Dual-Transformer based Asymmetrical Triple-Port Active Bridge (DT-ATAB) Isolated DC-DC Converter
Abstract
In this paper, a dual-transformer based asymmetrical triple-port active bridge converter (DTATAB) is proposed to interface two different dc-sources and a load. DT-ATAB consists of three active power electronic converters and two high-frequency transformers. All switches of these converters can be turned-on with zero-voltage-switching (ZVS) to reduce the switching losses. The bidirectional power flow operation is possible between the ports. The DT-ATAB also reduces the circulating powers between the ports for well-matched transformer turns ratios as compared to those in the other existing triple-port active bridge converters (TAB). Furthermore, the magnetic short circuit conditions arising in the three-winding transformer of the TAB are mitigated in DT-ATAB. The principle of operation, steady-state analysis, various modes of operation (three-port and twoport modes), and a closed loop controller of DT-ATAB are presented. The theoretical analysis of the paper is verified using both simulation and experimental studies. The illustrated results show that DT-ATAB can be used as a promising multi-port converter (MPC) to interface the multiple sources and load to achieve wide-ranging outputs with the minimal losses.
EXISTNNG SYSYETM:
The non-isolated and partially isolated MPCs offer a compact design, lower cost, higher power density, and efficiency. However, in such converters, the voltage levels of different ports are not flexible and achieving soft switching is difficult. On the other hand, even though isolated MPCs comprise a relatively higher number of active switches, they offer most of the key features of MPCs such as soft-switching, bi-directional power flow, flexible voltages at different ports, isolation between their ports, etc. Ast the available isolated MPC topologies, TAB is one of the most eminent topologies which offers most of the aforementioned key features. TABs are mostly suitable for hybrid and electric vehicle applications where MPCs are used as the interfacings between a dc sources, storage devices, and load. However, TABs are not suitable for the applications where two different sources are connected to supply the load power simultaneously. Because, a small difference in the magnitudes and/or phases between their corresponding high-frequency (HF) ac-voltages may lead to higher circulating powers between the source-ports due to the smaller leakage inductance between their interconnecting windings of the transformer. Also, the higher circulating powers result in higher losses and deterioration of the transformer core as well as windings.
PROPOSED SYSYTEM:
In this paper, a DT-ATAB converter which is derived from the combined features of the dual active bridge (DAB) , asymmetrical dual bridge converters, and TAB is proposed to achieve the simultaneous power management operation with the reduced aforementioned losses. The proposed DT-ATAB allows the converters of different source ports to operate with the extended range of phase delays and magnitudes to obtain the wide-ranging outputs with significantly reduced circulating currents as compared to the three-winding transformer based TAB. In DT-ATAB, the source ports can be easily isolated by operating some of the selected switches which are named in this paper as a two-port mode of operation. Further, in DTATAB, the switches can be operated with ZVS over wide ranges of the outputs to reduce the switching losses. In order to regulate the output voltage and the powers supplied from the source ports, a closed loop control technique is presented. A detailed investigation of the operational principle and steady state analysis of the proposed DT-ATAB are presented in the subsequent sections of this paper.
CONCLUSIONS
Dual transformer based asymmetrical triple port active bridge (DT-ATAB) converter is proposed in this paper to integrate two dc-sources and a load. The proposed converter consists of two FBs, a TLC, and two HF transformers. A detailed study on the principle of operation, steady state analysis, and closed-loop controller of DT-ATAB is presented. The proposed DT-ATAB offers isolation between the ports, ZVS turn-on of switches, bi-directional power flow operation, reduced circulating powers, mitigation of magnetically shortcircuiting conditions, etc. DT-ATAB can be operated over a wide-ranging phase shift ratios between the source port converters to achieve the substantial choices of the output voltage and power. The efficacy of the proposed converter is verified using the simulation and experimental studies. The illustrated studies show that the proposed DT-ATAB can be used as a promising MPC topology capable of versatile power management.
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