Query: DC-bias cancellation for phase shift controlled dual active bridge

Candidate papers:

abstract: The dual active bridge topology allows bidirectional power flow and galvanic isolation for DC/DC energy conversion. These features have made it the possible backbone of the future smart transformer for distribution. The different voltage drops and commutation dead times of the semiconductor switches result in DC voltage at the transformer terminals. Even small DC voltage components produce large DC bias currents as they are only limited by the transformer resistances. The DC bias degrades the transformer performance by increasing the losses. If the core saturates the resulting current pulses can damage the converter. A typical approach to avoid the DC bias is placing a capacitor in series with the transformer. This capacitor suffers large current variations, reducing its reliability, and complicates the control. The dual active bridge usually handles the power flow by modifying the phase shift of the converter square waveforms. In this paper the duty cycle of the converter waveforms is controlled to cancel the current DC bias in both transformer sides. A formula relating the reference power and phase shift is provided for the case of varying duty cycle waveforms. The implementation with constant sampling frequency and its limitations are explained.
author_names: Rafael Pena-Alzola

Laszlo Mathe

Marco Liserre

Frede Blaabjerg

Tamas Kerekes
title: DC bias cancellation for phase shift controlled dual active bridge
venue: IECON 2013 39th Annual Conference of the IEEE Industrial Electronics Society
year: 2013

abstract: A novel control method for eliminating DC bias of dual active bridge (DAB)converter under triple phase shift (TPS)control is proposed. This paper firstly analyzes three most representative working modes of TPS control, and the proportional relationship between the DC bias current and the duty cycle of the active bridges is derived. Secondly the transformer DC bias current detection circuit is designed, and the output voltage duty ratio of the active bridges is accurately controlled in real time according to the magnitude of the bias current to ensure the volt second balance of the high frequency transformer windings. Thus the magnetic saturation problem due to DC bias is effectively eliminated, and the reliability of the system is improved. Finally, the simulation results verify the correctness and feasibility of the proposed control method.
author_names: Bingxin Jia

Chunshui Du

Chaochao Song

Jiaben Lin

Qiong Liu
title: DC Bias Suppression Strategy in Dual Active Bridge Based on Triple Phase Shift Control
venue: 2018 Chinese Automation Congress (CAC)
year: 2018

abstract: The minimum current stress model based on Dual active bridge (DAB) DC DC converter is adopted, which is the independent variable of power transmission. In this paper, the phenomenon of dc bias caused by the sudden change of transmission power is analyzed, and the improvement scheme based on extended phase shift control method is proposed. Through changing the corresponding phase shift duty ratio and switch sequence, this method can eliminate the dc bias phenomenon in half a switching cycle and reach the steady state quickly. In the end, the proposed scheme is verified and compared with the traditional method through simulation experiment based on Matlab2017a/Simulink platform. Simulation results show that the transient current improvement scheme for the change of transmission power can obtain faster dynamic response speed, and has less losses, which improves the transmission efficiency.
author_names: Zhao Zhang

Jiazheng Sun

Panfeng Wang

Zhiyang Cai

Jianhong Kong

Xue Bai

Dazhong Ma
title: An Improved DC Bias Elimination Strategy with Extended Phase Shift Control for Dual Active Bridge DC DC
venue: 2019 Chinese Automation Congress (CAC)
year: 2019

abstract: A transient dc bias current due to the voltage second imbalance of isolated bidirectional dual active bridge (DAB) converters for the disturbance in line or load may result in the transformer saturation and oscillations in both sides dc currents. This article focuses on the transient dc bias current elimination by using an improved triple phase shift (ITPS) control for DAB converters. The inductor peak current stress optimization is adopted in the proposed ITPS to determine the steady state phase shift variables. Originated from the dc bias current model of DAB converters with the TPS control, the transient phase shift adjustment strategy can be determined, which has the ability to improve the inductor current changing slope and shorten the settling time. Both simulation and experiments for different conditions are provided to evaluate main dynamic indexes such as the transient period, dc bias current, and inductor current stress for three different transition cases. The proposed ITPS is proved as a promising solution in eliminating the dc bias current, minimizing the transient current stress.
author_names: Qinglei Bu

Huiqing Wen

Jia-cheng Wen

Yihua Hu

Yang Du
title: Transient DC Bias Elimination of Dual Active Bridge DC DC Converter With Improved Triple Phase Shift Control
venue: IEEE Transactions on Industrial Electronics
year: 2020

abstract: A kind of fast transient current control (FTCC) method for dual active bridge (DAB) dc dc converters based on triple phase shift (TPS) control strategy is proposed in this paper to suppression the transformer DC bias when the power instruction or the load changes suddenly. The proposed control method brings the benefit of dynamic performance during bidirectional operation, which can achieve new steady state for inductor current, remove dc bias in the isolation transformer effectively within several cycles hence preventing transformer saturation. To analyze both steady and dynamic performance of the DAB converter by using the superposition theorem. According to the results of transient inductance current analysis, a dynamic control approach is proposed to limit the current transient interval in one switching period. Finally, the theoretical analysis is verified by experiments.
author_names: Jinghui Xu

Yue Wang

Kai Li

Xiufang Hu

Shiyuan Yin

Rui Li

Chunhui Lv
title: Fast Transient Current Control for Dual Active Bridge DC DC Converters with Triple Phase Shift
venue: 2019 IEEE Applied Power Electronics Conference and Exposition (APEC)
year: 2019

abstract: Cooperative triple phase shift (CTPS) control for dual active bridge DC DC converter has the advantages of eliminating the dual DC sides flow back currents, minimizing the root mean square value of the inductor current and greatly improves the current characteristics. In this paper, the effect of the transient actions on CTPS is originally analyzed and the corresponding solution based on is proposed. When the sudden change of the three phase shifts occurs, the switching moments of the control signals of the power switches are recalculated considering the old and new values of the three phase shifts together to eliminate the transient DC bias currents and flow back currents. Detailed experimental results verify the theoretical analysis and proposed solutions.
author_names: Jianyong Su

Suhua Luo

Fengjiang Wu
title: Improvement on Transient Performance of Cooperative Triple Phase Shift Control for Dual Active Bridge DC DC Converter
venue: 2019 IEEE Energy Conversion Congress and Exposition (ECCE)
year: 2019

abstract: In this paper we introduce a novel closed loop hybrid phase shift control for a dual active bridge converter with variable input voltage. By keeping an inductor between the transformer middle tap and the midpoint of two split capacitors in DAB topology, this paper proposes an adjusted DAB converter for input applications. A closed loop HPS control plot is proposed to permit all power changes to get ZVS over the full working extent; accordingly, fundamentally limiting the losses and lightening electromagnetic interference. In addition, the proposed control plot does not fundamentally build the conduction losses in correlation with the expanded EPS control. In this way, the modified DAB can work efficiently. The topology deduction are first known. At that point, the EPS and TPS regulations are connected, and the comparing working standards and qualities, including the switching, power transfer, and root mean square current, are investigated in detail with the help of MATLAB Simulink software with complete results with dynamic response.
author_names: D Sai Spandana

Sriram Narasimha
title: A Closed Loop Hybrid Phase Shift Controlled Dual Active Bridge Converter with Dynamic Input Voltage Change
year: 2017

abstract: The three phase dual active bridge converter is a promising topology for the high power high frequency dc dc conversion, due to the soft switching capability and inherent galvanic isolation. With the state of the art instantaneous current control (ICC) based on the single phase shift (SPS) operation, a bidirectional power flow can be controlled dynamically between two dc ports without inducing overshoots in the transformer currents. However, a transient dc bias flux may still occur in the transformer, which may cause the transformer core saturation in the dynamic operation such as start up, power off, and abrupt load changes. To analyze and address this issue, this paper presents a set of model based methods to avoid inducing the dc bias flux in various transient situations. The proposed double side SPS operation could nullify the dc bias flux in abrupt load changes and even instant power flow reversals. Furthermore, the soft magnetizing and soft demagnetizing techniques are presented to eliminate the initial and residual dc bias flux during start up and power off instantly. The proposed flux control method can be integrated with the ICC. Thus, the transformer magnetizing flux and the winding currents can be controlled simultaneously and instantaneously in transient situations. Simulations and experiments on a down scaled hardware prototype validate the effectiveness of the proposed methods.
author_names: Jingxin Hu

Shenghui Cui

Sihan Wang

Rik W De Doncker
title: Instantaneous Flux and Current Control for a Three Phase Dual Active Bridge DC DC Converter
venue: IEEE Transactions on Power Electronics
year: 2020

abstract: Power electronics based medium voltage direct current (MVdc) microgrids consist of several interconnected feedback controlled switching converters. Such systems experience bus voltage stability challenges owing to the negative incremental resistance of constant power loads and converter control loop interactions. To tackle the stability challenges, this paper presents the application of the interconnection and damping assignment passivity based control (IDA PBC) approach to the port controlled Hamiltonian model of dual active bridge (DAB) source side converters in an MVdc microgrid. For the DABs, a fundamental average model approach considering phase shift modulation is provided and used for deriving the corresponding IDA PBC control law. We analyze the effectiveness of the controller on large signal scenarios considering disturbances such as load step up, and DAB disconnection. Hardware in the Loop experiments using Opal RT and Labview field programmable gate arrays (FPGAs) as well as, low power prototype tests are carried out to demonstrate the validity and feasibility of the proposed approach.
author_names: Marco Cupelli

Sriram Karthik Gurumurthy

Siddharth Kiranbhai Bhanderi

Zhiqing Yang

Philipp Joebges

Antonello Monti

Rik W De Doncker
title: Port Controlled Hamiltonian Modeling and IDA PBC Control of Dual Active Bridge Converters for DC Microgrids
venue: IEEE Transactions on Industrial Electronics
year: 2019

abstract: A new and simple DC bias elimination technique for a Dual Active Bridge DC/DC converter is proposed in this paper. The principle is to make the positive and negative volt seconds of the magnetizing inductance balance when the phase shift changes. This can be done with minimum disruption on the overall control system by some minor modifications on the setting of the PWM modules of the digital signal processor. Thanks to the technique, the DC bias is completely eliminated. Besides, the system dynamics is much improved.
author_names: Duy-Dinh Nguyen

Kazuto Yukita

Goro Fujita

Minh C Ta
title: A simple DC bias elimination technique for Dual Active Bridge DC/DC converters
venue: 2019 10th International Conference on Power Electronics and ECCE Asia (ICPE 2019 ECCE Asia)
year: 2019