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Three-port converter topologies based on dual-input/dual-output converter
Abstract
The topology mechanism of a three-port converter is discovered in the light of power flow, and a novel topology derivation theory for generation of combined and integrated three-port converter topologies was proposed based on the integration of dual-input and dual-output topologies. The generation principle and methods for a series of new topologies were given. And the three-port converter topologies derived from basic Buck, Boost and Buck/Boost converters were presented. Operational mode analysis is conducted, and experimental results verify the analysis.
To address the instability of the input voltage of photovoltaic (PV) in a stand-alone PV storage power generation system, a wide input range non-isolated three-port converter that can operate in a range that is greater than and less than the voltage of the storage port is proposed in this paper. The proposed converter can realize the energy flow and power balance between the PV, the battery, and the load. This converter is a combination of conventional Buck, Boost, and Buck–Boost converters with a four-switch bi-directional Buck–Boost converter (FSBB). The FSBB is used to connect the PV and battery ports, which can reduce the voltage constraint of the storage port on the PV port voltage, and broaden the selection of the voltage levels of the storage port to meet the application requirements of the PV port with a wide voltage input. In this paper, an experimental prototype is designed by combining the Boost converter and the FSBB converter. Finally, the correctness of the theoretical analysis and the feasibility of the energy management strategy of the converter are verified through experimental results.
Employing three-port converters (TPC) instead of several independent converters in stand-alone renewable power system has some favorable features such as high efficiency, high power density, high reliability and low cost. Based on the fact that the primary circuit of half-bridge converter (HBC) is the same as bi-directional Buck/Boost converter, ideas for generation three-port half-bridge converter (TP-HBC) were proposed and two types of TP-HBC, TP-HBC with post regulation scheme and TP-HBC with primary regulation, were proposed. One of the TP-HBC with post regulation was analyzed with operation principles, voltage relations and design considerations were given and verified with experimental results.
A non-isolated three-port bidirectional DC-DC converter and its power control were proposed. The converter was derived from three bidirectional Buck/Boost switching cells cascaded with each other with DC-link capacitor removed. Compared with conventional solution of multiple bidirectional converters connected with a shared common DC bus, the proposed converter has the advantage of reduced size, lower cost and better reliability from DC-link capacitor eliminated, and it also greatly improved the efficiency and power density from single-stage step-up/-down conversion between any two of the multiple ports. The operational principles were analyzed in detail with power control and PWM strategy given. Finally, the topology and analysis were verified with the experimental results.
A parallel/series-interleaved three-port half-bridge converter is proposed. This converter is composed of two half-bridge converters. The primary circuits of the two half-bridge converters are paralleled, and the secondary windings of the transformer are in series and share a common rectifier/filter circuit. The parasitized Buck/Boost converter in the primary side of the half-bridge converter is utilized to interface a primary source and a battery. The duty cycles of the switches are used to balance the voltage/power of the primary source and the battery. Load side control and zero-voltage-switching of the switches are achieved by introducing phase-shift control between the two switching-bridges on the primary side. The operation principles are analyzed in detail with voltage relations and design considerations given and verified with experimental results.
A novel control strategy with decoupling was proposed for three-port half-bridge converters (TP-HBC), achieving power management between multiple ports with decoupled close-loop control. To realize smooth and seamless mode transition, a competitive strategy was used to obtain steady-state functions under various working modes. The small signal model of TP-HBC was built by the state-space averaging method, and interactions between the control and controlled variables of the multiple control loops were analyzed in detail. Based on that, the decoupling variables were employed and the bandwidth of the multiple control loops were set far away, to decouple the multi-input multi-output control system into several single-input single-output subsystems. Thus, the decoupling control of TP-HBC is approximately achieved. Finally, experimental results verify the effectiveness and correctness of the control strategy and the decoupling method.
This paper proposes a novel stand-alone photovoltaic (PV) lighting system with optimal energy management and control. The system includes maximum power point tracking (MPPT) for PV panels and self-adaptive control over lead-acid storage battery. In charge process, charging controller can automatically adjust itself to obtain the highest possible power from PV panels under various light intensity and temperature. Based on environment temperature and battery terminal voltage, the controller can also adopt proper charge mode, such as overcharge and floating charge, to extend the battery life. The system also can provide functional illumination based on high-pressure sodium (HPS) lamp, which works at very high efficiency with specially designed ballast and ignitor. Experimental results show the high stability and high efficiency of this PV energy management system.
This paper presents the design and analysis of a satellite platform power system, which utilizes several three-port converters to interface various independent solar panels, one battery to a regulated bus. The three-port converter features low component count and compact structure. The paralleled three-port converters can not only boost the power level, but also provide redundancy, which is important to such critical applications. The proposed output port ¿hybrid¿ current sharing (CS) method shows good transients while requiring no interchannel level CS bus, meanwhile, the proposed passive CS method is well suited to both the MPPT algorithm for the input port and the battery charge control for the battery port. The analysis and design of the system level control strategy, the CS methods for three different ports, the MPPT and battery charging algorithms are verified by simulation and experiments.