• Journal of Power Electronics
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• v.17 no.6
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• pp.1433-1444
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• 2017

A family of non-isolated DC-DC three-port converters (TPCs) that allows for a more flexible power flow among a renewable energy source, an energy storage device and a current-reversible DC bus is introduced. Most of the reported non-isolated topologies in this area consider only a power consuming load. However, for applications such as hybrid-electric vehicle braking systems and DC microgrids, the load power generating capability should also be considered. The proposed three-port family consists of one unidirectional port and two bi-directional ports. Hence, they are well-suited for photovoltaic (PV)-battery-DC bus systems from the power flow viewpoint. Three-port converters are derived by combining different commonly known power converters in an integrated manner while considering the voltage polarity, voltage levels among the ports and the overall voltage conversion ratio. The derived converter topologies are able to allow for seven different modes of operation among the sources and load. A three-port converter which integrates a boost converter with a buck converter is used as a design example. Extensions of these topologies by combining the soft-switching technique with the proposed design example are also presented. Experiment results are given to verify the proposed three-port converter family and its analysis.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1223-1234
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• 2018

In this paper, a new three-port multidirectional DC-DC converter is proposed for integrating an energy storage system (ESS) to a bipolar DC microgrid (BPDCMG). The proposed converter provides a voltage-balancing function for the BPDCMG and adjusts the charge of the ESS. Thanks to the multi-functional operation of the proposed converter, the conversion stages of the system are reduced. In addition, the efficiency and weight of the system are improved. Therefore, this converter has a significant capability when it comes to use in portable BPDCMGs such as electric DC ships. The converter modes are analyzed and small-signal models of the converter in each of the independent modes are extracted. Finally, comprehensive simulation studies are carried out and a BPDCMG laboratory prototype is implemented in order to verify the performance of the proposed voltage balancer using the burst mode control scheme.