Self-regulated transformer-inductor with air gaps

• US 4,766,365 A
• Filed: 07/20/1987
• Issued: 08/23/1988
• Est. Priority Date: 04/15/1987
• Status: Expired due to Fees

• Current Assignee: Hydro-Quebec (Province of Québec)
• Original Assignee: Hydro-Quebec (Province of Québec)
• Inventors: Pare, Gregoire, Bolduc, Leonard
• Primary Examiner(s): Salce, Patrick R.
• Assistant Examiner(s): Ault, Anita M.
• Application Number:
  US07/075,759
• Time in Patent Office: 400 Days
• Field of Search: 323/249, 323/250, 323/251, 323/308, 323/310, 323/329, 323/331, 323/332, 323/334, 363/75, 363/82, 363/90, 363/91, 363/93, 336/155, 336/160, 336/165, 336/178, 336/186
• US Class Current: 323/308
• CPC Class Codes: G05F 3/06 using combinations of saturated and unsaturated inductive devices, e.g. combined with resonant circuit
• CPC Class Codes: H01F 2029/143 with control winding for generating magnetic bias
• 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

The transformer comprises a three-limbed magnetic core having two outer limbs each defining a central air gap. Two windings, an alternating current one and a direct current one, are wound around each outer limb. Primary and secondary windings are disposed on the center limb, the primary one being supplied with alternating current from a source, and the secondary one supplying with alternating current an external load. The two alternating current windings are connected in series and supplied with alternating current by the source, possibly through an additional winding wound around the center limb, while the two direct current windings are connected in series and supplied by the current in the alternating current windings rectified through a diode bridge. The current in the two direct current windings induces a magnetic flux in a closed circuit defined by the outer limbs. The alternating currents in the primary winding and in the two alternating current windings are coupled to first and second alternating current magnetic fluxes assisting each other in the center limb and respectively flowing in two closed magnetic circuits defined, on the one hand, by the center limb and one outer limb, and, on the other hand, by the center limb and the other outer limb. The transformer supplies the external load with electric energy from the source while regulating the source and supply voltages.

Claims

1. A self-regulated transformer-inductor comprising:

a magnetic core defining a first limb, a second limb, and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

transformer means including primary winding means wound around at least one of said limbs of the magnetic core and supplied with alternating current by a source of electric energy; and

variable inductor means including second winding means different from said primary winding means, wound around at least one of said limbs of the magnetic core, and supplied with an alternating current generated by said source of electric energy;

said primary and second winding means being so positioned on the magnetic core that the said two alternating currents in the primary and second winding means are coupled to an alternating current magnetic flux induced in each of the second and third limbs;

said variable inductor means also including control winding means supplied with direct current and so disposed on the magnetic core that the said direct current current induces a direct current magnetic flux in each of said second and third limbs;

the alternating current and direct current magnetic fluxes in one of the second and third limbs assisting each other while the alternating current and direct current magnetic fluxes in the other of said second and third limbs are in opposition with respect to each other;

said varaible inductor means further comprising means for converting the alternating current in the second winding means into direct current for the supply of the control winding means, the direct current supplying the control winding means having an amplitude which varies with the amplitude of the alternating current in the second winding means for thereby varying the density of the direct current magnetic flux in the second and third limbs and controlling the permeability of said second and third limbs to the alternating current magnetic flux; and

said transformer means also including secondary winding means subjected to the alternating PG,23 current magnetic flux in said second and third limbs, and connected to an electric load for the supply of said load.

2. A transformer comprising:

a magnetic core defining a first limb, a second limb, and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

primary winding means wound around at least one of said limbs of the magnetic core and supplied with alternating current by a source of electric energy;

second winding means also wound around at least one of said limbs of the magnetic core and supplied with an alternating current generated by said source of electric energy;

said primary and second winding means being so positioned on the magnetic core that the said two alternating currents in the primary and second winding means are coupled to an alternating current magnetic flux induced in each of the second and third limbs;

control winding means supplied with direct current and so disposed on the magnetic core that the said direct current induces a direct current magnetic flux in each of said second and third limbs;

the alternating current and direct current magnetic fluxes in one of the second and third limbs assisting each other while the alternating current and direct current magnetic fluxes in the other of said second and third limbs are in opposition with respect to each other;

means for converting the alternating current in the second winding means into direct current for the supply of the control winding means, the direct current supplying the control winding means having an amplitude which varies with the amplitude of the alternating current in the second winding means for thereby varying the density of the direct current magnetic flux in the second and third limbs and controlling the permeability of said second and third limbs to the alternating current magnetic flux;

secondary winding means subjected to the alternating current magnetic flux in said second and third limbs, and connected to an electric load for the supply of said load; and

the second limb comprising gap means traversed by the resultant magnetic flux in said second limb, and the third limb also comprising gap means traversed by the resultant magnetic flux in said third limb.

3. A transformer according to claim 2, wherein said current converting means comprises a diode bridge for rectifying the alternating current supplying the second winding means and for supplying the so rectified current to the control winding means, the rectified current constituting the direct current supplying the control winding means.

4. A transformer according to claim 3, further comprising an inductor connected in parallel with said second winding means.

5. A transformer according to claim 3, wherein said diode bridge comprises an input and an output traversed by the alternating current supplying the second winding means, and wherein said transformer further comprises a current transformer subjected to the alternating current in the second winding means and comprising a secondary winding provided with first and second terminals respectively connected to said input and output of the diode bridge.

6. A transformer according to claim 2, wherein said primary winding means is disposed on the first limb and has a number of turns N_P, the second winding means comprises first and second windings disposed on the second and third limbs, respectively, connected in series and each comprising a number of turns N_S, the first limb has a cross section of area S₁, and the second and third limbs each have a cross section of area S₂₃, the parameters N_P, N_S, S₁ and S₂₃ satisfying the following relationship:

space="preserve" listing-type="equation">N.sub.P ·

S.sub.1 ≧

N.sub.S ·

S.sub.23 ·

7. A transformer comprising:

a magnetic core defining a first limb, a second limb, and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

primary winding means wound around at least one of said limbs of the magnetic core and supplied with alternating current by a source of electric energy;

second winding means also wound around at least one of said limbs of the magnetic core and supplied with an alternating current generated by said source of electric energy;

said primary and second winding means being so positioned on the magnetic core that the said two alternating currents in the primary and second winding means are coupled to an alternating current magnetic flux induced in each of the second and third limbs;

control winding means supplied with direct current and so disposed on the magnetic core that the said direct current induces a direct current magnetic flux in each of said second and third limbs;

the alternating current and direct current magnetic fluxes in one of the second and third limbs assisting each other while the alternating current and direct current magnetic fluxes in the other of said second and third limbs are in opposition with respect to each other;

means for converting the alternating current in the second winding means into direct current for the supply of the control winding means, the direct current supplying the control winding means having an amplitude which varies with the amplitude of the alternating current in the second winding means for thereby varying the density of the direct current magnetic flux in the second and third limbs and controlling the permeability of said second and third limbs to the alternating current magnetic flux;

secondary winding means subjected to the alternating current magnetic flux in said second and third limbs, and connected to an electric load for the supply of said load; and

said primary and secondary winding means being formed by a single winding mounted on said first limb and comprising a plurality of taps.

8. A transformer comprising:

a magnetic core defining a first limb, a second limb, and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

primary winding means wound around at least one of said limbs of the magnetic core and supplied with alternating current by a source of electric energy;

second winding means also wound around at least one of said limbs of the magnetic core and supplied with an alternating current generated by said source of electric energy;

said primary and second winding means being so positioned on the magnetic core that the said two alternating currents in the primary and second winding means are coupled to an alternating current magnetic flux induced in each of the second and third limbs;

control winding means supplied with direct current and so disposed on the magnetic core that the said direct current induces a direct current magnetic flux in each of said second the third limbs;

the alternating current and direct current magnetic fluxes in one of the second and third limbs assisting each other while the alternating current and direct current magnetic fluxes in the other of said second and third limbs are in opposition with respect to each other;

means for converting the alternating current in the second winding means into direct current for the supply of the control winding means, the direct current supplying the control winding means having an amplitude which varies with the amplitude of the alternating current in the second winding means for thereby varying the density of the direct current magnetic flux in the second and third limbs and controlling the permeability of said second and third limbs to the alternating current magnetic flux;

secondary winding means subjected to the alternating current magnetic flux in said second and third limbs, and connected to an electric load for the supply of said load; and

said primary winding means being disposed on the first limb and having a number of turns N_P, the second winding means comprising first and second windings disposed on the second and third limbs, respectively, connected in series and each comprising a number of turns N_S, the first limb having a cross section of areas S₁, the second and third limbs each having a cross section of the area S₂₃, and the parameters N_P, N_S, S₁ and S₂₃ satisfying the following relationship;

space="preserve" listing-type="equation">N.sub.P ·

S.sub.1 ≧

N.sub.S ·

S.sub.23.

9. A transformer comprising:

a magnetic core defining a first limb, a second limb and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

primary winding means wound around said first limb and supplied with alternating current by a source of electric energy;

second winding means wound around at least one of said limbs of the magnetic core and supplied with an alternating current generated by said source;

said alternating currents in the primary and second winding means being coupled to a first alternating current magnetic flux flowing in a closed magnetic circuit defined by the first and second limbs and to a second alternating current magnetic flux flowing in a closed magnetic circuit defined by the first and third limbs, the first and second alternating current magnetic fluxes assisting each other in the first limb;

a first control winding and a second control winding wound around the second and third limbs, respectively, said first and second control windings being so connected in series and supplied with direct current that the said direct current induces a direct current magnetic flux flowing in a closed magnetic circuit defined by the second and third limbs;

means for converting the alternating current in the second winding means into direct current for the supply of the first and second control windings, the direct current supplying the control windings having an amplitude which varies with the amplitude of the alternating current in the second winding means to thereby vary the density of said direct current magnetic flux and controlling the permeability of the second and third limbs to the first and second alternating current magnetic fluxes, respectively; and

secondary winding means wound around said first limb, subjected to the first and second alternating current magnetic fluxes which assist each other in the first limb, and connected to an electric load for the supply of said load.

10. A transformer according to claim 9, wherein said second limb comprises first gap means traversed by the resultant magnetic flux in said second limb, and wherein the third limb comprises second gap means traversed by the resultant magnetic flux in said third limb.

11. A transformer according to claim 10, wherein said second winding means comprises a first alternating current winding and a second alternating current winding connected in series and disposed around the second and third limbs, respectively.

12. A transformer according to claim 11, wherein said load is an external load and wherein said transformer further comprises additional secondary winding means wound around said first limb and provided with two terminals between which the first and second alternating current windings of the second windings means are connected in series, said additional secondary winding means generating the alternating current supplying the first and second windings of the second winding means in response to the resultant magnetic flux induced in said first limb.

13. A transformer according to claim 12, wherein said primary winding means, and said two secondary winding means are formed by a single winding disposed around said first limb and comprising a plurality of taps.

14. A transformer according to claim 12, wherein said additional secondary winding means supplying with alternating current the first and second alternating current windings of the second winding means has a number of turns N_S, each of the first and second alternating current windings of the second winding means has a number of turns N_A, the first limb has a cross section of area S₁ and the second and third limbs each have a cross section of area S₂₃, which satisfy the following relationship:

space="preserve" listing-type="equation">N.sub.S ·

S.sub.1 ≧

N.sub.A ·

S.sub.23.

15. A transformer according to claim 11, wherein said current converting means comprises a diode bridge for rectifying the alternating current supplying the second winding means, and for supplying the so rectified current to the first and second control windings, the rectified current constituting the direct current supplying the first and second control windings.

16. A transformer according to claim 15, further comprising an inductor connected in parallel with the serially interconnected first and second windings of the second winding means.

17. A transformer according to claim 15, wherein said diode bridge comprises an input and an output traversed by the alternating current supplying the first and second windings of the second winding means, and wherein said transformer further comprises a current transformer responsive to the alternating current in the first and second windings of the second winding means and including a secondary winding provided with first and second terminals respectively connected to said input and output of the diode bridge.

18. A transformer according to claim 11, wherein said first alternating current winding of the second winding means and said first control winding are so superposed around said second limb that the said first gap means is located in the center of said first winding of the second winding means and in the center of said first control winding, wherein said second alternating current winding of the second winding means and said second control winding are so superposed around the third limb that said second gap means is located in the center of said second winding of the second winding means and in the center of said second control winding, and wherein said primary and secondary winding means are superposed around said first limb.

19. A transformer according to claim 10, wherein said current converting means comprises a diode bridge for rectifying the alternating current supplying the second winding means and for supplying the so rectified current to the first and second control windings, the rectified current constituting the direct current supplying the first and second control windings.

20. A transformer according to claim 18, further comprising an inductor connected in parallel with said second winding means.

21. A transformer according to claim 18, wherein the diode bridge comprises an input and an output traversed by the alternating current supplying the second winding means, and wherein said transformer further comprises a current transformer responsive to the alternating current in the second winding means and including a secondary winding provided with first and second terminals respectively connected to said input and output of the diode bridge.

22. A transformer according to claim 10, wherein said primary and secondary winding means are formed by a single winding mounted on said first limb and comprising a plurality of taps.

23. A transformer comprising:

a magnetic core defining a first limb, a second limb and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

a primary winding wound around said first limb and supplied with alternating current by a source of electric energy;

a first alternating current winding and a second alternating current winding disposed around said second and third limbs, respectively, connected in series and supplied with an alternating current generated by said source;

said alternating currents in the primary winding and in the first and second alternating current windings being coupled to a first alternating current magnetic flux flowing in a closed magnetic circuit defined by the first and second limbs and to a second alternating current magnetic flux flowing in a closed magnetic circuit defined by the first and third limbs, said first and second alternating current magnetic fluxes assisting each other in the first limb;

a first control winding and a second control winding disposed around the second and third limbs, respectively, said first and second control windings being connected in series and supplied with direct current to induce a direct current magnetic flux flowing in a closed magnetic circuit defined by the second and third limbs;

means for converting the alternating current supplying the first and second alternating current windings into direct current for the supply of the first and second control windings, the direct current supplying said control windings having an amplitude which varies with the amplitude of the alternating current in the first and second alternating current windings to thereby vary the density of said direct current magnetic flux and controlling the permeability of the second and third limbs to the first and second alternating current magnetic fluxes, respectively; and

a secondary winding wound around the first limb and consequently subjected to the first and second alternating current magnetic fluxes which assist each other in said first limb, said secondary winding being provided with two terminals between which the first and second alternating current windings are connected in series, whereby the alternating current in the first and second alternating current windings is supplied to said first and second alternating current windings through the two terminals of the secondary winding.

24. A transformer according to claim 23, wherein said second limb comprises gap means traversed by the resultant magnetic flux in said second limb, and wherein the third limb also comprises gap means traversed by the resultant magnetic flux in said third limb.

25. A transformer according to claim 24, wherein said secondary winding wound around the first limb and subjected to the first and second alternating current magnetic fluxes has a number of turns N_S, each of the first and second alternating current windings has a number of turns N_A, the first limb has a cross section of area S₁, and the second and third limbs each have a cross section of area S₂₃, which satisfy the following relationship:

space="preserve" listing-type="equation">N.sub.S ·

S.sub.1 ≧

N.sub.A ·

S.sub.23.

26. A transformer comprising:

a magnetic core defining a first limb, a second limb, and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

primary winding means wound around at least one of said limbs of the magnetic core and supplied with alternating current by a source of electric energy;

second winding means also wound around at least one of said limbs of the magnetic core and supplied with an alternating current generated by said source of electric energy;

said primary and second winding means being so positioned on the magnetic core that the said two alternating currents in the primary and second winding means are coupled to an alternating current magnetic flux induced in each of the second and third limbs;

control winding means supplied with direct current and so disposed on the magnetic core that the said direct current induces a direct current magnetic flux in each of said second and third limbs;

the alternating current and direct current magnetic fluxes in one of the second and third limbs assisting each other while the alternating current and direct current magnetic fluxes in the other of said second and third limbs are in opposition with respect to each other;

means for converting the alternating current in the second winding means into direct current for the supply of the control winding means, the direct current supplying the control winding means having an amplitude which varies with the amplitude of the alternating current in the second winding means for thereby varying the density of the direct current magnetic flux in the second and third limbs and controlling the permeability of said second and third limbs to the alternating current magnetic flux; and

secondary winding means subjected to the alternating current magnetic flux in said second and third limbs, and connected to an electric load for the supply of said load;

wherein (a) said current converting means comprises a diode bridge for rectifying the alternating current supplying the second winding means and for supplying the so rectified current to the control winding means, the rectified current constituting the direct current supplying the control winding means, and (b) the said transformer further comprises an inductor connected in parallel with said second winding means.

27. A transformer comprising:

a magnetic core defining a first limb, a second limb, and a third limb each having a first end and a second end, said first ends being interconnected through a first common point of the magnetic core and said second ends being interconnected through a second common point of said magnetic core;

primary winding means wound around at least one of said limbs of the magnetic core and supplied with alternating current by a source of electric energy;

second winding means also wound around at least one of said limbs of the magnetic core and supplied with an alternating current generated by said source of electric energy;

said primary and second winding means being so positioned on the magnetic core that the said two alternating currents in the primary and second winding means are coupled to an alternating current magnetic flux induced in each of the second and third limbs;

control winding means supplied with direct current and so disposed on the magnetic core that the said direct current induces a direct current magnetic flux in each of said second and third limbs;

the alternating current and direct current magnetic fluxes in one of the second and third limbs assisting each other while the alternating current and direct current magnetic fluxes in the other of said second and third limbs are in opposition with respect to each other;

means for converting the alternating current in the second winding means into direct current for the supply of the control winding means, the direct current supplying the control winding means having an amplitude which varies with the amplitude of the alternating current in the second winding means for thereby varying the density of the direct current magnetic flux in the second and third limbs and controlling the permeability of said second and third limbs to the alternating current magnetic flux; and

secondary winding means subjected to the alternating current magnetic flux in said second and third limbs, and connected to an electric load for the supply of said load;

wherein said current converting means comprises a diode bridge for rectifying the alternating current supplying the second winding means and for supplying the so rectified current to the control winding means, the rectified current constituting the direct current supplying the control winding means, wherein said diode bridge comprises an input and an output traversed by the alternating current supplying the second winding means, and wherein said transformer further comprises a current transformer subjected to the alternating current in the second winding means and comprising a secondary winding provided with first and second terminals respectively connected to said input and output of the diode bridge.