Smart Resistor for Stability Improvement of the dc Link in Turbo-Electric Aircrafts

The electrification of aircrafts is transforming the traditional power distribution architectures of the previous century. Turbo-electric propulsion power system features a dc link between turbo-electric generators on each wing tip and the distributed motor drives. Among the challenges of turbo-electric distributed propulsion (TEDP), the stability of the dc bus is vital to safe operation during flight. When these motor drives tightly regulate their output speed, they appear as constant power loads (CPL) on the bus. These CPLs exacerbate the effect of disturbances to the dc bus, such as load transients and voltage sags which can destabilize the system. It is important to keep the system stable without increasing the weight of the system with bulky filters. The Smart Resistor concept has been proposed as one such solution that reduces input capacitor sizes by making the CPL behave as an equivalent droop resistance. This is accomplished by interfacing existing energy storage at the point of load to provide high bandwidth current compensation. This paper first defines stability metrics for a system utilizing the Smart Resistor concept. A case study for a 2 MVA motor drive is used to showcase the improvement of stability using Smart Resistor based on these metrics. Finally, the quantitative improvement in the stability metrics is validated using a scaled down hardware prototype.