The invention discloses a method for determining an initial
position angle of a rotor of a permanent-magnetic
synchronous motor. The method comprises the steps of: inputting a high-frequency rotary
voltage vector
signal with an amplitude value as U, an
angular frequency as
omega and an
initial phase position as thetaci to obtain an alpha-axis current ialpha and a beta-axis current ibeta; converting the ialpha and the ibeta into a coordinate which rotates synchronously for the
angular frequency omega to obtain a d-axis current id and a q-axis iq; performing low-pass filtering on the id and iq to obtain Idf and Iqf; calculating a predicted value thetari of the initial
position angle of the rotor by utilizing a formula; inputting a
pulse voltage vector in the
stator winding, wherein the angle is equal to thetari; obtaining the d-axis current and an integral under the action of the
pulse voltage vector, thereby obtaining sigmaI0; after 3 ms-10 ms, inputting another
pulse voltage vector to the
stator winding, wherein the angle is equal to thetari plus 180 degrees; obtaining the d-axis current and an integral under the action of the other pulse
voltage vector, thereby obtaining sigmaIpi; and comparing the absolute values of the sigmaI0 and the sigmaIpi, wherein if the absolute value of the sigmaIpi is greater than the absolute value of the sigmaIpi, the initial
position angle of the rotor is equal to thetari; otherwise, the initial position angle of the rotor is equal to thetari plus 180 degrees. The method for determining the initial position angle of the rotor of the permanent-magnetic
synchronous motor, disclosed by the invention, has the advantages of simple treatment process and high detection precision.