Query: A medium voltage  bidirectional  DC-DC  converter  combining  resonant  and  dual  active  bridge  converters

Candidate papers:

abstract: In this paper, an isolated bidirectional dc dc converter for medium voltage application is proposed. It combines the resonant converter and dual active bridge converter (DAB) Under normal load condition, this isolated converter operates at resonant point to achieve zero voltage (ZVS) turn on at primary side and zero current (ZCS) turn off at secondary side. When over current happens, the voltage across the resonant capacitor will be clamped by paralleled diode and the converter will automatically switch to resonant and DAB mixed operation mode, therefore cycle by cycle over current protection is achieved with constant switching frequency. Different operation modes are analyzed for the proposed circuits using time domain waveform and state trajectory. Detailed theoretical analysis and design procedure for transformer, resonant tank and semiconductor devices are discussed. Performance of the proposed circuit is verified by a 3 kV to 200 V, 2.5 kW experimental prototype with high voltage SiC devices.
author_names: Li Wang

Qianlai Zhu

Yu Wensong

Alex Q Huang
title: A medium voltage bidirectional DC DC converter combining resonant and dual active bridge converters
venue: 2015 IEEE Applied Power Electronics Conference and Exposition (APEC)
year: 2015

abstract: the DC DC converter which is capable of transferring the power in both the directions is proposed. The existing system has the DC DC converter based on immittance network is proposed which is acting as filter and to achieve unity power factor. This immittance network is helpful to attain the resonant condition. It is making the system complex and the efficiency of the system is decreased. To overcome this proposed system has the resonant and dual active bridge converter. It produces the resonant condition by the system configuration. It works in normal as well as over current operation. In the normal operation, the converter carries out the resonant condition by the soft switching techniques such as ZVS and ZCS, attained by frequency control. In the over current operation, the diode conducts the electric current in only one direction and prevents exceeding the reference value and across the capacitor. This is used to protect the circuit from over current. It is functioning partly as resonant converter and partly as dual active bridge converter with the constant switching frequency. Thus over current protection is afforded by the diode clamping and the power flow analysis is done by the boost and buck modes using the simulation software PLEXIM. Keywordsimmittance network (IMN) dual active bridge (DAB) zero voltage (ZVS) and current switching (ZCS) resonant converter, isolated bidirectional converter
author_names: K Palanivelrajan

K C Karthika
title: A Medium Voltage Bidirectional Dual Active Bridge Resonant DC DC Converter
year: 2016

abstract: Dual active bridge (DAB) DC/DC converter is an ideal high power bidirectional DC/DC converter with multiple control methods. In this paper, the working characteristics of the DAB converters are analysed by the example of medium power mode, in which the voltage transfer ratio is less than 1. For the situation that the DAB converter is difficult to achieve soft switching at light load, a triple phase shift (TPS) control method is used. Combining with RMS current optimisation, a control method to achieve soft switching for full power range is proposed. The control strategy enables the converter to realise zero voltage switching (ZVS) of all the switching device, which not only improves the operating conditions of the switching device, but also improves the converter efficiency. Finally, a prototype of DAB was built. Compared with the traditional control method, the experimental results verify the effectiveness of the proposed control strategy.
author_names: Kai Shen

Anping Tong

Chi Shao

Lijun Hang

Yuanbin He

Yao Zhang

Guojie Li

Jianmin Zhang
title: ZVS Control strategy of dual active bridge DC/DC converter with triple phase shift modulation considering RMS current optimization
venue: The Journal of Engineering
year: 2019

abstract: The dual active bridge (DAB) converter is widely used in different fields, such as electric vehicles, distributed power generation system, energy networks. it also can be introduced in railway applications to implement power electronic transformers, bidirectional battery chargers etc. The DAB converter is usually designed combining with series resonant to reduce the switching off loss. Nevertheless this will make it hard to achieve the zero voltage switching on of the primary power semiconductor at light load, especially when voltage conversion ratio is far away from one. Besides, the dead time has great effect to the soft switching implementation. The voltage polarity reversal and voltage sag phenomena etc. are caused by the dead time effect. This paper provides a precise mathematical transmission power model considering the resonant and dead time effect respectively. A comprehensive theoretical analysis of the dead time effect on the series resonant DAB converter is presented. By improving the dead time, the soft switching rang is increased and the efficiency will be improved at light load. The experimental results are provided to verify the theoretical analysis.
author_names: Feng-wu Zhou

Xiaoyong Zhang

Peinan Rao

Qing Zhang

Jinzhou Cao

Pan Luo
title: Dead Time Effect and Efficiency Improvement of the High Power Dual Active Bridge DC DC Converter with Series Resonant
venue: 2019 IEEE Vehicle Power and Propulsion Conference (VPPC)
year: 2019

abstract: This paper proposes a practical model for the DC DC stage of solid state transformer (SST) focusing on analysis and modeling for modular Dual Active Bridge (DAB) The proposed converter topology is based on cascaded H bridge to handle the high voltage conditions. The multi limb core (MLC) medium/high frequency transformer has been introduced to realize galvanic isolation. Synchronized half duty cycle switching method is applied to every H bridge and relative DC voltage value is controlled to manipulate the power flow. LC symmetrical resonant network has been used to improve the converter performance. Simulation and experimental results are also presented for verification.
author_names: Umar Khalid

Muhammad Mansoor Khan

Zihang Xiang

Yu Jianyang
title: Bidirectional modular Dual Active Bridge (DAB) converter using multi limb core transformer with symmetrical LC series resonant tank based on cascaded converters in solid state transformer (SST)
venue: 2017 China International Electrical and Energy Conference (CIEEC)
year: 2017

abstract: In this paper, a novel isolated dc dc converter topology for medium voltage (MV) applications is proposed by combining the advantages of resonant converters and dual active bridge (DAB) converters. In normal load scenario, this converter operates in an open loop resonant mode with a fixed switching frequency equals to the resonant frequency of the series resonant tank. Thus, zero voltage turn on at primary side and zero current turn off at secondary side are secured from zero to full load. When overload happens, the resonant capacitors will be clamped to the output voltage by the additional paralleled diodes. The proposed converter automatically switches to resonant and DAB mixed operation mode; therefore, the resonant current is naturedly limited. With zero to full load range soft switching and fast overload protection, the proposed topology is especially suitable for MV medium frequency applications utilizing high voltage SiC MOSFETs. The converter operation modes are analyzed using time domain waveforms and graphical state trajectory to derive the quantitative relationship between duty cycle, output voltage, and the overload current. Based on these relationships, a predictive duty cycle control is proposed to further limit the overload current of the resonant tank by sensing the output voltage. Combing the proposed topology and the predictive control, cycle by cycle overload and short circuit protections are achieved. To fully utilize the capability of the 15 kV SiC MOSFET, magnetizing inductance, dead time, MV transformer, and resonant components are optimized with the operating range of 6 12 kV and 20 100 kHz. An experimental prototype running at 6 kV and 40 kHz is successfully tested with peak efficiency exceeding 98% Test waveforms at no load and 10 kW full load validate the zero to full load range soft switching capability. Short circuit protection test demonstrates a 25 \mu \text{s} overload protection speed.
author_names: Li Wang

Qianlai Zhu

Wensong Yu

Alex Q Huang
title: A Medium Voltage Medium Frequency Isolated DC DC Converter Based on 15 kV SiC MOSFETs
venue: IEEE Journal of Emerging and Selected Topics in Power Electronics
year: 2017

abstract: The extensive use of electric vehicles (EVs) needs ultra fast charging stations with high charging power greater than 22 kW (PCharging >22kW) Medium voltage direct current (MVDC) grids can provide the best solution for the high demand of EVs and fast charging stations infrastructures with the existing distribution grids. The resonant bidirectional dual active bridge (DAB) DC DC converter can be a promising technology in integrating an electric vehicle charging station (EVCS) with MVDC grid. This work focuses on the converter design with voltage control and stability by applying two different control strategies mainly: PI control and sliding mode control (SMC) All simulations will be performed in order to present the feasibility of the proposed solution and compare the results of each control methods. This comparison, for the first time, in the medium voltage level can open new insights for using nonlinear control methods such as SMC to ensure stability and obtain better dynamic performance
author_names: Ibrahim Alhurayyis

Ahmad Elkhateb

D John Morrow
title: Bidirectional DC DC Resonant Converter Design for Electric Vehicle Charging Stations Integration to MVDC Grids
venue: 2020 9th International Conference on Renewable Energy Research and Application (ICRERA)
year: 2020

abstract: Soft switching techniques are very attractive and often mandatory requirements in medium voltage and medium frequency applications such as solid state transformers. The effectiveness of these soft switching techniques is tightly related to the dynamic behavior of the internal stored charge in the utilized semiconductor devices. For this reason, this paper analyzes the behavior of the internal charge dynamics in high voltage semiconductors, giving a clear base to understand the previously proposed zero current switching techniques for IGBT based resonant dual active bridges. From these previous approaches, the two main concepts that allow switching loss reduction in high voltage semiconductors are identified: 1) shaping of the conducted current in order to achieve a high recombination time in the previously conducting semiconductors and 2) achieving ZVS in the turning on device. The means to implement these techniques in a triangular current mode dual active bridge converter together with the benefits of the proposed approaches are analyzed and experimentally verified with a 1:7 kV IGBT based NPC bridge. Additionally, the impact of the modified currents in the converter's performance are quantified in order to determine the benefits of the introduced concepts in the overall converter.
author_names: Gabriel Ortiz

Dominik Bortis

Johann Walter Kolar

Oscar Apeldoorn
title: Soft switching techniques for medium voltage isolated bidirectional DC/DC converters in solid state transformers
venue: IECON 2012 38th Annual Conference on IEEE Industrial Electronics Society
year: 2012

abstract: DC DC converter plays an important role in high voltage direct current (HVDC) transmission and medium voltage DC (MVDC) distribution system. Dual active bridge topology with modular multilevel converter (DAB MMC) is a preferred choice due to the small transformer size and high voltage handling ability. However, DAB MMC cannot achieve soft switching over entire load conditions. Meanwhile, the traditional LLC resonant converter, which is widely used for low voltage application, features inherent ZVS soft switching because of the resonant network. Combine the DAB MMC and traditional LLC resonant converter, this paper proposes a LLC resonant converter with MMC structure (LLC MMC) The pulse frequency modulation (PFM) method with quasi square wave is utilized to achieve low dv/dt stress. Besides, capacitor voltage balance control strategy executed in dead time is proposed to maintain the balance. LLC MMC guarantees full ZVS soft switching over a wide load resistance range. Finally, the proposed modulation method and balance strategy are verified by the sufficient simulation and experimental results.
author_names: Z P Lu

Lei Lin

Xuehua Wang

Chen Xu
title: LLC MMC Resonant DC DC Converter: Modulation Method and Capacitor Voltage Balance Control Strategy
venue: 2020 IEEE Applied Power Electronics Conference and Exposition (APEC)
year: 2020

abstract: The Dual Active Bridge appears as a promising DC DC converter topology when galvanic isolation and bidirectional power flow are required. Among its advantages, Zero Voltage Switching allows the switching losses to be significantly reduced. For high power applications, the three phase topology variant may be interesting in order to reach a higher power density, especially when a three phase transformer is implemented instead of three single phase transformers. Moreover, the transformer vector group offers a new degree of freedom for the designers. In this paper, the authors present the experimental validation of a 1.2 kV 100 kW 20 kHz three phase Dual Active Bridge converter using two medium frequency transformers and different vector groups.
author_names: Thomas Lagier

Piotr Dworakowski

Cyril Buttay

Philippe Ladoux

Andrzej Wilk

Philippe Camail

Elissa Cresenta Anak Justin
title: Experimental validation and comparison of a SiC MOSFET based 100 kW 1.2 kV 20 kHz three phase dual active bridge converter using two vector groups
venue: 2020 22nd European Conference on Power Electronics and Applications (EPE'20 ECCE Europe)
year: 2020