2.7 Electrical Subsystems The flow of electrical power is shown in Figure 2.14. Heat from the reactor is converted to ac or de electrical power by the power conversion subsystem as described in the Sections 2.1 through 2.6. The electrical power is then carried down the separation boom via a transmission line and converted to the appropriate voltages by the power conditioning subsystem. The transmission line is sized to have a minimal mass while at the same time having a reasonably small power loss. This is achieved by calculating the mass, power loss, and temperature of the transmission line and, using standard wire size data, determining the optimum cable diameter and number of conductors as a function of power level, boom length, operating voltage, conductor material properties, etc. For power system concepts with conversion devices that supply de power, the power conditioner is a de to de converter utilizing power MOSFET switch technology operating at 20 kHz. Separate converter modules supply each of the required voltage outputs. For concepts with conversion devices which produce ac power, the power conditioner consists of a rectifier/filter circuit for each output voltage. This assumes that a tapped alternator having the necessary number of output windings is used. The electronics technology used for the power conditioning subsystems is described in Reference 10. 3 .0 Analysis Approach In any comparative systems analysis it is absolutely essential to pick a common set of ground rules against which to assess the various concepts. When time and resources are limited, as in this case, these ground rules must be simplified to the point that they address only major issues. As a result, we have performed top level system mass, area, and performance analyses. We have optimized component performance within the constraint of minimizing overall power system mass for all of the more massive components, intentionally omitting many minor components which when added together may make real system masses different than the estimates shown here. However, special care was taken to treat the SP-100 thermoelectric concept in identical fashion to the other concepts since it has received more design funding and has therefore identified many additional contributors to total system mass. We did not permit major concept re-design in our optimization process but only varied component parameters within the range permitted by each design. Because of the simplifying assumptions, our results will not be completely representative of real systems nor are they intended to be because many design details are unknown at this time. They should however provide good relative comparisons among the various concepts. We believe our approach is reasonable because our results agree well with those obtained from the SP-100 program for the SP-100 thermoelectric and innovative SP-100 concepts.
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