Application of Multivariable PI-based Current Controller in Decoupled Control of Nonlinear Loads

This paper investigates the control strategies of voltage source converters (VSCs) where supply nonlinear loads. Two conventional and multivariable PI-based current control strategies for VSC to drive a nonlinear industrial load like an induction machine during start process have been adopted. The transient response and steady state error of the conventional and multivariable controller has been evaluated against the entrance of a nonlinear load. Contrary to the conventional PI-based controllers which utilize the feed-forward signals, the multivariable PI controller adopts integrators to minimize the effect of coupling terms of d-q current components. Therefore, the decoupled control of d-q components of the current is resulted. Thus, for instance independent control of flux and torque of the induction machine as a nonlinear load could be obtained. The superiority of the multivariable control strategy has been shown because providing fewer transients and achieving zero steady state error very sooner than the conventional approach

Keywords:

voltage source converter , nonlinear load , induction machine , multivariable controller