Power supply for electrostatic precipitator
View Patent ↗A high-voltage AC-DC converter is provided that converts alternating current into high-voltage direct current to be provided to a load, e.g. for use as an electrostatic precipitator. The converter includes at least one transformer, wherein the transformer includes at least one primary winding on the AC-side and at least two secondary windings on the DC-side. The converter further includes at least one rectifier rectifying alternating input current, comprising at least one transistor bridge converting the resulting direct current into alternating current, the transformer transforming the resulting alternating current, and comprising at least two high-voltage rectifiers connected to each of the secondary windings, wherein the output voltage of the high-voltage rectifiers is connected in series.
1. High-voltage AC-DC converter for converting alternating current ( 1 - 3 ) into high-voltage direct current to be provided to a load ( 12 ), said converter comprising at least one transformer ( 10 ), having at least one primary winding ( 18 , 22 - 25 ) on an AC-side and at least eight secondary windings ( 27 ) on a DC-side, the converter further comprising at least one rectifier ( 6 ) rectifying alternating input current, comprising at least one transistor bridge ( 8 ) for converting the resulting direct current into alternating current, said at least one transformer ( 10 ) transforming the resulting alternating current, and comprising at least eight high-voltage rectifiers ( 11 , 29 ) with one of the high-voltage rectifiers ( 11 , 29 ) connected to each of the secondary windings ( 27 ), wherein the output voltage of the high-voltage rectifiers ( 11 , 29 ) is connected in series, and each of the secondary windings ( 27 ) has an individual magnetic core ( 30 ).
2. Converter according to claim 1 , wherein three phase input alternating current ( 1 - 3 ) is rectified in the rectifier ( 6 ), wherein the resulting direct current is input to the at least one transistor bridge ( 8 ) via a DC link ( 7 ) with two conductors comprising a filter element ( 13 ), said filter element comprises at least one capacitor ( 13 ) between the two conductors, and the at least one transistor bridge ( 8 ) is a H-bridge with at least four switchable transistors ( 14 , 14 ′, 15 , 15 ′).
3. Converter according to claim 1 , wherein between the at least one transistor bridge ( 8 ) and the at least one transformer ( 10 ) there is located a resonant tank ( 9 ), comprising at least one series resonator with at least one inductor ( 16 ) and at least one capacitor ( 17 ).
4. Converter according to claim 1 , wherein the at least one transformer ( 10 ) comprises at least two magnetic cores ( 30 ), and each of the secondary windings ( 27 ) is associated with an individual magnetic core ( 30 ).
5. Converter according to claim 1 , wherein each of the secondary windings ( 27 ) is connected to an individual one of the high-voltage rectifiers ( 11 , 29 ), and all of the high-voltage rectifiers ( 11 , 29 ) are connected in series to add to the total DC voltage.
6. Converter according to claim 1 , wherein the at least one transformer ( 10 ) comprises at least 4 of the secondary windings ( 27 ), in combination with an equal number of individual magnetic cores ( 30 ).
7. Converter according to claim 1 , wherein the at least one transformer ( 10 ) comprises at least 16 of the secondary windings ( 27 ), in combination with an equal number of the individual magnetic cores ( 30 ).
8. Converter according to claim 1 , wherein the at least one transformer ( 10 ) comprises at least two of the primary windings ( 22 - 25 ).
9. Converter according to claim 1 , wherein there is at least four of the secondary windings ( 27 ) which are provided around closed magnetic cores ( 30 ), having an opening where the at least one primary winding ( 18 , 22 - 25 ) is located.
10. Converter according to claim 9 , wherein the at least one primary winding ( 18 , 22 - 25 ) is provided as a loop comprising at least two turns, and wherein two groups of at least two of the secondary windings ( 27 ) and associated closed magnetic cores ( 30 ) are arranged as coaxial stacks in two substantially parallel legs of the transformer.
11. High-voltage AC-DC converter for converting alternating current ( 1 - 3 ) into high-voltage direct current to be provided to a load ( 12 ), said converter comprising at least one transformer ( 10 ), having at least one primary winding ( 18 , 22 - 25 ) on an AC-side and at least eight secondary windings ( 27 ) on a DC-side, the converter further comprising at least one rectifier ( 6 ) rectifying alternating input current, comprising at least one transistor bridge ( 8 ) for converting the resulting direct current into alternating current, said at least one transformer ( 10 ) transforming the resulting alternating current, and comprising at least eight high-voltage rectifiers ( 11 , 29 ) with a separate one of the high-voltage rectifiers ( 11 , 29 ) connected to each of the secondary windings ( 27 ), wherein the output voltage of the high-voltage rectifiers ( 11 , 29 ) is connected in series, the secondary windings ( 27 ) are provided around closed magnetic cores ( 30 ), having an opening where the at least one primary winding ( 18 , 22 - 25 ) is located, the at least one primary winding ( 18 , 22 - 25 ) is provided as two loops each comprising at least two turns, the secondary windings ( 27 ) are arranged in four groups of each having at least two of the secondary windings ( 27 ) and the associated closed magnetic cores ( 30 ) are arranged in coaxial stacks of four substantially parallel oriented legs of the transformer.
12. High-voltage AC-DC converter for converting alternating current ( 1 - 3 ) into high-voltage direct current to be provided to a load ( 12 ), said converter comprising at least one transformer ( 10 ), having at least one primary winding ( 18 , 22 - 25 ) on an AC-side and at least 16 secondary windings ( 27 ) on a DC-side, the converter further comprising at least one rectifier ( 6 ) rectifying alternating input current, comprising at least one transistor bridge ( 8 ) for converting the resulting direct current into alternating current, said at least one transformer ( 10 ) transforming the resulting alternating current, and comprising at least 16 high-voltage rectifiers ( 11 , 29 ) with a separate one of the high-voltage rectifiers ( 11 , 29 ) connected to each of the secondary windings ( 27 ), wherein the output voltage of the high-voltage rectifiers ( 11 , 29 ) is connected in series, the secondary windings ( 27 ) are provided around closed magnetic cores ( 30 ), having an opening where the at least one primary winding ( 18 , 22 - 25 ) is located, the at least one primary winding ( 18 , 22 - 25 ) is provided as two loops each comprising at least two turns, the secondary windings ( 27 ) are arranged in four groups of each having at least four of the secondary windings ( 27 ) and the associated closed magnetic cores ( 30 ) are arranged in coaxial stacks of four substantially parallel oriented legs of the transformer.
13. Converter according to claim 11 , wherein the two loops of the primary winding ( 18 , 22 - 25 ) are connected such that an opposite and self cancelling orientation of stray fields in the four legged structure results.
14. Converter according to claim 12 , wherein the two loops of the primary winding ( 18 , 22 - 25 ) are connected such that an opposite and self cancelling orientation of stray fields in the four legged structure results.
15. Converter according to claim 1 , wherein the transformer is at least partially, immersed in oil.
16. Converter according to claim 1 , wherein it is rated for at least one of power in a range of 20-200 kW or for output DC-voltages in a range of 50-150 kV.