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Title: Flux Balancing Control of Ungapped Nanocrystalline Core-Based Transformer in Dual Active Bridge Converters

Abstract

Transformer flux dc bias is a critical issue, impacting the reliable operation of dual active bridge (DAB) converters especially when ungapped high permeability nanocrystalline core is used. Steady state current dc bias can easily saturate ungapped nanocrystalline transformers, and it is even more dangerous in transient conditions. A dc bias model is proposed to analyze steady state dc bias in different load conditions. The magnetizing current detection is necessary for closed-loop control of dc bias; conductors' position is shown to impact sensor noise, and it is analyzed in detail. To deal with both steady state and transient dc bias, a unified flux balancing control (UFBC) is proposed introducing a predictive bias suppression (PBS) method with closed-loop flux balancing control (CFBC). With the proposed PBS, both primary/secondary current balance and flux balance can be achieved within one switching cycle using UFBC. Power characteristics and interaction between power control and flux balancing control of DAB converters are analyzed, and the CFBC needs to work in a low bandwidth due to sensor bandwidth limitation and interaction between power control and flux balancing control. Lastly, the UFBC is verified on a 300-kW cascaded DAB converter prototype.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1];  [1];  [1]
  1. Tsinghua Univ., Beijing (China)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Electricity (OE)
OSTI Identifier:
1808181
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
IEEE Transactions on Power Electronics
Additional Journal Information:
Journal Volume: 35; Journal Issue: 11; Journal ID: ISSN 0885-8993
Publisher:
IEEE
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; dc bias; dual active bridge (DAB); flux balancing control; isolated dc-dc converters; magnetizing current

Citation Formats

Yao, Pengfei, Jiang, Xiaohua, Xue, Peng, Ji, Shiqi, and Wang, Fred. Flux Balancing Control of Ungapped Nanocrystalline Core-Based Transformer in Dual Active Bridge Converters. United States: N. p., 2020. Web. doi:10.1109/tpel.2020.2984789.
Yao, Pengfei, Jiang, Xiaohua, Xue, Peng, Ji, Shiqi, & Wang, Fred. Flux Balancing Control of Ungapped Nanocrystalline Core-Based Transformer in Dual Active Bridge Converters. United States. https://doi.org/10.1109/tpel.2020.2984789
Yao, Pengfei, Jiang, Xiaohua, Xue, Peng, Ji, Shiqi, and Wang, Fred. Fri . "Flux Balancing Control of Ungapped Nanocrystalline Core-Based Transformer in Dual Active Bridge Converters". United States. https://doi.org/10.1109/tpel.2020.2984789. https://www.osti.gov/servlets/purl/1808181.
@article{osti_1808181,
title = {Flux Balancing Control of Ungapped Nanocrystalline Core-Based Transformer in Dual Active Bridge Converters},
author = {Yao, Pengfei and Jiang, Xiaohua and Xue, Peng and Ji, Shiqi and Wang, Fred},
abstractNote = {Transformer flux dc bias is a critical issue, impacting the reliable operation of dual active bridge (DAB) converters especially when ungapped high permeability nanocrystalline core is used. Steady state current dc bias can easily saturate ungapped nanocrystalline transformers, and it is even more dangerous in transient conditions. A dc bias model is proposed to analyze steady state dc bias in different load conditions. The magnetizing current detection is necessary for closed-loop control of dc bias; conductors' position is shown to impact sensor noise, and it is analyzed in detail. To deal with both steady state and transient dc bias, a unified flux balancing control (UFBC) is proposed introducing a predictive bias suppression (PBS) method with closed-loop flux balancing control (CFBC). With the proposed PBS, both primary/secondary current balance and flux balance can be achieved within one switching cycle using UFBC. Power characteristics and interaction between power control and flux balancing control of DAB converters are analyzed, and the CFBC needs to work in a low bandwidth due to sensor bandwidth limitation and interaction between power control and flux balancing control. Lastly, the UFBC is verified on a 300-kW cascaded DAB converter prototype.},
doi = {10.1109/tpel.2020.2984789},
journal = {IEEE Transactions on Power Electronics},
number = 11,
volume = 35,
place = {United States},
year = {2020},
month = {4}
}