A High Precision Resolver-to-Digital Conversion Method with Pre-filtering DDSRF Used in Electric Vehicle

Resolver is extensively used as absolute position sensor in many electric transportation applications, such as electric vehicles. Resolver output signals are sine and cosine waves coupled by high-frequency excitation signal, which contains angular position information. Due to the resolver manufacturing tolerance and installation eccentricity, the unexpected amplitude imbalance, offset error and quadrature error occur, which influences the accuracy of angle measurement. The traditional angular tracking observer (ATO) is sensitive to such errors and led inaccuracy in angle and speed measurement. In this paper, the resolver output signals are reconstructed by multiplier with excitation signals. The adaptive band-pass filter is designed to eliminate offset error and high frequency excitation components. The double decoupled synchronous reference frame (DDSRF)-ATO is then proposed to eliminate the amplitude imbalance and quadrature error. The simulation results reveal that the proposed Pre-filtering DDSRF can easily cancel the related error and improve accuracy of resolver-to-digital conversion.