Self-compensation Method for Harmonic Error of Resolver Based on Characteristic Frequency Observer

The amplitude error and quadrature error of the resolver are reflected in the angular velocity spectrum as the second frequency of the resolver precision machine rotational frequency, which is called the second harmonic error and is the main component of the resolver angular measurement error. In order to compensate the second harmonic error of the resolver and improve the accuracy of resolver angle measurement, this paper proposes a software self-compensation method of resolver harmonic error based on the characteristic frequency observer. Firstly, we model and analyze the resolver harmonic error; then we use the Characteristic Frequency observer constructed by adaptive notch filter (ANF) to filter out the resolver harmonic error accurately; then, we identify the amount of rotating transformer harmonic error according to the convergence coefficient of the Characteristic Frequency observer and compensate the error of the resolver original angle measurement. Finally, this method is experimentally verified to significantly reduce the harmonic error of the resolver.