Electric Vehicles (EVs) play a significant role in the reduction of CO2 emissions and other health-threatening air pollutants Accordingly, several research studies are introduced owing to replacing conventional gasoli...
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Electric Vehicles (EVs) play a significant role in the reduction of CO2 emissions and other health-threatening air pollutants Accordingly, several research studies are introduced owing to replacing conventional gasoline-powered vehicles with battery-powered EVs. However, the ultra-fast charging (UFC) of the battery pack or the rapid recharging of the battery requires specific demands, including both: the EV battery and the influence on the power grid. In this regard, advanced power electronics technologies are emerging significantly to replace the currently existing gas station infrastructures with the EV charging stations to move from conventional charging (range of hours) to UFC (range of minutes). Among these power electronics conversion systems, the DC-DC conversion stage plays an essential role in supplying energy to the EV via charging the EV's battery. Accordingly, this paper aims to present possible architectures of connecting multiple Dual Active Bridge (DAB) units as the DC-DC stage of the EV fast charger and study their Small-Signal Modeling (SSM) and their control scheme. These are, namely, input-seriesoutput-series (ISOS), input-series output-parallel (ISOP), input-paralleloutput-parallel (IPOP), and input-paralleloutput-series (IPOS). The control scheme for each system is studied through controlling the output filter inductor current such that the current profile is based on Reflex Charging (RC). The main contribution of this paper can be highlighted in providing generalized SSM as well as providing a generalized control approach for the input-seriesinput-paralleloutput-seriesoutput-parallel (ISIP-OSOP) connection. The generalized model is verified with three different architectures. The control strategy for each architecture is studied to ensure equal power sharing, where simulation results are provided to elucidate the presented concept considering a three-module ISOS, IPOP, ISOP, and IPOS DC-DC converters.
As the core apparatus in dc distribution grid, the reliability of dc transformer (DCT) directly affects the safe and stable operation of the entire dc grid. Firstly, the structure and characteristics of dual active br...
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ISBN:
(纸本)9781728148786
As the core apparatus in dc distribution grid, the reliability of dc transformer (DCT) directly affects the safe and stable operation of the entire dc grid. Firstly, the structure and characteristics of dual active bridge (DAB) based dc transformer are analyzed. Then, the hierarchical reliability model of dc transformer is established by using reliability block diagram (RBD). Furthermore, based on k-out-of-n redundancy model and Markov process theory, considering module redundant number, redundancy mode and component repair rate, a detailed and comprehensive reliability evaluation model of dc transformer is proposed. Finally, based on the proposed reliability model of dc transformer, the influence of different redundancy designs and the component repair rate on the reliability of dc transformers are investigated through an example. The research results can provide a theoretical basis for redundancy design, redundancy mode selection and maintenance strategy of dc transformer, and contribute to the reliability of the whole dc grid.
This paper deals with high voltage and high power DC-DC converters in the load side of non-grid-connected wind power system. The circuit is based on input-series output-parallel (ISOP) connected DC-DC converters topol...
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ISBN:
(纸本)9781424447022
This paper deals with high voltage and high power DC-DC converters in the load side of non-grid-connected wind power system. The circuit is based on input-series output-parallel (ISOP) connected DC-DC converters topology because this kind of topology reduce the large voltage stress of all switches in each module. ISOP converters composed of DC-DC transformers which are their basic modules can realize the multi-module voltage balancing and current sharing automatically. Another advantage is each module achieves soft-switching by the resonance between the transformer leakage inductor and the parasitic capacitors of switches. So, the whole converters get high efficient. The scheme is so convenient that we only need to add the number of basic modules when the input voltage increases. Every circuit parameters which possibly influence the voltage sharing are enumerated. The effect of the dynamic voltage balancing is given by the simulation and experimental results. The experimental waveforms show that this kind of ISOP converters not only achieves voltage balancing and current sharing, but also has fast response to dynamic voltage equalization.
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