SLAU958A January 2025 – March 2025 MSPM0G3507
In applications similar to home appliances, mechanical sensor adds to cost, reliability and maintenance. In general, Sensorless based rotor position estimation methods are employed to efficiently drive the motor in applications where ultralow speed operation is not a requirement. To detect the rotor position in sensorless methods, BEMF of the motor is estimated through various methods and there by the rotor speed and angle are approximated. In the Universal Motor Control Application code, user has option to select either of Sliding Mode Observer or the Finite difference BEMF Estimation methods.The sliding mode observer is commonly utlized due to reliability and robustness against system parameter variations. The finite BEMF estimation is simple equation based BEMF estimation without sliding mode controller and filter for BEMF, this eliminates the Kslide tuning and filter tuing but BEMF is prone to noise and can create stability issues . Estimated BEMF's from both of the methods are used for rotor position tracking using a PLL as detailed below.

SMO based BEMF estimation is chosen as default by keeping the predefined symbol "ESMO_ESTIMATOR. To select the Finite difference equation based BEMF estimator, user can modify this predefined symbol to ESMO_ESTIMATOR_N from the CCS project settings as below.
