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A series of three-port forward converters with a compact structure and extended duty cycle range is presented for the standalone renewable energy system. Bidirectional power-flow port embedding and switch device sharing can be used to derive these converters from conventional two-switches forward converters. In comparison to the conventional two-switch forward converter, only one switch and one diode are added to build an energy storage port with bidirectional power flow characteristics, which has the benefits of compact structure and low cost. Meanwhile, the embedding of the energy storage port provides an additional demagnetization loop for the magnetic inductor, which extends the duty cycle range of the forward converter so that the proposed converter no longer requires a duty cycle of less than 0.5 as in the case of conventional forward converters. The proposed converters also offer the advantages of fewer components, easy control, and independent control of power flow between multiple ports when compared to similar solutions. Finally, an experimental setup with a photovoltaic battery as an application is developed, and the experimental results verify the effectiveness and flexibility of the proposed topology and control method. [ABSTRACT FROM AUTHOR]

For a photovoltaic (PV)/battery power system consisting of PV module, energy storage system, and local load, using a three‐port converter (TPC) instead of several single‐input converters is more desirable, such as simpler circuit, higher efficiency, lower cost, and centralized control without communication circuit. In this paper, a TPC is proposed and analyzed, which includes operating modes, steady‐state performance, and parameter design. Compared with other converters, the proposed TPC has a low cost, compact structure, and a more flexible voltage relationship among all ports. Moreover, energy management and control methods are further proposed for PV/battery systems based on the proposed converter, which can achieve maximum power point tracking (MPPT) of PV module and constant output voltage. In order to design the control loop and realize multivariable optimal control, a small‐signal model of the converter is obtained in each operation mode. Then a detailed decoupling design approach based on a small‐signal model is provided to allow a separate controller design for the proposed converter. Finally, the validity of the proposed converter and its energy management and control method are verified by experimental results. [ABSTRACT FROM AUTHOR]

In the standalone renewable energy system, a multiport converter is more desirable than several single-input converters as it has advantages of a simpler circuit, higher efficiency, and lower cost. This article proposes a novel topology synthesis method to derive integrated three-port converters with low cost and compact structure. With the proposed topology synthesis method, integrated three-port converters can be easily developed from conventional single-input single-output (SISO) converters by replacing a switch and a diode with a basic cell, including bidirectional power flow. Compared with the SISO converter, the derived integrated three-port converters only need to add the extra switch and diode, which makes them have low cost and compact structure. As an example, topology synthesis based on buck, boost, buck–boost, Cuk, SEPIC, and zeta converters is performed in this article. The proposed topology synthesis method can also be extended to deduce a series of n-port converters. In order to achieve a better understanding of the proposed converters, the integrated three-port SEPIC converter is specifically analyzed, including its operation principle, steady-state performance, small-signal modeling, and control system. Finally, experimental verifications have been carried out to illustrate the feasibility and effectiveness of the proposed topology synthesis method. [ABSTRACT FROM AUTHOR]