Design of plug-in repetitive controllers for single-phase PWM inverters

This paper presents a design procedure of discrete-time plug-in repetitive controllers for single-phase PWM inverters. The presented methodology can be applied to inverters with different servo controller and takes into consideration the most usual nonlinear cyclic loads. The basic principles of the repetitive controllers used in PWM inverters are discussed as well as the design guidelines to obtain a stable closed-loop controller with suitable steady-state performance and improved rate of convergence. To illustrate the proposed procedure is presented a design example of repetitive controllers using a PID-feedforward as the servo controller. Experimental results have been provided to show the response of the controllers under different load conditions.