| 摘要 |
An AC generator or other AC source has two identical output sections which are connected through corresponding rectifiers to drive a DC load such as a group of DC traction motors connected in parallel for driving a locomotive. The rectifiers are selectively placed in parallel to provide a high current low voltage mode and in series to provide a low current high voltage mode, thus furnishing a wide range of voltage and current at a given power level to satisfy a broad range of motor requirements with a power source of limited size and capability. To effect smooth transition, one of the rectifiers includes SCR's to modulate the rectifier output voltage. During transition that rectifier is phase back to zero voltage, allowing the other rectifier to supply the full load requirements and then the rectifiers are switched from series to parallel or vice versa whereupon the modulated rectifier is returned to its full voltage. Whenever the rectifiers are in series, the modulation of the one rectifier is accomplished gradually to allow the other rectifier time to take on added voltage.
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