| 摘要 |
PURPOSE:To make a magnetic sensor unnecessary by causing a cosine wave current having a given phase and the same magnitude to flow through two windings out of three-phase windings at the time of starting an apparatus and thereafter applying a given three-phase AC. CONSTITUTION:When power is applied at the time of starting an apparatus, an initializing circuit 27 specifies the address of ROM 25 so that said ROM supplies a cosine current having a given phase in the phase U and phase V of a linear three-phase synchronous motor and the same magnitude. Further, said circuit 27 outputs a thrust command to an adder 29. Thus, a movable element equipped with a primary side winding is positioned at a constant place relative to a secondary side magnetic pole. After that, a current output command is stopped and a counter 23 is preset. Then, a speed command is outputted to a comparator 19 to start the motor to operate a position feedback loop. |
