Rotor Position Estimation Based on Fast Terminal Sliding Mode for Magnetic Suspension Centrifugal Compressor Drives

This article establishes a novel fast terminal sliding mode observer (FTSMO) with chattering suppression and finite-time convergence of state variables for the speed and position estimation in sensorless drives of magnetic suspension centrifugal compressors (MSCCs). First, a fast terminal sliding mode (TSM) function is established, which converges faster and overcomes the difficulty of solving the power function when the traditional TSM variable is negative. Second, an extended back electromotive force (back EMF) observer with equivalent proportional integral control law is designed to suppress chattering without a low-pass filter based on the fast TSM function. Then, the stability of the FTSMO is proved by Lyapunov's second theory. Finally, the comparative experiments are performed on a 1.2-kW/90000-r/min MSCC test platform. The steady-state and dynamic experiments indicate that the FTSMO has a better performance on chattering suppression and rotor position estimation compared to the conventional sliding mode.