Came from the principle of brushless doubly-fed machine, combined the space vector pulse width modulation, modeled bidirectional PWM converter with unity power factor and feed-forward decoupling control using MATLAB/SIMULINK, studied the simulation characteristics, the results confirmed the correctness and effectiveness of the model, and provided reference for further research of the control scheme.

In order to ensure the real-time tracking of weld ultrasonic testing, applied CCD weld image sensor image, through image processing technology, used homomorphic filtering, two value methods to pre-process the image acquisition, extracted image feature information used region growing and linear regression method, and thus determined the edge weld, after A/D conversion, got feedback of the voltage signal position deviation amount, controlled servo motor drive the bracket to move, ensured effective tracking ultrasonic tester. Through simulation, verified the accuracy and feasibility of the image processing algorithm,which got ideal effectused in the practical application.