| 摘要 |
PURPOSE:To control accurately the speed and the stopping position of a DC brushless motor in its low-rotational-speed region, by providing respectively control regions in its low-speed regions in the cases of its positive rotation and inverse rotation, and by holding respectively its signal levels in its command levels according to its rotational directions when the speed of the motor escapes from the control regions, and further, by switching alternately its signal level to the levels specified in its positive-rotation and inverse-rotation command times when the speed of the motor remains in the control regions. CONSTITUTION:To an output control part 6, one of a rotation command signal Cr and a stop command signal Cs, a rotational-speed command Sn, a rotational-direction command Sc' and a signal Vn fed from a rotational-speed sensor 5 are inputted respectively. To a drive circuit 402, a pulse width modulation signal Wm and a rotational-direction command signal Sc are given respectively. In a motor drive part 4, the two sets of switches Tu-Tw and Tx-Tz are provided respectively. In the drive circuit 402, according to the level of the rotational-direction command signal Sc and the levels of signals eu-ew fed from a position sensor 3, the pulse width modulation signals Wm are given respectively to one of the switches Tu-Tw and one of the switches Tx-Tz, while the combination of the foregoing two switches is changed in succession. Then, the excitation current for the positive or inverse rotation of a DC brushless motor is made to flow in the motor. Thereby, without any reception of the effects of the operating delay times of the switching elements, the rotational speed of the DC brushless motor can be adjusted precisely. |
