Ultra-capacitors, used as short-term energy storage devices, are growing in popularity especially in the transportation and renewable energy sectors. This text provides an up-to-date and comprehensive analysis of ultra-capacitor theory, modeling and module design from an application perspective, focusing on the practical aspects of power conversion and ultra-capacitor integration with power electronics systems. Key features:  clearly explains the theoretical and practical aspects of ultra-capacitor, analysis, modelling and design  describes different power conversion applications such as variable speed drives, renewable energy systems, traction, power quality, diesel electric hybrid applications  provides detailed guidelines for the design and selection of ultra-capacitor modules and interface dc-dc converters includes end-of-chapter exercises and design examples This is an essential reference for power electronics engineers and professionals wanting to expand their knowledge of advanced ultra-capacitor energy storage devices and their application in power conversion. It is also a valuable resource  for industrial design engineers as well as academics and advanced students in power electronics who want to develop their understanding about this highly topical subject.