Electric power conversion systems – Frequency conversion without intermediate conversion to d.c. – By semiconductor converter
Reexamination Certificate
2007-03-06
2007-03-06
Laxton, Gary L (Department: 2838)
Electric power conversion systems
Frequency conversion without intermediate conversion to d.c.
By semiconductor converter
C363S085000, C363S128000
Reexamination Certificate
active
10492314
ABSTRACT:
An apparatus for generating electronic signals for application in subsea electromagnetic exploration. A surface generated high-voltage low-current source signal stabilized at a first frequency is supplied to a deep-tow vehicle (18) via an umbilical cable (16). The high-voltage low-current signal is transformed at the deep-tow vehicle to a high-current low-voltage a.c. signal by a transformer (52) within a cycloconverter (30). A semiconductor relay bridge (104) provides switchable rectification of the high-current low-voltage a.c. signal to provide a quasi-square wave at a second frequency, lower than the first frequency, for supply to a transmitting antenna (22) towed by the deep-tow vehicle. The times of the rectification switching are dependent on zero crossings of the high-current low-voltage a.c. signal. Allowable rectification switching times may be gated to occur only within pre-determined time windows to avoid noise-induced zero-crossing switching. The apparatus allows multiple transmission frequencies to be derived from a single stabilized source and improves spectral integrity by avoiding rectification switching at zero-crossings not occurring at the first frequency.
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MacGregor Lucy M.
Sinha Martin C.
Laxton Gary L
Renner , Otto, Boisselle & Sklar, LLP
University of Southampton
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