Title :
On the Distribution of AC and DC Winding Capacitances in High-Frequency Power Transformers With Rectifier Loads
Author :
Ranstad, Per ; Nee, Hans-Peter
Author_Institution :
Alstom Power, Växjo, Sweden
fDate :
5/1/2011 12:00:00 AM
Abstract :
In this paper, a method to adjust the ac winding capacitance of high-voltage high-frequency transformers by means of winding-rectifier integration is described. First, a theoretical background to the method is given. From the theory, an equivalent circuit describing the characteristics of the combination of the transformer and the rectifier is derived. The derived circuit introduces the concept of a dc capacitance. Finally, the equivalent circuit and the method itself are verified by means of experiments on a transformer-rectifier system from an industrial application with the ratings 70 kV, 30 kW, and 25 kHz. The results from the experiments show that it is possible to vary the ac component of the winding capacitance from a few percent up to 95% of the total winding capacitance. This means that it is virtually free to choose between ac and dc capacitances during the design stage. This is very important in applications such as resonant converters with transformers having secondary windings connected to rectifiers with capacitive output filters.
Keywords :
equivalent circuits; machine windings; power transformers; rectifiers; resonant invertors; transformer windings; AC winding capacitance; DC winding capacitance; capacitive output filters; equivalent circuit; frequency 25 kHz; high-frequency power transformers; high-voltage transformers; power 30 kW; resonant converters; secondary windings; voltage 70 kV; winding-rectifier; Controllability; Electrical equipment industry; Equivalent circuits; Filters; Parasitic capacitance; Permission; Power conversion; Power transformers; Rectifiers; Resonance; High-voltage conversion; resonant converters; transformer parasitics; winding capacitance;
Journal_Title :
Industrial Electronics, IEEE Transactions on
DOI :
10.1109/TIE.2010.2055773