Method and device to determine a relative position using a resolver

A device to determine a relative position (ρ) of a resolver comprising:

• a signal source that excite an exciter winding of a resolver with a reference signal U(t);
• a processor configured to sample a first signal US1(t) resulting from the reference signal in a first winding of the resolver and to sample a second signal US2(t) resulting from the reference signal in a second winding of the resolver;
• said processor being configured to determine an uncompensated Fourier coefficient zS1 for the first signal US1(t) and an uncompensated Fourier coefficient zS2 for the second signal US2(t);
• and
• said processor being configured to determine a compensated Fourier coefficient zS1,com for the first signal US1(t) and a compensated Fourier coefficient zS2, com for the second signal US2(t) that essentially compensate a change of the uncompensated Fourier coefficients zS1, zS2 that is due to at least one of a phase shift of the resolver and a change of the relative position during said sampling.

A non-transitory computer-readable storage medium encoded with programming instructions for determining a relative position (ρ)of a resolver having an exciter winding that is excited with a reference (U(t), said storage medium being loadable into a processor and said programming instructions causing said processor to:

• sample a first signal US1(t) resulting from the reference signal in a first winding of the resolver and sample a second signal US2(t) resulting from the reference signal in a second winding of the resolver;
• determine an uncompensated Fourier coefficient zS1 for the first signal US1(t) and an uncompensated Fourier coefficient zS2 for the second signal US2(t);
• and
• determine a compensated Fourier coefficient zS1,com for the first signal US1(t) and a compensated Fourier coefficient zS2,com for the second signal US2(t) that essentially compensate a change of the uncompensated Fourier coefficients zS1, zS2 that is due to at least one of a phase shift of the resolver and a change of the relative position during said sampling.