Abstract
Abstract Resolver-to-Digital Converter (RDC) can offer accurate position information and has been applied to many industrial applications. The accuracy of a RDC depends on the signals of position sensor, but no sensor generates ideal signal in reality. The main non-ideal characteristics of position sensor signals are: imbalanced amplitude, imperfect quadrature, noticeable dc offset and harmonics distortion. This thesis presents a wavelet transform based RDC design to reduce the error caused by these non-ideal characteristics. The wavelet transform has good properties both in time and frequency domain and is capable of multi-resolution analysis (MRA). The wavelet transform can effectively reduce the dc offset and harmonics distortion. Then combing with the gain-phase correction scheme can eliminate the imbalanced amplitude and imperfect quadrature further. After this processing, an error compensation table can be built upon to provide a real-time error compensation. This is a self- calibrating scheme. The plant under study in the thesis is the spindle of an optical disk drive. The position sensor of the spindle is three Hall sensors with 1200 apart spatially. First, an experiment platform and peripheral circuits were devised. Then a RDC was implemented utilizing the CPLD (Complex Programmable Logic Device). The signals of Hall sensors were processed adopted using wavelet transform to eliminate the non-ideal characteristics. Thus the accuracy of RDC can be enhanced. Experiments were performed to show its efficacy.