Adaptation of motor parameters in densorless PMSM drives

The paper proposes an on-line method for the estimation of the stator resistance and the permanent magnet flux in sensorless permanent magnet synchronous motor drives. An adaptive observer augmented with a high-frequency signal injection technique is used for sensorless control. The observer contains excess information that is not used for the speed and position estimation. This information is used for the adaptation of the motor parameters. At low speeds, the stator resistance is estimated, whereas at medium and high speeds, the permanent magnet flux is estimated. Steady-state analysis and small-signal analysis are carried out to investigate the parameter estimation, and adaptation mechanisms are defined for the parameters. The convergence of the parameter estimates is shown by simulations and laboratory experiments. The stator resistance adaptation works down to zero speed in sensorless control.