Multiple-Complex-Vector-Filter-Based Phase-Locked Loop Synchronization Technique for Seneorless Linear Induction Motor Drive System

The conventional synchronous reference frame phase-locked loop (SRF-PLL)-based speed estimation scheme is commonly applied in the speed-sensorless drive system. However, the inability in accurately tracking speed during the acceleration/deceleration process is a drawback of the SRF-PLL scheme. To tackle this issue, this digest proposes a new-PLL-based scheme for speed-sensorless linear induction motor (LIM) drives. The proposed scheme has two components: (1) the multiple-complex-vector-filter and the amplitude normalization are provided to reject the disturbing effect; (2) a new PLL is used for enforcing the estimated speed information. Simulations are implemented to demonstrate the speed scheme in LIM speed-sensorless systems.