Characteristic Investigation of VFRM Multiplexed as Transformer in Integrated on-Board Charger

Isolated on-board integrated charger (IOBIC) decreases the cost of electrical vehicles and ensures the galvanic isolation between battery and grid. This paper investigates the characteristics of the 6-stator-slots VFRMs multiplexed as transformers in IOBIC. According to the analysis, the coupling coefficient and voltage transfer ratio between two arbitrary windings of VFRMs are low, which is undesirable for a transformer. To construct the multiplexed VFRMs with high transfer characteristics, the field winding is split in this paper to build a new winding that is tightly coupled with phase winding. The voltage transfer ratio is improved greatly when the new winding and phase winding are multiplexed as the two sides of the transformer. Further, the loss and efficiency of the multiplexed VFRMs with/without load are analyzed. The 6/4 multiplexed VFRM has the lowest no-load loss and highest on-load efficiency compared with that of the other three multiplexed VFRMs.