing the best results for controlling the stack voltage.