Simulator and hardware emulator of a short electrodynamic tether system

Abstract

A simulator and a hardware-in-the-loop (HIL) setup for the study of the electric system made by a short electrodynamic tether (EDT), an Electric Power Module (EPM) and a heaterless Hollow Cathode (HC) are presented. In the simulator, the EDT is modeled by the current–voltage (IV) characteristic of a bare EDT, the EPM involves a power supply and a variable resistor, and the IV curves of the emitter and the keeper of the HC are given by the linear fittings of the experimental curves obtained in the laboratory. The simulator was used to study an important problem for short EDT: the minimum power required by the power supply to reach an electric current at the cathode above the critical threshold to keep the plasma discharge as a function of ambient variables (the motional electric field and plasma density). Regarding the HIL, it emulates the EDT with a programmable power supply and a resistor, the EPM with a power supply and a set of resistors, and the HC by a set of Zener diodes. Additionally, the emulator has a computer and a microcontroller that allow to measure key electrical variables and command in real time and in closed-loop the programmable power supply to ensure that the EDT emulator satisfy the bare EDT IV curve. The three elements of the HIL were tested and compared with the theoretical model to validate its correct implementation and operation. Finally, the HIL was used to test and verify the electronic boards of the device of the E.T.PACK-F project.