GB411145A - Improvements in and relating to electric converting apparatus - Google Patents

Abstract

411,145. Converting. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Willis, C. H. ; 184, Prospect Avenue, Princeton, New Jersey, U.S.A.) Oct. 1, 1932, No. 27307. Convention date, Oct. 1, 1931. Addition to 409,713. [Class 38 (ii).] In apparatus of the kind claimed in the parent Specification, for transmitting energy in either direction between D.C. and A.C. circuits 10, 11 under any desired power factor conditions, an inductive winding is interposed in the connections between the valves and the D.C. circuit, and means are provided for producing across the inductive winding an alternating potential which is a harmonic of that of the A.C. circuit. In one arrangement, Fig. 1, the circuits are interconnected through a polyphase network 12, valves 20 ....31, and windings 33, 34 of a commutating transformer 32 as shown, and the commutating transformer is excited at a harmonic frequency by means of an auxiliary valve inverting connected across the D.C. circuit. The auxiliary inverter comprises a winding 36, condenser 39 and valves 37, 38, the grids of which are excited at triple frequency from a frequency changer comprising a synchronous motor 42 energized from the A.C. circuit 11 and a synchronous generator 43 connected to the motor. For varying the power factor conditions on the A.C. circuit, a phase-shifting transformer 17<a> is interposed in the connections to the grid transformer 17, controlling the valves 20 .... 31, and the frequency changer. In a modification, Fig. 2 (not shown), the auxiliary inverter is connected in series, instead of in parallel, with the main converting apparatus In another arrangement, Fig. 3, the commutating transformer is replaced by reactors 44, 45 associated with condensers 46, 47. The latter reverse polarity whenever the current is transferred from one valve to another, so that the potential across the condensers is the third harmonic of the fundamental. In a modification, Fig. 4 (not shown) the condensers are connected so as to be charged in parallel to opposite polarity, and then discharged in series through the valves to be commutated. Specifications 219,026, [Class 38 (ii)], 347,474, and 390,184 are referred to.