Control Strategy Based on Improved Sliding Mode Control for T-type 3L PV Grid-connected Inverter

Abstract

This paper analyzes the mathematical model and working principle of a T-type 3 L PV inverter and introduces the control structure of a grid-connected PV inverter. In view of the influence of the sliding mode controller (SMC) rooted on the traditional reaching law (RL) on the control performance for grid-connected PV inverters as the current inner loop, such as large THD, this paper proposes a novel RL in the inner loop SMC to improve the tracking effect and robustness of the controller. The design method of each link of the SMC based on the proposed novel RL is described in the paper. Then, the stability analysis of the improved SMC is carried out. The experiment has been carried out on the experimental operating platform of the T-type 3 L PV grid-connected inverter system. The experimental results allow expressing that the designed control strategy can modify the dynamic performance of the system, reduce the harmonic distortion rate of the incoming current, and maintain the system with strong anti-interference capability under the premise of making the PV power generation system operate stably.