Multi-Channel Stirling Convertor Space Controller (MC-SCSC)

West Coast Solutions (WCS) and Sunpower, Inc. propose to build on a recent and highly successful NASA Phase I demonstration of a single-channel Stirling Convertor Space Controller (SCSC) by extending the architecture to support up to eight (8) convertors with the Multi-Channel SCSC (MC-SCSC). The proposed MC-SCSC Phase I Program directly addresses the electronic controller technical challenge identified under Topic S13.06. Phase I will focus on defining the optimum controller architecture to maximize the Stirling power convertor system performance and reliability. In addition, a brassboard demonstration of a multi-channel electronic controller will be performed with a combination of SCSC drives modified as required to incorporate the new functionality (e.g., synchronization, power sharing, etc.) and a representative set of simulated loads. WCS will thus exit Phase I with a clear definition of what is required to deliver a complete prototype, flight-design, radiation hard MC-SCSC in Phase II. By the end of Phase I, WCS and Sunpower will have defined the optimum multi-channel electronic controller architecture to maximize system reliability, maximize fault tolerance, and optimize performance. The team will also have performed risk reduction laboratory experiments with multiple simulated SRSC loads (minimum two, baseline four) as a robust proof-of-concept demonstration. During Phase II, a path-to-flight engineering development unit (EDU) MC-SCSC will be built and tested with Sunpower- or possibly government-provided SRSCs (or equivalent) to verify complete end-to-end performance of a multi-convertor Stirling power generation system, exiting the Phase II Program at TRL 5 (minimum). Achieving TRL 5 in Phase II will put the WCS-Sunpower Team in a strong position to offer this technology for near term future missions where solar power is not an option and there exists a need for long term operation of a spacecraft, lander, or rover for exploration.
Benefits: There are many regions of space where solar power is not an option and there exists a need for long term operation of a spacecraft, lander, or rover for exploration. Radioisotope Power Systems (RPS) offer the technical advantage of a small size and long life, but the main drawback is the low thermal heat to electrical energy conversion rates of the leading technology, thermoelectric (TE) materials. Given the high cost and limited supply of suitable radioisotopes, this solution is not ideal. Per the Topic 13.06 stated objectives of high thermal-to-electrical efficiency, low mass, long life and high reliability for planetary spacecraft, landers, and rovers, the SRSC represents an industry-best solution. However, the SRSC single-module capacity of nominally 60 W is insufficient for all applications, and a single SRSC-based system has the SRSC as a single point failure. Combining multiple SRSCs together provides both higher power capability and enhances system reliability by reducing single point failure modes. The proposed effort enables critical RPS-based missions up to the 400W level immediately, and higher power in the future. As commercial entities continue to engage in lunar exploration, the commercial need for RPS-based systems will arise.