MODULATED OUTPUT TRANSFORMERS

• US 3,716,719 A
• Filed: 06/07/1971
• Issued: 02/13/1973
• Est. Priority Date: 06/07/1971
• Status: Expired due to Term

• Current Assignee: Glenn R. Mohr, Henry W. Angelery
• Original Assignee: Glenn R. Mohr, Henry W. Angelery
• Inventors: Angelery, Henry W., Mohr, Glenn R.
• Primary Examiner(s): Pellinen, A. D.
• Application Number:
  US05/150,682
• Time in Patent Office: 617 Days
• Field of Search: 307/17,30 323/44R,48,50,51 336/130,170,184
• US Class Current: 307/17
• CPC Class Codes: H01F 2029/143 with control winding for generating magnetic bias
• CPC Class Codes: H01F 29/10 having movable part of magnetic circuit high leakage transformers H01F38/08; dynamo-electric machines with movable part of magnetic circuit H02K23/44, H02K23/48
• CPC Class Codes: H01F 29/14 with variable magnetic bias amplitude modulation by means of variable impedance element H03C1/08 ; magnetic amplifiers H03F; circuits for automatic telephonic communication H04M3/00
• CPC Class Codes: Y10S 174/17 in an electric power conversion, regulation, or protection system
• CPC Class Codes: Y10S 174/25 Transformer

Abstract

A transformer core has three legs. A variable output secondary winding encircles one leg, and a primary winding encircles another. The voltage across the variable output secondary winding is controlled by varying the amount of leakage flux passing through the third leg. This can be accomplished by providing a separately formed core piece that is movable to vary its area of contact with the third leg. Alternatively, a control winding can be provided which encircles the third leg. The current induced in the control winding, which is modulated by a variable control impedance connected across it, produces a flux that, in proportion to its strength, opposes the primary winding flux, thereby increasing the amount of flux that passes through the secondary winding. A fixed output voltage can be obtained from an additional secondary winding that encircles the same leg as the primary winding.

Claims

1. A transformer having fixed and variable outputs comprising a core including three interconnected legs, a variable output secondary winding encircling the first leg, a primary winding encircling the second leg, a fixed output secondary winding encircling the second leg, a control winding encircling the third leg, a variable control impedance connected across the control coil, the direction of each winding being such that the flux produced in the third leg by the control winding opposes the primary winding flux, whereby the voltage induced in the variable output secondary winding varies in accordance with the control impedance value selected and a set of leads and at least one switch arranged to selectively connect the control winding in parallel with a winding that encircles the second leg to produce additional flux in the third leg which opposes the flux produced by the primary winding.

2. The transformer of claim 1 wherein the control impedance is a variable inductor.

3. The transformer of claim 1 wherein a portion of the core is movable to interpose at least one non-magnetic gap in the path of the leakage flux passing through the third leg and increasing the flux passing through the first leg.

4. The transformer of claim 1 wherein the core is dimensioned so that it does not become saturated at any point by the voltage applied to the primary coil.

5. A variable output transformer comprising a core including three legs, a secondary winding encircling the first leg, a primary winding encircling the second leg, a control winding encircling the third leg, a variable control impedance connected across the control winding, and a set of leads and at least one switch arranged to connect the control winding to a winding that encircles the second leg, the direction of The windings and the arrangement of the leads being such that the primary winding flux and the voltage applied by the leads both contribute to a current flow in the control winding that produces a flux in opposition to the primary winding flux in the third leg.

6. The transformer of claim 5 wherein the winding that the leads are connected to is a portion of the primary winding.

7. A variable output transformer comprising a core including three legs, a secondary winding encircling the first leg, a primary winding encircling the second leg, a control winding encircling the third leg, the direction of the windings being such that the current induced in the control winding produces a flux which opposes the flow of primary winding flux in the third leg, a variable control impedance connected across the control winding whereby the current flowing therethrough can be varied, a movable core piece, a means for moving the movable core piece whereby at least one non-magnetic gap can be interposed in the path of primary winding flux passing through the third leg to further attenuate its flow and a set of leads and at least one switch arranged to selectively connect the control winding in parallel with a winding that encircles the second leg to produce additional flux in the third leg which opposes the flux produced by the primary winding.