GB749726A - Static current converter using voltage commutation - Google Patents

Abstract

749,726. Converting. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET. Nov. 30, 1953, No. 33162/53. Class 38 (2). In a converter comprising several constituent converters connected in series on the D.C. side, and so connected in parallel on the A.C. side that the voltages at the terminals are all mutually phase displaced, each main path between A.C. and D.C. terminals having in parallel an auxiliary path which allows current flow in the reverse direction, there being a voltage smoothing arrangement such as one or more capacitors connected to the D.C. terminals, the circuit is arranged so that the voltage harmonics are not short-circuited through the constituent converters. Fig. 1 shows four bridge-connected constituent converters 1, 2, 3, 4 so connected to a three-phase supply as to operate in a 24-phase manner, a common smoothing condenser 11 being connected across the outer D.C. terminals whereby harmonics are cancelled as between the constituent converters. Circuits 15, 16 and 17, 18 tuned respectively to the A.C. line frequency and twice that frequency reduce the voltage components of these frequencies which arise under disturbed circuit conditions. The reactive power for commutation may be provided by a condenser battery 19. An interphase transformer arrangement may be connected between the two primary winding arrangements 6, 9 to prevent the voltage harmonics from circulating current, and condensers may be connected across the constituent converters in pairs, Fig. 2 (not shown). Specifications 519,925 and 524,620 are referred to.