| 摘要 |
PROBLEM TO BE SOLVED: To suppress the time width of a spike voltage, and prevent step-out and half of a brushless motor. SOLUTION: Flowing of an armature winding current of a brushless motor 4 is changed over by position detecting signals A, B, C, detecting the armature 4a of the brushless motor 4. When a control circuit 11 detects the end of a spike voltage, the circuit 11 detects an input current (motor drive current) of the equipment by a current-detecting part 10, and calculates the time width of the spike voltage. When the time width is at least a specific value, the on time width of the present chopping drive is decreased by a specific time, the present on time width is made equal to the upper limit time width, the present number of revolution is made equal to the upper limit number of revolution, and the detected motor driving current is made equal to the upper limit motor driving current value. Also when the time width of the spike voltage does not exceed a specific value, the on time width of the present chopping drive is decreased by a specific time, and a motor voltage is lowered, by compared results of the present on time width, the present number of revolution and the motor driving current with the upper limit time width, the upper limit number of revolution and the upper limit motor driving current value. The control circuit 11 calculates and updates the above specific values for every position detection. The specific values are calculated by the position detection interval time × 25/360. |
