A novel scaling method for sinusoidal quadrature encoder

This paper presents a novel scaling method for sinusoidal quadrature encoder without look-up table (LUT). A high-order sinusoidal carrier and a sawtooth serving as the LUT are generated in the DSP to detect the phase of the sinusoidal encoder signal. The scaling process is described in detail. And the principle to generate the discrete sinusoidal carrier is also illustrated. After that, the factors that decide the scaling resolution are analysed and the requirement to antialiase at high speed is deduced. Finally, the proposed method is implemented and verified by the results on a DSP controlled permanent magnet synchronous motor with an incremental encoder ERN487 from HEIDENHAIN.