| 摘要 |
A shutter operating alternating current motor has forward and reverse windings (2A,2B), a coupling capacitance (7) and electronic selector switches (8A,8B). The motor voltage and current are detected (9, 10, 13) and their phase difference measured (11). The actual phase difference at any time is compared (12) to a reference value and used to stop the motor at the end of travel |
