| 摘要 |
It makes possible to control a movable element to be smoothly movable by a sensor-less vector control in an equal speed area, without using a position sensor, and possible to perform a stop control and control it in a low speed area. In a case when a moving speed of the armature is faster than a predetermined speed preliminarily determined within a range in which the movable element is moved in synchronous with movement of the magnetic field generated by the armature by a predetermined sensor-less vector control, the current passing through the armature is controlled by the sensor-less vector control, and in a case when the moving speed of the armature is slower than the predetermined speed, in a d-q coordinate in which a d-axis represents a direction of a flux generated by field and a q-axis represents a phase advanced by &pgr;/2 with respect to the d-axis, a d-axis armature current and a q-axis armature current are controlled so that a d-axis electric angle is produced, and current passes through the d-axis armature and does not pass through the q-axis armature.
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