Rad-hard Electronic Control and Power Integrated Circuit for Stirling-based Radioisotope Power System

In response to the NASA SBIR topic S13.06 “Dynamic Power Conversion”, subtopic “Radiation-hardened electronic controllers and power processing” from 1 to 100 watts, Alphacore Inc. will develop a full Radiation-Hardened (Rad Hard) Controller and Power Management Integrated Circuit (PMIC) for Radioisotope Power System (RPS) free-piston Stirling cycle converter inclusive of Stirling engine, engine controller, and DC/DC converter, yielding a 28V regulated output with total high system efficiency (>30%). We refer to it as the PMIC or simply the Controller. Alphacore controller will work with hardware from our partner Sunpower, both the 65W Sunpower Robust Stirling Convertor (SRSC) and the 35W EE-35 Stirling converter. Professor Seth Sander from University of California at Berkeley will consult with Alphacore on the controller design. Prof. Sanders spent about 15 years on the Stirling engine front, mostly developing free-piston type machines. The controller will be simulated in Phase I and a complete RPS prototype will be delivered in Phase II. The controller will have a credible path to flight and able to control a dynamic convertor without relying on feedback from vulnerable short-lived sensors. The controller radiation tolerance will be greater than 5x1011 n/cm2 + 3x102 krad + 40 MeV-cm2/mg (linear energy transfer) to achieve higher tolerance to radiation, thereby enabling a reduction in shielding mass. The controller will operate over a wide temperature range(-150 ºC to 150 ºC). The developed PMIC will have a reduced component count, enabling reduced failure modes, and smaller area of PCB (printed circuit board). It will include over-voltage protection, fault tolerance, load monitoring, as well as allow control and status monitoring by a remote power system controller. This PMIC includes all controller circuitry and drivers integrated in a single die and drives an external wide-bandgap (WBG)-based power stage for electric power delivery.