Method of estimating initial pole position of permanent magnet brushless motor

Abstract

In order to estimate a magnetic pole position of a permanent magnet type brushless motor, the following steps are conducted. A given γ axis and a given δ axis in an advanced from the γ axis by an electrical angle of 90° are set. A closed-loop electric current control system in the γ axis direction is formed while forming an open-loop electric current control system in the δ axis direction. It is calculated an interference current generating in the δ axis direction when a current command in the γ axis direction is given as a stepwise alternating current command. The γ axis is finely advanced by an angle of Δθ when a sign of a product of an integral value of the interference current and a value of the current command in the γ axis direction is positive. Alternatively, the γ axis is finely delayed by an angle of Δθ when the sign is negative. Thereby, the γ axis is made accord with either a d axis as a true magnetic axis or with a -d axis advanced by 180° from the true magnetic axis.

Dependencies are inferred from the claim text.