METHOD FOR SENSORLESS ESTIMATION OF ROTOR SPEED AND POSITION OF A PERMANENT MAGNET SYNCHRONOUS MACHINE

摘要

A method for sensorless estimation of rotor speed and position of a permanent magnet synchronous machine, when the permanent magnet synchronous machine is fed with a frequency converter, the method comprising the steps of forming a stator voltage reference for the permanent magnet synchronous machine, injecting a high frequency signal (u_c) into the stator voltage reference, measuring a DC-link current (i_dc) of the frequency converter when the permanent magnet synchronous machine (4) is fed with a voltage (U_s,ref) corresponding to a sum of the stator voltage reference and the injected signal, calculating a stator current estimate (î_s), calculating a current error (ĩ_s) as a difference between the stator current estimate and the measured DC-link current, and estimating a rotor speed ({circumflex over (ω)}_m) and position ({circumflex over (θ)}_m) of the permanent synchronous machine based on the current error. The injected high frequency signal (u_c) comprises a direct axis component and a quadrature axis component, the direct axis component having a first frequency and the quadrature axis component having a second frequency, the first and second frequencies being different.