The invention provides an initial positioning method for a permanent-
magnet synchronous motor. The method includes that a
rotary transformer, a rotation-digit conversion module and a level conversion module are additionally arranged, wherein a
stator winding and a rotor winding of the
rotary transformer are respectively fixed on a
stator and a rotor of the permanent-
magnet synchronous motor, the
stator winding comprises a primary winding and a secondary winding, the rotation-digit conversion module provides
exciter signals for the primary winding and converts envelop signals output by the secondary winding into absolute angle signals, the rotation-digit conversion module communicates with a main processor of a
system through the level conversion module, when the
system is powered on initially, the rotor stops in the position of an angle of 0 degree, and the main processor acquires the initial angle A0 of the motor, then the permanent-
magnet synchronous motor runs in a closed-loop
vector mode, the main processor acquires an absolute angle Ax of the motor, and the
position angle of the rotor of the permanent-magnet synchronous motor satisfies the equation that theta=Ax-A0, every time the
system is powered off, the current
position angle of the rotor is stored, and when the system is powered on again, the current
position angle of the motor is taken as an initial angle.