Investigation of High-Frequency Power Conversion and Generator Techniques

This paper reports on an investigation of techniques concerned with development of efficient and lightweight power conversion units for use with space power systems currently being developed. Results of the investigation provide an insight into the best system approach for supplying high frequency power. The effort was accomplished as part of Contract AF33(657)-11049 for the Research and Technology Division of Air Force Systems Command with Captain Harold L. Briggs as the Project Officer. Specifically, the conversion units analyzed are for supplying high-frequency (50 to 800KC), high-voltage power to accelerate plasma in an electric propulsion engine. Various conversion and power generation techniques are reviewed. Conceptual designs are established for conversion of 60 KW and 300 KW of power from a basic nuclear turbine system. A high frequency alternator is compared with a low frequency alternator using a frequency converter. A number of high frequency alternators are compared. Also, three frequency converter approaches are evaluated and compared; namely, a motor-generator unit, a transistor unit and a vacuum tube unit. The alternate system approaches are compared. Significant design data was derived for a high-speed, solid-rotor type of generator for generating a c power with frequencies up to 200 KC. Parametric data is included to show component sizes, weights and losses for converter units and high-frequency generator concepts. Problem areas for each conversion and generation technique are outlined.