Transformer for 12-pulse series connection of converters
OwnerDerek A. Paiceinventor
Life of this patent
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Abstract
In a multi-pulse converter system a three-phase transformer with tapped wye-connected primary winding and isolated delta-connected secondary winding is used to power two 6-pulse converter bridges connected in series to give 12-pulse operation. The transformer equivalent kVA rating is a fraction, typically less than 60%, of the total dc power. By adjusting the tapping on the wye-connected primary winding the converter dc output voltage is readily adjusted to provide higher or lower dc voltage than is attainable by a three-phase 6-pulse converter. By these means a reliable and versatile 12-pulse converter is obtained which, without additional hardware, gives excellent performance in the face of practical power sources which may incorporate voltage unbalance and pre-existing harmonic voltages.
Claims6
A multiple AC/DC converter system comprising a three-phase wye connected transformer having a minimum of three windings on each phase with two windings being connected in series to provide a tapped coil with one section of the coil being connected to form a neutral with the same coils from the other phases;
- with the end of the coil which is remote from the tapping and the neutral being connected to one of the three power source lines;
- with the same connections on the other phases such that each of the lines of the three-phase source are connected to each transformer phase;
- with one winding from each phase being connected in series with the same winding from each of the other phases to produce a closed delta connection isolated from the first two windings;
- wherein the winding electrically connected to the neutral is called the OUTPUT winding;
- the winding electrically connected to the end of the output winding is called the MAIN winding, the winding connected to form an isolated closed path with other windings is called the DELTA winding;
- wherein the MAIN winding includes a fraction (1-K) of the sum of the turns in the main and output windings;
- with the OUTPUT winding including a fraction K of the sum of the turns in the main and output winding;
- with the DELTA winding incorporating nominally 1.73 times the turns in the OUTPUT winding;
- wherein the factor K is any positive number not exceeding unity.
Dependencies are inferred from the claim text.