GB826992A - Improvements in and relating to magnetic networks - Google Patents

Abstract

826,992. Magnetic amplifiers. GENERAL ELECTRIC CO. Oct. 31, 1956 [Oct. 31, 1955], No. 33248/56. Class 40 (9). [Also in Group XXXV] In a magnetic amplifier for use in a voltage control system, cores 5, 7, each provided with a power winding 6, 8, are shunted by a capacitor 4 and connected in series with a linear inductor 3 to an A.C. supply V, the degree of energization of a control winding 11 determining the time position in each half-cycle of the supply at which one of the cores saturates so that the condenser discharges into a parallelconnected load 15. In one arrangement, Fig. 4, the power windings are associated with rectifiers 9, 10 and are connected in auto-self-excited parallel relationship. The circuit of Fig. 4 illustrates a voltage control system in which the amplifier is energized from winding section 28 of an auto-transformer 26 and its output is combined with the voltage across transformer winding section 27. After rectification and smoothing at 29, 30, the combined output is applied to a load 15 and also to a preamplifier 40, in a feedback loop, this amplifier being controlled by comparison of the load voltage in the winding 32 with a reference voltage Vr applied to a winding 38. The amplifier 40 operates in the same manner as the main amplifier and comprises a transformer 39 fed from the A.C. supply which has a centretapped secondary winding connected to both amplifier power windings 33, 34 by way of an output-developing condenser 37 and rectifiers 35, 36. In a modified circuit, Fig. 5, the preamplifier 40 is energized from a voltage stabilizer comprising a saturable transformer 43 the primary winding of which is connected to a condenser 42 and a linear inductor 41, as described in Specification 824,326, [Group XXXV]. A further arrangement is described, Fig. 6, in which the pre-amplifier 40 is energized from the combined output to the load instead of from a secondary winding on the voltage stabilizer 43. The main amplifier in this circuit is biased by application of the reference potential Vr to a winding 45, while a shunt resistor 46 across the main windings is provided to equalize the magnetizing currents of the amplifier and voltage stabilizer 43. An alternative form of main amplifier is shown in Fig. 7 in which the output voltage developed across the power windings is applied over a transformer 50 having a centre-tapped primary winding. In both the latter embodiments a single condenser 4 and a linear inductor 3 are connected directly across the supply voltage. Amplifier arrangements are also described in which a condenser 4, Fig. 2, is connected across the primary winding of a transformer supplying the amplifier power windings 6, 8 through a centre-tapped secondary, and in which the power windings, Fig. 3, are connected in series with a full-wave rectifier to a D.C. feed-back winding 21.