Angle decoding method of rotary transformer in electric power steering system

The invention discloses an angle decoding method of a rotary transformer in an electric power steering system. A primary winding and two secondary windings are arranged on the rotary transformer; and the two secondary windings are mechanically staggered at 90 degrees. The angle decoding method comprises the following steps of (S1) obtaining cosine analogue voltage signals Va and Vb of the primary windings by using an AD sampling module, and transforming and outputting two digital voltage signals; (S2) carrying out inverse tangent operation on transformed cosine digital voltage signals by using an FPGA hardware resource on the basis of a CORDIC algorithm and decoding to obtain a position angle of a rotary transformer rotor; and (S3) outputting the position angle obtained through decoding to an EPS controller as an angle feedback input signal. By adopting discrete devices of the FPGA, an AD conversion chip and the like, the analogue signals output by the rotary transformer are processed on the basis of the CORD