Disturbance Observer-based Sliding Mode Control of PV-Battery Assisted EV Charging Station

This article presents a grid integrated single-stage solar photovoltaic system supported with a battery energy storage to charge the battery of an electric vehicle. An efficient energy management system based on the state of charge, generated SPV power, and total load demand is designed for battery energy storage. Each connected EV can choose to operate either in grid-to-vehicle or vehicle-to-grid mode without affecting the DC link voltage. Deficient power is taken from the grid and surplus SPV power is fed into the grid at unity power factor, where the grid-connected converter control plays a significant role. Sliding mode control (SMC) with an improved reaching law is implemented for DC link voltage and grid-connected converter current control. Model uncertainties and mismatched disturbances are estimated using a nonlinear disturbance observer (NDO). The NDO based SMC is compared with conventional SMC and linear PI control under various transient scenarios. The Lyapunov candidate function determines the stability of the proposed control system. The simulation results prove the robustness of NDO-SMC based control of grid-connected converter under varying irradiance and load requirements.