| 摘要 |
1,225,695. Frequency changing. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 19 March, 1968 [22 March, 1967], No. 13258/68. Heading H2F. A frequency converter comprises a bridge of controlled rectifiers 1.. 4 having a low frequency A.C. input fed to the A.C. points of the bridge, the D.C. points being connected by inductors 10, 11 to one side of a load, the other side of the load being connected to the neutral point of the low frequency A.C. supply. The controlled rectifiers 1 ... 4 are triggered by a generator 7 so that the converter output frequency is higher than that of the input. Inductors 10, 11 are preferably series tuned by capactor 16 to 1À4 times the output frequency. As shown, a filter 21 ... 27 isolates the high frequency output from the 50 Hz input 20; components 30 ... 37 protect thyristors 1 ... 4 from high voltage peaks and capacitors 17, 18 provide an artificial neutral for the supply 20. The converter may supply a magnetron 43 in an h.f. oven with 2À5 kW at 5À6 kV by coupling via a high frequency step-up transformer 13 and rectifiers 42. The load is tuned by capacitor 16 and inductor 15 (wound on the same core as transformer 13) to the output frequency 6À5 kHz. The converter is suitable for supplying loads such as discharge lamps, motors, rectifiers with input capacitor filters or accumulators. Figs. 3 and 5 (not shown) relate to frequency converters comprising a three-phase bridge and providing a higher frequency single-phase output for a commutator motor. |
