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A Novel Concept for Transformer Volt Second Balancing of a VIENNA Rectifier III Based on Direct Magnetizing Current Measurement
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| Author(s) |
Franz Stögerer; Johann W. Kolar; Uwe Drofenik |
| Abstract |
For a VIENNA Rectifier III different turn-on and turn-off
delay times of the power transistors and different on-state
voltages of the valves would cause an unbalance of the
positive and negative volt seconds applied to the high
frequency transformer within a pulse period and/or result
in transformer saturation without additional measures.
This paper proposes a novel concept for actively
ensuring a symmetric magnetization with switching
frequency of the transformer magnetic core of a VIENNA
Rectifier III based on direct measurement of the
magnetizing current. The magnetizing current is
determined by subtraction of the transformer primary and
the secondary currents being weighted according to the
transformer turns ratio. The subtraction is realized by
magnetic compensation employing a through-hole DC
current transducer. A deviation from a symmetric
magnetization within a pulse period is detected and used by
a controller for closed-loop balancing of the volt seconds
applied to the transformer primary in order to eliminate an
existing asymmetry. The controller is designed based on
sampled data system theory. The theoretical considerations
and the controller dimensioning are verified by
experimental results gained from a 8.5kW prototype of the
VIENNA Rectifier III. |
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| Filename: | Unnamed file |
| Filesize: | 187 KB |
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| Type |
Members Only |
| Date |
Last modified 2006-02-20 by System |
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