New repetitive control system of PWM inverters with improved dynamic performance under nonperiodic disturbances

Although repetitive controlled PWM inverters present an excellent steady-state performance even under severe nonlinear cyclic loads, they do not present a good dynamic performance under nonperiodic disturbances. Aiming to solve this problem, this paper proposes an algorithm for improving the transient response of repetitive controlled PWM inverters under nonperiodic disturbances, such as sudden linear load changes or removal of a nonlinear cyclic load. The proposed algorithm is based on the analysis of the output error behavior to identify the occurrence of a nonperiodic disturbance. Once identified the occurrence of this disturbance, it is possible to reset the repetitive control action so that the repetitive controller can storage the correct information concerning this new load. Simulation and experimental results are presented (1 kVA @ 110 V_RMS) to illustrate the good performance of the proposed algorithm under different load conditions.