| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of the stepping out of a motor, even if an excitation phase is shifted because of a power source is turned off by matching the excitation phase, before the motor is rotated, when the power source for supplying motor is shut down. SOLUTION: When the turning off state of the power source has occurred, processing to the step S12 is taken place. In the step S12, A- and B- shases are energized at a frequency exceeding a self-starting frequency and being sufficiently lower than a normal frequency. Processing is shifted to the step S13. The steps S13-S15 have a sequence of phase matching operations like the step S12 and B- and /A-phases, /A- and /B-phases and /B- and A-phases are energized at the same frequency as that in the step S12, in the steps S13, S14 and S15 respectively, to establish the excitation phase. Thus, the excitation phase is established so that when the motor is one having required torque, the stepping out can be prevented. Since it is discriminated that a door is opened or not, a sequence of starting operations can be made an optimum one. |
