High-frequency operation of magnetic amplifiers

RECENT IMPROVEMENTS in frequency-multiplier techniques and the development of a simple transistor inverter have made possible high-frequency power supplies which have ruggedness and reliability commensurate with that of magnetic amplifiers. Consequently, it becomes practical to operate magnetic amplifiers at frequencies above the readily available 60- or 400-cycle power supplies. The possibility exists of making magnetic amplifiers with shorter response times, smaller size, and greater power gain than presently attainable in the power frequency range. At high frequencies it is possible to control a given voltage with fewer load turns or with much smaller cores. From the standpoint of keeping amplifier exciting currents small, it is desirable to keep the number of load turns reasonably large. The equation defining the power required to drive the amplifier from cutoff to full output gives an even more important reason for keeping the number of load turns relatively high and reducing the iron cross-sectional area at higher frequencies.