Cost-Effective DC Source Emulator for Microgrid Testing

The DC Source Emulator methodology combines impedance characterization, custom filter design, and external control implementation to replicate any DC power source using standard laboratory equipment. Engineers first identify the system requiring verification and determine the impedance characteristics of the power source at the interface through hardware testing, simulation, or circuit analysis. Using this impedance data, they design a filter network that matches the target characteristics as seen from the interface. This custom filter connects to the output of a commercially available dynamic DC power supply or linear amplifier. External voltage and current sensing circuits work with external controllers to command the power supply output to respond identically to the physical hardware being emulated. The supply must be capable of changing its output voltage and current in response to external inputs. Transient load step response, impedance response, and ripple characteristics can all be verified to match the target system. Controllers such as PI or PID configurations command the supply output, capturing small signal response for minor variations and transient response for sudden changes. An optional ripple injection stage using an amplifier can be added for increased emulation accuracy. Once configured, the emulated system can be tested for stability across all loading conditions without requiring actual power source hardware. The methodology shapes impedance on a target impedance plot while using high-bandwidth power supplies in either current or voltage mode. The same equipment can be dynamically reconfigured for different emulation targets by changing the output filter and controller parameters, making it highly adaptable across various DC power architectures including converters, batteries, fuel cells, and complex multi-source systems. The DC Source Emulator is available for patent licensing. Testing complex DC microgrid systems traditionally requires recreating entire power architectures with actual hardware copies, a process that can take months or years and cost millions of dollars. This is especially challenging in aerospace applications where specialty components are expensive, scarce, or still under development. Researchers at NASA’s Glenn Research Center have developed a practical methodology that enables engineers to emulate DC power sources using commercially available dynamic power supplies combined with custom-designed filters and external controllers. This hardware-in-the-loop approach uses impedance matching and external control circuits to replicate the electrical characteristics of any DC power source without requiring the actual hardware. By measuring or simulating the impedance of a target power source, engineers can design equivalent filter networks and tune controller gains to make standard lab equipment behave identically to specialized systems. This technique has been validated to TRL 7 and is actively used to define power supply requirements and specifications for NASA's Gateway lunar outpost program. The methodology reduces verification testing from millions of dollars and months of effort down to tens of thousands of dollars and weeks of timeline, enabling rapid iteration and troubleshooting without risking expensive flight hardware.