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A linearly controlled direct-current power source for high-current inductive loads in a magnetic suspension wind tunnelThe NASA Langley 6 inch magnetic suspension and balance system (MSBS) requires an independently controlled bidirectional DC power source for each of six positioning electromagnets. These electromagnets provide five-degree-of-freedom control over a suspended aerodynamic test model. Existing power equipment, which employs resistance coupled thyratron controlled rectifiers as well as AC to DC motor generator converters, is obsolete, inefficient, and unreliable. A replacement six phase bidirectional controlled bridge rectifier is proposed, which employs power MOSFET switches sequenced by hybrid analog/digital circuits. Full load efficiency is 80 percent compared to 25 percent for the resistance coupled thyratron system. Current feedback provides high control linearity, adjustable current limiting, and current overload protection. A quenching circuit suppresses inductive voltage impulses. It is shown that 20 kHz interference from positioning magnet power into MSBS electromagnetic model position sensors results predominantly from capacitively coupled electric fields. Hence, proper shielding and grounding techniques are necessary. Inductively coupled magnetic interference is negligible.
Document ID
19900016003
Acquisition Source
Legacy CDMS
Document Type
Technical Memorandum (TM)
Authors
Tripp, John S. (NASA Langley Research Center Hampton, VA, United States)
Daniels, Taumi S. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 6, 2013
Publication Date
August 1, 1990
Subject Category
Instrumentation And Photography
Report/Patent Number
NAS 1.15:4198
NASA-TM-4198
L-16717
Accession Number
90N25319
Funding Number(s)
PROJECT: RTOP 505-61-01-05
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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