Isolation transformer

About: Isolation transformer is a research topic. Over the lifetime, 8145 publications have been published within this topic receiving 72396 citations.

Dual transformer device for power converters

Abstract: A dual transformer device (34) for use in a power converter (30) is provided. The dual transformer device is preferably implemented as an integrated magnetics device suitable for use in high density power converters. Two transformers, T1 and T2, have series connected primary windings (300 and 302), and secondary windings (304 and 306) connected at a common node (312). T1 and T2 have magnetizing inductances, L1 and L2, that independently store energy responsive to an AC voltage, V p . Diodes, D1 and D2, operate to rectify substantially out-of-phase secondary voltages, V S1 and V S2 and produce a rectified voltage V R . D1 and D2 cause L1 and L2 to store discharge energy such that the magnitude of an output current, I5, is always equal to the sum of magnetizing currents, I L1 and I L2 . An output filter (38) reduces current ripple in I5 and voltage ripple in V R . Another inductance, L3, supplies energy to an AC voltage supply (32) to reduce switching losses.

Transformer apparatus with -superimposed insulated switch and transformer units

Abstract: This invention relates to improvements in a transformer apparatus in which a transformer unit insulated with insulating oil and a switch unit insulated with insulating gas are combined. The transformer unit is accommodated in a transformer tank filled with the insulating oil. The switch unit is accommodated in a switch tank filled with the insulating gas. The switch tank is disposed on the top of the transformer unit and made integral therewith such that these tanks are communicated with each other in the interior of the communicated tanks.

Analysis of rotary transformer concepts for high-speed applications

Abstract: In many applications electrical energy has to be transferred to rotating parts. Usually a cylindrical transformer with a rotating and a stationary part is used, which are separated by a small air gap. In order to achieve a high magnetic coupling, on both parts a highly permeable core material is employed. In high-speed applications the diameter of the rotary transformer should be small since the mechanical stresses can be high. Therefore, a high electrical frequency has to be selected. This high switching frequency would result in high core losses; ferrite would be the best suited material. However, ferrite is brittle and has a limited mechanical strength. Therefore, in this paper two concepts of rotary transformers are analyzed, where no core material is used on the rotating part. The major advantage of these concepts is a simple and mechanically robust design with a lightweight construction resulting in very small unbalanced mass.

Method of making electrical transformer means

Abstract: This disclosure relates to improved electrical transformer means which has heat transfer surface means for transferring heat outwardly from within electrical coil means of such transformer means to thereby provide optimum electrical performance and to an improved method of making such transformer means and associated coil means.

High-reliability high-efficiency electronic ballast

Abstract: An electronic ballast is adapted for operation on regular 120 volt/60 Hz power line voltage and comprises: (i) full bridge rectifier means, (ii) ripple filter means consisting of an LC circuit series-resonant at 120 Hz, (iii) self-oscillating inverter means operating into an LC output circuit parallel-resonant at about 30 kHz, and (iv) means to disable the inverter in case a 30 kHz ground-fault current flows from its output circuit. A key element in achieving high reliability as well as high durability relates to the use of the series-resonant LC circuit instead of the conventional electrolytic capacitor for DC voltage ripple filtering. A key element in achieving high efficiency relates to the use of ground-fault interruption to achieve the required safety from electric shock hazard, thereby obviating the need for the more conventionally used isolation transformer with its attendant added cost and inefficiency.