Development of a Multi -bus, Multi -source Reconfigurable Stirling Radioisotope Power System Test Bed
The National Aeronautics and Space Administration (NASA) has typic ally used Radioisotope Ther mo electric Gene rators (RTG) as their source of electric power for deep space missions. A more efficient and potentially more cost effective alternative to the RTG , the high efficiency 110 watt Stirling Radioisotope Generator 110 (SRG110) is being develope d by the Department of Energy (DOE), Lockheed Martin (LM), Stirling Technology Company (STC) and NASA Glenn Research Center (GRC). The SRG110 consists of two Stirling convertors (Stirling Engine and Linear Alternator) in a dual -opposed configuration , and two General Purpose Heat Source (GPHS) modu les. Although Stirling convertors have been successfully operated as a power source for the utility grid and as a stand -alone portable generator, demonstration of the technology required to interconnect two Stirl ing convertors for a spacecraft power system has not been attempted. NASA GRC is developing a Power System Test Bed (PSTB) to evaluate the pe rformance of a Stirling convertor in an integrated electrical power system application. This paper will describe t he status of the PSTB and on -going activities pertaining to the PSTB in the NASA Thermal -Energy Conversion Branch of the Power and On -Board Propulsion Technology Division.
A novel multi-port bidirectional converter for interfacing distributed DC micro-grid
A novel multi-port bidirectional DC-DC converter (MPBDC) is proposed for a stand-alone renewable power system which is composed of multiple distributed DC sub-systems. With the proposed MPBDC, the DC buses of these sub-systems can be interconnected with single stage and step-up/-down power conversion. The MPBDC is derived by interconnect multiple bidirectional buck/boost switching cells via DC-link inductors. The equivalent circuit between any two of the DC buses is a H-Bridge step-up/-down converter, which achieves single stage conversion. Compared with the conventional common DC-bus-based solution, the bulky DC-link capacitors have been eliminated with the MPBDC, which benefits reduced size, lower cost and better reliability. The operational principles, power management and pulse width modulation scheme are presented in detail. A prototype is built with experimental results given to verify the topology and control.
NASA GRC Stirling Technology Development Overview
The Department of Energy, Lockheed Martin (LM), Stirling Technology Company, and NASA Glenn Research Center (GRC) are developing a high‐efficiency Stirling Radioisotope Generator (SRG) for potential NASA Space Science missions. The SRG is being developed for multimission use, including providing spacecraft onboard electric power for NASA deep space missions and power for unmanned Mars rovers. NASA GRC is conducting an in‐house supporting technology project to assist in developing the Stirling convertor for space qualification and mission implementation. Preparations are underway for a thermal/vacuum system demonstration and unattended operation during endurance testing of the 55‐We Technology Demonstration Convertors. Heater head life assessment efforts continue, including verification of the heater head brazing and heat treatment schedules and evaluation of any potential regenerator oxidation. Long‐term magnet aging tests are continuing to characterize any possible aging in the strength or demagnetizatio...