Research on Dual-Loop Digital Control for PWM Inverters

This paper focuses on the research of dual-loop digital control for PWM inverters. A method based on pole assignment is proposed to tune the control parameters. To avoid one-timestep delay caused by the sampling and calculating time of digital processors, design of state observer and disturbance observer are brought in. Due to the ripples of DC voltage and dead time effect, an un-neglected predict error of state observer will presents. To overcome the predict error, a repetitive compensator is added to the state observer, and its nice performance is proved by both simulations and experiments. The experiment results are presented also to show nice steady state characteristics and fast transient response of the proposed control system.