Development and Electromagnetic Optimization of a Modified Six-Limb Hybrid Distribution Transformer with Magnetically Integrated Power Electronic Control

This paper presents the design and multi-objective optimization of a six-limb magnetically integrated hybrid distribution transformer (HDT). The increasing demand for efficient and compact transformer solutions in modern distribution networks motivates the development of improved design methodologies. In this work, a detailed design procedure is established, including core geometry definition, winding configuration, and magnetic circuit considerations. A multi-objective optimization framework is formulated to minimize total transformer mass and power losses while satisfying operational constraints such as magnetic flux density and current density limits in the windings. Key design parameters, including core dimensions and winding configurations, are systematically varied to identify an optimal trade-off between material usage and performance. The optimization results show a noticeable reduction in total mass with a slight improvement in total losses, while all design constraints are maintained within acceptable limits. A laboratory-scale prototype was constructed to demonstrate the proposed magnetic configuration, and experimental validation was performed under steady-state, open-loop operating conditions to verify the voltage injection principle through the integrated control and extension windings. The presented approach offers a structured pathway for the design and optimization of HDT and can serve as a basis for further studies involving advanced control and operational strategies.