Hi Mr. Kumar,

As we that the initial rotor position is required for Field Oriented Control (FOC) of PMSM drives. There are some sensorless rotor position estimation methods which can detect the initial position for the FOC control of PMSM. Here are some reference:

[1] S. Nakashima, Y. Inagaki, and I. Miki, “Sensorless initial rotor position

estimation of surface permanent magnet synchronous motor,” IEEE Trans.

Ind. Appl., vol. 36, no. 6, pp. 1598–1603, Nov./Dec. 2000.

[2] M. Tursini, “Initial rotor position estimation method for PMmotors,” IEEE

Trans. Ind. Appl., vol. 39, no. 6, pp. 1630–1640, Nov./Dec. 2003.

Hope this can help

Regards,

Rotor position is essential for vector control of PMSM otherwise the response of the system will deteriorate and give erroneous results.