| With the popularization of Renewable Energy,the research on Power Electronic Transformers(PET)has received more and more attention.In this paper,a three-port isolated bidirectional DC/DC(TAB)and a DC/AC converter are used as basic modules for a multi-port PET and related experimental verification were completed.(1)The paper analyzed the working characteristics of the TAB.The operating characteristics and the small signal modeling were carried out.Then a unit matrix decoupling method was introduced for decoupling.On the one hand,the decoupling parameters will cause singular point problem with change of steady state point.On the other hand,there is the problem of ambiguity between port power and phase shift angle.This paper derives the maximum effective range of the phase shift angle and uses different phase shift angle limiting strategies to avoid the above two problems.What's more,this paper introduces a neural network instead of the traditional look-up table method for decoupling to avoid the memory limitation caused by dimension.Finally,the proposed method are verified by experiments and simulations.(2)The composition of the multi-port PET is designed.Based on the working characteristics,the current sharing control of the module is realized based on the masterslave algorithm.In addition,two common working modes are designed for power transmission,respectively.Simulation and experimental results are both given.(3)Relying on a project,a prototype of a 100 kVA multi-port PET was developed and tested in practice.The hardware circuit design which mainly includes selection of parameters and software program design which mainly includes main program design,soft start program design,and user interface design are also provided.Finally,not only the experimental verification of the method proposed in this article,but also the transmission efficiency of the prototype is tested,and the results show that the prototype has a transmission efficiency of more than 96.5%. |
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