Abstract: 

Multilevel power electronic converters offer significant advantages for high-powered conversion systems by using multiple stages of series connected devices in order to operate at voltages higher than the ratings of a single device. This allows higher power ratings and increased voltage levels to be managed without requiring higher rated switching devices. 

Multilevel converters can also offer significant harmonic advantages, as the multilevel converter can be modulated so as to achieve harmonic cancellation between the individual stages. However, variation in the DC link voltages across the converter load range can lead to imperfect cancellation of these harmonics. In order to limit this variation, most multilevel converters use large electrolytic capacitors, which are expensive, heavy and have a significant maintenance requirement. 

An alternative strategy would be to dynamically control these DC bus voltages so as to maintain adequate harmonic cancellation. This would also allow the size of the necessary electrolytic capacitor to be significantly reduced, with corresponding volume and cost benefits. However, little work has been done to date to explore topologies and algorithms that might be used to regulate this DC voltage.

This project will investigate the use of Bidirectional DC-DC converters to supply the DC links for a multilevel inverter. The project will first develop an understanding of Bidirectional DC-DC Converters, their operation, modulation and performance. It will then focus on developing appropriate algorithms for closed loop control of these converters, and then experimentally confirming the viability of this topology for this application under various operating conditions. 

This presentation will therefore focus on my research to date in this field, as well as my proposed research plan for the future.

About the Speaker:

Dinesh is a Masters Research student with the Department of Electrical and Computer Systems Engineering at Monash University, Clayton campus.