IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE) e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 7, Issue 2 (Jul. - Aug. 2013), PP 81-87 www.iosrjournals.org www.iosrjournals.org 81 | Page Design and Performance of a Bidirectional Isolated Dc-Dc Converter for Renewable Power System Dr.K.Ravichandrudu 1 , Sk.Fathima 2 , Mr.P.Yohan Babu 3 , Mr.G.V.P.Anjaneyulu 4 1,2,3 Krishnaveni Engineering College for Women,Narasaraopet,Guntur,AP,India. 4 Reaserch scholar SVU College of engineering,S.V.U.,Tirupathi. Abstract: This paper contributes to the steady-state analysis of the isolated bidirectional dc–dc converter. The circuit configuration of the proposed converter is very simple. The proposed converter employs a coupled inductor with same winding turns in the primary and secondary sides..Thus, the proposed converter has higher step-up and step-down voltage gains than the conventional bidirectional DC-DC boost/buck converter. Bidirectional dc-dc converters (BDC) Have recently received a lot of attention due to the increasing need to systems with the capabilityBidirectional energy transfer betweentwo dc buses. Apart from traditional application in dc motor drives, new applications of BDC include energy storage in renewable energy systems, fuel cell energy systems, hybrid electric vehicles (HEV). The bidirectional converter, has less switching losses with zero voltage switching, and has high gain buck-boost operations.. The complete PV system with a boost dc to dc converter controller to regulate the dc link voltage, bidirectional converter based battery charge controller, and an inverter with its associated vector mode controller is implemented in the Simulink/Simpower environment. Index Terms: Bidirectional dc–dc converter, current-fed, solar panel. I. Introduction Bidirectional DC–DC converters are used to transfer the power between two DC sources in either direction. These converters are widely used in applications, such as hybrid electric vehicle energy systems, uninterrupted power supplies, fuel-cell hybrid power systems, PV hybrid power systems, and battery chargers. Many bidirectional DC-DC converters have been researched.Some literatures research the isolated bidirectional DCDC converters, which include the half-bridge types and full-bridge types. These converters can provide high step-up and step-down voltage gain by adjusting the turns ratio of the transformer. The integration of photovoltaic (PV) power systems and energy storage schemes is one of the most significant issues in renewable power generation technology. The rising number of PV installations due to increasingly attractive economies,substantial environmental advantages and supportive energy policies require enhanced strategies for their operation in order to improve the power supply stability and reliability. Energy storage system for the PV powergenerationisaddressed in the literature. Some concentrates on the system configurations as well as control strategies whereas some others focus solely on the converter topo-logies or on the control techniques. In the conventional PV system architecture, the PV power is transferred to the load through a unidirectional and a bidirectional converter where a considerable amount of power loss occurs in each conversion stage. Hence, the system efficiency deteriorates with the increasing number of power conversions. These disadvantages arise from the fact that bothof the converters in the conventional system process the PV array output power. In some previous applications, the battery-bank is directly connected to a dc bus without a bidirectional converter.This configuration requires more battery stacks and reduces thesystem efficiency. Also, the battery life is degraded without proper control of charging and discharging of the battery. Though series strings of storage batteries provide high voltage, a slight mismatch or temperature difference can cause charge imbalance if the series string is charged as a unit. Such high voltage batteries are expensive and produce more arcing on the switches than the low voltage batteries. Another problem with higher voltage batteries is the possibility of one cell failing. A faulty cell would produce lower voltage, however, in an extreme case,one open cell could break the current flow. A modified DC-DC boost converter is presented. The voltage gain of this converter is higher than the conventional DC-DC boost converter. Based on this converters, a bidirectional DC-DC converter is pro- posed. The proposed converter employs a coupled inductor with same winding turns in the primary and secondary sides. Comparing to the proposed converter and the conventional bidirectional boost/buck converter, the proposed converter has the following advantages: 1) higher step-up and step-down voltage gains; 2) lower average value of the switch-current under same electric specifications. In thecustomary bidirectional converters, more switchesandtransformer-basedschemes increases production costs and reduces conversion efficiency.Moreover, the conventional PV energy storage systems use time based energy scheduling to operate the operation mode control of the battery charger based on the time