Integrated On-Board Chargers for Electric Vehicles: Topologies, Control Strategies, Challenges, and Future Research Directions

The rapid adoption of electric vehicles (EVs) is increasing the demand for charging solutions that are compact, cost-effective, and grid-friendly. Conventional off-board charging stations face challenges such as high infrastructure cost, distribution-grid stress from high-power charging, and limited flexibility for RE integration. Integrated on-board chargers (IOBCs) offer a promising alternative by reusing the traction inverter and motor for charging, thereby reducing system size, weight, and cost, while improving hardware utilization. Despite growing research interest, a consolidated and critical assessment of IOBC architectures and control strategies remains limited. This paper presents a comprehensive review of IOBC technologies, covering key topologies and control approaches for charging, traction, and vehicle-to-grid (V2G) operation. It critically examines major implementation challenges, including unintended charging torque and torque ripple, harmonic current distortion and grid-code compliance, thermal stress due to high power density, and safety and isolation constraints. Finally, future research directions are discussed, with an emphasis on advanced converter topologies, wide-bandgap devices, enhanced thermal management, cybersecurity, and data-driven resilience for secure and reliable EV charging systems.