Army Small Business Innovative Research Phase II

High Power High Voltage High Density Bi-directional DC-DC Converters

The inherent limitations relating to power density, conversion efficiency, and thermal tolerance establish barriers to future development in key military, automotive, and aerospace applications. This research aims to overcome these limitations and develop an unprecedented compact, high power, high efficiency, high temperature, bidirectional dc-dc converter. The Phase I effort successfully demonstrated the feasibility of this converter through a unique marriage of state-of-the-art technologies in semiconductor packaging, power electronics system design, control design, and thermal management. The semiconductor packaging and thermal management innovations consist of developing a new IGBT/diode package compatible with evaporative spray cooling (ESC) technology, with a substantial reduction in thermal resistance. The power stage is modular and consists of multiple, parallel connected, interleaved, and soft-switched units that have distributed heat load, lower losses, and smaller magnetics. Control of the system is performed through a mixed analog/digital hybrid scheme that combines speed and flexibility. The Phase II effort will consist of implementing, testing, and optimizing the techniques adopted in Phase I and will result in a prototype that meets the Army’s challenging requirements.

In addition to military applications, the results of this research will also be valuable in commercial Hybrid Electric Vehicles, renewable energy systems, and power electronic systems packaging.

Power electronics represents a core enabling technology for virtually all aspects of electronic systems worldwide. As an enabling technology, its inherent limitations relating to power density, conversion efficiency, and thermal tolerance establish barriers to future development in key military, automotive, aerospace, and microprocessing applications. As these obstacles are addressed, new advances in power electronics will usher in developments that will advance the state of the art in many other, seemingly unrelated, fields. As such, the benefit of this research and development activity is to work to overcome these obstacles and make way for future development.

The initiative here is directly challenging the state of the art in power density for power conversion by driving the present limits of 60-80W/in³ to over 130W/in³. In the near term, the most significant impact of this work will be in high power applications where volumetric and/or thermal constraints have limited the usefulness of electrical energy. As such, the mobile applications found in the automotive and aerospace industries will be able to realize the most immediate benefit.

In addition, in the near future, high power, interleaved boost architectures will be in high demand. The growing interest here is a direct result of developments in the area of renewable energy technologies. Energy sources, such as fuel and solar cells, often operate at a lower output voltage levels. A high power, front-end, boost converter will be necessary to effectively distribute and use the energy from any renewable source.