Using Sampled-Data Modeling Method to Derive Equivalent Circuit and Linearized Control Method for Dual-Active-Bridge Converter

• Published in: IEEE journal of emerging and selected topics in power electronics Vol. 9; no. 2; pp. 1361 - 1374
• Main Authors: Tong, Anping, Hang, Lijun, Chung, Henry Shu-Hung, Li, Guojie
• Format: Journal Article
• Language: English
• Published: Piscataway IEEE 01.04.2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Active control; Alternating current; Circuit stability; Control methods; Control stability; Dual active bridge (DAB) converter; Dynamic characteristics; Electric bridges; Electric converters; Electric potential; equivalent circuit; Equivalent circuits; Inductors; Integrated circuit modeling; Linearization; linearized control method; Load modeling; Modelling; Numerical models; sampled-data modeling method; Stability analysis; State variable; Systems stability; Voltage
• ISSN: 2168-6777; 2168-6785
• DOI: 10.1109/JESTPE.2019.2961138

In this article, based on sampled-data modeling technique, a second-order equivalent circuit that can describe the global dynamic characteristics of dual active bridge (DAB) converter is developed. The proposed technique can characterize the dynamics of the ac current through the transformer and the output voltage. Afterward, by using a sensitive-based tool, named participation factor, it is identified which state variables are critical for system stability and which state variables provide negligible effects. On this basis, the large-signal equivalent circuit is simplified, meanwhile, the parasitic resistance is still taken into account by an intuitive "loss branch." This model can be used to comprehensively investigate the relationship of the DAB converter stability versus circuit parameters, controller gain, input/reference voltage, and the load conditions, and these results can be expressed analytically. Furthermore, a linearized control method is proposed to eliminate the nonlinear terms in the equivalent circuit model. It facilitates to reduce the sensitivity of system stability to the load condition and reference voltage and helps to enlarge the stable region. Finally, the proposed model is validated by comparing the results obtained by the model with the simulations and experimental results. The effectiveness of the linearized control method is also demonstrated.