Patent ID: 8593087

Claim:
A magnetic pole position estimation method for an AC synchronous motor that controls a relative position or relative speed of a motor mover by inputting into a position/speed control unit a value sensed by a motor sensor, performs coordinate transformation, in the use of a pole-error estimation value that the position/speed control unit outputs, of phases of currents or voltages applied to the motor, and estimates a motor magnetic pole position being a relative position of the motor mover by making the pole-error estimation value approximate a true pole-error value that is the difference between the motor magnetic pole position being the relative position of the motor mover and a target magnetic pole position being a target relative position of the motor mover, the method comprising: a first pole-error inputting step of inputting a first pole-error estimation value whose phase is shifted by +α from a reference phase; a forward movement step of making the pole-error estimation value approximate the true pole-error value, in the use of a value sensed by the motor sensor when the relative position of the motor mover is moved forward by the first pole-error inputting step; a first phase movement storing step of storing a first pole-error-estimate convergence value that is a phase when relative movement of the motor mover has converged in the forward movement step; a second pole-error inputting step of inputting a second pole-error estimation value whose phase is shifted by −a from the reference phase; a backward movement step of making the pole-error estimation value approximate the true pole-error value, in the use of a value sensed by the motor sensor when the relative position of the motor mover is moved backward by the second pole-error inputting step; a second phase movement storing step of storing a second pole-error-estimate convergence value that is a phase when relative movement of the motor mover has converged in the backward movement step; and a pole position estimating step of estimating the true magnetic pole position on the basis of the pole-error-estimate convergence values stored in the first phase movement storing step and the second phase movement storing step.