TECHNOLOGY AREAS: Ground/Sea Vehicles, Electronics

ACQUISITION PROGRAM: PEO SHIPS, PMS 500 (ACAT I)

OBJECTIVE: Development and demonstration of a low voltage, low power (

100 kW) prototype bi-directional power conversion module. The use of innovative passive (inductor and capacitor) technologies is encouraged to maximize power conversion power density and efficiency. Successful demonstration of the prototype could transition to the Compact Power Conversion Technologies program and then to a follow on flight of DD(X) and baseline CG(X) platforms.

DESCRIPTION: As stated in the existing vision for the Navy�s Power Conversion Module (PCM) is a non-isolated unidirectional AC-DC and DC-DC converter. There are several technical risks and issues (i.e., problems) with this choice for the interconnection of a port or starboard electrical distribution bus with a zone:

a) A single ground fault of an output of any converter in a zone with a simultaneous fault anywhere else in any zone throughout the vessel will fault the entire ship service network. This issues effectively defeats the Integrated Fight Through Power (IFTP) principle. Galvanic isolation prevents ship service power interruptions via ground faults in different zones. Therefore, the ships hull will only become a current path if multiple faults occur on direct-coupled converters in the same string (or zone).

b) Unidirectional power flow does not permit interzone distributed power source (such as fuel cells) access to the entire ship service network when desired. Converter topologies (e.g., buck/boost converter) can easily be used to provide the bidirectional function required for distributed power source architecture (beneficial for dark ship startup or possible low power quiet ops). As a result, emergency power can be used to provide power to vital loads (command, control, communications and computers) functions needed for warfighting missions.

c) Galvanically isolated bidirectional converter topologies are inherently mirror images thus lending themselves to Power Electronic Building Block (PEBB) concepts.

d) Through the use of a high frequency transformer link, any combination of voltages can be achieved. Therefore, this link governs the input and output voltages instead of topology or control strategies. This truly enables the Navy to take advantage of PEBB benefits because the engineering will be done once without the expense of recurring engineering costs. Also, more commercial distribution voltages can be selected for longitudinal buses as well as interzonal buses enabling better use of commercial-off-the-shelf(COTS) equipment. For example, instead of 1000 Vdc for the longitudinal bus and 800 Vdc for the interzonal bus, 700 Vdc could be used for both. This value will allow the use of 1200 V IGBT switches which have lower losses at the higher frequencies and is common for commercial drives.

PHASE I: Using available modeling tools and technology, design a proof of concept bi-directional power conversion module. Using design data, develop a "bread board" notionally 10-20 kW, proof of concept bi-directional power converter and demonstrate successful bi-direction power flow from DC and AC voltage sources. Using the results from the proof of concept demonstration and the design, scaling laws will be developed and used to design a 100 kW bi-directional power conversion module. Additionally, an investigation into high frequency transformer integration with the power conversion module will be made. This will facilitate the output of a variety of voltages and frequencies which would serve to govern input and output voltages instead of the more traditional costly path of topology re-design and risky implementation of alternative control strategies. A final phase I report will be written and delivered documenting the design, fabrication, and testing efforts.

PHASE II: Using results from Phase I, design, fabricate and demonstrate a 100 kW bi-directional power module. The module will be capable of either an AC or DC voltage and current input and output either AC or DC voltage or current. Best engineering practices will be used to maximize power density and power conversion efficiency, but not at the degradation of the bi-directional capability. The module will contain a high frequency transformer section which will optimize input and output voltage and frequency. A final report will be submitted that summarizes the 100 kW design and results of the bi-directional demonstration.

PHASE III: If this technology is proven to meet the requirements specified above at the end of Phase II, it will be transitioned to the Compact Power Conversion Technologies (CPCT). Under the CPCT program, this technology will be demonstrated 1) in simulation on the ONR funded Virtual Test Bed (VTB) and 2) in a full scale medium voltage demonstrator (TBD) together with global power system management capabilities. Successful demonstration could result in a transition to a follow-on flight DD(X) and Baseline CG(X).

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Private Industry has a vested interest in improving availability of power to their processes which produce products to generate profit. Bi-Directional power converters could result in more robust power distribution for private industry; the application of this technology limits faults to the local loads. The Bi-Directional power converter becomes a basic building block that industry can use to step to any voltage (within reason) and begin to use very high frequency magnetics (especially with nanocrystaline cores) with the objective to improve operating efficiency (less heat dissipation), and to an extent, improve power density. Although, power density is not as critical with land based industries as they are with ships with limited volume and footprint. However, availability is of importance to industry. Having the capability of incorporating interruptible power supply (UPS) with the system minimizes the risk of equipment going off line because of a low voltage fault.

REFERENCES:
1. Chang, J, Tom Sum, Anhua Wang "Highly Compact AC-AC Converter Achieving High Voltage Transfer Ratio" IEEE Transactions on Power Electronics (IES), 2 April 2002.
2. Klumpner, Christian and Frede Blaabjberg "Experimental Evaluation of Ride-Through Capabilities for a Matrix Converter under Short Power Interruptions" IEEE Transactions on Power Electronics (IES), 2 April 2002.
3. Simon, O., J. Mahlein, M. Muenzer, M. Bruckmann, "Modern Solutions for Industrial Matrix Converter Applications", IEEE Transactions on Power Electronics (IES), 2 April 2002.

KEYWORDS: Bi-Directional Power Control; Power Conversion Module; Galvanic Isolation; Ride-Through; Power Density; Fault Tolerance

TPOC: Lynn Petersen
Phone: (703)696-1291
Fax: (703)696-0308
Email: [email protected]
2nd TPOC: Terry Ericsen
Phone: (703)696-7441
Fax: (703)696-0308
Email: [email protected]

** TOPIC AUTHOR (TPOC) **

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