Modified Model Predictive Control of a Bidirectional AC-DC Converter Based on Lyapunov Function for Energy Storage Systems

Energy storage systems have been widely applied in power distribution sectors as well as in renewable energy sources to ensure uninterruptible power supply. This paper proposes a modified model predictive control (MMPC) method based on the Lyapunov function to improve the performance of a bidirectional ac-dc converter, which is used in an energy storage system for bidirectional power transfer between the three-phase ac voltage supply and energy storage devices. The proposed control technique utilizes the discrete behavior of the converter, considering the unavoidable quantization errors between the controller and the control actions selected from the finite control set of the bidirectional ac-dc converter. The proposed control method reduces the execution time delay by 18% compared with the conventional model predictive control. Moreover, the nonlinear system stability of the proposed MMPC technique is ensured by the direct Lyapunov method and a nonlinear experimental system model. Detailed experimental results with a 2.5-kW downscaled hardware prototype are provided to show the efficacy of the proposed control system.