Converter circuit with coupled inductances having asymmetrical air gap arrangement
View Patent ↗The invention relates to a converter circuit with coupled inductances L 1 and L 2 which have a core K having an air gap S which is asymmetrical with respect to the inductances.
1. A SEPIC converter circuit having
two input branches,
a switch (T 1 ) between the first input branch and the second input branch,
a first inductance (L 1 ) in the first input branch on the input side of the connection of the switch (T 1 ),
a capacitor (C 1 ) in the first input branch on the output side of the connection of the switch (T 1 ),
a second inductance (L 2 ) between the first and the second input branches on the output side of the capacitor (C 1 ),
a diode (D 1 ) in the first input branch on the output side of the connection of the second inductance (L 2 ),
a second capacitor (C 2 ) between the first and the second input branches,
in the case of which the first and the second inductances (L 1 , L 2 ) have a common core (K) with an air gap (S),
and the second inductance (L 2 ) for ripple current compensation approximately corresponds to the inductance of a parallel circuit comprising the first and the second inductances (L 1 , L 2 ),
characterized in that the air gap (S) is asymmetrical with respect to the winding in the first and the second inductances (L 1 , L 2 ) and lies to a greater extent in the region of the winding of the second inductance (L 2 ).
2. The converter circuit as claimed in claim 1 , in which the coupling factor between the first and the second inductances (L 1 , L 2 ) is between 0.6 and 0.9, inclusive.
3. The converter circuit as claimed in claim 1 , in which the chamber volume of the winding of the first inductance (L 1 ) is smaller than the chamber volume of the winding of the second inductance (L 2 ).
4. The converter circuit as claimed in claim 1 , in which the windings of the first and the second inductances (L 1 , L 2 ) are axially separate.
5. The converter circuit as claimed in claim 1 , in which the core (K) comprises two symmetrical core halves (K 1 , K 2 ).
6. The converter circuit as claimed in claim 1 , in which the winding of the first inductance (L 1 ) is made of a single wire, and the winding of the second inductance (L 2 ) is made of a radiofrequency litz wire.
7. The converter circuit as claimed in claim 1 , in which the air gap (S) is surrounded exclusively by the winding of the second inductance (L 2 ).
8. The converter circuit as claimed in claim 7 , in which the coupling factor between the first and the second inductances (L 1 , L 2 ) is between 0.6 and 0.9, inclusive.
9. The converter circuit as claimed in claim 7 , in which the chamber volume of the winding of the first inductance (L 1 ) is smaller than the chamber volume of the winding of the second inductance (L 2 ).
10. An electronic device having the converter circuit as claimed in claim 1 as a power factor correction circuit.
11. The electronic device as claimed in claim 10 , which is designed as an electronic ballast for a light-generating element.
12. The electronic ballast as claimed in claim 11 , which is designed to supply power to a low-pressure discharge lamp.