Asymmetrically Switched CHB Multilevel Inverters with Harmonic Mitigation Techniques Applied to Photovoltaic Power Generation

Abstract

For the last few years, Multilevel Inverter (MLI) researchers have been motivated to reduce the component count in a significant manner by keeping the output level generation the same or increasing enough to be noticed. In this work asymmetrically switched Cascaded H Bridge (CHB) multilevel inverters with fundamental frequency switching are proposed for photovoltaic (PV) applications. Essentially different types of asymmetrically switched improved CHB topologies are discovered in brief and compared with necessary figures of merits including scaled versions. It is an approach to design different levels of voltages with the same number of switches and reduced device count. This paper reports different types of harmonic mitigation techniques, where the best switching angle optimizations are proposed to generate different levels. Moreover, the performance of the topologies is evaluated through THD minimizations by reducing the lower order harmonics. A few combinations of DC voltage sources are used from PV panels/batteries as input to the inverters for generating different output levels and THD is compared for different mitigation techniques. Theoretical calculation of THD is also shown and compared to simulation results for the proposed inverters. The proposed and simulated inverters are verified and tested though hardware in loop (HIL) implementation. As MLI needs compact filter requirements and better quality of output THD, this kind of proposed CHB inverters is suitable for medium and high power PV applications especially grid-tied PV inverters.

KEYWORDS:

• Asymmetrical switching
• CHB multilevel inverter
• Hardware in loop (HIL)
• Harmonic mitigation techniques
• Low frequency switching
• Photovoltaic applications
• Total harmonic distortion (THD)

Additional information

Notes on contributors

Rubell Sen Goopta

Rubell Sen Goopta was born and brought up at Chattogram, Bangladesh. He has been working as a research scholar in the Department of Electrical Engineering at Indian Institute of Technology Roorkee since July 2017. Earlier, he worked as an assistant professor in the School of Science and Engineering of Chittagong Independent University, Chattogram, Bangladesh from January 2009. He received his BSc and MSc degrees with academic distinction in electrical and electronic engineering Chittagong University of Engineering and Technology, Chattogram, Bangladesh in 2008 and 2015, respectively. His research interests include power electronic switching, power quality improvement techniques, renewable energy technology and intelligent systems design.

Avik Bhattacharya

Avik Bhattacharya is from Kolkata, West Bengal. He received his MTech degree in machine drives and power electronics and PhD in power quality from IIT, Kharagpur, in 2005 and 2010, respectively. Currently, he is working as an assistant professor in the Department of Electrical Engineering, Indian Institute of Technology, Roorkee. He is the author of many papers published in national and international journals and conferences. His area of research includes power quality, AC–DC microgrids, solid state transformers, direct and indirect matrix converters, FACTS devices, electric machines, power electronics, electric drives and electric vehicles. Email: [email protected]