Exactly decoupled robust passivity-based control of PMSM based on Luenberger observer

This paper addresses the problems of uncertainties in practical permanent magnet synchronous motors (PMSM) and the inexactly decoupling of passivity-based controller (PBC), and proposes an exactly decoupled robust passivity-based current control strategy based on observer as a solution. The passivity-based controller is designed by using the energy shaping and damping injection method based on a three-phase PMSM Euler-Lagrange (EL) model with uncertainties. This controller, however, cannot restrain the fluctuations when parameters variations occur in the actual system and have a poor decoupling characteristic. To overcome these problems, a new Luenberger observer is designed for the approximately decoupled PMSM model to observe the uncertainties caused by parameter variations, and the errors caused by imperfectly compensation of passivity-based controller to the coupling voltage and back-electromotive force (EMF). The output of the observer will be used for the calculation of the reference voltages by a feedforward control. Simulation has proved that the new observer is superior to conventional observer. The effect of coupling caused by imperfectly compensation has been eliminated, and the exactly decoupled robust control of current loop has been achieved.