Some aspects of half-wave magnetic amplifiers

The paper deals with the properties of half-wave magnetic amplifiers having finite control-circuit resistance or rectifier reverse conductance. The analysis is based on the concept of `reset factor¿, which is related to the magnetic-amplifier Q-factor during the reverse half-cycle of excitation voltage. It is shown that maximum power gain of a half-wave magnetic amplifier is a function merely of the ratio of unsaturated load-winding reactance to load resistance. In most practical cases maximum gain is obtained with a very small number of control turns, so that nearly all the winding space can be used for the load winding. Curves are presented which may be used to determine optimum turns ratio and maximum gain for various combinations of control-circuit resistance and rectifier leakage. Experimental results for magnetic amplifiers using different core materials are presented. These results agree well with theory. Finally, the effect of various bias circuits on half-wave magnetic-amplifier performance is examined.