Concept of level doubling network (LDN) to increase the resolution of any multilevel inverter topology is introduced. Such networks can almost double the number of output-voltage-levels of an available multilevel inverter topology. Therefore, it opens up a new paradigm. LDNs can be added to standard symmetrical as well as asymmetrical cascaded topologies. More importantly multiple LDNs can be added to increase the output voltage levels further. And all these need to happen without any closed loop control which is the highlight of this development. Step-by-step approach to unearth a new series of converter topology utilizing LDN will be presented. Availability of a huge number of voltage levels automatically creates many challenges. Optimization of the topology to have a definite number of voltage levels using minimum number of switches, development of the controller to detect the right space vector in real-time maintaining several constraints and application of the technique to different utilities such as Solar PV, medium and high voltage drives, off- shore wind power station etc. are some of the areas those will be discussed. LDN based topologies and its parallel development presently happening elsewhere will also be compared. All proposals are extensively simulated and confirmed by laboratory based prototypes.
Sumit K. Chattopadhyay received PhD in Electrical Engineering from IIT Kharagpur, in 2016. He has about 5 years of industry experience working in the areas of Power Electronic converters, Naval Defence, Renewable Energy and HVDC. He has proposed a new series of Multi Level Inverter Topology using Level Doubling Network. He has filed patents and published papers on this topic. His areas of interest are power electronic converter topology modulation control and applications. After having his B.E. degree in Electrical Engineering from Burdwan University, Burdwan, India, in 2004 and M.Tech. degree in Industrial Electrical Systems from the National Institute of Technology Durgapur in 2006 he joined Larsen & Toubro Ltd., Navi Mumbai, India, where he was responsible for power electronic system design of multiple industrial and mission-critical naval projects executed for the first time in India. He worked in L&T until January 2010. From January 2010 to March 2015, he was a full-time Research Scholar with the Department of Electrical Engineering, IIT Kharagpur. There he spent most of his time on topology, modulation, control and application of high resolution multilevel inverters. From March 2015 to July 2016 he has served as Scientist of HVDC Grid System RnD with ABB Global Industries Service Ltd., Chennai, India. While working there he has received a comprehensive training on VSC based HVDC systems from Swedish Corporate Research Centre of ABB located at Vasteras/Sweden. In July 2016 he joined back to IIT Kharagpur as the first PDF of Electrical Engineering Dept. to explore further the use of Level Doubling Network in various applications. During his stay at Kharagpur he is also associated with three Ph.D candidates to help their activities and contribute to the UK-India consortium on Clean Energy. One of his proposed topologies is going to be installed on the rooftop of Nalanda Complex of IIT Kharagpur to evacuate power from 90kWp solar PV array into the local grid.