An Interleaved Half-Bridge Three-Port Converter With Enhanced Power Transfer Capability Using Three-Leg Rectifier for Renewable Energy Applications Introduction: Renewable energy power systems attract more and more attention, because the energy and environmental problems are becoming increasingly serious. A renewable energy system needs to interface several energy sources, such as photovoltaic (PV) panels and fuel cells with the load along with battery backup. It leads to a supreme need for integrated power converters that are capable of interfacing and controlling several power terminals with low cost and a compact structure. An integrated three-port converter (TPC), instead of several independent two-port converters, finds applications in such systems, because it has the advantages of reduced conversion stages, less component count, lower overall mass, improved reliability, and enhanced dynamic performance due to power stage integration. In addition, since the control and power management of a TPC can be realized using a single controller, the communication that would be necessary in the conventional structure based on multiple two-port converters is not required. Hence, the communication delay and error can be avoided by the centralized control of the TPC. Existing system: A bidirectional buck boost converter and a half-bridge converter are integrated to derive a tri-modal half-bridge TPC. Its main advantage is that zero-voltage switching (ZVS) can be achieved for all switches.
However, a middle branch is introduced to satisfy the requirement of power control, which leads to a complex topology and additional conduction losses. A family of half-bridge TPCs is proposed based on the integration of bidirectional buck boost, forward flyback, and halfbridge converters. The main attractive features of these TPCs are simple circuit and high-power density. However, hard switching and the large circulating current caused by the free-wheeling operation stage will increase the switching and conduction losses. Besides, the power rating of the half-bridge converter-based TPCs is limited. Interleaved bidirectional nonisolated dc dc converters and full-bridge converters are integrated to generate a family of TPCs by sharing the switching bridges. ZVS can be easily achieved with these TPCs. However, at least four magnetic components are required, because the filter inductors and transformer are not integrated, which limits the power density of these TPCs. Meanwhile, the large circulating current associated with the freewheeling operation stage will decrease the conversion efficiency as well. The full-bridge TPCs presented are a combination of two half-bridge TPCs. They inherit the advantages of half-bridge and full-bridge TPCs, such as high integration, high-power density, and ZVS capability. However, the circulating current associated with the free-wheeling operation stage still exists and introduces additional conduction losses.
Drawbacks: Complex topology and additional conduction losses. Hard switching and the large circulating current caused by the freewheeling operation stage. Decrease the conversion efficiency. Proposed system: An interleaved half-bridge (IHB) three-port converter (TPC) is proposed for a renewable power system. The IHB-TPC is used to interface three power ports: 1) one source port; 2) one battery port; and 3) one isolated load port. The proposed IHB-TPC is derived by integrating two half-bridge TPC modules. A parallel configuration is adopted for the primary side of the two half-bridge modules, while a parallel series configuration is adopted for the secondary side of the two modules. The power can be transferred from the source and the battery to the load within the whole switching cycle with the proposed IHB- TPC. It means there are no additional conduction losses caused by the circulating current or the free-wheeling operation stage. Hence, the voltage gain can be extended, and the output filter can be reduced. Zerovoltage switching is realized for all the four main switches to reduce the switching losses. Two of the three ports can be tightly regulated by adopting pulse width modulation plus phase-shift control, while the third port is left unregulated to maintain power balance for the system. The proposed IHB-TPC is applied to a PV-sourced power system with battery backup. In general, there are three power flows in a threeport power system composed by PV, battery, and load: 1) from the PV to
the load; 2) from the PV to the battery; and 3) from the battery to the load. Advantages: The circulating current is eliminated with the power transfer capability through the whole switching cycle. The voltage gain of the load port is extended, and the output filter is reduced. Soft switching is available for all the primary-side switches. Applications: Renewable Energy Power Systems.
Block diagram: Input Solar Supply Filter Full Bridge Inverter Transformer 1 Three Leg Diode Rectifiers Battery Transformer 2 12V DC Driver Circuit Output Filter Load Buffer Circuit 5V DC Micro Controller Circuit