Phase analog encoding system with compensation

A resolver based phase analog encoding system for indicating position with compensation for an inherent electrical phase shift across said resolver comprising:

• (a) a resolver transducer;
• (b) a resolver reference means electrically connected to said resolver transducer for generating and applying a plurality of reference signals to said resolver transducer, wherein said resolver reference means comprises:
• a reference signal generator for generating reference signals;
• a reference signal switch electrically connecting the output of said reference signal generator to said resolver transducer such that the position of said reference switch determines whether a resolver encoding means measures a sum (.phi.+.alpha.) of a mechanical displacement .phi. and an inherent electrical phase shift across said resolver transducer .alpha.0 or an inherent electrical phase shift across said resolver transducer .alpha.;
• and an amplifying means electrically located between said reference signal generator and said resolver transducer for increasing the magnitude of said reference signals that are applied to said resolver transducer;
• (c) a resolver encoding means electrically connected to said resolver transducer and said resolver reference means for measuring said sum (.phi.+.alpha.) of said mechanical displacement .phi. and said inherent electrical phase shift across said resolver transducer .alpha., or said inherent electrical phase shift across said resolver transducer .alpha. independent of the mechanical displacement .phi., or said inherent electrical phase shift due to said encoding means .gamma.;
• wherein said resolver encoding means comprises:
• a digital counting means, the output of said counting means being proportional to (.phi.+.alpha.), .alpha. or .gamma.;
• a zero crossing detector electrically connected to said digital counting means for starting said digital counting means, said zero crossing detector measuring when a reference signal is zero;
• a second zero crossing detector electrically connected to said digital counting means for stopping said digital counting means, said second zero crossing detector measuring when either the output of said resolver transducer or a reference signal is zero;
• and control electronics for electrically connecting either the output of said resolver transducer or said reference signal to said second zero crossing detector;
• and
• (d) a calculating means electrically connected to said resolver encoding means and said resolver reference means for compensating said measured sum (.phi.+.alpha.) by said measured inherent electrical phase shift .alpha. to obtain a value of said mechanical displacement .phi., said calculating means also compensating for said inherent electrical phase shift due to said encoding means .gamma., said calculating means controlling said resolver reference means and said resolver encoding means so that said sum (.phi.+.alpha.), said inherent electrical phase shift across said resolver transducer .alpha. and said inherent electrical phase shift due to said encoding means .gamma., are measured in a time multiplexed manner;
• and wherein the calculating means, when the system is to measure the inherent electrical phase shift .alpha. sends a feedback signal to the resolver reference means to activate the reference signal switch in the resolver reference means thereby applying the correct reference signal from the reference signal generator in the correct orientation to the resolver transducer to compensate for the current value of the mechanical displacement .phi. thereby ensuring that the measurement of the inherent electrical phase shift .alpha. will be valid independent of the mechanical displacement .phi. of the resolver.

A resolver based phase analog encoding system for indicating the position of a rotatable shaft with compensation for an inherent electrical phase shift across said resolver comprising:

• (a) a resolver transducer;
• (b) a resolver reference means electrically connected to said resolver transducer for generating and applying a plurality of reference signals to said resolver transducer, wherein said resolver reference means comprises:
• a reference signal generator for generating reference signals;
• a reference signal switch electrically connecting the output of said reference signal generator to said resolver transducer such that the position of said reference switch helps determine whether a resolver encoding means measures a sum (.phi.+.alpha.) of a mechanical rotor angle .phi. and an inherent electrical phase shift across said resolver transducer .alpha. or an inherent electrical phase shift across said resolver transducer .alpha.;
• and an amplifying means electrically located between said reference signal generator and said resolver transducer for increasing the magnitude of said reference signals that are applied to said resolver transducer;
• (c) a resolver encoding means electrically connected to said resolver transducer and said resolver reference means for measuring said sum (.phi.+.alpha.) of said mechanical rotor angle .phi. and said inherent electrical phase shift across said resolver transducer .alpha., or said inherent electrical phase shift across said resolver transducer .alpha. independent of the mechanical rotor angle .phi., or said inherent electrical phase shift due to said encoding means .gamma.;
• wherein said resolver encoding means comprises:
• a digital counting means, the output of said counting means being proportional to (.phi.+.alpha.), .alpha. or .gamma.;
• a zero crossing detector electrically connected to said digital counting means for starting said digital counting means, said zero crossing detector measuring when a reference signal is zero;
• a second zero crossing detector electrically connected to said digital counting means for stopping said digital counting means, said second zero crossing detector measuring when either the output of said resolver transducer or a reference signal is zero;
• and control electronics for electrically connecting either the output of said resolver transducer or said reference signal to said second zero crossing detector;
• and
• (d) a calculating means electrically connected to said resolver encoding means and said resolver reference means for compensating said measured sum (.phi.+.alpha.) by said measured inherent electrical phase shift .alpha. to obtain a value of said mechanical rotor angle .phi., said calculating means also compensating for said inherent electrical phase shift due to said encoding means .gamma., said calculating means controlling said resolver reference means and said resolver encoding means so that said sum (.phi.+.alpha.), said inherent electrical phase shift across said resolver transducer .alpha. and said inherent electrical phase shift due to said encoding means .gamma., are measured in a time multiplexed manner;
• and wherein the calculating means, when the system is to measure the inherent electrical phase shift .alpha. sends a feedback signal to the resolver reference means to activate the reference signal switch in the resolver reference means thereby applying the correct reference signal from the reference signal generator in the correct orientation to the resolver transducer to compensate for the current value of the mechanical displacement .phi. thereby ensuring that the measurement of the inherent electrical phase shift .alpha. will be valid independent of the rotor angle .phi. of the resolver.