A Contribution to the Theory of Magnetic Frequency Changers

Using iron-core one-to-one transformers, with (or without) supplementary d.c. excitation, the well-known magnetic frequency doublers and triplers can be arranged. The theory of these is developed, assuming a cubic relation between flux and field intensity. The emf. in the secondary, the effect of supplementary d.c. excitation, the primary current and phase, and the secondary current for the un-loaded doubler are derived. The results are extended to the loaded doubler, the efficiency and operating characteristics of which are calculated. The modification of the derived formulas due to iron hysteresis is obtained. The theory is clearly illustrated by a number of calculated curves; of which the primary current-voltage curves show an interesting combination of stable (rising) and unstable (falling) portions. The resulting desirable methods of practical operation are fully considered. The theory is to be further developed to cover phenomena dependent on iron saturation above the knee-point of the magnetization curve.