Translated Abstract
The isolated bi-directional DC / DC converter not only can realize bi-directional energy transmission, but also provides electrical isolation by transformer. The Dual Active Bridge converter is one kind of high power isolated bi-directional DC / DC converter, with high power density, large voltage transfer ratio, and easy to realize soft switching. It is usually used in microgrid energy storage system, UPS, electric cars, electric power electronic transformer. In this paper, DAB is studied deeply, including the modulation method, the generalized average model and the peak current predictive control.
In this paper, the modulation strategy of DAB were studied. In order to improve the light load efficiency of DAB under pure phase shift modulation, the basic characteristics of DAB under single PWM modulaiton were studied, such as the current effective value, the range of soft switching. The control parameters were determined by using Lagrange method, then the unified modulation strategy was proposed. This new modulation strategy can achieve soft switching under full power range and the effective value of current is minimized. At last, the unified modulation strategy was verified thougth experiment.
In this paper, considering both the model accuracy and complexity, this paper obtained the one order and three order model of DAB under pure phase shift modulaiton and single PWM modulation. Finally, the precision of the generalized average model is verified by comparising the bode plot and the step responseof DAB.
In this paper, peak current predictive control of DAB was studied and verified by simulation. The peak current predictive control algorithm was estabished based on the simplified modle of DAB. Then the influence of control frequency was discussesed by simulaiton. Finally, according to the simulation results before, the improved model was proposed to improve the dynamic performance of predictive control.
Finally, this paper completed the design of DAB experimental platform. Then finished the colsed loopcontrol experiment.
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