| 摘要 |
A chopping type electrical converter having a primary circuit utilizing controlled rectifiers for chopping the input voltage, a secondary circuit for providing a DC output voltage, and a control unit which continuously monitors current flow in the secondary circuit and delays trigger pulses to the controlled rectifiers in the primary circuit whenever it is unsafe or undesirable to trigger them. In a preferred embodiment, the controlled rectifiers are mounted in series-connected pairs with a step-down transformer for each controlled rectifier. The number of pairs and the interwoven triggering order of the controlled rectifiers enables high voltage and high frequency operation with minimal stress on the converter components. The control unit prevents each member of each pair of controlled rectifiers from being triggered whenever the other member of the pair is still conducting, or whenever current is flowing in the secondary winding of the transformer associated with the controlled rectifier. The control unit also provides output voltage regulation and current limiting, and shuts down converter operation during overload or malfunctions. Accoustical noise suppression is incorporated, wherein the converter operating frequency is continuously modulated even under a constant load to spread the converter noise throughout the audible spectrum and thereby submerge it beneath the noise background.
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