Iyer Receives Best Presentation Award at 2017 IEEE Applied Power Electronics Conference

Vishnu Mahadeva Iyer, a research assistant at the FREEDM Systems Center at NC State, won the Outstanding Presenter award at the IEEE Applied Power Electronics Conference (APEC) held in Tampa, FL in March 2017. The topic of his presentation is entitled “Hybrid Control Strategy to Extend the ZVS Range of a Dual Active Bridge Converter”.

Iyer’s presentation on extending the zero voltage switch (ZVS) range of a dual active bridge (DAB) converter applies to real-world applications such as electric vehicle and other battery charging systems, solid-state transformers and energy storage integration to the power grid. DAB converters are used for battery charging and energy storage due to their capability of bi-directional power processing and ability to isolate an energy source from the load. However, wide variations in input or output voltage make it difficult to achieve ZVS in the operating load range. Iyer’s research on a new hybrid control strategy suggests the ability to extend the ZVS range of a DAB converter when voltage variation is present. The proposed control method also improves light load efficiency and extends the ZVS range of DAB.

Vishnu is a power electronics researcher who is passionate about all aspects of power conversion and control. His research interests include fast charging systems for electric vehicles, grid connected power converters, resonant and soft-switched dc-dc converters, power electronic solutions based on wide band-gap semiconductor devices, etc.

After receiving his B-Tech in Electrical & Electronics Engineering (2011) and an ME in Electrical Engineering (2013) back home in India, Vishnu decided to enter the workforce to gain industry exposure and get a better understanding of challenges the power industry faces. He worked for GE Global Research in India as a Power Electronics Engineer for two years and won the GE Beliefs Champion Award for innovation and technical excellence during his employment with the company.  In August 2015, Vishnu returned to academia in pursuit of his PhD degree at NC State University in the Electrical & Computer Engineering department.

This research will be published in a future issue of IEEE Conference Proceedings.


Abstract—This paper presents a hybrid control strategy for a dual active bridge (DAB) based dc-dc converter which combines the benefits of traditional phase shift and burst mode modulation schemes. The advantage of using such a control strategy stems from the fact that it can extend the zero voltage switching (ZVS) range of all power switches in both the primary and secondary bridges when there is a wide variation in input or output voltage. In addition, the hybrid control strategy improves the light load efficiency of the DAB converter. The paper focuses on the development of the average and small signal models for the DAB converter with the hybrid modulation scheme. Digital implementation considerations of the hybrid control scheme are discussed. The effectiveness of the proposed control strategy has been tested and validated through simulations and experiments.

Dr. Subhashish Bhattacharya, an Associate Engineering Professor and NSF FREEDM Systems Center faculty member at NC State University advises Vishnu.