Advances in Intelligent Systems and Technologies Proceedings ECIT2010 – 6 th European Conference on Intelligent Systems and Technologies Iasi, Romania, October 07-09, 2010 Low Frequency Ripple Mitigation of the Fuel Cell Inverter System using a Controlled Buck Current Source – Part I: Hysteretic Control Nicu Bizon, Emil Sofron, Marian Raducu University of Pitesti Abstract: This paper analyzes the possibility to mitigate the current ripple of fuel cell inverter system. The low frequency ripple mitigation is based on active control. In the tracking loop of controlled buck current source an anti-ripple current that is injected in common node of the DC input port is generated. The ripple mitigation performances are evaluated by indicators that are defined to measure the mitigation ratio of the low frequency harmonics. In this paper it is shown that good performances are obtained by using the hysteretic current control. Keywords: Fuel cells, inverter system, current ripple, ripple mitigation control, energy efficiency, hysteretic control. 1. Introduction One of the most used solutions as main energy source in Energy Generation System (EGS) and vehicle applications is the Polymer Electrolyte Membrane Fuel Cell (PEMFC) stack because of its small size, ease of construction, fast start-up and low operating temperature. Unfortunately, the relatively short PEMFC’s life represents the main obstacle to their commercialization [1]. As it is known, the inverter current ripple is the main factor for low performance regarding the PEMFC energy efficiency [2,3] and PEMFC life cycle [4,5,6]. Also, it is known that PEMFC low frequency (LF) current ripple affects in great measure the PEMFC life cycle and it causes hysteretic losses and subsequently more fuel