Research On Method Of Resolver Decoding Based On Single Vector S Transform

With the wide application of modern AC servo motor,AC servo control technology has become one of the supporting technologies of industrial automation.The sensor is an important part of the servo system.The accuracy and reliability determine the performance of the servo system.As displacement and speed sensor,The resolver can satisfy the needs of measurement of angular displacement and angular speed in harsh environment and complex conditions but resolving the output of the analog signal with high precision and low cost is still a problem.This paper targeted the signal decoding of resolver,proposing a signal decoding algorithm based on single vector S transform(SVST),which provides a new reliable scheme for the software decoding of resolver signals.According to the single-frequency and non-stationary characteristics of the resolver signal,this paper draws on the idea that the incomplete S-transform only calculates the eigenvectors for the main frequency.It proposes to use SVST to extract the mode envelope of the resolver’s signal,which lays a foundation for the subsequent decoding algorithm.Firstly,in order to meet the accuracy and real-time of decoding,the two key problems of single vector S transformation are solved,including the determination of the optimal window width coefficient of SVST kernel function and the elimination of SVST end effect.In this paper,by analyzing the influence of different window width coefficients on the flatness and transition time of the modulus vector,the relationship between the optimal window width coefficient and the signal length is derived by combining the SVST kernel function expression.Furthermore,the SVST end data is discarded by the splicing and rounding method to solve the problem that the mode envelope is not accurate due to the end effect.Secondly,according to the modulus vector of the two output signals of the resolver obtained by SVST,the quadrant information is obtained by using the excitation signal of the resolver and the polarity of the two output signals to obtain the quadrant information,and the veracity of the angle value is obtained by the inverse tangent method and the angle correction.On this basis,in order to verify the validity of the method in this paper,the decoding precision of the revolving transformer decodingmethod designed by the paper under various working conditions is verified by MATLAB simulation software.Finally,building a hardware test platform by using the TMS320F28335 DSP chip as the core of the decoding system to realize the application of the proposed method in the actual environment.The accuracy and real-time performance of the proposed method are verified by comparing the results of the motor speed set by the inverter.In this paper,the effectiveness of the proposed method is verified under various speed conditions and different signal-to-noise ratios.The static test results show that the absolute error of the proposed method is less than 0.025°,and the physical experiment results show that the system meets accuracy and real-time technical indicators of the actual operating conditions for the decoding system.