| 摘要 |
PURPOSE:To improve a degradation of the performance of a motor, which is generated at the time of starting the motor, etc., using no expensive absolute value encoder of a high resolution, by judging a motor current to be increased or decreased, and by changing the initial value of a ROM, which issues a current command, in the direction of the motor current decreasing. CONSTITUTION:A counter starts in response to a signal CS and counts encoder pulses EC appearing during the period defined by the signal CS. The output of the counter 30 is used as a lower order address AdL of a ROM 50. Further, after converting a sensed value Iman of a motor current into a digital signal Imd by an A/D converter 20, the digital signal Imd is inputted to a circuit 40 for setting an initial value, and set is the initial value for counting an indeterminate term of a rotor position which extends until the change of signal CS is sensed. In the circuit 40 for setting the initial value, the count value corresponding to the half of the angle of a rotor position being resolved, is outputted, and the motor current at this time is measured. Then, the count value is changed, and the motor current is measured similarly. When the count value corresponding to the minimum motor current is generated, the operation of setting the initial value is completed. |
