| 摘要 |
PURPOSE:To avoid the sudden fluctuation of a motor current caused by the interruption of feedback by a method wherein a detected current value is held at the time of the input of a driving phase switching timing signal and the detected current value is fed back as a virtual current value and the momentary interruption of the motor current caused by the driving phase switching is made not to be fed back and the current at that moment is continuously controlled. CONSTITUTION:A sample holding signal having a short pulse width is supplied to a sample holding circuit 22 at the time of switching of the driving phase of a motor coil. A motor current detected value is sampled in the rising period of the sample holding signal and the sampled value is held until the rise of the sample holding signal is finished. Therefore, a current detected value immediately before the decline of the motor current is sampled and, further, the value is held until the switching of the driving phase of the motor coil is stabilized. With this constitution, a signal having almost no level fluctuation is taken out from the sample holding circuit 22 as a current feedback value. |
