US 5,615,091 AGranted

Isolation transformer for medical equipment

AssigneeBiochem International Inc.

InventorEugene S. Palatnik

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Abstract

A power supply has a transformer for isolating circuitry to which power is furnished from the electrical supply lines. The transformer includes a core of ferro-magnetic material with primary and secondary windings wound side-by-side on the core. The primary winding has two layers of turns with a center tap formed at a connection of the turns of each layer that are closest to the secondary winding. Similarly, the secondary winding has two layers of turns with a center tap formed at a connection of the turns of each layer which are closest to the primary winding. A driver applies excitation voltage across the center tap, which also is coupled to earth ground, and a turn of the innermost primary winding layer. The center tap of the secondary winding is used as an isolated ground and a supply voltage is produced between two turns from different layers of the secondary winding. Because the ground connection of each winding is made a turns that are closest to the other winding, the parasitic capacitance is the greatest between those turns which minimizes any difference in potential between the earth ground and the isolated ground.

Claims9

Dependent claims

An isolation power supply comprising:

isolation transformer including:
(a) a core of ferro-magnetic material,
(b) a primary winding with a first edge and a second edge, and having a first layer formed by a plurality of turns wound around said core with an exterior turn adjacent the first edge and an interior turn adjacent the second edge, said primary winding further having a second layer formed by a plurality of turns wound around the first layer with an exterior turn adjacent the first edge and an interior turn adjacent the second edge, wherein the interior turn of the first layer is electrically connected at a first point to the interior turn of the second layer, and
(c) a secondary winding with a third edge and a fourth edge, and located on said core to one side of the primary winding with the third edge facing the second edge, said secondary winding having a third layer formed by a plurality of turns wound around said core with an exterior turn adjacent the fourth edge and an interior turn adjacent the third edge, said secondary winding further having a fourth layer formed by a plurality of turns wound around the third layer with an exterior turn adjacent the fourth edge and an interior turn adjacent the third edge, wherein the interior turn of the third layer is electrically connected at a second point to the interior turn of the fourth layer;
a transformer driver circuit which applies an alternating signal between the first point and one of the exterior turn of the first layer and the exterior turn of the second layer, wherein the other exterior turn is unconnected;
and
an isolated circuit wherein having an isolated ground to which the second point is connected and utilizing a voltage produced between the exterior turn of the third layer and the exterior turn of the fourth layer.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/541,074Filed 11 Oct 1995
Granted: 25 Mar 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification7 codes

H02M 3/28
By static converters: using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate AC
H01F 19/08
Transformers or mutual inductances suitable for handling frequencies considerably beyond the audio range: transformers having magnetic bias, e.g.…
H01F 21/12
Variable inductances or transformers of the signal type: discontinuously variable, e.g. tapped
H01F 27/2823
Coils; Windings; Conductive connections: wires