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A three-year program to develop a Direct Drive Hall Effect Thruster (D2HET) system began 15 months ago as part of the NASA Advanced Cross-Enterprise Technology Development initiative. The system is expected to reduce significantly the power processing, complexity, weight, and cost over conventional low-voltage systems. The D2HET will employ solar arrays that operate at voltages greater than 300V, and will be an enabling technology for affordable planetary exploration. It will also be a stepping-stone in the production of the next generation of power systems for Earth orbiting satellites. This paper provides a general overview of the program and reports the first year's findings from both theoretical and experimental components of the program.

Controllers for flywheel magnetic bearing designed by the usual “position direct feedback” approach are prone to system imbalance and sensor error problems. Remedies for such problems with that approach are complex and unreliable. In the long run, fatigue cycles would eventually change the flywheel system characteristics from their initial values on which the remedy parameters were designed. In this paper, a simple and reliable alternative design approach will be presented to help avoid most flywheel control problems. This design approach is based on an adaptive Kalman-Bucy state estimator that in spite of various system uncertainties can accurately track the motion of the wheel polar principal axis for feedback to the magnetic bearing controls. An implementation of this design on a Digital Signal Processor was tested for robustness, energy efficiency, and versatility. This controller prototype is easy to use for nearly any high-speed flywheel.