| 摘要 |
1,267,335. Inverting; frequency converters. BORG-WARNER CORP. 4 March, 1970 [28 May, 1969], No. 10518/70. Heading H2F. An inverter comprises thyristors 28, 33, commutating transformer windings 30, 31, isolating diodes 27, 32 and commutating capacitors 34, 35 connected across a D.C. supply 25, 26 as shown, with means 36, 37 for pre-charging the commutating capacitor 34, 35 from a D.C. supply of constant voltage. The invention is applicable to arrangements in which the A.C. mains is rectified, then fed via an adjustable D.C.-D.C. converter to terminals 25, 26, the D.C.-D.C. converter and inverter frequency being adjusted so that the volts/Hertz ratio is constant, e.g. for feeding a variable-speed induction motor. The precharge circuit 36, 37 ensures the commutating capacitors 34, 35 are adequately charged when the inverter is providing a low voltage output. An energy return transformer 42 with diodes 40, 41, 45, 46 may be provided. |
