| 摘要 |
PROBLEM TO BE SOLVED: To attain a finer rotational angle resolution of rotor as compared with a case where a motor is driven only through two-phase excitation by switching the driving frequency when the motor is driven through combination of two-phase excitation and when the motor is driven through combination of two-phase and single-phase excitation. SOLUTION: A shaft 302 is inserted into a synchronous motor 301 and telescoped according to the rotation thus opening and closing a valve 303. The synchronous motor 301 is fed with a motor drive signal in synchronism with the driving period and the rotor is shifted to a stop position corresponding to each drive pattern. The motor is driven with two-phase excitation until a slice level spaced apart specifically from a target position is reached and then driven with 1-2 phase excitation at lower rate than the driving period of two-phase excitation until a target value is reached. Since the motor is driven with 1-2 phase excitation when the target value is approached, a finer rotational angle resolution of rotor can be attained as compared with a case where the motor is driven only through two-phase excitation. |
