NON-SYMMETRIC SEMI-BRIDGE VOLTAGE TRANSFORMER WITH EXPANDED OUTPUT VOLTAGE RANGE Russian patent published in 2007 - IPC H02M3/335 

FIELD: transformation equipment, in particular, engineering of non-symmetric semi-bridge transformers, transforming direct voltage to direct voltage, which may be used in energy supply systems for telecommunications.

SUBSTANCE: primary winding of transformer by one end is connected to key connection point, and by other one through capacitor is connected to first pole of input voltage source and to one of key elements. Key elements switch synchronously and in counter-phased manner, providing required coefficient D of impulse filling, i.e. ratio of duration of time length of conductive status of key element, connected to second pole of input voltage source, to period T of switching of key elements. Secondary winding of transformer is connected to two serially connected throttles and anodes of two diodes, cathodes of which are connected to first outputs of output capacitor of transformer and load. Secondary winding of transformer has branch, which through additional diode and field transistor connected serially with it, is connected to first output of output capacitor and load. Control circuit, consisting of additional power source, supporting voltage source, comparator and transistor key, enables field transistor at high values of output voltage, providing influx of voltage from secondary winding and drain to load, and disables aforementioned transistor, if lowered voltage is needed at output or, if low voltage at output is produced as a result of current protection action of non-symmetric semi-bridge transformer. Control over additional field transistor during operation of non-symmetric semi-bridge transformer with expanded output voltage spectrum allows increased efficiency of non-symmetric semi-bridge transformer, simultaneously increasing reliability of operation of output diode, working in time interval (1-D)T, because average current passing through this diode is reduced, and reverse voltage on same is reduced as well. Therefore, requirements to diode, conducting current during time interval (1-D)T are reduced. As a result reliability of entire non-symmetric semi-bridge transformer is increased.

EFFECT: reliable operation of transformer, increased efficiency and expanded spectrum of outputted signal.

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