Feasibility Assessment of Adaptive Sliding Mode Controllers for Grid-Tied Inverters with LCL Filter

This paper proposes a comparative performance analysis between two robust adaptive controllers grounded on Robust Model Reference Adaptive Control (RMRAC) and Sliding Mode Control (SMC) theories. Both controllers are totally developed on discrete-time domain. The first controller is an RMRAC integrated to an adaptive SMC, named RMRAC-SM, which has a first order sliding surface. The second controller is an RMRAC-based Super-Twisting Sliding Mode (STSM) Controller, named RMRAC-STSM. Both controllers were applied on grid-injected current control of a three-phase grid-tied Voltage Source Inverter (VSI) with LCL filter. Moreover, both structures were designed considering a reduced order plant model. Experimental results using a 5.4 kW VSI with LCL filter are presented to discuss the performance and robustness differences of proposed control structures. The main advantage of RMRAC-STSM in relation to the RMRAC-SM is the chattering smoothing, which reduces even more the tracking and augmented errors. It implies straightforwardly on power converter Total Harmonic Distortion (THD) decrease, which was 2.82% for RMRAC-STSM against 3.04% for RMRAC-SM.