An Optimal Sliding-Integral-Derivative (SID) Control of a Grid-Tied Multilevel Inverter under Parameters Mismatch

This paper presents an optimal sliding mode control technique for a single-phase seven-level Switched-Capacitor inverter in grid-connected mode. The utilization of the proposed control makes it possible to properly supply the output changes under parameters mismatch. To this end, the current dynamics of the multilevel inverter are used to develop a closed-loop control description aiming at the assessment of a transfer function. Using the second-order responses of the converter currents, a cost function is minimized to achieve optimal values for the Sliding-Integral-Derivative control coefficients. Using the damping ratio and the cost function, a regulation coefficient is defined, and eventually, the variation trend of the coefficients is also evaluated through the stability margin improvement of the converter. The proposed control algorithm has good dynamics in transient load change condition with parameters mismatch. Eventually, this control algorithm is validated by simulation in the MATLAB SIMULINK environment and experimental results.