1158 IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, VOL. 9, NO. 2, MAY 2013 Design and Implementation of Digital Control in a Fuel Cell System Minsoo Jang, Member, IEEE, Mihai Ciobotaru, Member, IEEE, and Vassilios G. Agelidis, Senior Member, IEEE Abstract—Digital control implementation is crucial in modern power electronic converters and energy conversion systems, as more complex control and friendly user interface are required. The fuel cell (FC) is a promising clean energy source and a reli- able technology for niche applications providing high conversion efficiency. In this paper, a digitally controlled FC system is doc- umented based on the boost-inverter topology that achieves both boosting and inversion functions in a single-stage. A digital signal processor TMS320F28335 is used to implement the control of the FC system in order to provide a number of benefits including low-cost, good performance, an easy implementation of a rela- tively complicated algorithm, and user friendly interface. The control design, analysis, simulation and experimental results are presented in the paper to confirm the performance of the digitally controlled FC system. Index Terms—Boost-inverter, digital control, digital signal pro- cessors (DSPs), fuel cell (FC) system. I. INTRODUCTION P OWER electronic converters are the enabling technology for the interface of modern energy generation sources such as photovoltaic (PV) systems and fuel cells (FC), and control of modern loads including electronics and motors [1]–[3]. As the applications of power electronic converters continue to expand, the development of suitable low cost and high-per- formance controllers has become important. Digital control is the fundamental step forward to provide implementation of more complicated algorithms with attractive benefits such as programmability, adaptability, low part count, reduced suscepti- bility to environmental variations, low-cost, high-performance, expandability, and modularity [4], [5]. Therefore, recent re- search effort has been concentrated on digital controllers, which perform the previously mentioned functions that are not easily achievable with analog control technologies. Especially, some digital signal processors [digital signal processors (DSPs), for example Texas Instruments TMS F28335] are developed for power electronics applications such as dc–dc converters and dc-ac inverters. The DSPs are considered as an effective controller unit and have been widely used in numerous research papers to implement different control methods [4]–[10]. Manuscript received November 30, 2011; revised March 15, 2012 and May 10, 2012; accepted September 17, 2012. Date of publication October 02, 2012; date of current version January 09, 2013. Paper no. TII-11-945. The authors are with the School of Electrical Engineering and Telecommu- nications, The University of New South Wales, Sydney, NSW 2052, Australia (e-mail: minsoo@ieee.org; mihai.ciobotaru@unsw.edu.au; vassilios.age- lidis@unsw.edu.au). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TII.2012.2221724 Fig. 1. Illustration of the beginning of life (BOL) polarization characteristics of the Nexa 1.2 kW PEMFC power module: voltage-current and power-current characteristics with parasitic power graph. The net output power ranges from zero being idle to 1200 W at rated power. The net output current ranges from zero to 46 A across the operating range. The output voltage varies with the oper- ating load according to the polarization characteristics of the fuel cell stack. The normal idle voltages of the Nexa system are approximately 43 V. At rated power, the Nexa system output voltage ranges from 26 to 29 V at beginning-of-life. However on a positive note, the clean energy sources are continuously increasing and the power electronics is the en- abling technology. The FC is one of the attractive solutions for a number of niche applications due to its high efficiency, being environmentally friendly, modularity and cost effective- ness [2], [3], [6], [11]–[13]. The FC systems need to be condi- tioned which may include energy conversion stages. Addition- ally, the FCs must be supported by energy storage devices to achieve high quality supply of power [1], [2], [11]–[13]. When the FCs are used to power ac loads or to be connected with the electricity grid, an inversion stage is also required. To ad- dress the load requirements of a FC system, a single-stage FC system based on a boost-inverter has been proposed in [11]. The single-stage system is able to minimize the drawbacks of a two-stage FC power conditioning system such as being bulky, costly, and relatively inefficient due to its cascaded power con- version stages [11]. Some recent research papers have been focusing on the de- velopment of high performance and low cost digital controller to address various requirements for the FC system design, e.g., voltage regulation, power quality, and protection for stand-alone/grid connected applications [5], [6], [8]. However, the detailed design and implementation of the dig- ital control for a FC system based on a boost-inverter have not been reported yet in the technical literature. The objective of this paper is to document the design and development of a digitally controlled FC system. The DSP TMS320F28335 is a standalone controller unit which performs 1551-3203/$31.00 © 2012 IEEE