MTPA and FW based robust nonlinear speed control of IPMSM drive using Lyapunov stability criterion

This paper presents a robust nonlinear control technique for wide range speed operation of interior permanent magnet (IPM) synchronous machines based on the use of maximum torque per ampere (MTPA) and flux weakening (FW) controls. The global asymptotic stability of the drive is demonstrated by Lyapunov stability criterion in conjuncture with Barbalat's lemma. For the proposed nonlinear controller the MTPA and FW schemes are used to control the d-axis stator current below and above the rated speed, respectively. Control laws are developed based on adaptive backstepping technique to ensure robust system stability. The system nonlinearities are also accommodated through the online estimation of critical parameters. The control and adaptive backstepping laws have been successfully implemented in a MATLAB/Simulink simulation environment. Simulation results indicate robust speed tracking performance for the IPM synchronous motor ensuring global stability of the drive system.