Flexible Operation and Control of Bidirectional Chargers Using ISMC for Electric Vehicle Applications

The increasing integration of electric vehicles and renewable energy systems requires high-performance, reliable, and intelligent battery charging infrastructure. This paper presents a novel design and analysis of a bidirectional fast battery charging system connected to the power grid, employing a robust improved sliding mode control (ISMC) to overcome the limitations of conventional control methods. Conventional controllers such as PID, FL-PID, and ADRC suffer from parameter sensitivity, computational burden, and noise susceptibility under uncertain and dynamic conditions. In contrast, the proposed ISMC approach achieves improved robustness, fast dynamic response, and high tracking accuracy. The proposed architecture consists of two stages: a three-phase bidirectional voltage source converter on the AC side and a buck-boost DC/DC converter on the DC side. The voltage source converter employs the proposed ISMC to regulate the dq-axis grid currents and manage the active/reactive power flow, while the DC/DC converter is also governed by an ISMC approach to stabilize the DC-link and battery voltage across varying charge/discharge states. A significant contribution of this work is the proposed flexible operating algorithm that enables seamless transitions between grid-connected and islanded modes, ensuring uninterrupted supply to local AC and DC loads during grid outages through grid-forming control. Additionally, a battery management algorithm is integrated, which dynamically adjusts charging and discharging actions based on the battery’s state of charge, thereby prolonging battery lifespan and ensuring safe operation. Verifications via simulations in MATLAB/Simulink confirm the superiority of the proposed control strategy by demonstrating less than 3% total harmonic distortion in grid current, accurate current tracking, and a stable DC voltage profile with negligible overshoot and fast settling time. In comparison, the PI controller exhibits 0.4% overshoot and 50 ms settling time, while the ADRC shows about 0.3% overshoot and 40 ms settling time. The ISMC-based framework can be applied to next-generation smart battery charging stations, providing enhanced grid support, improved power quality, and advanced battery health management.