| 摘要 |
<p>1,156,828. Converting circuits; control of A.C. motors. BROWN, BOVERI & CO. Ltd. 16 Nov., 1966 [18 Nov., 1965], No. 51338/66. Headings H2F and H2J. A converting circuit for supplying a variable frequency to a load comprises a load 40, 50, 60 connected to an A.C. supply via a rectifier circuit 1. Firing controlled rectifier 17 allows the diodes 11-16 to become conductive to connect the load to the supply. The frequency applied to the load being the difference between the supply frequency and the firing pulse frequency. The controlled rectifier 17 is extinguished by a capacitor 19 in series with a saturable inductor 18. A further capacitor 71 is included to pass reactive current when the rectifier 17 is non- conductive. The load 4, 5, 6 may be the winding of a squirrel cage motor, and in order to increase the frequency range, two rectifier circuits may be employed, Fig. 4 (not shown), with their controlled rectifiers fired in antiphase. An arrangement employing three rectifier bridges is also described Fig. 5 (not shown) for producing a single phase variable frequency supply from a three-phase source. If the firing frequency is made the same as the supply frequency, a variable D.C. output may be obtained, Fig. 1 (not shown). Mercury vapour valves may be used in place of thyristors.</p> |
