Phase Method of Resolver Decoding - RF Cafe Forums
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Post subject: Phase Method of Resolver Decoding
Unread post Posted: Thu Mar 03, 2005 3:18 pm
RESOLVER DECODING (PHASE METHOD)
Looking for any information on circuits that will decode analog resolver signals into unambiguous binary positional data.
I'm specifically looking for information on a technique called the PHASE METHOD of decoding, wherein the sin & cosine windings are driven and the position data is extracted from the rotor signal. The rotor phase, relative to the reference signal phase, is compared to determine the amount of shaft rotation. The phases are compared by keeping track of their zero crossings, and a binary count output that represents their phase difference, (zero crossings) is generated. The binary output is generated by utilizing zero crossing detectors on the reference signal to start a binary up/down counter and alternately, zero crossings from the rotor signal are used to latch the binary count when they occur, the count that is latched by the rotor's zero crossing represents the difference in phase between the two signals and thus the amount of angular rotation of the shaft in binary. For example, a zero count, would mean the two signals are in phase, a 1/2 max count, signals are 180 out of phase, and so on. One must also keep track of rotation direction so the counter can count up or down in coordination with the direction. This system is not as complicated as it might first seem but I am looking for help from anyone who has experience with this technique.
I am specifically NOT looking for information on ratiometric tracking converters that typically drive the resolver's rotor and decode the sine and cosine signals. But rather, only information on this alternate PHASE METHOD.
Any info on this subject is wanted, explanations, insights, schematics, IC's, etc.
(I apologize if this is the wrong forum for this post. Please point me to the correct one.)