FREQUENCY CONVERTER FOR POWER SUPPLY TO VARIABLE SPEED SYNCHRONOUS MACHINES

摘要

1464778 Frequency changing ATELIERS DE CONSTRUCTIONS ELECTRIQUES DE CHARLEROI 2 April 1974 [2 April 1973] 14535/74 Heading H2F A frequency changer comprises 3 threephase bridges of thyristors T11 ... T92 connected as shown to two sets of secondary windings S1, S2 of a three phase transformer and to a three-phase load such as a synchronous motor MS. A futher circuit including a smoothing inductor L and six diodes or thyristors T1 ... T6 is connected between the two sets of secondary windings S1, S2. As described, the circuit including inductor L may include a D.C. circuit breaker and may provide excitation for the synchronous motor MS. Harmonics may be reduced by connecting one of the sets S1, S2 of secondary windings in delta. Fig. 1 (not shown) relates to a frequency changer having the transformer replaced by a balanced three-phase choke. The power factor is improved by the auxiliary thyristors or diodes.