Permanent magnet synchronous motor speed loop control method and system

The invention discloses a permanent magnet synchronous motor speed loop control method and system, and the method comprises the steps: building a surface-mounted permanent magnet synchronous motor mathematical model and a kinematical equation under a synchronous rotating coordinate system according to the structure parameters of a surface-mounted permanent magnet synchronous motor, the internal parameter error of the motor, and load disturbance change data; bounded variables are preset, a mathematical model and a kinematics equation of the surface-mounted permanent magnet synchronous motor are improved in combination with the bounded variables, and a nonlinear expansion state observer is designed according to an improvement result; and the difference value between the expected rotating speed and the actual rotating speed of the surface-mounted permanent magnet synchronous motor is obtained, a superhelix integral sliding mode speed controller is designed according to the difference value, and the speed of the