Integration of OBC and LDC Using Adaptive DC Link Voltage

The OBC employs a high frequency transformer for the galvanic isolation between the grid and the propulsion battery. And LDC also adopts a high frequency transformer for step-down about 10 times from 240 [V] to 24 [V] and electrical insulation. However, in the case of a magnetic component, it is desirable to minimize the use because of the reduction of the traveling distance due to the increase in weight and volume and the insulation breakdown between the transformer windings due to vibration. Therefore, this paper proposes a dc-link voltage-variable integrated system that uses OBC and LDC transformers in common. The proposed circuit is divided into four operation modes. We also present the transformer design conditions that satisfy the voltage conversion of all conditions. Finally, PSIM simulation is performed to verify the validity of the proposed integrated system.