An investigation of certain problems in the use of sample cores in analog simulation of magnetic amplifier circuits
Pope, Herman Lloyd
Pfeiffer, Paul E.
Master of Science
In order to establish the conversion factors between an actual circuit and its computer simulation, the simple half wave magnetic amplifier-circuit was used. The Computer simulation of this circuit requires three operational amplifiers, with the associated scaling factors involving all of the variables of the actual circuit core material area, mean length of path, and number of turns. In addition to establishing these scaling factors in the computer circuit, these variables affect the inductance-resistance ratio. of the magnetic amplifier core and are used to determine the resistance to be added in the test core circuit so-that the L/R of the test core matches that of the actual core being simulated. Computer circuits were set up to simulate several actual circuits having cores with size and number of turns different from those of the test core of the computer circuit. Comparison of actual circuit data with simulated circuit data showed considerable difference, and thia difference was found to be due to the difference in losses of the cores. It was necessary to scale the computer circuit data by a factor proportional to the ratio of the losses of the two cores. This factor was determined from a comparison of the B-H loops of the two cores, since the width of the B-H loop is proportional to the losses in the core. It should be noted, in connection with this part of the study, that the geometry of the core is of some importance in the simulation process. Cores having different outside to inside diameter ratios have B_H curves which differ somewhat in slope. Although the half-wave circuit serves to establish the necessary conversion factors in the simulation process, more complicated circuits should be studied to check the accuracy of the derived relationships. No data was taken on other circuits, due to time and computer limitations, but two more complicated circuits and their simulation are described, and recommendations for further studies are given in this report.