Universal Power Converter for a Lunar Power Grid

Combining a dynamic load emulation technique with a PWM dithering technique, NASA’s technology provides a more efficient, cost-effective, and practical method to emulate complex loads. While there are commercially available electronic device loads on the market that meet basic emulation needs, these devices are limited; they are limited with respect to small input voltage changes, and to feedback signals from the device’s power system, which may lack the strength and resolution needed to emulate accurately. A common solution for the bus emulation limitation is to construct a model of an actual microgrid using representative loads and connections. But this can be complex, costly, and have limitations in performance. NASA’s approach addresses these challenges without creating an actual model microgrid to replicate the systems. As opposed to stand-alone COTS electronic load devices or model microgrids using representative loads and connections for a given test, NASA’s technology is a system constructed of an input power filter, a COTS electronic load device or load subsystem, and a power control circuit. The input power filter is designed to emulate load or bus performance at the medium to high frequency range. The power control circuit combined with the electronic load or load subsystem emulates lower frequency and constant power dynamics of the system. Lastly, the power control circuit linearizes digitization and quantization issues present with digitally controlled COTS electronic loads. The power control circuit can be set to measure a load voltage, which is divided by a determined value for power, and combined with a triangle wave dither (the power control circuit block image demonstrates how to integrate a triangle wave dither). This dither dynamically adjusts the electrical current or power to keep it constant within the commercially purchased load device, enabling accurate emulation of complex DC microgrid systems.

NASA’s LESSH BCM is a compact, high-performance, ruggedized system designed to support extended science operations in harsh lunar environments. With a mass of 9.4 kg and dimensions of 50 x 25 x 10 cm, the BCM is engineered for seamless integration with the interface bank on the HLS. A 1.5-meter flexible harness with an EVA-compatible connector and removable dust cover enables reliable operation in austere environments. Astronaut-operated controls, such as a guarded power switch and LED indicators, simplify usability and reduce the potential for errors during high-stakes lunar operations. The BCM is optimized for safety and efficiency, incorporating state-of-the-art power and charging capabilities. It supports charging of 28V astronaut-rated batteries with a power output rated at 215W and integrates a battery pre-heater to maintain optimal performance in extreme temperatures. The BCM features a 4-hour charge time with software adjustability for charging parameters such as current, voltage, overvoltage, and undervoltage setpoints. Battery longevity is ensured through passive rebalancing of cell voltages and advanced safety features. Its 2-fault tolerant hardware and adjustable safety setpoints safeguard against potential hazards. Additionally, the BCM supports 1000BASE-T Ethernet pass-through for high-speed data transfer. Originally designed to extend the length of lunar surface science experiments by enabling astronauts to recharge instrumentation, NASA’s LESSH BCM may be desired by companies seeking to operate sensors on the lunar or Martian lunar surface. The design may also be suitable for terrestrial applications involving harsh environments where interchangeable sealed sensors must operate on their own or with rovers, robotics, and drones. The BCM is at technology readiness level (TRL) 4 (component and/or breadboard validation in lab) and is available for patent licensing.

The new transparent EDS technology is lighter, easier to manufacture, and operates at a lower voltage than current transparent EDS technologies. The coating combines an optimized electrode pattern with a vapor deposited protective coating of SiO2 on top of the electrodes, which replaces either polymer layers or manually adhered cover glass (see figure on the right). The new technology has been shown to achieve similar performances (i.e., over 90% dust clearing efficiency) to previous technologies while being operated at half the voltage. The key improvement of the new EDS coating comes from an innovative method to successfully deposit a protective layer of SiO2 that is much thinner than typical cover glass. Using vapor deposition enables the new EDS to scale more successfully than other technologies that may require more manual manufacturing methods. The EDS here has been proven to reduce dust buildup well under vacuum and may be adapted for terrestrial uses where cleaning is done manually. The coatings could provide a significant improvement for dust removal of solar cells in regions (e.g., deserts) where dust buildup is inevitable, but water access is limited. The EDS may also be applicable for any transparent surface that must remain transparent in a harsh or dirty environment. The related patent is now available to license. Please note that NASA does not manufacturer products itself for commercial sale.

NASA GSFCs EHD pump uses electric fields to move a dielectric fluid coolant in a thermal loop to dissipate heat generated by electrical components with a low power system. The pump has only a few key components and no moving parts, increasing the simplicity and robustness of the system. In addition, the lightweight pump consumes very little power during operation and is modular in nature. The pump design takes a modular approach to the pumping sections by means of an electrically insulating cartridge casing that houses the high voltage and ground electrodes along with spacers that act as both an insulator and flow channel for the dielectric fluid. The external electrical connections are accomplished by means of commercially available pin and jack assemblies that are configurable for a variety of application interfaces. It can be sized to work with small electric components or lab-on-a-chip devices and multiple pumps can be placed in line for pumping greater distances or used as a feeder system for smaller downstream pumps. All this is done as a one-piece construction consolidating an assembly of 21 components over previous iterations.

The Modular Robotic Vehicle (MRV) is a vehicle designed for transportation in congested areas. The MRV is relatively small, easy to maneuver and park. The MRV was designed without a central power plant, transmission, fuel tank, and direct mechanical linkages between driver input devices and the actuators used to accelerate, brake and/or steer the car. These core vehicle functions are located at the corners of the vehicle in a modular electric corner assembly or eCorner. Because the MRV uses a by-wire control system, substantial space and weight is conserved compared to conventional designs. Moreover, the functional capabilities that are provided by the individual eCorners enable control of the vehicle in a variety of different operating modes. The eCorners provide significant flexibility in driving options. For example, the driving mode can be switched so that all four wheels point and move in the same direction achieving an omni-directional motion or all wheels can be pointed perpendicular to the center of the vehicle allowing rotation around its center axis. This mode makes some driving maneuvers like parallel parking as easy as driving next to the spot, turning the wheels 90 degrees, and driving into the open spot in a sideways motion. Each eCorner includes its own redundancy to protect for electrical failures within the systems. The driver can choose to control the vehicle with a conventional steering wheel or add inputs through a multi-axis joystick for additional control in some of the more advanced drive modes. The vehicle has the propulsion motors located inside of each eCorner with the capability of producing 190 ft-lbs of torque with a current top speed of 40 mph. An active thermal control loop maintains the temperatures of these high powered motors and a separate thermal loop cools the avionics and the custom lithium-ion battery packs. The linked vehicles are able to exchange or share control data and electrical power. Finally, the MRV has remote driving control capability.