Multi-resonant current controller for grid-tied inverters with LCL filters based on pole placement under robustness constraints

In this paper, a multi-resonant current controller for grid-connected inverters with LCL filters is presented with the aim of improving the dynamic performance and robustness of inverter systems. A pole placement technique is used to calculate the controller parameters, allowing the closed-loop poles to be precisely placed to achieve the required performance and robustness. A new feedforward reference response forming method is also proposed to improve the reference tracking capabilities of the controller, and a new anti-windup algorithm is proposed to avoid the performance deterioration caused by the saturation of the multi-resonant controller. The effectiveness of the proposed controller is demonstrated using simulation results that confirm its robustness to parameter changes and disturbances, as well as its effectiveness in terms of current tracking. The functionality of the controller is also tested with a prototype inverter system, and the test results are presented to confirm the effectiveness of the controller.