Bi-directional power converters for smart grids: Isolated bidirectional DC-DC converter

Abstract

AbstractAs part of my master thesis I have take part in Isolated Bidirectional DC_DC LLC resonant converter from Eltak company. Application of power exchanges takes place in either direction using two unidirectional DC-DC converters. Even though it is common to use power flow in unidirectional, but later due to many application growing emphasis on small size, compact the two unidirectional way of power flow and efficient power systems. This gives increasing interest to develop a bidirectional type of power flow with bidirectional converter. This is especially for DC power application like motor drives, uninterruptible power supplies(UPS), alternate energy system, telecommunication, space technology, hybrid Automotives, battery charger and battery discharger.After a literature study of different types of converter topology , the isolated bidirectional DC-DC LLC resonant converter has been selected. This resulted in LLC resonant tank have for both mode of operation. The converter is dual active bridge with isolated high switching frequency transformer. The bridge on the high side is voltage-fed and current-fed on the low side of the converter. Since the isolated bidirectional DC-DC converters have the capability to perform the bidirectional power flow in a compact form or a single device to perform such application. Therefore for this specialization project it is proposed to have dual full-bridge isolated bidirectional DC-DC LLC resonant converter in a compact and single device converter. The topology computable for this type of isolated bidirectional DC-DC converter. In this bidirectional converter mainly discussed about the role LLC resonant arrangement instead of PWM for reducing power loss in high switching frequency.