Advanced compulsator topologies and technologies
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Increasing the compactness of compensated pulsed alternators (compulsators) has been an ongoing effort at since the mid-1980’s, when the U. S. Army interest in electric armaments began to emerge in a significant way. Much progress has been made from the early proof of concept machine built at UTCEM in the late 1970’s after its invention by Weldon, Driga, and Woodson. Today, the compulsator is the best approach for achieving compact energy storage and pulsed power generation for multi-MJ, multi-GW applications requiring voltages of up to 20 kV and discharge durations between 1 and 10 milliseconds. Electromagnetic railguns, coil launchers, and directed energy systems requiring high-power, high-energy pulsed-power in compact form are ideal candidate loads for compulsators. Since the initial validation of compulsator theory in the late 1970’s, a transition from iron-core to air-core magnetic circuits and the associated incorporation of composite materials for the rotor and self-excitation has provided substantial increases in both stored energy density and power density. While the advancement has been significant, further gains in compactness are possible by exploiting continued innovation in the topology of the machine, the mode in which it operates, and by developing new component technologies specifically for compulsator application. In addition, the use of this type of machine in very high voltage (>50 kV) pulsed power application, a concept not previously explored, is considered through the novel integration of resonant and cascaded transformer arrangements to boost the output voltage. In contributing to the continued compulsator performance improvement, this research effort has performed an in depth study of machine topologies and identified a new topology, the flywheel-compulsator. When combined with improvements in materials and switching technologies, this new machine configuration can improve energy and power density by factors of three and five, respectively, compared to the current state of the art. To allow rapid sizing of compulsator systems, a scaling algorithm was developed, validated against demonstrated machines and advanced designs, and used to design systems for advanced applications. Reduced to a set of linked spreadsheets, the scaling algorithms were also used to identify compulsator component technologies areas where improvements will provide the greatest overall performance impact. Another area of significant contribution to compulsator technology embodied in this research is the application of these machines to very high voltage systems. Two general concepts were conceived and developed. The first combines the energy storage and pulsed power generation of the compulsator with voltage increasing circuits, including both resonant and cascaded transformers. For compact high voltage systems, the concept of generating the high voltage directly within the compulsator was evaluated, and a high voltage compulsator using a helical winding was optimized for a specific set of requirements.