Design and implementation of H∞ controller for three-phase PWM rectifiers

For the three-phase pulse-width modulated (PWM) rectifiers, the controller's performance can be influenced by the mathematic model error, parameter variation and external disturbances, etc. This paper presents a robust H∞ control method for the PWM rectifiers to improve the control performance. The outer voltage loop controller and the inner current loop controller are designed separately. Based on the mathematical model of the PWM rectifiers, state equations of the voltage and current loop are established separately for the standard setup H∞ control problem with suitable weighting functions. In order to derive the algorithm of the designed controllers, the Riccati equations are solved separately. Simulation results demonstrate that the designed H∞ controller is suitable for the PWM rectifiers and has a better external disturbance rejection capability compared with the conventional PI controller.