| 摘要 |
The arrangement includes a mains transformer having a primary winding and a secondary winding, with the secondary winding being connected to a load circuit including a full wave rectifier, smoothing devices, and at least one positively quenchable, or positive cut-off, controlled semi-conductor rectifier associated with a respective control device. The smoothing devices consist of at least one condenser, at least one choke and at least one filter tuned to double the frequency of the AC voltage mains. The magnitude of the alternating or direct current, available on the secondary side of the mains transformer in the form of current or voltage, is controlled by one or more positively quenchable controlled semi-conductor rectifiers, and the control device controls the controlled rectifier or rectifiers by pulse width modulation thereof to maintain the time slope of the power in the load circuit substantially in phase with the slope of the power, fluctuating with twice the mains frequency about the constant-per-unit-of-time mean load power, of the load alternating current which is in phase with the mains AC voltage. In one embodiment, the current flowing from the AC voltage mains through a full wave rectifier into the DC load circuit is maintained constant and an AC voltage, of twice the mains frequency, is superposed on the DC voltage. In another embodiment, the DC voltage of the DC load is maintained constant and alternating current of twice the mains frequency is superposed on the direct current.
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