Flexible transformers WE-FLEX

There is another outcome if the inductors are on a single core, as in the case of the flex- transformers. The series connection of two windings doubles the ...
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Flexible transformers WE-FLEX Flex-transformer applications The value of inductance when inductors are connected in series or parallel is calculated similar to that of resistors by addition or reciprocals addition. n

LSeries = L1 + L2 + L3 + ... + Ln = ∑ Li i =1

n

LParallel = 1 /(1 / L1 + 1 / L2 + 1 / L3 + ... + 1 / Ln ) = 1 / ∑ (1 / Li ) i =1

There is another outcome if the inductors are on a single core, as in the case of the flextransformers. The series connection of two windings doubles the winding turns. This has a square effect on the inductance. The inductance is therefore quadrupled. In case of parallel connection of two windings, the inductance does not change. The result is that twice the current can be carried. A general calculation rule is now given, based on the series and parallel connection of two windings:

10µH 1A

10µH 1A

10µH 1A

10µH 1A

Series connection of two windings

Ltotal = LBase ⋅ S 2 Ltotal = 10µH ⋅ 2 Ltotal = 40µH

2

Parallel connection of two windings

I max = I Base ⋅ P

Ltotal = LBase ⋅ S 2

I max = I Base ⋅ P

I max = 1A ⋅ 1

Ltotal = 10µH ⋅ 1

I max = 1A ⋅ 2

I max = 1A

Ltotal = 10 µH

I max = 2 A

2

Lbase = inductance of one winding P = number of windings connected in parallel S = number of windings connected in series Ibase = maximum current rating of one winding

Flexible transformers WE-FLEX Application examples: Every flex-transformer can be connected in a large number of variants. Only the circuit board layout needs to be adapted for the respective application. Parallel connection increases the current rating, series connection does multiply the inductance. Six different inductances and 15 different transformation ratios can be achieved with each of the 25 flex-transformers. This serves to replace over 500 different components. Choke connection examples 1) Series connection of 6 windings 1

7491961xx / 7491962xx 1

7491963xx / 7491965xx

1

12

1

12

6

7

6

7

7

Ltotal = 36 * LBase; Isat = IBase; IN = IBase

2) Series connection of 5 windings 1

7491961xx / 7491962xx 1

7491963xx / 7491965xx

1

12

1

12

6

7

6

7

7

7

Ltotal = 25 * LBase; Isat = 1,15*ISatBase; IN = INBase

3) Series connection of 4 windings 1

7491961xx / 7491962xx 1

7491963xx / 7491965xx

1

12

1

12

6

7

6

7

7

7

Ltotal = 16 * LBase; Isat = 1,4*ISatBase; IN = INBase

Flexible transformers WE-FLEX 4) Series connection of 3 windings 1

7491961xx / 7491962xx 1

7491963xx / 7491965xx

1

12

1

12

6

7

6

7

7

7

Ltotal = 9 * LBase; Isat = 2*ISatBase; IN = 2*INBase

5) Series connection of 2 windings 1

7491961xx / 7491962xx 1

7491963xx / 7491965xx

1

12

1

12

6

7

6

7

7

7

Ltotal = 4 * LBase; Isat = 3*ISatBase; IN = 3*INBase

6) 1 winding 7491961xx / 7491962xx

1 1

7491963xx / 7491965xx

1

12

1

12

6

7

6

7

7 7

Ltotal = 1 * LBase; Isat = 6*ISatBase; IN = 6*INBase

Flexible transformers WE-FLEX Application notes for transformer 1) 1 : 1 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

1

12

A1

A2 A1

E1

E1

E2 A2

A2

6

6

7

7

Ltotal = 1 * LBase; Isat = 3*ISatBase; IN = 3*INBase

2) 1 : 2 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

1

12

A2 A1

A1

E1

A2

A2

E1 6

7

E2

6

7

Ltotal = 1 * LBase; Isat = 2*ISatBase; IN = 2*INBase

3) 1 : 3 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

1

12

A2 A1

A1

E1

A2

E1

E2 6

Ltotal = 1 * LBase; Isat = 3*ISatBase; IN = 3*INBase

7

E2

6

7

Flexible transformers WE-FLEX 4) 1 : 4 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

1

A2

A1

12

A1 A2

E1

E1 E2

6

6

7

7

E2

Ltotal = 1 * LBase; Isat = 2*ISatBase; IN = 2*INBase

5) 1 : 5 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

1

A1 A2

12

E1

A1 A2

E1 6

7

E2

6

7

E2

Ltotal = 1 * LBase; Isat = 1*ISatBase; IN = 1*INBase

6) 2 : 2 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

A1

1

12

A2 A1 E1 A2

E1 6

Ltotal = 4 * LBase; Isat = 1,15*ISatBase; IN = 1*INBase

7

E2

E2 6

7

Flexible transformers WE-FLEX 7) 2 : 3 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

A1

1

12

A2 A1 E1 A2

E1 6

7

E2

E2

6

7

Ltotal = 4 * LBase; Isat = 1,15*ISatBase; IN = 1*INBase

8) 2 : 4 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

1

12

A2 A1

A1

E1

A2 E2

6

6

7

7

E2

Ltotal = 4 * LBase; Isat = 1*ISatBase; IN = 1*INBase

9) 3 : 3 7491961xx / 7491962xx 1

7491963xx / 7491965xx

12

A1

1

12

A2 A1 E1 A2

E1

Ltotal = 9 * LBase; Isat = 1*ISatBase; IN = 1*INBase

6

7

E2

6

7

E2