Complete decoupling and accurate maximum torque current ratio control method for permanent magnet synchronous motor

The invention discloses a complete decoupling and accurate maximum torque current ratio control method for a permanent magnet synchronous motor. The method comprises the following steps: acquiring three-phase stator current and electrical angle of a motor in real time and converting the three-phase stator current and electrical angle into dq-axis stator current and electrical angle speed; establishing an extended sliding-mode observer, inputting dq-axis stator current and electrical angular velocity, outputting observation values of dq-axis coupling term disturbance quantity, and performing superposition of coupling terms to obtain coupling terms after dq-axis compensation; the actual value of the dq-axis inductance is obtained after inductance variable quantity calculation, the given value of the dq-axis current is obtained through a maximum torque current ratio method, the given value is input into a dq-axis current regulator after superposition, the given value of the dq-axis voltage is obtained after the