An FPGA-based Closed-loop Approach of Angular Displacement for a Resolver-to-Digital-Converter

A closed-loop approach is proposed for the resolver-to-digital converter to obtain the accurate angular displacement. The proposed method can replace the analog conversion by efficient digital conversion with better accuracy. The approach is based on Co-ordinate Rotation Digital Computer (CORDIC) algorithm for fast calculation of trigonometric functions. This method employs two iterative strategies-direct iteration and continuous iteration to make the detection of the angular displacement fast. We analyze the discrete model using the iterative process, then implement and test on the FPGA Virtex-4QV. The design incorporates a photoelectric encoder and an FPGA which is feasible in high-temperature engineering applications while providing a better accuracy and high speed.