Research On Digital Signal Processing Technology In Servo System

With the development in digital control of motor drive systems,the demand of digital signal processing for motor drive system has attracted more attention.Whether real-time control functions,like the given control command and detection of feedback signals,or system analysis requirements,such as state observation and fault diagnosis,effective digital signal processing is necessary.In current digital signal processing researches for AC servo motor drive systems,the harmonic identification is usually done off-line.The accuracy of current harmonic suppression and the algorithm calculation speed do not meet the requirements,which restrict the application of digital signal processing technologies,and can't catch up high performance for motor drive system.In this thesis,digital signal processing application technologies are concerned for AC servo motor control system.Harmonic identification is realized by real-time fast Fourier transform.Meanwhile,high-order filters are designed to suppress harmonics and improve system stability.Specific signal components are extracted to provide valid data for system analysis.Firstly,the control structure of the motor drive system is described,and the demand for signal processing in digital control servo system is analyzed.On the one hand,considering the influence of harmonics on motor operation,it is essential for the stability and accuracy of motor drive system to detect and suppress harmonics efficiently in real time.On the other hand,monitoring and evaluating for system srun during the motor operation stage,so signal processing functions,such as signal extraction,transformation and analyzing,are necessary.Therefore,digital signal processing technologies for high accuracy design and digital realization methods in motor drive system are comprehensive analyze in this thesis,from the aspects of harmonic identification,harmonic suppression,signal extraction.Secondly,according to the requirements of signal analysis in motor drive system,the method and design law of fast Fourier transform are illustrated.In order to obtain the suitable harmonic suppression method,the commonly used filter functions are made the contrast by considering the characteristics of motor drive system.The direct discretization method converting analog low-pass filter to digital filter is explained,and a series of digital filters are used to implement signal extraction functions.The effectiveness of the design method is verified by comparing the simulation results in MATLAB and Modelsim environment.Finally,the experiment platform is set-up,and the control structure based on DSP and FPGA is applied.The design of digital signal processing function is made on FPGA in motor drive system.The validity of design is testified under different working conditions.The experiment results show that the proposed digital signal processing methods satisfy the requirements of the motor drive system.