| 摘要 |
PROBLEM TO BE SOLVED: To detect magnetic-pole position of a rotating body, without being influenced by an offset. SOLUTION: Three-phase magnetism detection signals, whose phases are shifted by 120 deg., are output to a digital conversion part 101 according to the rotation of a rotor 1A. Deformation of the three-phase signals is corrected by a correction part 102. In a signal selection part 103, a maximum signal and a minimum signal are selected from the three-phase signals, and an H-level signal and an L-level signal are allocated respectively. In a mean-value computing part 104, the mean value of the signals to which the level signals are allocated is computed. In a signal comparison part 106, the remaining signals are compared with a mean-value signal, and the level signals are allocated. In a relative magnetic-pole position computing part 105, a relative magnetic pole position within an angle range is detected by the mean-value signal. In an absolute magnetic-pole position detection part 107, the angle range is specified by the three-phase level signals, and an absolute magnetic pole position is detected by the relative magnetic pole position. |
