Method and means for combining a transformer and inductor on a single core structure

• US 5,783,984 A
• Filed: 06/16/1995
• Issued: 07/21/1998
• Est. Priority Date: 06/16/1995
• Status: Expired due to Fees

• Current Assignee: Undersea Sensor Systems, Inc. (Edge Autonomy SLO LLC)
• Original Assignee: Hughes Electronics Corporation (Rtx Corporation)
• Inventors: Keuneke, Carl Edward
• Primary Examiner(s): Spyrou, Cassandra C.
• Assistant Examiner(s): Chapik, Daniel
• Application Number:
  US08/491,554
• Time in Patent Office: 1,131 Days
• Field of Search: 336/155, 336/216, 336/217, 336/212, 336/165, 336/178
• US Class Current: 336/155
• CPC Class Codes: H01F 38/08 High-leakage transformers or inductances
• CPC Class Codes: H03H 7/38 Impedance-matching networks

Abstract

In a prefer embodiment, an integrated transformer and inductor on a singe core structure to provide an impedance matching function and an inductor in series with the transformer'"'"'s secondary which includes: a transformer core structure having a primary leg, a secondary leg, and a center leg containing an air gap, said center leg disposed parallel to said primary leg and secondary leg, whereby said air gap provides control of said inductor value; a primary winding on said primary leg; and a secondary winding on said secondary leg.

Claims

1. An integrated transformer and inductor on a monolithic core structure to provide an impedance matching function and an inductor in series with a secondary of said transformer which comprises:

(a) a transformer core structure having a primary leg, a secondary leg, and a center leg containing an air gap, whereby said air gap provides control of an inductor value;

(b) a primary winding on said primary leg; and

(c) a secondary winding on said secondary leg wherein a secondary-to-primary turns ratio of said primary windings is determined by

space="preserve" listing-type="equation">N.sub.s /N.sub.p =V.sub.Rl /V.sub.in

where N_s =a number of turns of said secondary winding,

N_p =a number of turns of said primary winding,

V_Rl =a desired RMS voltage across a load resistance at a resonant frequency, and

V_in =an RMS voltage of a signal applied to said primary winding at said resonant frequency.

2. An integrated transformer and inductor on a monolithic core structure to provide an impedance matching function and an inductor in series with a secondary of said transformer which comprises:

(a) a transformer core structure having a primary leg, a secondary leg, and a center leg containing an air gap, whereby said air gap provides control of an inductor value;

(b) a primary winding on said primary leg; and

(c) a secondary winding on said secondary leg wherein a core area of said primary leg is determined by

space="preserve" listing-type="equation">A.sub.p =(V.sub.p ×

10.sup.8)/(4.0×

Freq×

N.sub.p ×

B)

where A_p =a cross-sectional area of said core'"'"'s primary leg (in cm²),

V_p =an RMS voltage of a square wave applied to said primary winding,

Freq=a frequency of a square wave applied to said primary winding (in hertz),

N_p =a number of turns on said primary winding, and

B=a desired maximum operating flux density (in gausses).

3. An integrated transformer and inductor on a monolithic core structure to provide an impedance matching function and an inductor in series with a secondary of said transformer which comprises:

(a) a transformer core structure having a primary leg, a secondary leg, and a center leg containing an air gap, whereby said air gap provides control of an inductor value;

(b) a primary winding on said primary leg; and

(c) a secondary winding on said secondary leg wherein a core area of said secondary leg is determined by

space="preserve" listing-type="equation">A.sub.s =A.sub.p ×

(1+(1/R.sub.l ×

2×

Pi×

Freq×

C.sub.l)).sup.2).sup.1/2

where A_s =a cross-sectional area of said core'"'"'s secondary leg (in cm²),

A_p =a cross-sectional area of said core'"'"'s primary leg (in cm²),

R_l =a series resistance of a load (in ohms),

Pi=2.1416,

Freq=a frequency of a square wave applied to said primary winding (in hertz), and

C_l =a series capacitance of a load (in farads).

4. An integrated transformer and inductor on a monolithic core structure to provide an impedance matching function and an inductor in series with a secondary of said transformer which comprises:

(a) a transformer core structure having a primary leg, a secondary leg, and a center leg containing an air gap, whereby said air gap provides control of an inductor value;

(b) a primary winding on said primary leg; and

(c) a secondary winding on said secondary leg wherein a core of said center leg is determined by

space="preserve" listing-type="equation">A.sub.c =(V.sub.p ×

10.sup.8)/(8×

Freq×

N.sub.p ×

B×

Pi×

Freq×

C.sub.l ×

R.sub.l)

where A_c =a cross-sectional areas of said core'"'"'s center leg (in cm²),

V_p =an RMS voltage of a square wave applied to said primary winding,

Freq=a frequency of said square wave applied to said primary winding (in hertz),

N_p =a number of turns on said primary winding,

B=a desired maximum operating flux density (in gausses),

Pi=2.1416,

C_l =a series capacitance of a load (in farads), and

R_l =a series resistance of said load (in ohms).

5. An integrated transformer and inductor on a monolithic core structure to provide an impedance matching function and an inductor in series with a secondary of said transformer which comprises:

(a) a transformer core structure having a primary leg, a secondary leg, and a center leg containing an air gap, whereby said air gap provides control of an inductor value;

(b) a primary winding on said primary leg; and

(c) a secondary winding on said secondary leg wherein a width of said air gap is determined by

space="preserve" listing-type="equation">I.sub.g =(0.4×

Pi×

10.sup.-9 ×

N.sub.x.sup.2 ×

A.sub.c)/L

where I_g =said width of said air gap (in cm),

Pi=2.1416,

N_s =a number of turns of said secondary winding,

A_c =a cross-sectional area of said center leg (in cm²), and

L=a desired inductance of an equivalent series inductor (in henries).

6. A method of providing an integrated transformer and inductor on a monolithic core structure to provide an impedance matching function and an inductor in series with a secondary of said transformer which comprises:

(a) providing a transformer core structure having a primary leg, a secondary leg, and a center leg containing an air gap, whereby said air gap provides control of said inductor value;

(b) establishing a core area of said primary leg as given by

space="preserve" listing-type="equation">A.sub.p =(V.sub.p ×

10.sup.8)/(4.0×

Freq×

N.sub.p ×

B)

where A_p =a cross-sectional area of said primary leg (in cm²),

V_p =an RMS voltage of a square wave applied to said primary winding,

Freq=a frequency of said square wave applied to said primary winding (in hertz),

N_p =a number of turns on said primary winding, and

B=a desired maximum operating flux density (in gausses);

(c) establishing a core area of said secondary leg as given by

space="preserve" listing-type="equation">A.sub.s =A.sub.p ×

(1+(1/R.sub.L ×

2×

Pi×

Freq×

C.sub.L)).sup.2).sup.1/2

where A_s =a cross-sectional area of said secondary leg (in cm²),

A_p =a cross-sectional area of said primary leg (in cm²),

R_L =a series resistance of a load (in ohms),

Pi=3.1416 and,

Freq=a frequency of a square wave applied to said primary winding (in hertz),

C_L =a series capacitance of said load (in farads);

(d) establishing a core area of said center leg according as given by

space="preserve" listing-type="equation">A.sub.c =(V.sub.p ×

10.sup.8)/(8×

Freq×

N.sub.p ×

B×

Pi'"'"'Freq×

C.sub.L ×

R.sub.L)

where A_c =a cross-sectional area of said core'"'"'s center leg (in cm²),

V_p =an RMS voltage of a square wave applied to said primary winding,

Freq=a frequency of said square wave applied to said primary winding (in hertz),

N_p =a number of turns on said primary winding,

B=a desired maximum operating flux density (in gausses),

Pi=3.1416,

C_L =a series capacitance of a load (in farads), and

R_L =a series resistance of said load (in ohms),

(e) establishing a width of said air gap according to the equation

space="preserve" listing-type="equation">I.sub.g =(0.4×

Pi×

10.sup.-8 ×

N.sub.s.sup.2 ×

A.sub.c)/L

where I_g =an air gap width of said center leg (in cm),

Pi=3.1416,

N_s =a number of turns of said secondary winding,

A_c =a cross-sectional area of said center leg (in cm²), and

L=a desired inductance of an equivalent series inductor (in henries); and

(f) winding a primary winding on said primary leg and a secondary winding on said secondary leg whereby a secondary-to-primary turns ratio of said primary and secondary windings is given by

space="preserve" listing-type="equation">N.sub.s N.sub.p =V.sub.RL /V.sub.in

where N_s =a number of turns of said secondary winding,

N_p =a number of turns of said primary winding,

V_RL =a desired RMS voltage across a load resistance at a resonant frequency,

V_in =an RMS voltage of a signal applied to said primary winding at said resonant frequency (=0.9×

V_p for V_in =square wave), and

V_p =an RMS voltage of said square wave applied to said primary winding.