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Electrodynamic tethers are proposed as propulsion and energy harvesters for space probes orbiting planets with a magnetic field and ionosphere, however there are no descriptions in the technical literature of the design of an electrical power system for such an application at subsystem and circuit detail. This paper presents a proposal for such a power system that extracts energy from the kinetic energy of a spacecraft using a bare electrodynamic tether, i.e. an unsheathed conductive wire or band, in low-Earth orbit. The application of the system is the powering of the spacecraft while in its final de-orbiting maneuvers at end-of-life with no reliance on the main spacecraft bus.

A simple multiplier for the estimation of the maximum power yield of a solar panel may be realized with a pulsewidth modulator working as analog multiplier circuit. Though the output of the pulsewidth modulator multiplication is not proportional to the actual output power of the solar panel, it may be shown that its maximum follows the maximum of the power curve of the panel. The multiplier allows a complete analog implementation of the maximum power point tracker of the panel thus keeping the simplicity needed in robust electronic systems. This paper presents the working principle of the maximum power point regulator, its design procedure, and a practical implementation for a low power solar panel, 7.1 V and 487 mA, used in small satellite platform applications.