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Three-port converters (TPCs) combining two dc–dc converters into a single unit is a promising solution that can simplify and miniaturize satellite electrical power systems. Conventional nonisolated TPCs, however, face a variety of challenges, such as the necessity of a transformer, low effective duty cycle operation, and unshared ground issues. This article proposes a novel nonisolated TPC integrating a unidirectional and bidirectional pulsewidth modulation converters. The two converters can be integrated into a single unit with reducing total switch count without employing a transformer, thus achieving the simplified circuit. In addition, thanks to the capacitor added in series with switches, not only the voltage stress of semiconductor devices is reduced, but also miniaturized inductor design is feasible. The quantitative analysis revealed that the volume of passive components in the proposed TPC could be reduced by approximately 19% compared with a conventional nonisolated TPC. A 240-W prototype was built for the experimental verification, and the results agreed well with those of the analysis, demonstrating its efficacy. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) systems having rechargeable batteries are prone to be complex and costly because multiple converters are necessary to individually regulate a load, PV panel, and battery. This paper proposes novel nonisolated multiport converters (MPCs) integrating a bidirectional pulsewidth modulation (PWM) converter and phase-shift-switched capacitor converter (PS-SCC) for standalone PV systems. A PWM converter and PS-SCC are integrated by reducing the total switch count, realizing the simplified system and circuit. In the proposed MPCs, two control freedoms of duty cycle and phase shift angle are manipulated to individually regulate the load, PV panel, and/or battery. The detailed operation analysis was performed to mathematically derive gain characteristics and zero voltage switching operation boundaries. For the battery discharging mode, in which the PV panel is not available and the MPC behaves as a single-input–single-output converter with two control freedoms available, the optimized control scheme achieving the lowest rms current is also proposed to maximize power conversion efficiencies. Various kinds of experimental verification tests using a 200-W prototype were performed to verify the theoretical analysis and to demonstrate the performance of the proposed MPC. [ABSTRACT FROM AUTHOR]

Single-cell battery power systems are a promising bus architecture for small scientific satellites. However, to bridge the huge voltage gap between a single-cell battery and power bus, bidirectional converters with a high voltage conversion ratio and a large current capability for the low-voltage side are necessary. This article proposes a bidirectional interleaved pulse width modulation (PWM) converter with a high voltage conversion ratio and an automatic current balancing capability. By adding capacitors to conventional interleaved PWM converters, not only are inductor currents automatically balanced without feedback control or current sensors, but also voltage conversion ratios at a given duty cycle can be enhanced. Furthermore, the added capacitors can reduce voltage stresses of switches and charged-discharged energies of inductors, realizing more efficient power conversion and reduced circuit volume in comparison with conventional converters. A 100-W prototype was built for experimental verification, and results demonstrated the fundamental characteristics and efficacy of the proposed converter. [ABSTRACT FROM AUTHOR]