Sensorless control method and system for permanent magnet synchronous motor

The invention discloses a sensorless control method and system for a permanent magnet synchronous motor, and relates to the technical field of permanent magnet synchronous motor control, and the method comprises the steps: carrying out the data collection, building a current equation and a back electromotive force equation of a surface-mounted permanent magnet synchronous motor under a static coordinate system, and carrying out the correlation; according to the current equation and the counter electromotive force equation, on the basis of a traditional sliding-mode observer, designing a counter electromotive force adaptive rate, and observing the counter electromotive force in a static coordinate system; and designing a parameter adaptive phase-locked loop according to the observed back electromotive force, calculating the rotor angle and speed of the permanent magnet synchronous motor by combining an adaptive sliding-mode observer, and feeding the rotor speed back to a speed loop to form speed closed-loop co