| 摘要 |
PURPOSE: To determine a mechanical angle of a rotor by providing a resonance tank circuit using one phase coil of motor as a variable inductance and detecting changes in the output amplitude of the resonance tank circuit due to a difference between the resonance frequency of the resonance tank circuit and frequency of a signal supplied. CONSTITUTION: A low power signal in a frequency of F1 is supplied to resonance tank circuits 59a to 59d , including phase coils A1 to D2 of an SR motor 15. Here, effective inductance of the phase coils A1 to D2 changes, depending on the change of a mechanical angle of a rotor 17, and thereby a resonance frequency F0 of the resonance tank circuits 59a to 59d also changes between maximum and minimum values. When the difference between the resonance frequency F0 and frequency F1 is minimum, outputs of the resonance tank circuits 59a to 59d become maximum. As explained, position of the rotor 17 can be analyzed through a relationship between the periodical changes of the resonance frequency F0 and the mechanical angle of the rotor 17. Moreover, changes in the amplitude of an output signal is detected, and the firing angle of each phase can be controlled using the result detected. |
