Patent ID: 6954050

Claim:
A control method of a permanent-magnet type synchronous motor provided with a frequency arithmetic unit of alternating current fed to the motor so that axial displacement is reduced based upon the axial displacement of the permanent-magnet type synchronous motor and a power converter that feeds alternating current of a variable frequency and variable voltage to the motor according to d-axis and q-axis output voltage directions based upon its frequency direction and a rotational phase direction, comprising: a first step for operating axial displacement which is difference between the rotational phase direction and an actual rotational phase of the motor using a frequency or current information acquired from a control system as a first axial displacement signal; a second step for estimating axial displacement caused in the motor by a control response angular frequency in the frequency arithmetic unit as a second axial displacement signal; and a third step for inputting a third axial displacement signal acquired by adding the first and second axial displacement signals to the frequency arithmetic unit.