Abstract: The invention relates to a resonant converter (200, 300). The resonant converter (200, 300) consists of a first circuit, primarily a DC circuit (201, 301) connected to a resonant circuit (207, 307) which is further connected to a switch/filter circuit (212, 312) which is connected to a second circuit, primarily an AC circuit (219, 319).

Abstract: The present invention relates to a high efficiency three-level inverter apparatus containing both bipolar and field effect transistors. An embodiment of a modified control scheme is also presented whereby transistors are modulated differently for each quadrant of output voltage-current phase. This embodiment of a modified control scheme allows efficient switching of field effect transistors without additional freewheeling and series diodes.

Abstract: The invention relates to a combined AC-DC to DC converter. The converter (100, 300, 700, 740, 780, 800, 840, 880) provides the option of coupling to an AC supply source (103, 303, 703, 803) with at least one phase and the further option of coupling to at least one DC supply source (101, 102, 301, 701, 702, 801). The converter (100, 300, 700, 740, 780, 800, 840, 880) obtains supply from at least one supply source at a time; and the converter (100, 300, 700, 740, 780, 800, 840, 880) contains controllable contact means that are, upon switching between supply sources, capable of connecting and disconnecting the individual supply sources to/from the converter (100, 300, 700, 740, 780, 800, 840, 880), whereby a pulse signal is generated. The converter (100, 300, 700, 740, 780, 800, 840, 880) contains at least one coil (112, 113, 312) that is in connection with at least one DC output (125, 126, 325, 725, 726, 825).

Abstract: The invention relates to a resonant converter (200, 300). The resonant converter (200, 300) consists of a furst circuit, primarily a DC circuit (201, 301) connected to a resonant circuit (207, 307) which is further connected to a switch/filter circuit (212, 312) which is connected to a second circuit, primarily an AC circuit (219, 319).

Abstract: An emergency power system is connected between an AC voltage source and a load. The emergency power system ensures a stable voltage on the output, even if the AC voltage received from the AC voltage source is irregular or is interrupted briefly. The emergency power system includes an AC/DC converter coupled between the load terminals and an AC regulator positioned between the AC voltage source and the load. The AC/DC converter is coupled to a chargeable battery and serves as a charging rectifier for the battery in normal operation and as an inverter in emergency operation, the battery voltage being converted to AC voltage on the output of the emergency power system. The AC regulator is built as a controllable current generator supplying on its output an AC current which is in phase with the AC voltage received from the AC voltage source. Irrespective of the energy direction through it, the AC/DC converter maintains the predetermined AC voltage (V.sub.