General Electric Company

Samuel M Korzekwa

Joseph P Hesler

Robert J McFadyen

A static inverter employing an inductor and an electrical gain element for intermittent assymetric energization of the inductor from a dc source is described. Reliable intermittent operation of the gain element, typically a power transistor, is achieved by use of three feedback windings which in response to saturation of a branch of the core of the inductor but before full core saturation, discontinue regenerative feedback and then apply degenerative feedback. This turn off mechanism protects the transistor from high current stresses. Passive means are provided such as a capacitor for momentarily storing the energy or diode means for coupling the energy back to the source or to the load to protect the transistor from the high voltage surge and the energy release when current flow in the inductor is interrupted. Energy stored in the capacitor may be used for transistor commutation.

Static inverter employing an assymetrically energized inductor

The present invention relates to a regulated high voltage d.c. supply having an output voltage in the range of from 50 to 150 kilovolts such as is required for medical X-ray apparatus. The high voltage d.c. supply is constituted of a plurality of lower voltage d.c. to d.c. converter modules, whose output voltages are summed to produce the high voltage output. The converters are of a type which permits rapid activation and inactivation or 'modulation'. The modules are subjected to dynamic control to eliminate a.c. ripple, to regulate the high voltage output against supply line and load variations, and to turn the high voltage on and off in accurately timed intervals.

Regulated high voltage D.C. supply utilizing a plurality of D.C. to D.C.

A transformer designed to operate with a pair of power switching transistors in a d.c. to a.c. inverter is described. The transformer has an assembled core whose closed magnetic path is branched. A flux steering winding is used to ensure the prior saturation of a first branch associated with a regenerative feedback winding. Prior saturation of this branch reduces the forward drive on the switching transistors prior to full core saturation and avoids the consequent switching stresses on the transistors. The cores of the transformer are made from parts which abut at the branches so that both preformed power and preformed control windings may be used in assembling the transformer. The transformer may be assembled from conventional core configurations, and is thus of relatively low cost. A core arrangement is also disclosed in which the cross-section of the individual branches of the core may be adjusted.

Inverter transformer

A static inverter is disclosed for d.c. to a.c. conversion comprising a pair of switching semiconductor devices and a power transformer having primary, secondary and control windings associated with a double apertured linear magnetic core. Each aperture partitions the core cross section in a localized region into two branches. The primary and secondary power windings encircle the full core, which has a closed magnetic path, while the control windings are associated with only a branch. Means are provided to cause one branch to saturate before the other branch and before full core saturation. Saturation of one branch is used to reduce the regenerative feedback and increase the degenerative feedback to provide an advance turn off, allowing charge stored in the switching device to dissipate prior to the end of each conduction period. This mode of the feedback control avoids full core saturation and avoids overstressing the switching devices that full core saturation would produce. The arrangement permits one to develop high power outputs from relatively inexpensive power transistors.

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Baldwinsville, NY, United States of America

Samuel M Korzekwa