| 摘要 |
PROBLEM TO BE SOLVED: To provide a novel signal processing device capable of avoiding significant reduction of accuracy in demodulating rotation angle information of a rotor 10a.SOLUTION: A microcomputer 30 has an A/D converter 48 for sampling modulated waves Sin and Cos, each obtained by amplitude-modulating an AC excitation signal Sc according to a rotation angle &thetas; of the rotor 10a, and the excitation signal Sc at a predetermined sampling interval. The microcomputer 30 is also equipped with an angle computation unit 62 which computes the rotation angle &thetas; through detection based on a plurality of sampled modulated waves Sin and Cos and excitation signal SC. The phase of the excitation signal Sc is shifted such that the sampling timing for the excitation signal SC does not coincide with a period in which an absolute value of a reference REF is equal to or less than a predetermined value by performing phase shift processing which changes a comparison value in a PWM signal generation unit 32. |
