Patent ID: 7323840
Filing Date: 2008-01-29
Classification: H02P

Abstract:
1. A magnetic-pole detecting system for a synchronous AC motor, comprising: a synchronous AC motor having phase coils either in a moving element or in a stator; a position-detecting means for generating a position-detecting signal to detect positional relationship between the moving element and the stator; a movement-determining means for generating a movement signal upon determining that the moving element has moved, based on the position-detecting signal from the position-detecting means; a current command generating means for generating a first current command signal for making a plurality of different-phase currents flow so that the moving element moves to a plurality of stable points, and for generating a second current command signal that makes currents flow, the currents having a phase that makes the moving element move in reverse to the direction in which the moving element has moved based on the first current command signal; a current controlling means for making the currents flow in the phase coils, based on the first and the second current command signals; a current cut-off means for cutting off the currents flowing in the each-phase coils, based on the movement signal from the movement-determining means; a reversal-determining means for determining, based on a detection value from the position-detecting means, the direction in which the moving, element has moved based on the first current command signal, and for determining that the detected direction has reversed between previous and present instances; and a stable-point simulating means for simulating the position of the moving element by means of the stable point determined by the phase of the first current command signal when the reversal-determining means has detected a reversal, or by the phase prior to the phase at the reversal.