Limit for the harmonics of a current
View Patent ↗A wiring arrangement and an appliance for limiting the harmonics of a current supplied to a frequency converter from an AC electricity supply network, which frequency converter can be connected to a three-phase AC electricity supply network, in which frequency converter is an uncontrolled network bridge ( 10 ) for rectifying the AC voltage of the AC electricity supply network, a DC intermediate circuit, in which is a filtering capacitor (C DC ), and a load bridge ( 11 ) provided with power semiconductor switches for forming three-phase AC voltage (U, V, W), and which load bridge can be controlled with pulse-width modulation by means of a control unit, and in which DC intermediate circuit is a choke, in which is a choke part (L 1 , L 2 ) arranged on both the positive and the negative pole, and in which wiring arrangement is an absorption circuit for limiting the harmonics of the current supplied from the AC electricity supply network, in which the absorption circuit is arranged in the DC intermediate voltage circuit, the absorption circuit contains a serial connection of a choke (L 3 ) and a capacitor (C 1 ) connected in parallel with a filter capacitor (C DC ), the choke of the DC intermediate voltage circuit is a two-branch DC choke wound onto the common core, which contains pillars and the yokes between them, and in which an additional pillar for the choke of the absorption circuit is arranged in the magnetic core of the choke.
1. Wiring arrangement for limiting the harmonics of the current supplied from an AC mains supply to a frequency converter,
which frequency converter can be connected to a three-phase AC mains supply,
in which frequency converter is an uncontrolled network bridge ( 10 ) for rectifying the AC voltage of the AC electricity supply network, a DC intermediate circuit, in which is a filtering capacitor (C DC ), and a load bridge ( 11 ) provided with power semiconductor switches for forming three-phase AC voltage (U, V, W), and which load bridge can be controlled with pulse-width modulation by means of a control unit, and
in which DC intermediate circuit is a choke, in which is a choke part (L 1 , L 2 ) arranged on both the positive and the negative pole, and
in which wiring arrangement is an absorption circuit for limiting the harmonics of the current supplied from the AC electricity supply network,
characterized in that
the absorption circuit is arranged in the DC intermediate voltage circuit,
the absorption circuit contains a serial connection of a choke (L 3 ) and a capacitor (C 1 ) connected in parallel with a filter capacitor (C DC ),
the choke of the DC intermediate voltage circuit is a two-branch DC choke wound onto a common core, which contains pillars and the yokes between them, and
in which an additional pillar for the choke of the absorption circuit is arranged in the magnetic core of the choke.
2. Wiring arrangement according to claim 1 ,
characterized in that the inductance value of the choke of the absorption circuit is approx. double compared to the inductance values of the choke parts (Ldc+, Ldc−).
3. Wiring arrangement according to claim 2 ,
characterized in that the capacitance values of the capacitor of the absorption circuit and of the filtering capacitor are essentially of equal magnitude.
4. Wiring arrangement according to claim 2 ,
characterized in that one or more permanent magnets are arranged in the magnetic core of the choke that is used in the wiring arrangement.
5. Wiring arrangement according to claim 1 ,
characterized in that the capacitance values of the capacitor of the absorption circuit and of the filtering capacitor are essentially of equal magnitude.
6. Wiring arrangement according to claim 5 ,
characterized in that one or more permanent magnets are arranged in the magnetic core of the choke that is used in the wiring arrangement.
7. Wiring arrangement according to claim 1 ,
characterized in that one or more permanent magnets are arranged in the magnetic core of the choke that is used in the wiring arrangement.
8. Wiring arrangement according to claim 7 ,
characterized in that the permanent magnet is positioned at an angle with respect to the longitudinal direction of the part or parts of the magnetic core such that the cross-section surface of the permanent magnet is greater than the cross-section surface of the part of the magnetic core in question or the parts of the magnetic core in question.
9. Wiring arrangement according to claim 7 ,
characterized in that an air gap is arranged in one half or in both halves of the permanent magnet.
10. Wiring arrangement according to claim 7 ,
characterized in that the cross-section surfaces of the pillar parts and of the yoke parts of the magnetic core are of different magnitudes.
11. Wiring arrangement according to claim 7 ,
characterized in that there are two permanent magnets, positioned in opposite corners of the magnetic core.
12. A wiring arrangement according to claim 7 ,
characterized in that there are four permanent magnets, positioned in all the corners of the magnetic core.
13. Wiring arrangement for limiting the harmonics of the current supplied to a frequency converter from an AC mains supply,
which frequency converter can be connected to a three-phase AC mains supply,
in which frequency converter is an uncontrolled network bridge ( 10 ) for rectifying the AC voltage of the AC electricity supply network, a DC intermediate circuit, in which is a filtering capacitor (C DC ), and a load bridge ( 11 ) provided with power semiconductor switches for forming three-phase AC voltage (U, V, W), and which load bridge can be controlled with pulse-width modulation by means of a control unit, and
in which DC intermediate circuit is a choke, in which is a choke part (L 1 , L 2 ) arranged on both the positive and the negative pole, and
in which wiring arrangement is an absorption circuit for limiting the harmonics of the current supplied from the AC electricity supply network,
characterized in that
the absorption circuit is arranged in the DC intermediate voltage circuit,
the choke of the DC intermediate voltage circuit is a two-branch DC choke wound onto a common core, which contains pillars and the yokes between them, and
in which an additional pillar for the choke of the absorption circuit is arranged in the magnetic core of the choke.
14. Appliance according to claim 13 ,
characterized in that the absorption circuit is a serial connection of a choke (L 3 ) and a capacitor (C 1 ) connected in parallel with a filter capacitor.
15. Appliance according to claim 13 ,
characterized in that the windings and pillars of the choke parts (L 1 and L 2 ) arranged on the positive and on the negative pole of the DC intermediate circuit are dimensioned to be greater than the winding and the core of the absorption circuit.
16. Appliance according to claim 13 ,
characterized in that the capacitor (C 1 ) of the absorption circuit is a low-loss plastic capacitor, e.g. manufactured from polypropylene film.
17. Appliance according to claim 13 ,
characterized in that the filtering capacitor of the intermediate circuit is the same type as the capacitor of the absorption circuit, and the capacitors are arranged to have three poles such that both capacitors (C 1 , C DC ) are disposed in the same enclosure.
18. Appliance according to claim 13 ,
characterized in that one or more permanent magnets are arranged in the magnetic core of the choke in the appliance.
19. Appliance according to claim 13 ,
characterized in that the permanent magnet is positioned at an angle with respect to the longitudinal direction of the part or parts of the magnetic core such that the cross-section surface of the permanent magnet is greater than the cross-section surface of the part of the magnetic core in question or the parts of the magnetic core in question.
20. Appliance according to claim 13 ,
characterized in that an air gap is arranged in one half or in both halves of the permanent magnet.