150 KVA Samarium Cobalt VSCF Starter Generator Electrical System

This report documents the development, construction and test of a 150 KVA Starter/Generator Variable Speed Constant Frequency (VSCF) electrical system which includes a solid rotor machine using rare earth samarium cobalt magnets. The system consists of the solid rotor 14-pole starter/generator which in the generate mode, is driven at 12,000 to 21,000 RPM and a cycloconverter which, converts the 9-phase variable frequency power from the generator to a high quality 3-phase, 400 Hz, 150 KVA power source. In the start mode, the cycloconverter converts 3-phase, 400 Hz power to a 9-phase variable frequency, variable voltage which is used to power the starter/generator as the equivalent of a brushless DC motor. The rotor was developed during the first phase of the program which is reported on in detail in AFAPL-TR-76-8. The generator is oil cooled and uses a self-contained oil pump. It also includes a high speed mechanical disconnect which is solenoid operated to remove drive power and is mechanically reset at zero speed. The stator core uses 0.006 inch permendur laminations to handle high flux densities with a minimum of eddy current losses. The cycloconverter uses a dip brazed chassis, with liquid (oil) cooled cold plates for heat extraction. The major volume in the converter houses the power handling components which include 54 SCRs, 18 interphase transformers, 15 output filter capacitors and input despiker components.