| 摘要 |
1,108,325. Frequency changing. ALLM€NNA SVENSKA ELECTRISKA A.B. 26 July, 1965 [27 July, 1964], No. 31711/65. Heading H2F. An arrangement for converting a single phase alternating voltage to a multiphase alternating voltage of lower frequency comprises a number of branch circuits 2, 3, 4, one for each phase, each branch circuit comprising a centre tapped transformer secondary winding 23 and a pair of controllable rectifier elements 21, 22, connected in bi-phase connection and an inductor 24, the branch circuits being connected as a polygon (i.e. for the three phases shown a triangle-viz. delta connection) and the connection points forming the output terminals. Each circuit operates for a number of high frequency cycles at maximum rectifier operation, followed by a number at minimum rectifier operation and a number under blocking conditions, this sequence being displaced in the three circuits. Thus three-phase voltages are developed at the terminals r, s and t, and since one circuit is always operating under blocking conditions no circulating currents are produced in the delta circuit. |
