1. Design of a high efficiency converter for fuel cell applications Vaal University of Technology Energy Postgraduate Conference 2013 Christian Kuyula

2. Outline Introduction Fuel cell converter Converter design process Hardware tests Performance results Summary

3. [1] Source: The fuel cell review industry 2012 Fuel cell powered mine locomotive prototype launched by Anglo American Platinum in partnership with Ballard (May 2012) [1] “South Africa is in a unique position to reap significant benefits from a local fuel cell market… Fuel cell demonstration projects are under way around the country and it has the necessary manufacturing and engineering expertise. The window of opportunity to make it happen is now.” — Cynthia Carrol, former CEO of Anglo American. Introduction

4. Fuel cell converter DC-DC converter purpose: ●The converter is aimed to handle a wide range of input voltages and efficiently convert the unstable electrical voltage generated by a fuel cell into usable power for equipment operating on DC. ●The converter is key to prolong the a fuel cell’s life and improve its reliability. Voltage and current characteristic of a fuel cell [2] [2] S. Ang & A. Oliva, Power-Switching Converters, 3 rd ed. Boca Raton: CRC Press. 2011

5. Interleaved synchronous buck converter Non-synchronous vs. synchronous buck converter 2 phase interleaved synchronous buck converter

6. Converter design process Specifications Webench ® Designer Webench ® Designer Circuit Simulation Circuit Simulation Converter construction Converter construction Prototype completion Prototype completion Hardware testing Hardware testing Specifications Input voltage: 22-46 V Output voltage: 13.8 V Output power: 100 W High Efficiency > 85%

7. Hardware tests Step load transient response test Turn-on input voltage test

8. Performance results V in I in P in V out I out P out Efficiency 220.93520.5713.71.419.1893 221.85240.74413.592.838.05293 222.74460.36813.514.256.74294 223.66980.71813.475.675.43293 224.595101.0913.4793.893 V in I in P in V out I out P out Efficiency 460.4621.1613.71.419.1891 460.8940.9413.652.838.2293 461.3562.113.64.257.1292 461.7881.70213.55.675.693 462.2100.9813.48794.3693

9. Summary Since the fuel cell market in South Africa as well as the technical expertise on fuel cell ancillary technologies are currently gaining momentum, this research addresses the need for an efficient fuel cell converter providing usable DC current. An interleaved synchronous buck converter was used for the project. Design process steps, hardware tests and performance results were presented. The converter module enables regulation of a single high-current voltage (13.8 V @ 7 A) directly from a wide input voltage ranging from 22 to 46 V. The efficiency of the module was found to be superior to 90%. Much is needed to educate and prepare the general public for this established technology option.

10. Thank you!