Design Equation for Directly Computing Two Gains of PR Controller

This paper formulates the design equation which directly computes two gains of the proportional-resonant (PR) controller regulating grid current emitted from single-phase PWM inverter with passive LCL filter. Such a control system that is without grid-voltage sensing becomes the sixth-order one. Thus there is inconvenience against tuning the controller gains and it is also rather impractical to tune them by trial-and-error. When the PR gains are two unknowns, partial pole assignment and consideration over the closed-loop characteristic equation dispense the design equation which provides more effectiveness of tuning them. Simulations assert that utilization of the proposed design equation is able to enhance performance of response.